Heavy Vehicle Automatic Emergency Braking; AEB Test Devices, 43174-43246 [2023-13622]
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Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 / Proposed Rules
DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety
Administration
49 CFR Parts 571 and 596
[Docket No. NHTSA–2023–0023]
Federal Motor Carrier Safety
Administration
49 CFR Parts 393 and 396
[Docket No. FMCSA–2022–0171]
RIN 2126–AC49
Heavy Vehicle Automatic Emergency
Braking; AEB Test Devices
National Highway Traffic
Safety Administration (NHTSA),
Federal Motor Carrier Safety
Administration (FMCSA), Department
of Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
This NPRM proposes to adopt
a new Federal Motor Vehicle Safety
Standard (FMVSS) to require automatic
emergency braking (AEB) systems on
heavy vehicles, i.e., vehicles with a
gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds). This
notice also proposes to amend FMVSS
No. 136 to require nearly all heavy
vehicles to have an electronic stability
control system that meets the equipment
requirements, general system
operational capability requirements, and
malfunction detection requirements of
FMVSS No. 136. An AEB system uses
multiple sensor technologies and subsystems that work together to sense
when the vehicle is in a crash imminent
situation and automatically applies the
vehicle brakes if the driver has not done
so or automatically applies more
braking force to supplement the driver’s
applied braking. This NPRM follows
NHTSA’s 2015 grant of a petition for
rulemaking from the Truck Safety
Coalition, the Center for Auto Safety,
Advocates for Highway and Auto Safety
and Road Safe America, requesting that
NHTSA establish a safety standard to
require AEB on certain heavy vehicles.
This NPRM also responds to a mandate
under the Bipartisan Infrastructure Law,
as enacted as the Infrastructure
Investment and Jobs Act, directing the
Department to prescribe an FMVSS that
requires heavy commercial vehicles
with FMVSS-required electronic
stability control systems to be equipped
with an AEB system, and also promotes
DOT’s January 2022 National Roadway
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SUMMARY:
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Comments must be received on
or before September 5, 2023.
Proposed compliance dates: NHTSA
proposes a two-tiered phase-in schedule
for meeting the proposed standard. For
vehicles currently subject to FMVSS No.
136, ‘‘Electronic stability control
systems for heavy vehicles,’’ any vehicle
manufactured on or after the first
September 1 that is three years after the
date of publication of the final rule
would be required to meet the proposed
heavy vehicle AEB standard. For
vehicles with a gross vehicle weight
rating greater than 4,536 kilograms
(10,000 pounds) not currently subject to
FMVSS No. 136, any vehicle
manufactured on or after the first
September 1 that is four years after the
date of publication of the final rule
would be required to meet the proposed
AEB requirements and the proposed
amendments to the ESC requirements.
Small-volume manufacturers, final-stage
manufacturers, and alterers would be
provided an additional year to comply
with this proposal beyond the dates
identified above.
FMCSA proposes that vehicles
currently subject to FMVSS No. 136
would be required to comply with
FMCSA’s proposed ESC regulation on
the final rule’s effective date. Vehicles
with a GVWR greater than 4,536
kilograms (10,000 pounds) not currently
subject to FMVSS No. 136 would be
required to meet the proposed ESC
regulation on or after the first September
1 that is five years after the date of
publication of the final rule.
FMCSA proposes that, for vehicles
currently subject to FMVSS No. 136,
any vehicle manufactured on or after the
first September 1 that is three years after
the date of publication of the final rule
would be required to meet FMCSA’s
proposed AEB regulation. FMCSA
proposes that vehicles with a gross
vehicle weight rating greater than 4,536
kilograms (10,000 pounds) not currently
subject to FMVSS No. 136 and vehicles
supplied to motor carriers by smallvolume manufacturers, final-stage
manufacturers, and alterers would be
required to meet the proposed AEB
regulation on or after the first September
1 that is five years after the date of
publication of the final rule.
This proposed implementation
timeframe simplifies FMCSR training
and enforcement because the Agency
DATES:
RIN 2127–AM36
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Safety Strategy to initiate a rulemaking
to require AEB on heavy trucks. This
NPRM also proposes Federal Motor
Carrier Safety Regulations requiring the
electronic stability control and AEB
systems to be on during vehicle
operation.
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expects a large number of final stage
manufacturers supplying vehicles to
motor carriers in the category of
vehicles with a gross vehicle weight
rating greater than 4,536 kilograms
(10,000 pounds).
FMCSA’s phase-in schedule would
require the ESC and AEB systems to be
inspected and maintained in accordance
with § 396.3.
Early compliance is permitted but
optional.
You may submit comments
to the docket number identified in the
heading of this document by any of the
following methods:
• Federal eRulemaking Portal: Go to
https://www.regulations.gov. Follow the
online instructions for submitting
comments.
• Mail: Docket Management Facility,
M–30, U.S. Department of
Transportation, West Building, Ground
Floor, Rm. W12–140, 1200 New Jersey
Avenue SE, Washington, DC 20590.
• Hand Delivery or Courier: West
Building, Ground Floor, Room W12–
140, 1200 New Jersey Avenue SE,
between 9 a.m. and 5 p.m. Eastern Time,
Monday through Friday, except Federal
holidays. To be sure someone is there to
help you, please call 202–366–9332
before coming.
• Fax: 202–493–2251.
Regardless of how you submit your
comments, please provide the docket
number of this document.
Instructions: For detailed instructions
on submitting comments and additional
information on the rulemaking process,
see the Public Participation heading of
the SUPPLEMENTARY INFORMATION section
of this document. Note that all
comments received will be posted
without change to https://
www.regulations.gov, including any
personal information provided.
Privacy Act: In accordance with 5
U.S.C. 553(c), DOT solicits comments
from the public to better inform its
decision-making process. DOT posts
these comments, without edit, including
any personal information the
commenter provides, to https://
www.regulations.gov, as described in
the system of records notice (DOT/ALL–
14 FDMS), which can be reviewed at
https://www.transportation.gov/privacy.
In order to facilitate comment tracking
and response, the agency encourages
commenters to provide their name, or
the name of their organization; however,
submission of names is completely
optional. Whether or not commenters
identify themselves, all timely
comments will be fully considered.
Docket: For access to the docket to
read background documents or
ADDRESSES:
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Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 / Proposed Rules
comments received, go to https://
www.regulations.gov, or the street
address listed above. To be sure
someone is there to help you, please call
202–366–9322 before coming. Follow
the online instructions for accessing the
dockets.
FOR FURTHER INFORMATION CONTACT:
NHTSA: For non-legal issues: Hisham
Mohamed, Office of Crash Avoidance
Standards (telephone: 202–366–0307).
For legal issues: David Jasinski, Office of
the Chief Counsel (telephone: 202–366–
2992, fax: 202–366–3820). The mailing
address for these officials is: National
Highway Traffic Safety Administration,
1200 New Jersey Avenue SE,
Washington, DC 20590. FMCSA: For
FMCSA issues: David Sutula, Office of
Vehicle and Roadside Operations
Division (telephone: 202–366–9209).
The mailing address for this official is:
Federal Motor Carrier Safety
Administration, 1200 New Jersey
Avenue SE, Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Safety Problem
III. Efforts To Promote AEB Deployment in
Heavy Vehicles
A. NHTSA’s Foundational AEB Research
B. NHTSA’s 2015 Grant of a Petition for
Rulemaking
C. Congressional Interest
1. MAP–21
2. Bipartisan Infrastructure Law
D. IIHS Effectiveness Study
E. DOT’s National Roadway Safety Strategy
(January 2022)
F. National Transportation Safety Board
Recommendations
G. FMCSA Initiatives
IV. NHTSA and FMCSA Research and
Testing
A. NHTSA-Sponsored Research
1. 2012 Study on Effectiveness of FCW and
AEB
2. 2016 Field Study
3. 2017 Target Population Study
4. 2018 Cost and Weight Analysis
B. VRTC Research Report Summaries and
Test Track Data
1. Relevance of Research Efforts on AEB for
Light Vehicles
2. Phase I Testing of Class 8 Truck-Tractors
and Motorcoach
3. Phase II Testing of Class 8 TruckTractors
4. NHTSA’s 2018 Heavy Vehicle AEB
Testing
5. NHTSA’s Research Test Track
Procedures
6. 2021 VRTC Testing
C. NHTSA Field Study of a New
Generation Heavy Vehicle AEB System
D. FMCSA-Sponsored Research
V. Need for This Proposed Rule and Guiding
Principles
A. Estimating AEB System Effectiveness
B. AEB Performance Over a Range of
Speeds Is Necessary and Practicable
C. Market Penetration Varies Significantly
Among Classes of Heavy Vehicles
D. This NPRM Would Compel
Improvements in AEB
E. BIL Section 23010(b)(2)(B)
F. Vehicles Excluded From Braking
Requirements
VI. Heavy Vehicles Not Currently Subject to
ESC Requirements
A. AEB and ESC Are Less Available on
These Vehicles
B. This NPRM Proposes To Require ESC
C. BIL Section 23010(d)
D. Multi-Stage Vehicle Manufacturers and
Alterers
VII. Proposed Performance Requirements
A. Proposed Requirements When
Approaching a Lead Vehicle
1. Automatic Emergency Brake Application
Requirements
2. Forward Collision Warning Requirement
i. FCW Modalities
ii. FCW Auditory Signal Characteristics
iii. FCW Visual Signal Characteristics
iv. FCW Haptic Signal Discussion
3. Performance Test Requirements
4. Performance Test Scenarios
i. Stopped Lead Vehicle
ii. Slower-Moving Lead Vehicle
iii. Decelerating Lead Vehicle
5. Parameters for Vehicle Tests
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i. Vehicle Speed Parameters
ii. Headway
iii. Lead Vehicle Deceleration Parameter
6. Manual Brake Application in the Subject
Vehicle
B. Conditions for Vehicle Tests
1. Environmental Conditions
2. Road Service Conditions
3. Subject Vehicle Conditions
C. Proposed Requirements for False
Activation
1. No Automatic Braking Requirement
2. Vehicle Test Scenarios
i. Steel Trench Plate
ii. Pass-Through
D. Conditions for False Activation Tests
E. Potential Alternatives to False
Activation Tests
F. Proposed Requirements for Malfunction
Indication
G. Deactivation Switch
H. System Documentation
I. ESC Performance Test
J. Severability
VIII. Vehicle Test Device
A. Description and Development
B. Specifications
C. Alternatives Considered
IX. Proposed Compliance Date Schedule
X. Retrofitting
XI. Summary of Estimated Effectiveness,
Cost, Benefits, and Comparison of
Regulatory Alternatives
A. Crash Problem
B. AEB System Effectiveness
C. ESC System Effectiveness
D. Avoided Crashes and Related Benefits
E. Technology Costs
F. Monetized Benefits
G. Alternatives
XII. Regulatory Notices and Analyses
XIII. Public Participation
XIV. Appendices to the Preamble
A. Description of Technologies
B. International Regulatory Requirements
and Other Standards
Abbreviations Frequently Used in This
Document
The following table is provided for
the convenience of readers for
illustration purposes only.
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TABLE 1—ABBREVIATIONS
Abbreviation
Full term
Notes
ABS ................
Antilock Braking System ..........
AEB ................
CIB ..................
Automatic Emergency Braking
Crash Imminent Braking ..........
CMV ................
CRSS ..............
DBS ................
Commercial Motor Vehicle ......
Crash Report Sampling System.
Dynamic Brake Support ..........
ESC ................
Electronic Stability Control ......
FARS ..............
Fatality Analysis Reporting
System.
Automatically controls the degree of longitudinal wheel slip during braking to prevent wheel
lock and minimize skidding by sensing the rate of angular rotation of each wheel and modulating the braking force at the wheels to keep the wheels from slipping.
Applies a vehicle’s brakes automatically to avoid or mitigate an impending forward crash.
Applies automatic braking when forward-looking sensors indicate a crash is imminent and the
driver has not applied the brakes.
Has the meaning given the term in 49 U.S.C. 31101.
A sample of police-reported crashes involving all types of motor vehicles, pedestrians, and
cyclists, ranging from property-damage-only crashes to those that result in fatalities.
Supplements the driver’s application of the brake pedal with additional braking when sensors
determine the driver-applied braking is insufficient to avoid an imminent crash.
Able to determine intended steering direction (steering wheel angle sensor), compare it to the
actual vehicle direction, and then modulate braking forces at each wheel to induce a
counter yaw when the vehicle starts to lose lateral stability.
A nationwide census providing annual data regarding fatal injuries suffered in motor vehicle
crashes.
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TABLE 1—ABBREVIATIONS—Continued
Abbreviation
Full term
FCW ...............
Forward Collision Warning ......
FMCSR ...........
GES ................
Federal Motor Carrier Safety
Regulations.
Federal Motor Vehicle Safety
Standards.
General Estimates System ......
GVWR ............
Gross Vehicle Weight Rating ..
BIL ..................
MAIS ...............
Bipartisan Infrastructure Law ...
Maximum Abbreviated Injury
Scale.
The Moving Ahead for
Progress in the 21st Century
Act.
New Car Assessment Program
Property-damage-only .............
FMVSS ...........
MAP–21 ..........
NCAP ..............
PDO ................
PDOV .............
TTC .................
VRTC ..............
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VTD ................
Notes
Property-Damage-Only-Vehicles.
Time to collision .......................
Vehicle Research and Test
Center.
Vehicle Test Device .................
An auditory and visual warning provided to the vehicle operator by the AEB system that is
designed to induce an immediate forward crash avoidance response by the vehicle operator.
49 CFR parts 350–399.
Data from a nationally representative sample of police reported motor vehicle crashes of all
types, from minor to fatal.
The value specified by the manufacturer as the maximum design loaded weight of a single
vehicle.
Public Law 117–58 (Nov. 15, 2021).
A means of describing injury severity based on an ordinal scale. An MAIS 1 injury is a minor
injury and an MAIS 5 injury is a critical injury.
A funding and authorization bill to govern United States Federal surface transportation spending. It was enacted into law on July 6, 2012.
A police-reported crash involving a motor vehicle in transport on a trafficway in which no one
involved in the crash suffered any injuries.
Damaged vehicles involved in property-damage-only crashes.
The theoretical time, given the current speed of the vehicles, after which a rear-end collision
with the lead vehicle would occur if no corrective action was taken.
NHTSA’s in-house laboratory.
A test device used to test AEB system performance.
I. Executive Summary
There were 38,824 people killed in
motor vehicle crashes on U.S. roadways
in 2020 and early estimates put the
number of fatalities at 42,915 for 2021.1
The Department established the
National Roadway Safety Strategy in
January 2022 to address this rising
number of transportation deaths
occurring on this country’s streets,
roads, and highways.2 This NPRM takes
a crucial step in implementing this
strategy by proposing to adopt a new
Federal motor vehicle safety standard
(FMVSS) that would require heavy
vehicles to have automatic emergency
braking (AEB) systems that mitigate the
frequency and severity of rear-end
collisions with vehicles.
The crash problem addressed by
heavy vehicle AEB is substantial, as are
the safety benefits to be gained. This
NPRM addresses lead vehicle rear-end,
rollover, and loss of control crashes, and
their associated fatalities, injuries, and
property damage. The NPRM also
proposes new Federal Motor Carrier
Safety Regulations requiring the
electronic stability control and AEB
systems to be on during vehicle
operation. Considering the effectiveness
of AEB and electronic stability control
technology (ESC) at avoiding these
crashes, the proposed rule would
conservatively prevent an estimated
19,118 crashes, save 155 lives, and
reduce 8,814 non-fatal injuries annually
once all vehicles covered in this rule are
equipped with AEB and ESC. In
addition, it would eliminate 24,828
property-damage-only crashes annually.
In this NPRM, the term ‘‘heavy
vehicles’’ refers to vehicles with a gross
vehicle weight rating (GVWR) greater
than 4,536 kilograms (10,000 pounds).
For application of the FMVSS, it is often
necessary to further categorize these
heavy vehicles, as the FMVSS must be
appropriate for the particular type of
motor vehicle for which they are
prescribed.3 4 Certain vehicles have
common characteristics relevant to the
application of AEB, and categorizing
those vehicles accordingly allows for
useful analyses, proposals, or other
considerations that are particularly
appropriate for the vehicle group and
application of the safety standards.
One useful way to categorize vehicles
further is by GVWR. This NPRM uses
vehicle class numbers designed by
NHTSA in 49 CFR 565, ‘‘Vehicle
identification number requirements,’’
and the Federal Highway
Administration that are based on
GVWR.5 These class numbers, shown in
Table 2 below, are widely used by
industry and States in categorizing
vehicles. In this NPRM, ‘‘heavy vehicle’’
and ‘‘class 3 through 8’’ both refer to all
vehicles with a GVWR greater than
4,536 kg (10,000 lbs.). The term ‘‘class
3 through 6’’ refers to vehicles with a
GVWR greater than 4,536 kg (10,000
lbs.) and up to 11,793 kg (26,000 lbs.),
while the term ‘‘class 7 to 8’’ refers to
vehicles with a GVWR greater than
11,793 kg (26,000 lbs.).
1 https://crashstats.nhtsa.dot.gov/Api/Public/
ViewPublication/813266, https://crashstats.nhtsa.
dot.gov/Api/Public/ViewPublication/813283,
https://www.nhtsa.gov/press-releases/earlyestimate-2021-traffic-fatalities#:∼:text=
Preliminary%20data%20reported
%20by%20the,from%201.34%
20fatalities%20in%202020.
2 https://www.transportation.gov/sites/dot.gov/
files/2022-01/USDOT_National_Roadway_Safety_
Strategy_0.pdf. Last accessed August 23, 2022.
3 As required by 49 U.S.C 30111(b)(3), NHTSA
shall consider whether a proposed standard is
reasonable, practicable, and appropriate for the
particular type of motor vehicle or motor vehicle
equipment for which it is prescribed.
4 This NPRM excludes heavy trailers because they
typically do not have braking components
necessary for AEB.
5 See https://ops.fhwa.dot.gov/publications/
fhwahop10014/s5.htm#f21 (Last viewed on May 5,
2022).
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TABLE 2—VEHICLE CLASS BY GVWR
Vehicle class
1 ...........................................
2a .........................................
2b .........................................
3 ...........................................
4 ...........................................
5 ...........................................
6 ...........................................
7 ...........................................
8 ...........................................
GVWR
Not greater than 2,722 kg (6,000 lbs.).
Greater than 2,722 kg (6,000 lbs.) and up to 3,856 kg (8,500 lbs.).
Greater than 3,856 kg (8,500 lbs.) and up to 4,536 kg (10,000 lbs.).
Greater than 4,536 kg (10,000 lbs.) and up to 6,350 kg (14,000 lbs.).
Greater than 6,350 kg (14,000 lbs.) and up to 7,257 kg (16,000 lbs.).
Greater than 7,257 kg (16,000 lbs.) and up to 8,845 kg (19,500 lbs.).
Greater than 8,845 kg (19,500 lbs.) and up to 11,793 kg (26,000 lbs.).
Greater than 11,793 kg (26,000 lbs.) and up to 14,969 kg (33,000 lbs.).
Greater than 14,969 kg (33,000 lbs.).
NHTSA and FMCSA have jointly
developed this NPRM. Both agencies
will have complementary standards that
respond to mandates in Section 23010
of the Bipartisan Infrastructure Law
(BIL), as enacted as the Infrastructure
Investment and Jobs Act. Section
23010(b) requires the Secretary to
prescribe an FMVSS that requires any
commercial motor vehicle subject to
FMVSS No. 136, ‘‘Electronic stability
control systems for heavy vehicles,’’ to
be equipped with an AEB system
meeting performance requirements
established in the new FMVSS not later
than two years after enactment. Section
23010(c) requires the Secretary to
prescribe a Federal Motor Carrier Safety
Regulation (FMCSR) that requires, for
commercial motor vehicles subject to
FMVSS No. 136, that an AEB system
installed pursuant to the new Federal
motor vehicle safety standard must be
used at any time during which the
commercial motor vehicle is in
operation. This NPRM sets forth
NHTSA’s proposed FMVSS and
FMCSA’s proposed FMCSR issued
pursuant to these provisions of the BIL.
In order to provide the benefits of AEB
to a greater number of vehicles, this
proposal would also require that many
heavy vehicles not currently subject to
FMVSS No. 136, including vehicles in
classes 3 through 6, be equipped with
ESC and AEB systems under the
authority provided in the Motor Vehicle
Safety Act. Pursuant to section 23010(d)
of the BIL, NHTSA seeks public
comment on this proposal.
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NHTSA’s Statutory Authority
NHTSA is proposing this NPRM
under the National Traffic and Motor
Vehicle Safety Act (‘‘Motor Vehicle
Safety Act’’) and in response to the
Bipartisan Infrastructure Law. Under 49
U.S.C. Chapter 301, Motor Vehicle
Safety (49 U.S.C. 30101 et seq.), the
Secretary of Transportation is
responsible for prescribing motor
vehicle safety standards that are
practicable, meet the need for motor
vehicle safety, and are stated in
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objective terms. ‘‘Motor vehicle safety’’
is defined in the Motor Vehicle Safety
Act as ‘‘the performance of a motor
vehicle or motor vehicle equipment in
a way that protects the public against
unreasonable risk of accidents occurring
because of the design, construction, or
performance of a motor vehicle, and
against unreasonable risk of death or
injury in a crash, and includes
nonoperational safety of a motor
vehicle.’’ ‘‘Motor vehicle safety
standard’’ means a minimum
performance standard for motor vehicles
or motor vehicle equipment. When
prescribing such standards, the
Secretary must consider all relevant,
available motor vehicle safety
information. The Secretary must also
consider whether a proposed standard is
reasonable, practicable, and appropriate
for the types of motor vehicles or motor
vehicle equipment for which it is
prescribed and the extent to which the
standard will further the statutory
purpose of reducing traffic accidents
and associated deaths. The
responsibility for promulgation of
Federal motor vehicle safety standards
is delegated to NHTSA.
In developing this NPRM, NHTSA
carefully considered these statutory
requirements, and relevant Executive
Orders, Departmental Orders, and
administrative laws and procedures.
NHTSA is also issuing this NPRM in
response to the Bipartisan Infrastructure
Law. Section 23010 of BIL 6 requires the
Secretary to prescribe a Federal motor
vehicle safety standard to require all
commercial motor vehicles subject to a
particular brake system standard to be
equipped with an AEB system meeting
established performance requirements.
BIL directs the Secretary to prescribe the
standard not later than two years after
the date of enactment of the Act.
FMCSA’s Statutory Authority
For purposes of this NPRM, FMCSA’s
authority is found in the Motor Carrier
Act of 1935 (1935 Act, 49 U.S.C. 31502)
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and the Motor Carrier Safety Act of 1984
(1984 Act, 49 U.S.C. 31132 et seq.), both
as amended. The authorities assigned to
the Secretary in these two acts are
delegated to the FMCSA Administrator
in 49 CFR 1.87(i) and (f), respectively.
In addition, section 23010(c) of the BIL,
Public Law 117–58, 135 Stat. 429, 766–
767, Nov. 15, 2021, requires FMCSA to
adopt an AEB regulation consistent with
the companion NHTSA AEB regulation.
The 1935 Act authorizes the DOT to
‘‘prescribe requirements for—(1)
qualifications and maximum hours of
service of employees of and safety of
operation and equipment of a motor
carrier; and (2) qualifications and
maximum hours of service of employees
of, and standards of equipment of, a
motor private carrier, when needed to
promote safety of operations’’ (49 U.S.C.
31502(b)). FMCSA’s proposed ESC and
AEB regulations, which incorporate the
ESC and AEB requirements of the
NHTSA rule, will require most motor
carriers to maintain and use the ESC
and AEB systems required by the
corresponding NHTSA regulations to
promote safety of operations.
The 1984 Act confers on DOT the
authority to regulate drivers, motor
carriers, and vehicle equipment. ‘‘At a
minimum, the regulations shall ensure
that—(1) commercial motor vehicles are
maintained, equipped, loaded, and
operated safely; (2) the responsibilities
imposed on operators of commercial
motor vehicles do not impair their
ability to operate the vehicles safely; (3)
the physical condition of operators of
commercial motor vehicles is adequate
to enable them to operate the vehicles
safely; (4) the operation of commercial
motor vehicles does not have a
deleterious effect on the physical
condition of the operators; and (5) an
operator of a commercial motor vehicle
is not coerced by a motor carrier,
shipper, receiver, or transportation
intermediary to operate a commercial
motor vehicle in violation of a
regulation promulgated under this
section, or chapter 51 or chapter 313 of
this title’’ (49 U.S.C. 31136(a)(1)–(5)).
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FMCSA’s proposed rule will help to
ensure that commercial motor vehicles
(CMVs) equipped with the ESC and AEB
systems mandated by NHTSA are
maintained and operated safely, as
required by 49 U.S.C. 31136(a)(1). While
the FMCSA proposal does not explicitly
address the remaining provisions of
section 31136, it will enhance the
ability of drivers to operate safely,
consistent with 49 U.S.C. 31136(a)(2)–
(4).
Section 23010(c) of BIL requires
FMCSA to prescribe a regulation under
49 U.S.C. 31136 that requires that an
automatic emergency braking system
installed in a commercial motor vehicle
manufactured after the effective date of
the NHTSA standard that is in operation
on or after that date and is subject to 49
CFR 571.136 be used at any time during
which the commercial motor vehicle is
in operation’’ (135 Stat. 767). Consistent
with the BIL mandate, part of FMCSA’s
proposal would require that motor
carriers operating CMVs manufactured
subject to FMVSS No. 136 maintain and
use the required AEB devices as
prescribed by NHTSA whenever the
CMV is operating.
AEB and ESC Systems
An AEB system employs multiple
sensor technologies and sub-systems
that work together to sense when a
vehicle is in a crash imminent situation
with a lead vehicle and, when
necessary, automatically apply the
vehicle brakes if the driver has not done
so, or apply the brakes to supplement
the driver’s applied braking. Current
systems use radar and camera-based
sensors or combinations thereof. AEB
builds upon older forward collision
warning-only systems. An FCW-only
system provides an alert to a driver of
an impending rear-end collision with a
lead vehicle to induce the driver to take
action to avoid the crash but does not
automatically apply the brakes. This
proposal would require both FCW and
AEB systems. For simplicity, when
referring to AEB systems in general, this
proposal is referring to both FCW and
AEB unless the context suggests
otherwise.
This proposal follows up on NHTSA’s
October 16, 2015 notice granting a
petition for rulemaking submitted by the
Truck Safety Coalition, the Center for
Auto Safety, Advocates for Highway and
Auto Safety, and Road Safe America.7
The petitioners requested that NHTSA
establish a safety standard to require
automatic forward collision avoidance
and mitigation systems on heavy
vehicles. This rulemaking also
7 80
8 These rear-end crashes are cases where the
heavy vehicle was the striking vehicle.
FR 62487.
VerDate Sep<11>2014
addresses recommendations made to
NHTSA by the National Transportation
Safety Board.
The safety problem addressed by AEB
is substantial. An annualized average of
2017 to 2019 data from NHTSA’s
Fatality Analysis Reporting System
(FARS) and the Crash Report Sampling
System (CRSS) shows that heavy
vehicles are involved in around 60,000
rear-end crashes in which the heavy
vehicle was the striking vehicle
annually, which represents 11 percent
of all crashes involving heavy vehicles.8
These rear-end crashes resulted in 388
fatalities annually, which comprises 7.4
percent of all fatalities in heavy vehicle
crashes. These crashes resulted in
approximately 30,000 injuries annually,
or 14.4 percent of all injuries in heavy
vehicle crashes, and 84,000 damaged
vehicles with no injuries or fatalities.
Considering vehicle size,
approximately half of the rear-end
crashes, injuries, and fatalities resulting
from rear-end crashes where the heavy
vehicle was the striking vehicle
involved vehicles with a gross vehicle
weight rating above 4,536 kilograms
(10,000 pounds) up to 11,793 kilograms
(26,000 pounds). Similarly, half of all
rear-end crashes and the fatalities and
injuries resulting from those crashes
where the heavy vehicle was the
striking vehicle involved vehicles with
a gross vehicle weight rating of greater
than 11.793 kilograms (26,000 pounds).
The speed of the striking vehicle is an
important factor in the severity of a
crash. For example, in approximately 53
percent of crashes, the striking vehicle
was traveling at or under 30 mph (47
km/h). Those crashes, though, were
responsible for only approximately 1
percent of fatalities. In contrast, in
approximately 17 percent of crashes, the
striking vehicle was traveling over 55
mph (89 km/h). Those crashes resulted
in 89 percent of the fatalities from rearend crashes involving heavy vehicles.
While the majority of crashes occur at
low speeds, the overwhelming majority
of fatalities result from high-speed
crashes. For AEB systems to address this
safety problem, they must function at
both low and high speeds.
NHTSA has been studying AEB
technologies since their conception over
15 years ago. NHTSA and FMCSA have
recognized the potential of heavy
vehicle AEB for many years and
continued to research this technology as
it evolved from early generations to its
current state. As part of NHTSA’s efforts
to better understand these new collision
prevention technologies, NHTSA
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sponsored and conducted numerous
research projects, including ones
focused on AEB and FCW for heavy
trucks. NHTSA conducted testing at its
in-house testing facility, the Vehicle
Research and Test Center, to examine
the effectiveness of AEB in different
crash scenarios and speeds. NHTSA and
FMCSA have also sponsored or
conducted projects with a specific focus
on the heavy vehicle rear-end crash
problem.
International standards for the
regulation of AEB systems on heavy
vehicles exist and are under
development. The European Union and
Asian countries have either already
adopted or are considering AEB
regulations for heavy vehicles. More
information can be found in Appendix
A of this document.
In 2016, NHTSA published its first
report of track testing of heavy vehicles
equipped with AEB systems. NHTSA
used its light vehicle test procedures,
similar to those used in NHTSA’s New
Car Assessment Program,9 as a
framework to adapt for use on heavy
vehicles. These scenarios included a
stopped lead vehicle scenario, a slower
moving lead vehicle scenario, a
decelerating lead vehicle scenario, and
a false positive scenario that consisted
of driving over a steel trench plate.
NHTSA’s initial testing of AEB systems
focused on vehicles equipped with
ESC—primarily Class 8 truck tractors
and motorcoaches. Adjustments had to
be made to the scenarios to account for
the greater stopping distances of heavy
vehicles compared to light vehicles and
to the surrogate vehicle and towing
device to ensure that the systems
performed as they would on the road.
Testing of early heavy vehicle systems
indicated that vehicles did not
automatically brake when encountering
a stopped lead vehicle. The false
positive test also resulted in FCW alerts,
but no automatic braking.
Later testing was intended to evaluate
the evolution of AEB systems, to further
refine the test procedures, and to test
other vehicle types such as single-unit
trucks and class 3 through 6 vehicles.
Newer FCW and AEB systems on heavy
vehicles generally performed better than
older versions. Testing of these updated
systems exhibited less severe rear-end
collisions through velocity reductions
before a collision or avoided contact
with a lead vehicle entirely. The refined
test procedures addressed previous
9 NHTSA’s New Car Assessment Program (NCAP)
provides comparative information on the safety
performance of new vehicles to assist consumers
with vehicle purchasing decisions and to encourage
safety improvements.
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issues with timing, range parameters,
and the vehicle test device.
NHTSA’s most recent testing of a
2021 Freightliner Cascadia, a class 8
truck tractor, indicated that the AEB
system was able to prevent a collision
with a lead vehicle at speeds between
40 km/h and 85 km/h. Collisions
occurred with the lead vehicle at lower
speeds, although significant speed
reductions were still achieved. This
suggests that collision avoidance at
lower speed cannot necessarily be
extrapolated to performance outcomes
at higher speed and may depend on the
specific ways AEB systems may be
programmed. It also indicates that AEB
systems that prevent collisions at higher
speeds are practicable.
NHTSA and FMCSA studies have also
examined system availability across all
types of heavy vehicles. Across larger
(class 7 and 8) air braked truck tractors
and motorcoaches, AEB systems are
widely available. A market analysis of
class 3 through 6 heavy vehicles showed
that nearly all manufacturers had at
least one vehicle model within each
class available with AEB. Two
manufacturers had AEB advertised as
standard equipment on at least one
model. All vehicles that were offered
with AEB systems were also equipped
with ESC systems. A few models that
offered FCW-only systems (not capable
of automatic brake application) did so
without also having ESC.
Based on these factors, and consistent
with the Motor Vehicle Safety Act and
the BIL, NHTSA is proposing a new
FMVSS that would require nearly all
heavy vehicles to be equipped with AEB
systems.10 Furthermore, FMCSA is
proposing that all commercial vehicles
equipped with ESC and AEB systems
required by NHTSA’s proposed rule be
used any time the commercial vehicle is
in operation. NHTSA is further
proposing minimum performance
criteria for AEB systems to meet the
need for safety. These performance
criteria would ensure that AEB systems
function at a wide range of speeds that
address the safety problem associated
with rear-end crashes, injuries, and
fatalities.
Based on NHTSA’s survey of publicly
available data on ESC and AEB system
availability, all manufacturers that have
equipped vehicles with AEB systems
(other than FCW-only systems) have
done so only if the vehicle is also
equipped with an ESC system.
Furthermore, NHTSA has consulted
10 The vehicles excluded from this proposal
include trailers, which by definition, are towed by
other vehicles, and vehicles already excluded from
NHTSA’s braking requirements. For details, see
section V.F.
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with two AEB system manufacturers for
heavy vehicles and both indicated that
they would equip vehicles with AEB
only if they were also equipped with
ESC.11 An ESC system provides stability
under braking by using differential
braking and engine torque reduction to
reduce lateral instability that could
induce rollover or loss of directional
control. An ABS system also provides
lateral stability under braking. ABS
systems are currently required on all
vehicles subject to this proposal under
FMVSS Nos. 105 and 121. However, the
absence of any AEB systems available
without ESC leads NHTSA to believe
that manufacturers have identified
scenarios in which the operation of an
AEB system without ESC may have
adverse safety effects that are not
adequately addressed by ABS systems
alone.
Summary of the Proposal
NHTSA has tentatively concluded
based upon this information that a
safety need exists for an ESC system to
be installed on a vehicle equipped with
AEB. Consequently, this proposal also
requires nearly all heavy vehicles to be
equipped with an ESC system.12 Even
separate from the benefits of AEB, the
safety problem related to the vehicles
addressed by the FMVSS No. 136
amendments is also substantial. Class 3
through 6 heavy vehicles are involved
in approximately 17,000 rollover and
loss of control crashes annually. These
crashes resulted in 178 fatalities
annually, approximately 4,000 non-fatal
injuries, and 13,000 damaged vehicles.
Currently, pursuant to FMVSS No. 136,
only class 7 and 8 truck tractors and
certain large buses are required to have
ESC systems. FMVSS No. 136 includes
both vehicle equipment requirements
and performance requirements. This
proposal would amend FMVSS No. 136
to require nearly all heavy vehicles to
have an ESC system that meets the
equipment requirements, the general
system operational capability
requirements, and malfunction
detection requirements of FMVSS No.
136. It would not, as proposed, require
vehicles not currently required to have
ESC systems to meet any test track
performance requirements for ESC
systems, though the agency does request
comment on whether to include a
performance test and, if so, what that
test should be. In designing any
11 On September 29, 2021, NHTSA met with
Daimler Truck North America (DTNA) and on
October 22, 2021, NHTSA met with Bendix to
discuss the AEB systems of heavy vehicles.
12 The vehicles excluded from the proposed ESC
requirements are the same vehicles excluded from
the proposed AEB requirements.
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43179
potential test, NHTSA wishes to remain
conscious of the potential testing
burden on small businesses and the
multi-stage vehicle manufacturers.
The proposed standard includes
certain requirements for AEB systems.
First, vehicles would be required to
provide the driver with a forward
collision warning at any forward speed
greater than 10 km/h (6.2 mph). NHTSA
is proposing that the forward collision
warning be auditory and visual with
limited specifications for each of the
warning modalities. NHTSA has
tentatively concluded that no further
specification of the warning is
necessary.
Second, vehicles would be required to
have an AEB system that applies the
service brakes automatically at any
forward speed greater than 10 km/h (6.2
mph) when a collision with a lead
vehicle is imminent. This requirement
serves to ensure that AEB systems
operate at all speeds above 10 km/h,
even if they are above the speeds tested
by NHTSA. This requirement also
assures at least some level of AEB
system performance in rear-end crashes
other than those for which NHTSA has
test procedures.
Third, the AEB system would be
required to prevent the vehicle from
colliding with a lead vehicle when
tested according to the proposed
standard’s test procedures. Vehicles
with AEB systems meeting the proposed
standard would have to automatically
activate the braking system when they
encounter a stopped lead vehicle, a
slower moving lead vehicle, or a
decelerating lead vehicle.
The proposed requirements also
include two tests to ensure that the AEB
system does not inappropriately activate
when no collision is actually imminent.
These false positive tests provide some
assurance that an AEB system is capable
of differentiating between an actual
imminent collision and a non-threat.
While these tests are not
comprehensive, they establish a
minimum performance for nonactivation of AEB systems. The two
scenarios NHTSA proposes to test are
driving over a steel trench plate and
driving between two parked vehicles.
The final proposed requirement for
AEB systems is that they be capable of
detecting a system malfunction and
notify the driver of any malfunction that
causes the AEB system not to operate.
This proposed requirement would
include any malfunction solely
attributable to sensor obstruction, such
as by accumulated snow or debris,
dense fog, or sunlight glare. The
malfunction telltale must remain active
as long as the malfunction exists, and
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the vehicle’s starting system is on. The
proposal does not include any
specifications for the form of this
notification to the driver.
The NPRM also includes proposed
test procedures. In this NPRM, the
heavy vehicle being evaluated with AEB
is referred to as the ‘‘subject vehicle.’’
Other vehicles involved in the test are
referred to as ‘‘vehicle test devices,’’
(VTDs) and a specific type of VTD
called the ‘‘lead vehicle’’ refers to a
vehicle which is ahead in the same lane,
in the path of the moving subject
vehicle. To ensure repeatable test
conduct that reflects how a subject
vehicle might respond in the real world,
this proposal includes broad
specifications for a vehicle test device to
be used as a lead vehicle or principal
other vehicle during testing. NHTSA is
proposing that the vehicle test device is
based on the specifications in the
International Organization for
Standardization (ISO) standard 19206–
3:2021.13 The vehicle test device is a
tool that NHTSA would use in the
agency’s compliance tests to measure
the performance of automatic
emergency braking systems required by
the FMVSS. For its research testing,
NHTSA has been using a full-size
surrogate vehicle, the Global Vehicle
Target (GVT). The GVT falls within the
specifications of ISO 19206–3:2021.
These specifications include
specifications for the dimensions, color
and reflectivity, and the radar cross
section of a vehicle test device that
ensure it appears like a real vehicle to
vehicle sensors.
NHTSA has included three test
scenarios in this proposed rule for AEB
when approaching a lead vehicle—a
stopped lead vehicle, a slower moving
lead vehicle, and a decelerating lead
vehicle. The stopped lead vehicle
scenario consists of the subject
vehicle—that is, the vehicle being
tested—traveling straight at a constant
speed approaching a stopped lead
vehicle in the center of its path. To
satisfy the proposed performance
requirement, the subject vehicle must
provide an FCW and stop prior to
colliding with the lead vehicle. NHTSA
proposes to conduct this scenario both
with no manual brake application and
with manual brake application. Testing
with manual brake application is similar
to the DBS test procedure that is
included in New Car Assessment
Program for light vehicles. While DBS is
13 ISO 19206–3:2021, ‘‘Road vehicles—Test
devices for target vehicles, vulnerable road users
and other objects, for assessment of active safety
functions—Part 3: Requirements for passenger
vehicle 3D targets.’’ https://www.iso.org/standard/
70133.html. May 2021.
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not generally advertised as a feature of
AEB systems on air braked vehicles,
driver-applied braking should not
suppress automatic braking. Testing
without manual brake application
would be conducted at any constant
speed between 10 km/h and 80 km/h.
The 80 km/h upper bound of testing
reflects safety limitations that would
result from any collision resulting from
a failure of an AEB system to activate in
the testing environment. However, with
manual brake application, NHTSA
proposes to test vehicles up to 100 km/
h. This is possible because the manual
brake application ensures at least some
level of speed reduction even in a test
failure where automatic braking does
not occur.
The second test scenario is a slower
moving lead vehicle. In this scenario,
the subject vehicle is traveling straight
at a constant speed, approaching a lead
vehicle traveling at a slower speed in
the subject vehicle’s path. To satisfy the
proposed performance test requirement,
the subject vehicle must provide an
FCW and slow to a speed equal to or
below the lead vehicle’s speed without
colliding with the lead vehicle. As with
the stopped lead vehicle test, NHTSA
proposes to perform this test with both
no manual brake application and
manual brake application. The subject
vehicle speed without manual brake
application would be any constant
speed between 40 km/h and 80 km/h,
and with manual brake application,
testing would be conducted at any
constant speed between 70 km/h and
100 km/h. The lead vehicle would travel
at 20 km/h in all tests.
The third test scenario is a
decelerating lead vehicle. In this
scenario, the subject vehicle and lead
vehicle are travelling at the same
constant speed in the same path and the
lead vehicle begins to decelerate. To
satisfy the proposed performance test
requirement, the subject vehicle must
provide an FCW and stop without
colliding with the lead vehicle. As with
the other AEB tests approaching a lead
vehicle, this test is performed both with
and without manual brake application.
However, the test speeds are the same
for both scenarios—either 50 km/h or 80
km/h. The lead vehicle would
decelerate with a magnitude between
0.3g and 0.4g and the headway between
the vehicles would be any distance
between 21 m and 40 m (for 50 km/h
tests) or 28 m and 40 m (for 80 km/h
tests). The upper bound of the lead
vehicle deceleration and the lower
bound of the headway were chosen to
ensure that the corresponding test
scenarios would not require a brake
performance beyond what is necessary
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to satisfy the minimum stopping
distance requirements in the FMVSS
applicable to brake performance.
This proposal would require that all
of the NHTSA AEB requirements be
phased in within four years of
publication of a final rule. Truck
tractors and certain large buses with a
GVWR of greater than 11,793 kilograms
(26,000 pounds) that are currently
subject to FMVSS No. 136 would be
required to meet all requirements within
three years. Vehicles not currently
subject to FMVSS No. 136 would be
required to have ESC and AEB systems
within four years of publication of a
final rule. Small-volume manufacturers,
final-stage manufacturers, and alterers
would be allowed one additional year
(five years total) of lead time.
Consistent with the BIL mandate,
FMCSA proposes to require that motor
carriers operating CMVs manufactured
subject to FMVSS No. 136, maintain and
use the required AEB and ESC systems
as prescribed by NHTSA for the
effective life of the CMV. FMCSA’s
proposed rule is intended to ensure that
commercial motor vehicles equipped
with the ESC and AEB systems
mandated by NHTSA are maintained
and operated safely, as required by 49
U.S.C. 31136(a)(1). While the FMCSA
proposal does not explicitly address the
remaining provisions of section 31136,
it will enhance the ability of drivers to
operate safely, consistent with 49 U.S.C.
31136(a)(2)–(4). FMCSA’s proposal
would require the ESC and AEB systems
to be inspected and maintained in
accordance with 49 CFR part 396,
Inspection, Repair, and Maintenance
(§ 396.3).
The proposed requirements would
ensure that the benefits resulting from
CMVs equipped with ESC and AEB
systems are sustained through proper
maintenance and operation. The
maintenance costs include annual costs
required to keep the ESC and AEB
systems operative. FMCSA believes the
cost of maintaining the ESC and AEB
systems over their lifetimes is minimal
compared to the cost of equipping
trucks with ESC and AEB systems and
may be covered by regular annual
maintenance.
NHTSA and FMCSA have jointly
determined not to propose retrofitting
requirements AEB for existing heavy
vehicles and ESC for vehicles not
currently subject to FMVSS No. 136. For
technical reasons, AEB and ESC retrofits
are difficult to apply broadly,
generically, or inexpensively and thus
this NPRM does not propose a retrofit
requirement.
NHTSA and FMCSA seek comments
and suggestions on any aspect of this
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proposal and any alternative
requirements to address this safety
problem. NHTSA and FMCSA also
request comments on the proposed lead
time for meeting these requirements,
and how the lead time can be structured
to maximize the benefits that can be
realized most quickly while ensuring
that the standard is practicable. Finally,
NHTSA and FMCSA seek comment on
whether and how this proposal may
disproportionately impact small
businesses and how NHTSA and
FMCSA could revise this proposal to
minimize any disproportionate impact.
impacts of this proposed rule. The PRIA
is available in the docket for this
NPRM.14 This proposed rule is expected
to substantially decrease risks
associated with rear-end, rollover, and
loss of control crashes. The effectiveness
of AEB and ESC at avoiding rear-end,
rollover, and loss of control crashes is
summarized in Table 3 for AEB and
Table 4 for ESC.
Benefits and Costs
NHTSA and FMCSA have issued a
Preliminary Regulatory Impact Analysis
(PRIA) that analyzes the potential
TABLE 3—AEB EFFECTIVENESS (%) BY VEHICLE CLASS RANGE AND CRASH SCENARIO
Stopped lead
vehicle
Vehicle class range
7–8 .......................................................................................................................
3–6 .......................................................................................................................
Slower-moving lead
vehicle
38.5
43.0
Decelerating lead
vehicle
49.2
47.8
49.2
47.8
TABLE 4—ESC EFFECTIVENESS (%) BY CRASH SCENARIO
Vehicle class range
Rollover
Loss of control
3–6 ...........................................................................................................................................................
48.0
14.0
Considering the annual rear-end,
rollover, and loss of control crashes, as
well as the effectiveness of AEB and
ESC at avoiding these crashes, the
proposed rule would prevent an
estimated 19,118 crashes, save 155 lives,
and reduce 8,814 non-fatal injuries,
annually. In addition, the proposed rule
would eliminate an estimated 24,828
property-damage-only-vehicles
(PDOVs), annually. Table 5 shows these
estimated benefits also by vehicle class
and technology.
TABLE 5—ESTIMATED ANNUAL BENEFITS OF THE PROPOSED RULE
Crashes
avoided
Fatalities
avoided
Non-fatal
injuries
avoided
PDOVs
avoided
By Vehicle Class
Class 7–8 .........................................................................................................
Class 3–6 .........................................................................................................
5,691
13,427
40
115
2,822
5,992
7,958
16,870
Total ..........................................................................................................
19,118
155
8,814
24,828
AEB ..................................................................................................................
ESC ..................................................................................................................
16,224
2,894
106
49
8,058
756
22,713
2,115
Total ..........................................................................................................
19,118
155
8,814
24,828
lotter on DSK11XQN23PROD with PROPOSALS2
By Technology
There are two potential unintended
consequences that cannot be quantified:
the impact of false activations on safety
and the potential impact of sensor
degradation over time on AEB
performance. However, the required
malfunction indicator combined with
FMCSA’s proposed AEB and ESC
inspection and maintenance
requirements would help vehicle
operators maintain AEB systems and
substantially reduce degradation of AEB
sensor performance. We seek comments
on these two issues and ask for any data
that can help us to quantify these
impacts.
The benefits estimate includes
assumptions that likely result in the
underestimation of the benefits of this
proposal because it does not quantify
the benefits from crash mitigation. That
is, the benefits only reflect those
resulting from crashes that are avoided
as a result of AEB and ESC. It is likely
that AEB will also reduce the severity of
crashes that are not prevented. Some of
these crashes mitigated may include
fatalities and significant injuries that
will be prevented or mitigated by AEB.
14 The PRIA may be obtained by downloading it
or by contacting Docket Management at the address
or telephone number provided at the beginning of
this document.
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Finally, this NPRM does not quantify
any potential benefits that AEB could
provide during adverse environmental
conditions (night, wet, etc.). While AEB
is likely to be effective in many of these
crashes, NHTSA is not aware of any
data to quantify the performance
degradation of AEB in adverse
conditions.
The benefits of this proposed rule,
monetized and analyzed with the total
annual cost, are summarized in Table 6.
The total annual cost, considering the
implementation of both AEB and ESC
technologies proposed in this rule, is
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estimated to be $353 million. The
proposed rule would generate a net
benefit of $2.58 to $1.81 billion,
annually under 3 and 7 percent
discount rates. The proposed rule would
be cost-effective given that the highest
estimated net cost per fatal equivalent
would be $0.50 million. Maintenance
costs are considered de minimis and
therefore not included in the cost
estimate.
TABLE 6—ESTIMATED ANNUAL COST, MONETIZED BENEFITS, COST-EFFECTIVENESS, AND NET BENEFITS OF THE
PROPOSED RULE
[2021 Dollars in millions]
Annual
cost *
Discount rates
3 Percent ...................................................................................................
7 Percent ...................................................................................................
Monetized
benefits
$353.3
353.3
Net cost per
fatal equivalent
$2,937.0
2,158.0
15 ¥$0.12
0.50
Net
benefits
$2,583.7
1,807.1
* Paid at purchasing; no need to discount.
NHTSA has issued an NPRM that
proposes to adopt an FMVSS for AEB
requirements for light vehicles,
including pedestrian AEB. 16 NHTSA
notes that it may decide to issue final
rules adopting the AEB requirements for
light and heavy vehicles in a way that
incorporates the AEB requirements into
a single Federal motor vehicle safety
standard for all vehicle classes.
The following is a brief explanation of
terms and technologies used to describe
AEB systems. More detailed information
can be found in Appendix A to this
preamble.
lotter on DSK11XQN23PROD with PROPOSALS2
Radar-Based Sensors
Heavy vehicle AEB systems typically
employ radar sensors. At its simplest,
radar is a time-of-flight sensor that
measures the time between when a
radio wave is transmitted and its
reflection is recorded. This time-offlight is then used to calculate how far
away the object is that caused the
reflection. Information about the
reflecting object, such as the speed at
which it is travelling, can also be
determined. Radar units are compact,
relatively easy to mount, and do not
require a line of sight to function
properly. Radar can penetrate most
rubbers and plastics, allowing for the
units to be installed behind grilles and
bumper fascia, increasing mounting
options. Radar can detect objects in lowlight situations and also works well in
environmental conditions like
precipitation and fog.
Camera Sensors
Cameras are passive sensors in which
optical data are recorded then processed
to allow for object detection and
classification. Cameras are an important
part of many automotive AEB systems,
and one or more cameras are typically
15 The negative net cost per fatal equivalent
reflects the fact that savings from reducing traffic
congestion and damaged property is greater the
total compliance costs of the proposed rule.
16 88 FR 38632 (June 13, 2023).
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mounted behind the front windshield
and often up high near the rearview
mirror. Cameras at this location provide
a good view of the road and are
protected by the windshield from
debris, grease, dirt, and other
contaminants that can cover the sensor.
Systems that utilize two or more
cameras can see stereoscopically,
allowing the processing system to
determine range information along with
detection and classification.
Electronically Modulated Braking
Systems
Automatic actuation of the vehicle
brakes requires more than just systems
to sense when a collision is imminent.
In addition to the sensing system,
hardware is needed to physically apply
the brakes without relying on the driver
to apply the brake pedal. AEB leverages
two foundational braking technologies,
antilock braking systems (ABS) and
electronic stability control. AEB uses
the hardware equipped for ESC and
electronically applies the brakes to
avoid certain scenarios where a crash
with a vehicle is imminent.
ABS: Antilock braking systems
automatically control the degree of
longitudinal wheel slip during braking
to prevent wheel lock and minimize
skidding by sensing the rate of angular
rotation of the wheels and modulating
the braking force at the wheels to keep
the wheels from locking. Preventing
wheel lock, and therefore skidding,
greatly increases the controllability of
the vehicle during a panic stop. Modern
ABS systems have wheel speed sensors,
independent brake modulation at each
wheel, and can increase or decrease
braking pressures as needed. During
modulation of a brake application, the
ABS system repeatedly relieves and
regenerates pressure to quickly release
and reapply, or ‘‘pulse,’’ the brake.
ESC: ESC builds upon the antilock
brakes system by adding two sensors, a
steering wheel angle sensor and an
inertial measurement unit. These
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sensors allow the ESC controller to
determine intended steering direction
(steering wheel angle sensor), compare
it to the actual vehicle direction, and
then modulate braking forces at each
wheel to induce a corrective yaw
moment when the vehicle starts to lose
lateral stability. An ESC system can
control the brakes even when the
vehicle operator is not pressing the
brake pedal.
When an AEB system activates in
response to an imminent collision,
much of the same or similar hardware
from ESC systems is used to
automatically control and modulate the
brakes. Like ESC, an AEB system
includes components that give the
vehicle the capacity to automatically
apply the brakes even when the vehicle
operator is not pressing the brake pedal.
To do this in hydraulic brake systems,
hydraulic brake pressure is generated by
a pump similarly as with ABS. In a
pneumatic brake system, the air
pressure is already available via the air
reservoir and air compressor, and the
ESC system must direct this pressure
accordingly. Additionally, the safety
benefits of ESC enable an AEB system
to operate at its potential. Especially
under the high-speed, heavydeceleration emergency braking events
that potentially occur during AEB
activation, ESC could improve vehicle
stability and reduce the propensity for
loss of control or rollover crashes that
may result from a steering response to
an impending rear-end collision.
Forward Collision Warning
A forward collision warning (FCW)
system uses the camera and radar
sensors described above, and couples
them with an alert mechanism. An FCW
system can monitor a vehicle’s speed,
the speed of the vehicle in front of it,
and the distance between the two
vehicles. If the FCW system determines
that the distance from the driver’s
vehicle to the vehicle in front of it is too
short, and the closing velocity between
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the two vehicles too high, the system
warns the driver of an impending rearend collision. Warning systems in use
today provide drivers with a visual
display, such as a light on the
instrument panel, an auditory signal
(e.g., beeping tone or chime), and/or a
haptic signal that provides tactile
feedback to the driver (e.g., rapid
vibrations of the seat pan or steering
wheel or a momentary brake pulse) to
alert the driver of an impending crash
so they may manually intervene. The
alerts provided by FCW systems, even
those that include momentary brake
pulses, are not intended to provide
significant and sustained vehicle
deceleration. Rather, the FCW system is
intended to inform the driver that they
must take corrective action in certain
rear-end crash-imminent driving
situations.
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Automatic Emergency Braking
An automatic emergency braking
system automatically applies the brakes
to help drivers avoid or mitigate the
severity of rear-end crashes. AEB has
two primary functions, crash imminent
braking (CIB) and a brake support
system that supplements a driver’s
applied braking, which is referred to as
dynamic brake support (DBS) in the
light vehicle context. CIB systems apply
automatic braking when forwardlooking sensors indicate a crash is
imminent and the driver has not applied
the brakes, while supplemental brake
support systems use the same forwardlooking sensors, but also supplement
the driver’s application of the brake
pedal with enhanced braking when
sensors determine the driver-applied
braking is insufficient to avoid the
imminent crash. This NPRM does not
split the terminology of these CIB and
supplemental brake support
functionalities, and instead considers
both functions as part of AEB. The
proposed standard includes
performance tests that would entail
installation of AEB that has both CIB
and supplemental brake support
functionalities.
‘‘AEB’’ as Used in This NPRM
As used in this NPRM, when we refer
to ‘‘AEB,’’ we mean a system that has:
(a) a forward collision warning (FCW)
component to alert the driver to an
impending collision; (b) a crash
imminent braking component (CIB) that
automatically applies the vehicle’s
brakes if the driver does not respond to
an imminent crash in the forward
direction regardless of whether there’s
an FCW alert; and, (c) a supplemental
brake support component that
automatically supplements the driver’s
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brake application if the driver applies
insufficient manual braking.
either stopped, travelling at a lower
speed, or decelerating.21
II. Safety Problem
Heavy Vehicle Rear-End Crashes
On average from 2017 to 2019, there
were 6.65 million annual policereported crashes resulting in 36,888
fatalities. Of the police-reported crashes,
approximately 550,000 involved a heavy
vehicle (a vehicle with a GVWR greater
than 4,536 kg (10,000 pounds)),
resulting in 5,255 fatalities.22 Thus,
heavy vehicle crashes represented 8.3
percent of the total number of crashes
and resulted in 14.2 percent of all
fatalities. Annually, the entire U.S. fleet
traveled a total of 3,237,449 million
miles, and 9.3 percent of total vehicle
miles traveled were in heavy vehicles.23
A typical heavy vehicle rear-end crash
is characterized by a heavy vehicle
travelling on a roadway and colliding
with another vehicle ahead of it
travelling in the same direction, but
which is stopped, moving slower, or
decelerating, usually within the same
lane. While these crashes occur
nationwide on all types of roads and in
all environments, they overwhelmingly
take place on straight roadways (99
percent) and in dry conditions (85
percent). Approximately 60,000 (11
percent of heavy vehicle crashes
annually), were rear-end crashes in
which the heavy vehicle was the
striking vehicle. These rear-end crashes
resulted in 388 fatalities annually (7.4
percent of all fatalities in heavy vehicle
crashes), approximately 30,000 injuries
(14.3 percent of injuries in all heavy
vehicle crashes.), and approximately
84,000 damaged vehicles (without
injuries or fatalities).24
The PRIA accompanying this proposal
includes a complete review and analysis
of the relevant crash data and provides
full details about the target population
of this NPRM. A summary of the PRIA
is contained in section XI. of this
proposal.
Overview
There were 38,824 people killed in
motor vehicle crashes on U.S. roadways
in 2020 and 42,939 in 2021.17 18 The
2021 data are the highest numbers of
fatalities since 2005. While the upward
trend in fatalities may be related to
increases in risky driving behaviors
during the COVID–19 pandemic,19
NHTSA data from 2010 to 2019 show an
increase of approximately 3,000
fatalities since 2010. There has also
been an upward trend since 2010 in the
total number of motor vehicle crashes,
which corresponds to an increase in
fatalities, injuries, and property damage.
NHTSA uses data from its FARS and the
CRSS, to account for and understand
motor vehicle crashes.20
Rear-End Crashes
As defined in a NHTSA technical
manual relating to data entry for FARS
and CRSS, rear-end crashes are
incidents where the first event is
defined as the frontal area of one vehicle
striking a vehicle ahead in the same
travel lane. In a rear-end crash, as
instructed by the FARS/CRSS Coding
and Validation Manual, the vehicle
ahead is categorized as intending to
head either straight, left or right, and is
17 https://crashstats.nhtsa.dot.gov/Api/Public/
ViewPublication/813266;, https://www.nhtsa.gov/
press-releases/early-estimate-2021-trafficfatalities#:∼:text=Preliminary%20data%20reported
%20by%20the,from%201.34%
20fatalities%20in%202020.
18 https://crashstats.nhtsa.dot.gov/Api/Public/
ViewPublication/813435; https://crashstats.
nhtsa.dot.gov/Api/Public/ViewPublication/813283;
https://www.nhtsa.gov/press-releases/earlyestimate-2021-traffic-fatalities#:∼:text=
Preliminary%20data%20reported
%20by%20the,from%201.34%
20fatalities%20in%202020.
19 These behaviors relate to increases in impaired
driving, the non-use of seat belts, and speeding.
20 The Crash Report Sampling System (CRSS)
builds on a previous, long-running National
Automotive Sampling System General Estimates
System (NASS GES). CRSS is a sample of policereported crashes involving all types of motor
vehicles, pedestrians, and cyclists, ranging from
property-damage-only crashes to those that result in
fatalities. CRSS is used to estimate the overall crash
picture, identify highway safety problem areas,
measure trends, drive consumer information
initiatives, and form the basis for cost and benefit
analyses of highway safety initiatives and
regulations. FARS contains data on every fatal
motor vehicle traffic crash within the 50 States, the
District of Columbia, and Puerto Rico. To be
included in FARS, a traffic crash must involve a
motor vehicle traveling on a public trafficway that
results in the death of a vehicle occupant or a
nonoccupant within 30 days of the crash.
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Rear-End Crashes by Heavy Vehicle
Class
Installing AEB on vehicles is related
to the installation of ESC on vehicles.
ESC is required by FMVSS No. 136 for
truck tractors and certain large buses
with a GVWR greater than 11,793 kg
21 https://crashstats.nhtsa.dot.gov/Api/Public/
ViewPublication/813251 Category II Configuration
D. Rear-End.
22 Data are from 2017–2019 FARS and CRSS crash
databases, as discussed in the accompanying PRIA.
23 See the Traffic Safety Report at https://
crashstats.nhtsa.dot.gov/Api/Public/
ViewPublication/813141 (Last viewed September
22, 2022).
24 All data in this paragraph are from 2017–2019
FARS and CRSS crash databases, and are discussed
in the accompanying PRIA.
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(26,000 lbs.). Although the group of
heavy vehicles that is not subject to
FMVSS No. 136 and the group of heavy
vehicles that is subject to FMVSS No.
136 are not solely defined by GVWR
range, those not subject to FMVSS No.
136 can be generally characterized as
class 3–6 vehicles, while those that are
subject to FMVSS No. 136 can be
generally characterized as class 7–8
vehicles. Accordingly, NHTSA has
further examined rear-end crash data for
each of these vehicle class ranges.
The lower weight range of class 3
through 6 includes vehicles such as
delivery vans, utility trucks, and smaller
buses. Sales data for 2018 and 2019
show that on average 454,692 class 3–
6 vehicles per year were sold in the
U.S.25 Approximately 57 percent of
these were class 3 vehicles. Based on
crash data, NHTSA determined that
class 3–6 vehicles are involved in an
annual average of 29,493 rear-end
crashes where the heavy vehicle is the
striking vehicle. As a result of these
crashes, there were 184 fatalities, 14,675
injuries, and 41,285 PDOVs per year on
average. A NHTSA study also shows
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25 This information is available in the S&P
Global’s presentation titled ‘‘MHCV Safety
Technology Study,’’ which has been placed in the
docket identified in the heading of this NPRM.
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that, according to FARS data, fatalities
related to crashes involving these
vehicles are on the rise.26 In 2015,
trucks and buses in this category were
involved in 2 percent of all fatal crashes
in the U.S., but that increased to 4
percent in 2019.27
The higher weight range of class 7 and
8 includes vehicles such as larger
single-unit trucks, combination tractortrailers, transit buses, and motorcoaches
(GVWR greater than 11,793 kg (26,000
lbs.)).28 Sales data for 2018 and 2019
shows that on average 332,558 class 7–
8 vehicles per year were sold in the U.S.
Approximately 77 percent of these were
class 8 vehicles. NHTSA estimates that
class 7 and 8 vehicles are involved in
30,416 rear-end crashes where the heavy
vehicle is the striking vehicle. As a
result of these crashes, there were an
annual average of 204 fatalities, 15,117
injuries, and 42,466 PDOVs. As these
data indicate, the numbers of crashes,
26 Mynatt, M., Zhang, F., Brophy, J.,
Subramanian, R., Morgan, T. (2022, September).
Medium Truck Special Study (Report No. DOT HS
813 371). Washington, DC: National Highway
Traffic Safety Administration.
27 In 2015, 655 of the 32,538 total fatalities
involved a class 3–6 truck. In 2019, it increased to
1,301 of the 33,244 total fatalities.
28 These vehicles are subject to FMVSS No. 136
and so must have ESC.
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fatalities, injuries, and PDOVs are very
similar for both class 3–6 and class 7–
8.
Rear-End Crashes by Vehicle Travel
Speed and Roadway Speed Limit
Pre-crash vehicle travel speed is
highly important in understanding the
heavy vehicle rear-end crash problem
and is perhaps the most influential
factor in outcome of these crashes. In
NHTSA’s analysis of the data, travel
speed of the striking vehicle was
markedly different when comparing
non-fatal and fatal rear-end truck
crashes. As shown in Figure 1, the
percentage of heavy vehicle rear-end
crashes with a fatality is greatest at
higher travel speeds.29 Approximately
89 percent of fatal heavy vehicle rearend crashes occur at above 80 km/h (50
mph). For non-fatal heavy vehicle rearend crashes, the trend is more or less
reversed, with approximately 83 percent
of these crashes occurring at travel
speeds below 80 km/h (50 mph). These
data illustrate the distribution of a crash
problem across all travel speeds.
BILLING CODE 4910–59–P
29 Note that the figure shows percentage of the
total number of fatal or non-fatal crashes. The total
number of crashes is much greater for non-fatal
crashes.
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The speed limits in heavy vehicle
rear-end crashes also show a similar
trend. NHTSA categorized the fatal and
non-fatal crash data according to posted
speed limit at the crash location, as
illustrated in Figure 2.31 These data
show that over 90 percent of heavy
vehicle rear-end crashes with a fatality
occur on roadways with a posted speed
limit higher than 50 mph (80 km/h).
This reinforces the association between
higher speeds and fatal crash outcome
in these types of crashes. In contrast,
non-fatal rear-end crashes tend to occur
30 Data are from 2017–2019 FARS and CRSS crash
databases, as discussed in the PRIA section on
target population.
31 These data naturally are clustered around 5
mph intervals normally assigned for posted speed
limits on roadways.
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most commonly on roads with lower
speed limit, with a peak frequency at
speed limits of 45 mph (72 km/h). These
data help in understanding the
conditions under which heavy vehicle
rear-end crashes of different severities
occur.
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Safety Problem That Can Be Addressed
by AEB
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NHTSA identified the set of crashes
that might be prevented by AEB systems
equipped on heavy vehicles. To
determine these crashes for this NPRM,
NHTSA analyzed 2017 through 2019
crash data for heavy vehicles. The 2017
through 2019 years were chosen because
they provide the most recent available
data, and thus reflect newer model year
vehicles, safety technologies, and crash
environments.33 The crash-related
statistics discussed in this section, often
depicted as annual averages, are derived
from these data.
To develop a target crash population
relevant to AEB, the agency identified
crashes that were classified as rear-end
crashes as instructed by the FARS/CRSS
32 Data are from 2017–2019 FARS and CRSS crash
databases, as discussed in the PRIA section on
target population.
33 Crash data from 2020, although available, were
excluded due to a significant reduction in weighted
cases for CRSS. The 2020 data was greatly
influenced by COVID–19 and might not reflect the
long-term trend of crash outcomes, as described in
the accompanying PRIA.
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manual and in which the striking
vehicle was a heavy vehicle. NHTSA
analyzed rear-end crashes in which the
vehicle ahead is categorized as being
either stopped, travelling at a lower
speed, or decelerating, and also
examined a few other categories to
account for rear-end crashes that did not
fit into the three categories.
Additionally, NHTSA included some
other cases which, although not
classified as rear-end, were multivehicle crashes that still involved the
front end of a heavy vehicle colliding
with the rear-end of another vehicle.
NHTSA believes that AEB will help
reduce the severity of rear-end crashes
occurring in a wide variety of real-world
situations. However, the data analysis
presented some rear-end crash cases
where, due to a significant sequence of
events or other conditions preceding the
crash, the agency had less certainty of
the extent to which AEB systems would
be able to reduce the crash severity. For
example, if the data indicated that the
heavy vehicle had changed lanes just
prior to colliding with a vehicle ahead,
there would potentially not have been
sufficient time and/or space for the AEB
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system to properly identify and track
that vehicle and brake in time to avoid
the crash. As another example, if the
road surface conditions were icy and
slippery, the AEB system may have been
less likely to prevent a crash due to the
reduced friction and increased stopping
distances. In another example, if the
struck vehicle was a motorcycle,
NHTSA is uncertain of the AEB
system’s capacity to perform optimally
since motorcycles may be more difficult
to detect.34
NHTSA believes that, even in these
situations where AEB performance may
be partially degraded, having AEB will
still be beneficial. It may not, for
example, prevent a crash but it may
reduce its severity by slowing the
34 NHTSA is currently conducting research tests
to understand AEB performance in light vehicle
rear-end crashes with motorcycles. Two types of
AEB sensor types (e.g., camera and camera+radar)
were investigated. See www.regulations.gov, Docket
No. NHTSA–2022–0091. A study by the RDW, the
vehicle authority in the Netherlands, indicated that
adaptive cruise control systems (which detect a
vehicle ahead, similar to AEB) had more difficulty
detecting motorcycles. https://
www.femamotorcycling.eu/wp-content/uploads/
Final%20Report_motorcycle_ADAS_RDW.pdf (last
accessed February 10, 2023).
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striking vehicle down. However, the
agency took a conservative approach
and excluded cases such as those above
from the target crash population, and
included only those cases in which AEB
systems would have the opportunity to
perform optimally. This approach gives
greater confidence that the crashes
included in the target crash population
would be prevented by having AEBequipped vehicles.35
The result is that out of the 550,000
annual police reported crashes
involving heavy vehicles, approximately
60,000 annually are rear-end crashes in
which the heavy vehicle was the
striking vehicle. Thus, if heavy vehicles
were equipped with AEB, a portion of
these 60,000 crashes could be
prevented. These 60,000 crashes,
between 2017 and 2019, resulted in an
annual average of approximately 388
43187
fatalities, 30,000 injuries, and 84,000
PDOVs.
By requiring ESC for most class 3
through 6 vehicles, the proposed rule
would affect approximately 17,000
rollover and loss of control crashes.
These crashes resulted in 178 fatalities,
4,000 injuries, and 13,000 PDOVs, a
portion of which could be prevented if
class 3 through 6 heavy vehicles were
equipped with ESC. These numbers are
set forth in Table 7.
TABLE 7—TARGET CRASH POPULATION
Crashes
AEB ..................................................................................................................
ESC ..................................................................................................................
60,000
17,000
388
178
Injuries
30,000
4,000
PDOVs
84,000
13,000
from brake fade, and having an
emergency (backup) brake system.
FMVSS No. 136 establishes
performance and equipment
requirements for electronic stability
control systems on truck tractors and
certain large buses, for the purpose of
reducing crashes caused by rollover or
by loss of directional control. This
standard currently applies to truck
tractors and certain large buses with a
GVWR greater than 11,793 kilograms
(26,000 lbs.). FMVSS No. 136 requires
vehicles to be equipped with an ESC
system, and to meet several minimum
performance requirements. For example,
when driven on a specified J-shaped test
lane under a variety of specified
conditions and parameters which
induce ESC activation, the wheels of the
heavy vehicle must remain within the
lane.
A. NHTSA’s Foundational AEB
Research
NHTSA has been studying emergency
braking technologies since
manufacturers first introduced these
technologies over fifteen years ago.
NHTSA has recognized the safety
potential of heavy vehicle AEB for many
years and continued to research this
technology as it evolved from early
generations to its current state. As part
of NHTSA’s efforts to better understand
these new crash avoidance technologies,
NHTSA sponsored and conducted
numerous research projects focused on
AEB and FCW for heavy trucks. NHTSA
conducted testing at its in-house testing
facility, the Vehicle Research and Test
Center, to examine the performance of
AEB in different combinations of crash
scenarios and speeds.
NHTSA’s foundational knowledge of
braking technology was built on a long
history of work on FMVSS No. 105,
‘‘Hydraulic and electric brake systems,’’
No. 121, ‘‘Air brake systems,’’ and No.
136, ‘‘Electronic stability control
systems for heavy vehicles.’’
FMVSS No. 105 applies to
multipurpose passenger vehicles,
trucks, and buses with a GVWR greater
than 3,500 kg (7,716 lbs.) that are
equipped with hydraulic or electric
brake systems. This standard sets
performance requirements for, among
other things, maximum stopping
distance, anti-lock braking systems,
stability and control under braking
(including a curved and wet road
surface), and recovery from brake
fade.37
FMVSS No. 121 applies to trucks,
buses, and trailers equipped with air
(pneumatic) brake systems, with a few
exceptions for special vehicle types.
Although NHTSA sets no standards
regarding the choice between using
hydraulic, electric, or air brakes,
vehicles with a larger size and load
carrying capacity are more likely to have
air brakes. Thus, air brakes are typically
installed on some class 6 and most class
7–8 vehicles. Lower classes often use
hydraulic brakes. A few examples of the
requirements in FMVSS No. 121 are
maximum stopping distance, having
ABS, maintaining stability and control
when braking to a stop on a curved and
wet roadway test surface, recovering
35 The PRIA discusses the rear-end crashes that
were excluded from the target population.
36 On March 17, 2016, NHTSA and the Insurance
Institute for Highway Safety (IIHS) announced a
commitment by 20 automakers representing more
than 99 percent of the U.S. auto market to make
lower speed AEB a standard feature on virtually all
new cars no later than Sept 1, 2022. https://
www.nhtsa.gov/press-releases/us-dot-and-iihsannounce-historic-commitment-20-automakersmake-automatic-emergency.
37 Brake fade events are associated with speed
control on roads with steep or gradual but long
downgrades. As brake temperature increases in a
drum, its diameter expands as the metal heats up;
this means the brake shoe displacement must also
increase to be effective. Eventually, the shoe
reaches the displacement limit, and then brake
effectiveness drops off.
III. Efforts To Promote AEB Deployment
in Heavy Vehicles
Unlike with light vehicles in the U.S.,
there is currently no voluntary
commitment by heavy vehicle
manufacturers to begin installing AEB
on all new vehicles.36 Nor is there a
program similar to NHTSA’s New Car
Assessment Program (NCAP) for heavy
vehicles. However, NHTSA and FMCSA
have researched heavy vehicle AEB. In
addition, Congress, other governmental
agencies, and a variety of stakeholders
recognize that this technology has the
potential to reduce the fatalities,
injuries, and property damage
associated with heavy vehicle rear-end
crashes. The installation rate of AEB in
the U.S. vehicle fleet has gradually
increased, and the latest generations of
the technology are higher performing
than the original implementations.
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Fatalities
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B. NHTSA’s 2015 Grant of a Petition for
Rulemaking
In October 2015, NHTSA granted a
petition for rulemaking from the Truck
Safety Coalition, the Center for Auto
Safety, Advocates for Highway and Auto
Safety, and Road Safe America. This
petition requested ‘‘the commencement
of a proceeding to establish a safety
regulation to require the use of [FCW
and AEB] on all vehicles (trucks and
buses) with a gross vehicle weight rating
(GVWR) of 10,000 pounds (lbs.) or
more.’’ The petitioners maintained that
AEB has important benefits and is a
technology that has been improving in
performance, but that a regulation is
needed to optimize the benefits of the
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technology and increase the frequency
of installation in heavy vehicles. The
agency granted this petition on October
16, 2015, noting that NHTSA’s research
and evaluation were ongoing, and
initiated a rulemaking proceeding with
respect to vehicles with a GVWR greater
than 4,536 kg (10,000 lbs.).38
C. Congressional Interest
1. MAP–21
In July 2012, the Moving Ahead for
Progress in the 21st Century Act was
enacted. MAP–21 included Subtitle G,
the ‘‘Motorcoach Enhanced Safety Act
of 2012.’’ 39 Section 32705 of MAP–21
directed the Secretary (NHTSA, by
delegation) to research and test forward
and lateral crash warning systems for
motorcoaches and decide whether a
corresponding safety standard would
accord with section 30111 of the Safety
Act. Section 32703(b)(3) directed the
Secretary to consider requiring
motorcoaches to be equipped with
stability enhancing technology, such as
electronic stability control, to reduce the
number and frequency of rollover
crashes, and prescribe a standard if it
would meet the requirements and
considerations of sections 30111(a) and
(b) of the Safety Act.40 In response,
NHTSA issued FMVSS No. 136,
requiring ESC for certain truck tractors
and buses (including motorcoaches)
with a GVWR greater than 13,154 kg
(26,000 lbs.).
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2. Bipartisan Infrastructure Law
In November 2021, the Bipartisan
Infrastructure Law (BIL) was signed into
law. Section 23010 of BIL is dedicated
to AEB. Section 23010(a) of BIL defines
an AEB system as a system on a
commercial motor vehicle that, based on
a predefined distance and closing rate
with respect to an obstacle in the path
of the vehicle, alerts the driver of an
obstacle and, if necessary, applies the
brakes automatically to avoid or
mitigate a collision with that obstacle.
Section 23010(b) requires the
Secretary to prescribe an FMVSS to
require all commercial motor vehicles 41
38 Grant of petition for rulemaking, 80 FR 62487
(October 16, 2015).
39 Public Law 112–141, Sec. 32705.
40 Section 32703(b) required a regulation not later
than two years after the date of enactment of the
Act if DOT determined that such standard met the
requirements of the Safety Act.
41 As defined in 49 U.S.C. 31101, ‘‘commercial
motor vehicle’’ means a self-propelled or towed
vehicle used on the highways in commerce
principally to transport passengers or cargo, if the
vehicle has a gross vehicle weight rating or gross
vehicle weight of at least 10,001 pounds, whichever
is greater; is designed to transport more than 10
passengers including the driver; or is used in
transporting material found by the Secretary of
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subject to FMVSS No. 136 (or a
successor regulation) to be equipped
with an AEB system. The FMVSS is also
required to establish performance
standards for AEB systems. BIL directs
the Secretary to prescribe the standard
not later than two years after the date of
enactment of the Act.
Under Section 23010(b)(2), prior to
prescribing the FMVSS, the Secretary is
required to conduct a review of AEB
systems in use in applicable commercial
motor vehicles and address any
identified deficiencies in those systems
in the rulemaking proceeding, if
practicable. In addition, the Secretary is
required to consult with representatives
of commercial motor vehicle drivers to
learn about their experience with AEB
(including malfunctions and/or
unwarranted activations).
This NPRM is issued to meet these
provisions of the BIL. NHTSA
conducted a review of AEB systems in
use in commercial motor vehicles to
identify limits in those systems. A
memorandum summarizing this review
has been placed in the docket for this
NPRM and has informed the
development of the proposal. NHTSA is
also currently conducting research to
study drivers’ experiences with
collision mitigation technologies,
including AEB. Comments are requested
on the feasibility of mandating AEB for
commercial motor vehicles with GVWR
greater than 10,000 pounds which are
not currently subject to FMVSS No. 136.
This NPRM requests comments from
representatives of commercial motor
vehicle drivers, and drivers themselves,
regarding the experience with the use of
AEB systems. This NPRM also includes
a series of questions in section VII.E on
which NHTSA seeks comment to obtain
information about drivers’ experiences
with AEB (including malfunctions and/
or unwarranted activations).
Section 23010(c) of the BIL relates to
the regulations of FMCSA, which
regulate the operation of commercial
motor vehicles. BIL requires an FMCSR
ensuring that the AEB systems required
by the FMVSS for new commercial
vehicles subject to FMVSS No. 136 be
in use at any time during which the
vehicle is in operation. This NPRM
proposes this FMCSR.42
Finally, section 23010(d) of BIL
requires DOT to complete a study on
equipping a variety of commercial
Transportation to be hazardous and transported in
a quantity requiring placarding under regulations.
42 FMCSA has also created an apprenticeship
program for novice drivers of commercial motor
vehicles pursuant to the BIL. The program requires
novice drivers to operate vehicles that possess an
active braking collision mitigation system, such as
AEB. 87 FR 2477, January 14, 2022.
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motor vehicles not currently required to
comply with FMVSS No. 136 with AEB.
This study is to include an assessment
of the feasibility, benefits, and costs
associated with installing AEB on these
vehicles. As discussed in greater detail
later, the analysis accompanying this
NPRM fulfills this requirement.
D. IIHS Effectiveness Study
In a 2020 report, the Insurance
Institute for Highway Safety studied the
effectiveness of FCW and AEB
technology on class 8 trucks and
concluded that safety will improve if
more trucks have these technologies
installed.43 IIHS used data extracted
from video camera footage and crash
rates of police-reportable crashes. While
the study sample did not contain a large
number of severe crashes, FCW and
AEB were still associated with
significant reductions in rear-end
crashes involving trucks. On average,
between the time of collision and
moment of system intervention, the
velocity of the striking vehicle was
reduced by greater than 50 percent. The
study concluded that safety would
improve if more trucks had these
technologies installed.44 The IIHS study
was limited to class 8 trucks and
involved certain fleets and drivers
which may not necessarily be
representative of the U.S. fleet as a
whole. Because of this limitation,
NHTSA could not use the findings to
calculate the potential benefits of this
proposal.
E. DOT’s National Roadway Safety
Strategy (January 2022)
This NPRM takes a crucial step in
implementing DOT’s January 2022
National Roadway Safety Strategy to
address the rising numbers of
transportation deaths occurring on this
country’s streets, roads, and highways.45
At the core of this strategy is the
Department-wide adoption of the Safe
System Approach, which focuses on
five key objectives: safer people, safer
roads, safer vehicles, safer speeds, and
post-crash care. The Department will
launch new programs, coordinate and
improve existing programs, and adopt a
43 Teoh, Eric R. (2020, September). Effectiveness
of front crash prevention systems in reducing large
truck crash rates. Arlington, VA: Insurance Institute
for Highway Safety. Available at https://
www.iihs.org/topics/bibliography/ref/2211#:∼:text=
Results%3A%20FCW%20
was%20associated%20with,%25%20for%20rear
%2Dend%20crashes. (last accessed August 30,
2022).
44 Id.
45 https://www.transportation.gov/sites/dot.gov/
files/2022-01/USDOT_National_Roadway_Safety_
Strategy_0.pdf (last accessed August 23, 2022).
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foundational set of principles to guide
this strategy.
The National Roadway Safety Strategy
highlights new priority actions that
target our most significant and urgent
problems and are, therefore, expected to
have the most substantial impact. One
of the key Departmental actions to
enable safer vehicles is initiating a
rulemaking to require AEB on heavy
trucks. This NPRM proposes a Federal
Motor Vehicle Safety Standard to
require AEB on heavy trucks and other
heavy vehicles.
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F. National Transportation Safety Board
Recommendations
The National Transportation Safety
Board (NTSB) included AEB for
commercial vehicles in its 2021–2023
Most Wanted List.46 Among other
things, NTSB stated that NHTSA should
complete standards for AEB in
commercial vehicles and require this
technology in all highway vehicles and
all new school buses.
In 2015, NTSB issued a special
investigation report,47 which
summarized previous, as well as new,
findings related to AEB in a variety of
vehicles. Regarding heavy vehicles, this
report presented the following
recommendation to NHTSA:
• H–15–05: Complete, as soon as
possible, the development and
application of performance standards
and protocols for the assessment of
forward collision avoidance systems in
commercial vehicles.
In a 2018 special investigation
report,48 the NTSB discussed two severe
accidents involving school buses. In the
conclusion of the report, the NTSB
stated that AEB could have helped
mitigate the severity of one of the
accidents, and that ESC could have
helped mitigate the other. Accordingly,
the following safety recommendations
were made or restated to NHTSA:
• H–18–08: Require all new school
buses to be equipped with collision
avoidance systems and automatic
emergency braking technologies.
46 NTSB Most Wanted List, https://www.ntsb.gov/
Advocacy/mwl/Pages/mwl-21-22/mwl-hs-04.aspx
(last accessed August 23, 2022).
47 National Transportation Safety Board. 2015.
The Use of Forward Collision Avoidance Systems to
Prevent and Mitigate Rear-End Crashes. Special
Investigation Report NTSB/SIR–15–01. Washington,
DC. Available at https://www.ntsb.gov/safety/safetystudies/Documents/SIR1501.pdf (last accessed
August 22, 2022).
48 National Transportation Safety Board. 2018.
Selective Issues in School Bus Transportation
Safety: Crashes in Baltimore, Maryland, and
Chattanooga, Tennessee. NTSB/SIR–18/02 PB2018–
100932. Washington, DC. Available at https://
www.ntsb.gov/investigations/AccidentReports/
Reports/SIR1802.pdf (last accessed August 22,
2022).
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• H–11–7: Develop stability control
system performance standards for all
commercial motor vehicles and buses
with a gross vehicle weight rating
greater than 10,000 pounds, regardless
of whether the vehicles are equipped
with a hydraulic or a pneumatic brake
system.
• H–11–8: Once the performance
standards from Safety Recommendation
H–11–7 have been developed, require
the installation of stability control
systems on all newly manufactured
commercial vehicles with a gross
vehicle weight rating greater than
10,000 pounds.
G. FMCSA Initiatives
FMCSA has been engaged in activities
to advance the voluntary adoption of
AEB for heavy vehicles, primarily
through the Tech-Celerate Now (TCN)
program. This program focuses on
accelerating the adoption of Advanced
Driver Assistance Systems (ADAS), such
as AEB, by the trucking industry to
reduce fatalities and prevent injuries
and crashes, in addition to realizing
substantial return-on-investment
through reducing costs associated with
such crashes for the motor carrier.
Initiated in September 2019 and
completed in February 2022, the first
phase of this program encompassed
research into ADAS technology
adoption barriers; a national outreach,
educational, and awareness campaign;
and data collection and analysis.
Outreach accomplishments included
development of training materials for
fleets, drivers, and maintenance
personnel related to AEB technology
and return-on-investment (ROI) guides;
educational videos on ADAS braking,
steering, warning, and monitoring
technologies; a web-based TCN ADASspecific ROI calculator; four articles on
ADAS technologies; and a program
website to host the training materials.
As part of the national outreach
campaign, the program was promoted
on social media including LinkedIn and
Twitter, and FMCSA conducted
presentations and booth exhibitions at
conferences, webinars, and virtual
meetings. Recent efforts have included
discussion of a safety effective analysis
project that is using two years of
naturalistic data collected from AEB and
other ADAS technologies at the
American Trucking Associations
Technology and Maintenance Council’s
2022 Annual meeting, the 2022 Midwest
Commercial Vehicle Safety Summit, and
the 2022 Southeast Commercial Vehicle
Safety Summit. The results of this
project are expected be published late in
calendar year 2023.
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Planning is underway for the second
phase of the TCN program, which
includes an expanded national outreach
and education campaign, additional
research into the barriers to ADAS
adoption by motor carriers, and
evaluation of the outreach campaign.
IV. NHTSA and FMCSA Research and
Testing
A. NHTSA-Sponsored Research
The following are brief summaries of
some of the research NHTSA sponsored
relating to strategies to avoid heavy
vehicle collisions with lead vehicles.
The agency funded several research
efforts to assess collision avoidance
systems, including AEB.
1. 2012 Study on Effectiveness of FCW
and AEB
On August 2012, the University of
Michigan Transportation Research
Institute (UMTRI) conducted a
simulation study under a cooperative
agreement between NHTSA and AEB
supplier WABCO.49 The objective of the
study was to estimate the safety benefits
FCW and AEB systems implemented on
heavy trucks, including single-unit and
tractor-semitrailers. The study
characterized technology, estimated a
target crash population, created a
simulated reference crash database, and
assessed the impact of the technologies
in a simulated environment. These
results were then applied to the target
crash population. The study not only
simulated benefits for equipping heavy
trucks with then-available technology,
but also simulated benefits for next and
future systems that were expected to
have enhanced capabilities.
The study simulated estimates based
on next and future systems that would
utilize radar as the main sensor, and
provided haptic, auditory, and visual
warnings to the driver (just as the
current in-production system). The inproduction system could decelerate the
vehicle up to a maximum of 0.35g
without any driver intervention.
However, it could not react to fixed
objects (i.e., objects that were stationary
before they were in the range of the
radar). The primary improvements
expected for the next system included
the ability to react and brake at about
0.3g in response to fixed objects and
increased braking control authority on
stopped and moving vehicles to engage
49 Woodrooffe, J., et al., ‘‘Performance
Characterization and Safety Effectiveness Estimates
of Forward Collision Avoidance and Mitigation
Systems for Medium/Heavy Commercial Vehicles,’’
Report No. UMTRI–2011–36, UMTRI (August 2012).
Docket No. NHTSA–2013–0067–0001, available at
https://www.regulations.gov/document/NHTSA2013-0067-0001.
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the foundation brakes to produce as
much as 0.6g of longitudinal
deceleration. The study used the same
increased control authority on stopped
and moving vehicles as the next
generation system, but required the
system to more aggressively react to
fixed objects with longitudinal
deceleration of up to 0.6g.
Based on these capabilities, the study
estimated that equipping all tractorsemitrailers with AEB and FCW would
reduce fatalities relative to the base
population for current, next, and future
generation systems by 24, 44, and 57
percent, respectively. Additionally, the
predicted reduction in injuries
compared to the base population for
current, next, and future generation
systems was estimated at 25, 47, and 54
percent, respectively. The combined
annual benefit for straight truck and
tractor semitrailers, including property
damage reduction for current, next, and
future generation systems was estimated
at $1.4, $2.6, and $3.1 billion,
respectively.
The study concluded with multiple
observations. The enhancements
depicted by the next generation system
in comparison to the current generation
system were substantially larger than
when comparing the next generation to
the future generation. These
improvements were due mainly to the
ability of the system to react to fixed
vehicles and the increased braking.
Overall, this evaluation depicted that
the collision mitigation measures
studied would achieve significant
benefits.
2. 2016 Field Study
NHTSA sponsored a field study with
the Virginia Tech Transportation
Institute (VTTI) to assess the
performance of heavy-vehicle crash
avoidance systems using 150 Class 8
tractor-trailers.50 The vehicles were
each equipped with a collision
avoidance system from one of two
companies that included AEB and FCW.
The purpose of the study was to
evaluate system reliability, assess driver
performance over time, assess overall
driving behavior, provide data on realworld conflicts, and generate inputs to
a safety benefits simulation model.
The vehicles were operated by drivers
for one year with a total of over 3
million miles travelled. Each vehicle
was equipped with a data acquisition
system that collected roadway-facing
video, driver-facing video, activations,
50 See ‘‘Field Study of Heavy-Vehicle Crash
Avoidance Systems’’ (June 2016), available at
https://www.nhtsa.gov/sites/nhtsa.gov/files/
812280_fieldstudyheavy-vehiclecas.pdf (last
accessed June 3, 2022).
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and vehicle network data. About 85,000
hours of driving and 885,000 activations
were collected across all activation
types. Of the sampled 6,000 activations,
264 were AEB activations and 1,965
were impact alerts.
According to the study, safety benefits
of collision avoidance systems could be
estimated based on data describing
driver use of systems and their
responses to the activations. Since the
systems depict warnings through an
audio and visual display, a precise
model of the benefits would show how
fast drivers react and if reactions vary
based on warning type. For 84 percent
of the AEB activations, the driver
reacted prior to the alert, and 13 percent
of the time, the driver responded to the
alert. Drivers did not respond to 3
percent of the AEB activations. Over 50
percent of the false AEB activations
received driver responses. Average
driving speeds and headway distances
at the initiation of AEB activations prior
to safety-critical events were similar to
values recorded for other activations.
While at the initiation of many
warranted AEB activations, drivers had
already implemented braking, every
warranted AEB activation did not
receive a driver reaction.
The analysis included a driver
frustration assessment for each AEB
activation. This was a subjective
assessment based on whether drivers
appeared to show frustration during an
activation. Advisory warnings resulted
in lower percentages of general
frustration. The highest instances of
frustration were noted during false
activations with frustration noted 11
percent of the time.
In summary, the study found that
crash avoidance systems can be effective
in collision avoidance. Driver
performance and behavior exhibited
almost no changes over time, and there
was limited frustration with the AEB
activations. There were some limitations
in the study including varied calibration
options between the systems, no control
group, different geographical locations,
and unequal driving time amongst
participants.
3. 2017 Target Population Study
In 2017, NHTSA completed a study
on a target population for AEB in
vehicles with a GVWR over 4,536 kg
(10,000 pounds).51 The objective of the
study was to determine which forward
collisions would theoretically benefit
from AEB if all vehicles over 4,536 kg
51 See ‘‘A Target Population for Automatic
Emergency Braking in Heavy Vehicles,’’ available at
https://crashstats.nhtsa.dot.gov/Api/Public/
Publication/812390 (last accessed June 7, 2022).
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(10,000 pounds) GVWR were equipped
with the system. First, NHTSA reviewed
literature for then-existing AEB systems
manufactured by Bendix and Meritor.
Although the systems varied in some
ways, they shared a tiered functionality
approach, including the sequential use
of auditory and visible warnings,
automatic torque reduction, application
of the engine retarder, and finally
automatic brake application as
needed.52 The research efforts
concentrated on the FCW and CIB
elements.
Second, collisions were sampled from
NHTSA and FMCSA’s Large Truck
Crash Causation Study 53 for an
engineering review because this
database provides comprehensive
information on heavy vehicle collisions
in the United States. The engineering
review focused on 29 crashes from the
Large Truck Crash Causation Study that
involved injuries and fatalities to
determine whether FCW and/or CIB
would be effective in preventing the
crash. Effectivity was defined as both
reviewing engineers determining that
there was a 50 percent chance or greater
that the crash would be prevented. The
analysis determined that FCW and CIB
would both be effective in preventing 17
of the 29 crashes, much more often than
cases in which only either was effective
or neither was effective. Considering a
summary of the weighted effectiveness,
the combination of FCW and CIB were
effective in 50 percent of the cases.
While FCW alone was effective in 23
percent of cases, there was a significant
21 percent of cases where neither FCW
nor CIB was effective.54
Third, the outcomes from the first two
phases allowed for the development of
filters to identify the categories of
collisions that AEB would improve.
These filters were then implemented to
collisions in NHTSA’s crash databases
to approximate how many collisions
annually AEB could have prevented. A
combination of data from the FARS and
the GES was used for the calculations
while ensuring that an overlap in fatal
crashes was removed to prevent
duplicate tallies. Vehicle collision
information for the United States
52 See page 8 ‘‘A Target Population for Automatic
Emergency Braking in Heavy Vehicles,’’ available at
https://crashstats.nhtsa.dot.gov/Api/Public/
Publication/812390 (last accessed June 7, 2022).
53 See ‘‘Large Truck Crash Causation Study,’’
available at https://www.fmcsa.dot.gov/safety/
research-and-analysis/large-truck-crash-causationstudy-analysis-brief (last accessed October 19,
2022).
54 Additionally, there was at least one case that
consensus was not reached regarding the
effectiveness of CIB, and there was no investigation
of crashes of lower severity where only property
damage resulted.
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involving injuries and fatalities for years
2010 to 2012 was utilized from these
databases.55 Both injury-related and
fatal collisions totaled 5,457,387, and
this total was filtered to determine the
target population. The filtering
exclusions were made cautiously in
order to yield a conservative benefit
estimate. Crashes during which the
subject vehicle departed from its
original travel lane and the lead vehicle
maintained the lane were not included.
Similarly, collisions involving the lead
vehicle changing from the original lane
and the subject vehicle remaining in its
lane were excluded. Additional
exclusions included collisions on icy
and snowy roads, situations where the
lead vehicle turns from a perpendicular
street in front of the subject vehicle,
cases involving acceleration maneuvers
to avoid collision, collisions where the
lead vehicle was obscured by an object,
collisions into motorcycles, and cases
where the subject vehicle was traveling
on a curved road toward an object such
as a guardrail.
Fourth, the target population
estimated in the third phase was
modified to reflect recent and probable
future regulations. This modification
eliminated collisions that would be
avoided based on the implementation of
other required technologies that had not
yet completely proliferated in heavy
vehicles. Accounting for safety
equipment including ESC, ABS, and
speed limiters allowed for the overall
target population to be modified to
reflect the anticipated number of future
collisions. Crashes that were included
in the final future target population
were those involving heavy vehicles in
which the rear-end crash resulted in
injuries and fatalities. Further, the
crashes were refined to include only
crashes where both vehicles remained
in the original lane after the crash was
deemed imminent and collisions where
lane changes prior to crash imminency
were allowed as long as only one of the
vehicles changed lanes. Additionally,
situations where the driver attempted to
steer around the collision or used
insufficient braking were included.
After all adjustments were completed,
the study estimated a target population
of 11,499 crashes annually involving
55 LTCCS was not selected due to the age of the
crash data, for it is possible heavy vehicle collisions
differ tremendously since 2001. The UMTRI Trucks
Involved in Fatal Accidents study (https://
deepblue.lib.umich.edu/bitstream/handle/2027.42/
107389/48532_A56.pdf?isAllowed=y&sequence=1,
last accessed June 3, 2022) was excluded because
its detailed information regarding vehicle style and
driving time is only provided for collisions
involving fatalities, where data for collisions of less
severity involving only injuries would not be
available.
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7,703 injured persons and 173 fatalities.
It also discussed possible sampling error
as well as three sources of uncertainty.
However, the size of a target population
provided only an estimated upper
bound to the benefits at that time. The
report added value in the detailed
descriptions of affected crashes and
subpopulation breakouts that have
traditionally fed into benefits
estimation.
4. 2018 Cost and Weight Analysis
In 2018, Ricardo Inc. completed a
study sponsored by NHTSA that
focused on the cost and weight
implications of requiring AEB on heavy
trucks. The study aimed to determine
the product price, total system cost,
incremental consumer price, and weight
of FCW and AEB systems on heavy
trucks to provide insight into the safety
and efficiency benefits of using the
systems.56 The initial steps of the study
were vehicle research, vehicle
segregation, and vehicle selection.
Model year 2015–2018 heavy vehicles
manufactured by Ford, Cascadia, Volvo,
Daimler, and International LT were
chosen for teardown examination and
ranged in mean annual sales from
approximately 24,000 to 86,542. The
associated FCW and AEB systems
installed on these vehicles were
manufactured by Delphi Technologies,
Meritor, Bendix Commercial Vehicle
Systems, and Detroit Assurance
(Daimler).
Service technician consultations,
manuals, and OEM parts descriptions
were used to itemize components of the
FCW and AEB systems. Specific
assessments of the related displays,
sensors, mounting hardware, and other
elements of the FCW and AEB systems
were provided to prevent extraneous
parts from being included in the cost
and weight evaluations. The cost and
weight evaluations were executed by a
group of automotive system and
integration experts, cost modeling
specialists, and procurement personnel.
A bill of materials was compiled using
a ‘‘teardown’’ process to inventory the
parts, define manufacturing processes,
and ascertain materials utilized.
Specialized cost software allowed for
calculation of cost and weight.
In general, components that were not
distinct to the FCW and AEB systems
were not included in the cost and
weight evaluation. Therefore, shared
parts such as electronic control units
and wiring harnesses were not
Inc. (2018), ‘‘Cost and Weight Analysis
of Heavy Vehicle Forward Collision Warning (FCW)
and Automatic Emergency Braking (AEB) Systems
for Heavy Trucks’’ Van Buren Township, MI.
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considered as additions if they were
already incorporated into the vehicle
configuration without FCW/AEB. The
manufacturing costs were estimated,
factoring in research and development,
labor, material costs, machinery,
machine occupancy and tooling.
The five selected vehicles were the
Ford F-Series Super Duty, Freightliner
M2–106, Freightliner Cascadia,
International LT, and Volvo VNL. While
there was some overlap of similar
components, the FCW and AEB systems
in the five selected vehicles had
substantial variation amongst the system
mechanisms and functionality. Based on
these differences the vehicles were
separated into four groups, and the
average manufacturing costs and
weights were assessed for each category.
Overall, the average incremental cost to
manufacturers for these FCW/AEB
systems ranged from $44.23 to $197.51;
and associated end-user prices ranged
from $70.80 to $316.18. Additionally,
the average incremental weights ranged
from approximately 0.46 to 3.10 kg.
B. VRTC Research Report Summaries
and Test Track Data
1. Relevance of Research Efforts on AEB
for Light Vehicles
AEB was first introduced on light
vehicles. For this reason, NHTSA’s
research and testing of AEB systems
began with light vehicles and was
subsequently used to inform NHTSA’s
work on heavy vehicle AEB.
NHTSA conducted extensive research
on AEB systems to support development
of the technology and eventual
deployment in vehicles. There were
three main components to this work.
Early research was conducted on FCW
systems that warn drivers of potential
rear-end crashes with other vehicles.
This was followed by research into AEB
systems designed to prevent or mitigate
rear-end collisions through automatic
braking.
NHTSA’s earliest research on FCW
systems began in the 1990s, at a time
when the systems were under
development and evaluation had been
conducted primarily by suppliers and
vehicle manufacturers. NHTSA
collaborated with industry stakeholders
to identify the specific crash types that
an FCW system could be designed to
address, the resulting minimum
functional requirements, and potential
objective test procedures for
evaluation.57 In the late 1990s, NHTSA
57 This research was documented in a report,
‘‘Development and Validation of Functional
Definitions and Evaluation Procedures for Collision
Warning/Avoidance Systems,’’ Kiefer, R., et al.,
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worked with industry to conduct a field
study, the Automotive Collision
Avoidance System Program. NHTSA
later contracted with the Volpe National
Transportation Systems Center (Volpe)
to conduct data analyses of data
recorded during that field study.58 From
this work, NHTSA learned about the
detection and alert timing and
information about warning signal
modality (auditory, visual, etc.) of FCW
systems, and predominant vehicle crash
avoidance scenarios where FCW
systems could most effectively play a
role in alerting a driver to brake and
avoid a crash. In 2009, NHTSA
synthesized this research in the
development and conduct of controlled
track test assessments on three vehicles
equipped with FCW.59
NHTSA’s research and test track
performance evaluations of AEB began
around 2010. The agency began a
thorough examination of the state of
forward-looking advanced braking
technologies, analyzing their
performance and identifying areas of
concern or uncertainty, to better
understand their safety potential.
NHTSA issued a report 60 and a request
for comments (RFC) seeking feedback on
its CIB and DBS research in July 2012.61
Specifically, NHTSA wanted to enhance
its knowledge further and help guide its
continued efforts pertaining to AEB
effectiveness, test operation (including
how to ensure repeatability using a
target or surrogate vehicle), refinement
of performance criteria, and exploration
of the need for ‘‘false positive’’ tests to
minimize the unintended negative
consequences of automatic braking in
non-critical driving situations where a
crash was not imminent.
NHTSA considered feedback it
received on the RFC and conducted
additional testing to support further
development of the test procedures. The
agency’s work was documented in two
additional reports, ‘‘Automatic
Emergency Braking System Research
Report’’ (August 2014) 62 and ‘‘NHTSA’s
2014 Automatic Emergency Braking
(AEB) Test Track Evaluations’’ (May
2015),63 and in accompanying draft CIB
and DBS test procedures.64
In 2016, NHTSA published a report
identifying the most recurrent AEBrelevant pre-crash scenarios for heavy
vehicles. NHTSA identified the three
most recurrent situations as a heavy
vehicle moving toward a stopped lead
vehicle, a heavy vehicle moving toward
a slower moving lead vehicle, and a
heavy vehicle moving toward a lead
vehicle that is decelerating.65 These
were the same three crash scenarios that
had been identified as the most
prevalent AEB-relevant crash scenarios
for light vehicles.
2. Phase I Testing of Class 8 TruckTractors and Motorcoach
In 2016, NHTSA published its first
report on track-testing of AEB for heavy
vehicles. The previous studies
describing the test procedures for light
vehicles provided a framework for the
establishment of heavy vehicle test
procedures. Since test procedures were
not yet developed for heavy vehicles,
the goal of the research was to first
adapt existing testing protocols for light
vehicle AEB and then follow these
adapted test procedures to quantify the
performance of FCW and AEB systems
on heavy vehicles. The research was
conducted in two phases.
NHTSA’s Phase I work began with
using a combination of the specific test
situations established for NHTSA’s
NCAP for assessment of FCW and AEB
systems and a modified version of the
light vehicle test procedures to create
heavy vehicle draft research test
procedures. NCAP tests involved use of
a strikable surrogate vehicle; however,
for early heavy vehicle Phase I work,
NHTSA used a surrogate lead vehicle
comprised of canvas-covered foam to
exhibit geometric and reflective features
of the rear of a passenger car. The
testing for Phase I was performed with
four heavy vehicles outfitted with FCW
and AEB, including three Class 8 trucktractors and one Class 8 motorcoach.
Specifically, the four Class 8 vehicles
were a 2006 Volvo VNL 64T630 6x4
tractor, a 2006 Freightliner Century
Class 6x4 tractor, a 2012 Freightliner
Cascadia 6x4 tractor, and a 2007 MCI
56-passenger motorcoach (bus). Each
vehicle was equipped with ABS, ESC,
FCW, and AEB systems. The 2006 and
2012 Freightliners and the MCI
motorcoach employed a Meritor
WABCO system, and the 2006 Volvo
was equipped with a Bendix Wingman
Advanced system. In general, the FCW
and AEB systems utilized a front
bumper mounted sensor to detect
objects in front of the vehicle and a
display to warn the driver with audio
and visual alerts.
For each vehicle, NHTSA planned to
run ten tests that are summarized in
Table 8. These situations covered the
three most common AEB-relevant precrash scenarios, as well as two false
positive tests and two tests performed at
different weighted conditions.
TABLE 8—PHASE I TEST SCENARIOS
Lead vehicle
speed (km/h)
Scenario
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Lead vehicle Stopped ................................................................
Lead Vehicle Moving .................................................................
Lead Vehicle Moving .................................................................
Lead Vehicle Decelerating .........................................................
Lead Vehicle Decelerating .........................................................
Lead Vehicle Decelerating .........................................................
Steel Trench Plate False Positive .............................................
DOT HS 808 964, August 1999. Additional NHTSA
FCW research is described in Zador, P.L., et al.,
‘‘Final Report—Automotive Collision Avoidance
System (ACAS) Program,’’ DOT HS 809 080, August
2000; and Ference, J.J., et al., ‘‘Objective Test
Scenarios for Integrated Vehicle-Based Safety
Systems,’’ Paper No. 07–0183, Proceedings of the
20th International Conference for the Enhanced
Safety of Vehicles, 2007.
58 Najm, W.G., Stearns, M.D., Howarth, H.,
Koopmann, J., and Hitz, J., ‘‘Evaluation of an
Automotive Rear-End Collision Avoidance
System,’’ DOT HS 810 569, April 2006 and Najm,
W.G., Stearns, M.D., and Yanagisawa, M., ‘‘Pre-
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Subject vehicle
speed (km/h)
0
16
32
40
48
56
N/A
40
40
72
40
48
56
40
Crash Scenario Typology for Crash Avoidance
Research,’’ DOT HS 810 767, April 2007.
59 Forkenbrock, G., O’Harra, B., ‘‘A Forward
Collision Warning (FCW) Program Evaluation,
Paper No. 09–0561, Proceedings of the 21st
International Technical Conference for the
Enhanced Safety of Vehicles, 2009.
60 The agency’s initial research and analysis of
CIB and DBS systems were documented in a report,
‘‘Forward-Looking Advanced Braking Technologies:
An analysis of current system performance,
effectiveness, and test protocols’’ (June 2012).
https://www.regulations.gov, NHTSA 2012–0057–
0001.
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Lightly loaded
(number of trials)
Loaded at GVWR
(number of trials)
10
10
10
10
................................
5
5
................................
10
10
10
10
5
5
61 77
FR 39561.
62 https://www.regulations.gov,
NHTSA 2012–
0057–0037.
63 DOT HS 812 166.
64 https://www.regulations.gov, NHTSA 2012–
0057–0038.
65 Boday, C., et al., ‘‘Class 8 Truck-Tractor and
Motorcoach Forward Collision Warning and
Automatic Emergency Braking Test Track
Research—Phase I,’’ Washington, DC: National
Highway Traffic Safety Administration (June 2016).
Docket No. NHTSA-2015–0024–0004.
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TABLE 8—PHASE I TEST SCENARIOS—Continued
Lead vehicle
speed (km/h)
Scenario
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Steel Trench Plate False Positive .............................................
The test scenarios were defined by the
initial speeds of the subject vehicle and
lead vehicle, and the starting headway
distance between the vehicle was
monitored. For all the tested scenarios,
the test driver was instructed to
modulate the accelerator pedal to
maintain the desired test speed until
FCW initiated, upon which the
accelerator pedal input was removed.
Steering was applied to maintain lateral
position test tolerances to the lead
vehicle. Manual brake pedal
applications were only applied in
certain scenarios where AEB was not
designed to activate, or an impact
occurred with the leading surrogate
vehicle. Additionally, the previously
described test situations were
conducted under both a lightly loaded
condition and a fully loaded vehicle
weight condition (i.e., loaded up to the
vehicle’s GVWR). Based upon potential
damage to the subject vehicle, the
feasibility of completing each test
scenario with the specific load, and the
fact that there was no discernable
difference between the performance
under the lightly loaded and GVWR
loaded conditions in the trials executed,
some of the speed combinations were
not investigated under both loads. The
false positive tests were conducted by
driving the selected vehicles toward and
over a steel trench plate to determine if
these commonly used road construction
covers would trigger false alerts or
unintentional automatic braking.
Stationary lead vehicle testing was
limited to the 2006 Volvo, as it was
equipped with the only system that
would trigger an FCW on stationary
vehicles. At the time these evaluations
were performed, none of the systems
tested were designed to activate AEB on
stationary vehicles. During every slower
moving lead vehicle test, FCW was
activated. Additionally, every vehicle’s
AEB activated and avoided collision
during each slower moving test
performed with a subject vehicle speed
of 40 km/h, and a lead vehicle speed of
16 km/h.
The lead vehicle decelerating test was
used to evaluate all four heavy vehicles,
but multiple test adjustments had to be
applied. For the lead vehicle
decelerating test performed with both
the subject and lead vehicle speeds of
40 km/h, the lead vehicle was slowed to
8 km/h instead of a stop to account for
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Subject vehicle
speed (km/h)
N/A
72
the failure of the subject vehicles to
activate AEB for stopped vehicles. Once
the change was implemented, both the
FCW and the AEB systems were
activated, and speeds were reduced.
Collisions between the subject and lead
vehicle did occur, but testing of this
scenario mainly led to the observation
that the test procedure’s headway would
also have to be adjusted since heavy
vehicles have different braking
capabilities than light vehicles.
The steel trench plate false positive
test was performed using the 2006
Volvo, 2006 Freightliner, and 2007 MCI
at 40 km/h and 72 km/h.66 For both
velocities examined, the 2006
Freightliner and 2007 MCI exhibited no
false positives in all five trials.
However, the 2006 Volvo triggered
unnecessary auditory warnings in all
five trials for both velocities. None of
the false positive testing trials resulted
in AEB system activation.
During this early testing, the surrogate
lead vehicle was towed onto the test
track and fixed laterally in the test lane
via a low-profile plastic monorail track.
Initially, the test system employed a
low-stretch rope to pull the surrogate
lead vehicle by a tow vehicle. This
configuration performed well in the
slower moving lead vehicle situation
because the lead vehicle moves at a
constant velocity, allowing the tow rope
to stay in tension. In contrast, when
testing the lead vehicle decelerating
scenario, the tension in the tow rope
was not maintained once the tow
vehicle decelerated, and subsequently
the tow rope was prone to becoming
stuck under the surrogate lead vehicle.
This issue resulted in a loss of surrogate
lead vehicle lateral stability and
consequently decreased the test
repeatability.
To address this shortcoming, the foam
surrogate lead vehicle was replaced
with a vertical cylinder wrapped with a
layer of radar reflective material secured
to the top of a movable platform with
more consistent and stable deceleration
properties. However, because the
cylinder was not representative of a real
vehicle, this was identified as needing
further development and modification
of the test protocols.
66 The 2012 Freightliner was not evaluated with
steel trench plate scenario due to the short window
that the vehicle was available for testing.
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Lightly loaded
(number of trials)
Loaded at GVWR
(number of trials)
5
5
A significant portion of this early AEB
testing focused on developing draft
research test procedures that could be
used to safely and objectively assess
AEB performance. The development
history of test protocols is important for
two reasons. First, it explains how
NHTSA came to the conclusion to
propose the performance parameters
described in the notice and its basis that
the performance requirements are
objective and practicable. Second, it
provides some context as to some of the
limitations of early performance
evaluations of AEB for heavy vehicles.
In general, this initial phase of research
demonstrated that the scenarios were
generally repeatable and practical, and
the tests showed additional
development would potentially result in
better controlled deceleration and
stability of the lead vehicle.
3. Phase II Testing of Class 8 TruckTractors
NHTSA’s primary objectives of the
Phase II efforts were to continue to
develop the FCW and AEB test
procedures executed in Phase I such
that they could be effectively utilized on
a closed-course track test to assess
performance of heavy vehicle FCW and
AEB systems. For this testing, NHTSA
used four Class 8, truck-tractors, three of
which were from Phase I. The fourth
vehicle from Phase I, the MCI
motorcoach, was replaced with a 2016
Freightliner. Specifically, these subject
vehicles were a 2016 Freightliner, a
2012 Freightliner, a 2006 Volvo, and a
2006 Freightliner. Like in Phase I, all
vehicles were outfitted with ABS, ESC,
FCW, and AEB systems. Both the 2006
and 2012 Freightliners employed the
Meritor WABCO system, the 2016
Freightliner had the Detroit Assurance
Safety System, and the 2006 Volvo
utilized the Bendix Wingman Advance
system. All AEB systems on the selected
vehicles utilized radar installed on the
front bumper and each AEB system
provided auditory and visual alerts. For
Phase II testing, NHTSA used the test
scenarios from Phase I; however, a
second false positive test scenario was
added. Specifically, NHTSA
investigated a pass-through test from
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Europe’s AEB requirements 67 involving
a subject vehicle being driven in a
central lane between two parked
vehicles.
While other standards 68 were
considered for this research study, the
use of United States collision data and
different testing goals led to
establishment of specific test
procedures. While vehicle test speeds
were similar, with some overlap,
NHTSA’s test procedures included
higher velocity tests to be executed at 55
km/h with more specifications
governing the test conditions and test
completion. NHTSA’s Phase II test
scenario matrix is summarized in Table
9.
Phase II also further enhanced the
testing of Phase I by implementing a
new strikable surrogate vehicle (SSV)
system as the lead vehicle. The SSV
system was created for NHTSA’s light
vehicle AEB assessment and was
engineered to enhance test repeatability
and lateral stability in higher velocity
tests.
TABLE 9—PHASE II TEST SCENARIOS
Lead vehicle
speed
(km/h)
Scenario
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Lead Vehicle Stopped ...............................................................
Lead Vehicle Moving .................................................................
Lead Vehicle Moving .................................................................
Lead Vehicle Decelerating .........................................................
Lead Vehicle Decelerating .........................................................
Steel Trench Plate False Positive .............................................
Steel Trench Plate False Positive .............................................
Stationary Vehicle False Positive ..............................................
Subject vehicle
speed
(km/h)
0
0
35
40
55
N/A
N/A
N/A
Lightly loaded
(number of trials)
40
40
75
40
55
40
75
50
6
8
8
8
6 or 8
8
8
8
Loaded at GVWR
(number of trials)
8
8
8
8
6 or 8
8
8
8
The SSV served as the lead vehicle or
the vehicle test device (VTD) in the AEB
tests. The rear of the SSV was designed
to depict features of a typical passenger
car. The carbon fiber surrogate
exemplified these aspects, considering
physical measurements, reflective
properties, and visual characteristics. Its
structure was not only developed to be
detected as a real vehicle by the AEB
systems, but it was also intended to
endure wind gusts and recurrent
impacts up to approximately 40 km/h.
The required surrogate test velocities
and deceleration of the VTD were
achieved by a tow vehicle equipped
with a brake controller in conjunction
with a towed two-rail track used to
move the SSV during the test.
NHTSA implemented changes in the
test procedures from Phase I to Phase II.
The Phase II test procedures contained
more detail as input from within
NHTSA and data collected during both
phases of heavy vehicle research were
used to develop and refine the
procedures. For example, the test
procedures contained structure for test
scenario descriptions, minimum data
channels to collect, and general testing
requirements (e.g., ambient temperature
range, wind, speed, brake burnish, etc.).
Definitions were added for when the
initial test conditions started, and more
detail was added to the definition of
when a test trial ended. The test
conditions were established to be on
dry, straight roadways in the daylight,
based on a previous analysis of crash
data and observed safety critical events
in field operation testing. FCW
activation, AEB activation, collision
detection, and accelerator pedal release
time were measured in the tests. Similar
to Phase I, the testing of each scenario
occurred under two different load
conditions.
After reviewing the Phase I test
outcomes, NHTSA determined that the
lead vehicle stopped scenario could
only be assessed by the latest model
year test vehicle outfitted with a capable
AEB system. In Phase II, the subject
vehicle traveled 40 km/h and
approached a stationary lead vehicle in
the same lane. Valid trials required the
driver to remain centered in the
traveling lane and continue driving at
the target velocity until AEB was
triggered. Once AEB was triggered, the
test driver fully released the accelerator
pedal, and the driver was not allowed
to use the brake pedal of the test vehicle
unless the vehicle collided with the lead
vehicle or if the AEB system completely
stopped the vehicle. The results showed
that FCW was activated, followed by
automatic braking by the AEB system in
all 8 trials performed under the GVWR
condition.
The lead vehicle moving test situation
was evaluated at multiple velocity
combinations for all four test vehicles.
During this test, the subject test vehicle
traveled at 40 km/h or 75 km/h and
approached a slower-moving lead
vehicle traveling at 15 km/h or 35 km/
h, respectively, in the same lane. Valid
trials required the driver to remain
centered in the traveling lane and
continue driving at the target velocity
until AEB was triggered. Once AEB was
triggered, the test driver fully released
the accelerator pedal. Testing for this
scenario was conducted for both lightly
loaded and GVWR conditions. All of the
vehicles tested consistently issued FCW
alerts and activated the AEB systems;
however, impacts occurred.
The lead vehicle decelerating
situation was executed with all the test
vehicles except the 2006 Volvo due to
its Phase I performance. Two initial
velocity and initial headway
combinations of the subject and lead
vehicles were tested (i.e., 40 km/h and
80 m; 55 km/h and 23 m). After a short
period of steady state driving using
constant speeds and a constant
headway, the lead vehicle was braked at
approximately 0.3g while traveling in
the same lane as the subject vehicle. The
subject vehicle driver kept the subject
vehicle centered in the traveling lane
and continued driving until AEB was
triggered. Under both the lightly loaded
and GVWR load conditions testing was
completed.
The lead vehicle decelerating test
scenario with initial test speeds of 55
km/h and 23 m of headway presented
the greatest challenges when compared
to other tests. In Phase II, the initial
headway was changed from 30.5 m to 23
67 United Nations, ‘‘Uniform provisions
concerning the approval of motor vehicles with
regard to the Advanced Emergency Braking Systems
(AEBS)’’ 2013. Available at https://unece.org/
fileadmin/DAM/trans/main/wp29/wp29regs/2013/
R131e.pdf (last accessed February 10, 2023).
68 The following were among the standards
considered: International Organization for
Standardization (ISO) 22839:2013, ‘‘Intelligent
transport systems—Forward vehicle collision
mitigation systems—Operation, performance, and
verification requirements; ISO 15623:2013,
‘‘Intelligent transport systems—Forward vehicle
collision warning systems—Performance
requirements and test procedures,’’ and SAE
International recommended practice J3029,
‘‘Forward collision warning and mitigation vehicle
test procedure—Truck and bus.’’
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m to keep the lead vehicle from
transitioning to a stopped lead vehicle
test scenario near the end of a test trial,
as it did in Phase I testing with a
headway of 30.5 m. Testing for this
scenario was conducted for both lightly
loaded and GVWR conditions and all
four vehicles. All of the vehicles
consistently issued FCW alerts and
activated the AEB systems; however,
most tests resulted in impact.
Two false positive test types were also
conducted. The steel trench plate
scenario was executed at 40 km/h and
75 km/h for all test vehicles. Each
vehicle was evaluated in the GVWR
load condition, but only the 2016
Freightliner was also assessed in the
lightly loaded condition. Most of the
vehicles did not exhibit any FCW or
AEB activations in these tests. However,
one vehicle’s FCW/AEB system
perceived the steel trench plate as a
stationary object on the path of travel
and the reaction to this false positive
detection was not consistent in terms of
warning time, brake initiation time, and
deceleration level. The second test
involved two stationary vehicles in
lanes on either side of the test vehicle’s
travel lane; and only the 2012
Freightliner and the 2016 Freightliner
were evaluated under the GVWR load
condition. Neither vehicle exhibited any
false FCW or AEB activations in this
test.
Overall, the Phase II test results
demonstrated the ability of the vehicles
and AEB systems tested to avoid contact
in the lead vehicle stopped and lead
vehicle moving test scenarios at the
different velocities and achieve no
collisions. These capabilities extended
to the lead vehicle decelerating tests
performed at 40 km/h and a headway of
80 m. In contrast, there was a much
lower likelihood of these vehicles
avoiding contact with the lead vehicle
using an initial speed of 55 km/h and a
headway of 23 m.
4. NHTSA’s 2018 Heavy Vehicle AEB
Testing
NHTSA conducted test track research
in 2017 and 2018 on heavy vehicles
equipped with FCW and AEB. This
section describes the third phase of
NHTSA’s heavy vehicle testing and the
results from three single-unit trucks.
These trucks included a class 3 2016
Freightliner 3500 Sprinter, a class 6
2017 International 4300 SBA 4x2, and a
class 7 2018 Freightliner M2–106. The
main goal of this third phase was to
develop objective test procedures for
evaluating the performance of heavy
vehicles equipped with FCW and AEB
systems on a closed course test track.
TABLE 10—PHASE III TEST SCENARIOS
Lead vehicle
speed
(km/h)
Scenario
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Lead Vehicle Stopped ...............................................................................................................
Lead Vehicle Moving .................................................................................................................
Lead Vehicle Moving .................................................................................................................
Lead Vehicle Decelerating .........................................................................................................
Lead Vehicle Decelerating .........................................................................................................
Steel Trench Plate False Positive .............................................................................................
Steel Trench Plate False Positive .............................................................................................
Stationary Vehicle Pass-Through False Positive ......................................................................
In this third phase of research, the
newly developed heavy vehicle AEB
test procedures included test conditions
where the driver applies the subject
vehicle brakes while approaching a lead
vehicle, but with an input insufficient to
prevent a rear-end crash, to complement
the previously developed scenarios.
The 2017 International 4300 was
outfitted with a Bendix system which
includes FCW and AEB. This system
was enhanced since Phase II of
NHTSA’s research where, in Phase III, it
used camera and radar to engage
automatic emergency braking and
demonstrated the ability to respond to
traveling and stationary vehicles. The
FCW provided alerts at velocities greater
than 8 and 15 km/h for moving and
stationary objects, respectively. For the
AEB system to be engaged, the vehicle
had to travel above 25 km/h.
The 2018 Freightliner M2–106 was
outfitted with an OnGuardACTIVE
Collision Mitigation system which
features FCW and AEB. This system
used radar to engage automatic
emergency braking and displayed the
ability to respond to traveling and
stationary vehicles. The FCW provided
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alerts with visual and auditory cues and
a braking warning was issued when the
AEB was activated. In order for the AEB
system to be engaged, the vehicle had to
travel above 25 km/h.
The study concluded that the test
procedures were reproducible and
appropriate for heavy vehicles outfitted
with FCW and AEB systems. After
Phase II, the test procedures and
scenarios were updated and applied to
heavy vehicles with different weight
classifications. The inclusion of heavy
vehicles with updated AEB systems in
Phase III allowed for evaluation of more
systems in the lead vehicle stopped
scenario; during the lead vehicle
stopped evaluations with no driver
braking, at least one vehicle experienced
no collisions for all trials tested. This
showed improvement in comparison to
the prior phase, which was only able to
test lead vehicle stopped on one vehicle
and resulted in multiple collisions. The
lead vehicle moving scenario test results
also displayed improvement where the
percentage of collisions decreased in
comparison to Phase II. Overall, the
outcomes showed that the FCW/AEB
systems have the capacity for being able
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0
15
35
40
55
N/A
N/A
N/A
Subject vehicle
speed
(km/h)
Initial
headway
(m)
40
40
75
40
55
40
75
50
55
35
56
80
23
56
105
60
to decrease rear-end collisions by
exhibiting velocity reductions before a
collision or avoiding contact with a lead
vehicle entirely. While some FCW false
positives were observed, the overall
results depicted that the systems have
the ability to avoid collision on the test
track.
The results of this research show that
the test procedures are applicable to
many heavy vehicles and indicate that
performance improvements in heavy
vehicles equipped with these safety
systems can be objectively measured.69
Further, this was the first phase of the
series that was able to apply the test
procedures to single-unit trucks across
multiple weight classifications; and new
test scenarios were added.
5. NHTSA’s Research Test Track
Procedures
NHTSA’s most recently published
heavy vehicle AEB research test track
69 Salaani, M.K., Elsasser, D., Boday, C.,
‘‘NHTSA’s 2018 Heavy Vehicle Automatic
Emergency Braking Test Track Research Results,’’
SAE International. J Advances & Current Practices
in Mobility 2(3):1685–1704, 2020, doi:10.4271/
2020–01–1001.
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procedures were published in March
2019 and evaluate AEB performance in
crash-imminent scenarios both with and
without manual brake pedal
applications.70 These procedures, with
some modification, form the basis for
the proposed test procedure in this
NPRM.
The test procedures were based upon
prior research and include the lead
vehicle stopped, lead vehicle moving,
and lead vehicle decelerating test
scenarios, as well as the steel trench
plate and stationary vehicles false
positive scenarios. The testing was
divided into three phases. First, the
subject vehicle and the lead vehicle are
situated on the test track to the proper
location and test velocity. The second
stage involves determining whether the
vehicles have met the proper starting
test conditions to achieve valid and
reproducible test outcomes. The third
and final stage serves to assess test
validity and system performance as well
as response to any FCW or AEB triggers.
In the research test procedure, if an
invalid test is detected, the test is
repeated until at least seven valid test
attempts are completed. Testing was
executed during daylight, avoiding
inclement weather and irrelevant
obstructions such as overhead signs,
bridges, overpasses, etc. For test
procedures that include manual brake
pedal applications, the pedal was
displaced at a rate of 254 mm/s to
achieve a target longitudinal
acceleration of ¥3.0 m/s2, simulating a
manual brake pedal application of a
panicked driver. Test procedures for
brake pedal input characterization and
verification assessment are described for
checking uniformity and to ensure the
set braking magnitude and response can
be achieved.
The lead vehicle stopped test scenario
requires the test subject vehicle to be
driven toward the stationary lead
vehicle at 40 km/h. The subject vehicle
is to maintain its velocity and relative
lateral position to the straight testing
path as it advances toward the lead
vehicle. When the time to collision is
equal to 5 seconds there is a nominal
separation distance of 56 m between the
front of the subject vehicle and the rear
of the lead vehicle. Once braking is
initiated, the accelerator pedal input of
the subject vehicle is discontinued fully
within 0.5 seconds after the start of
70 Elsasser, D., Salaani, M.K., & Boday, C., ‘‘Test
track procedures for heavy-vehicle forward
collision warning and automatic emergency braking
systems,’’ Report No. DOT HS 812 675, Washington,
DC: National Highway Traffic Safety
Administration (March 2019). Available at https://
rosap.ntl.bts.gov/view/dot/42186/dot_42186_
DS1.pdf (last accessed June 28, 2022).
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braking. For lead vehicle stopped tests
performed with insufficient brake pedal
applications, the brake pedal is applied
at a time to collision of 1.51 seconds.
The point at which the brake pedal rate
exceeds 50 mm/s is used to define the
beginning event of brake pedal input.
The conclusion of testing is marked by
a collision between the subject and lead
vehicle or the subject vehicle stopping
prior to colliding with the lead vehicle.
The test procedures are repeated until
seven valid test trials are obtained for
each lead vehicle stopped test with and
without brake pedal applications, to
obtain a total of 14 valid tests.
The test procedure for the lead
vehicle moving scenario is similar for its
two vehicle speed combinations. The
subject vehicle travels to reach the target
speed of 40 or 75 km/h for a minimum
of 1 second; and the lead vehicle travels
at 15 or 35 km/h, respectively. Prior to
approaching the lead vehicle there
should be a separation distance of at
least 100 m. Additionally, by a time to
collision equal to 5 seconds, the
separation range is 35 m for 40 km/h
and 56 m for 75 km/h. Once the subject
vehicle encounters the lead vehicle and
braking is automatically initiated, the
subject vehicle accelerator pedal was
fully released within 0.5 seconds.
The lead vehicle decelerating test
procedure starts with the subject vehicle
traveling toward the lead vehicle while
maintaining an 80 m separation
distance. Both the subject vehicle and
the lead vehicle are required to reach
and maintain a velocity of 40 km/h for
at least 1 second while keeping the
headway distance. Once the subject
vehicle encounters the lead vehicle and
braking is initiated, the subject vehicle
accelerator pedal was fully released
within 0.5 seconds. This test procedure
is repeated with similar steps for a 55
km/h velocity and a 23 m separation
distance.
In order to evaluate false positives,
the steel trench plate test scenario was
executed at 40 and 75 km/h, and the
stationary vehicles test was completed
at 50 km/h. For the seven test trials
performed at 40 and 75 km/h, a short
edge of the rectangular steel trench plate
was centered on the roadway about the
x-axis. The subject vehicle was driven
toward the steel trench plate such that
an initial 110.0 m headway existed, and
a nominal velocity of 40 or 75 km/h was
maintained for at least 1.0 second. The
test initial test condition began when
the separation distance between the
subject vehicle and steel trench plate
was 56 m and 105 m for 40 and 75 km/
h, respectively. Once the subject vehicle
encountered the steel trench plate at a
headway of 16.83 or 40.88 m for 40 and
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Sfmt 4702
75 km/h, respectively, the brakes of the
subject vehicle were engaged. The test
ends when either the subject vehicle
drives over the steep trench plate or the
subject vehicle stops before crossing
over the steel trench plate.
The preliminary conditions of the
stationary vehicles test involved two
vehicles parked with a lateral separation
of 4.5 m. These two vehicles were faced
in the forward direction of the test track
and were aligned. The subject vehicle
was driven along the test track with a
100.0 m headway from the stationary
vehicles. The subject vehicle was then
driven to maintain a velocity of 50 km/
h for at least 1.0 second. The starting
test condition is a headway of 60 m
where the steering wheel of the subject
vehicle was controlled to center the
vehicle along the test track. Once the
subject vehicle encountered the
stationary vehicles at a range of
approximately 23.74 m the subject
vehicle accelerator pedal was fully
released within 0.5 seconds of the
initiation of braking.
6. 2021 VRTC Testing
The test track data that follows
represents vehicle performance with the
latest generation AEB systems and the
procedures and conditions proposed in
this NPRM largely match the procedures
and conditions used for this testing.
2021 Freightliner Cascadia
The 2021 Freightliner Cascadia was
tested under the lead vehicle stopped,
lead vehicle moving, and lead vehicle
decelerating scenarios at the NHTSA
VRTC in 2021. The GVT was used as the
lead vehicle in these test scenarios. The
lead vehicle stopped scenario was
executed at multiple initial subject
vehicle velocities from 20 km/h up to 95
km/h. While contact with the VTD
occurred at 20, 25, 30, and 35 km/h,
there were measurable speed
reductions. At test velocities between 40
and 85 km/h, no collisions were
observed. Collisions also occurred at 90
and 95 km/h, but the FCW at both
speeds was issued earlier than 2
seconds before contact. Ten additional
test trials were conducted at 40 km/h,
and only one trial resulted in contact.
Four additional test trials were executed
at 50, 60, 70, 80, and 85 km/h; in all
four trials, there were no collisions at
three speeds and one collision at two
speeds (i.e., 80 and 85 km/h,
respectively) which ultimately resulted
in a speed reduction when compared to
the other trials.
The lead vehicle moving scenario was
performed at several combinations of
subject vehicle and lead vehicle initial
speeds. The first set of eight trials
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involved the subject vehicle at a range
of velocities of 30 km/h to 90 km/h and
the initial speed of the lead vehicle was
20 km/h for each. Contact occurred only
at the 30 and 60 km/h test velocities.
The initial speeds for the subject vehicle
and lead vehicle for the second set of
eight trials was 40 and 15 km/h,
respectively. One of these trials ended
in a collision and this run exhibited a
notably lower speed reduction when
compared to the other trials. The third
and fourth sets of trials included subject
vehicle and lead vehicle initial velocity
combinations of 75 and 35 km/h and 80
and 12 km/h, respectively, and contact
was avoided in all trials. For the lead
vehicle decelerating scenario collision
was avoided for all trials during the 40
km/h test. Impact occurred during four
43197
out of five runs in the 50 km/h test with
an initial headway of 18 m. However, at
the longer headway lengths of 21, 23,
25, and 40 m there were no collisions
during the 50 km/h tests. Additionally,
contact was avoided for the 80 km/h test
with headway lengths of 23, 25, 28, 40,
and 45 m.
TABLE 11—2021 FREIGHTLINER CASCADIA TEST TRACK SCENARIOS
Lead vehicle
speed
(km/h)
Scenario
Lead
Lead
Lead
Lead
Lead
Lead
Lead
Lead
Lead
Lead
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Vehicle
Stopped .......................................................................................................................................
Moving .........................................................................................................................................
Moving .........................................................................................................................................
Moving .........................................................................................................................................
Moving .........................................................................................................................................
Moving .........................................................................................................................................
Decelerating .................................................................................................................................
Decelerating .................................................................................................................................
Decelerating .................................................................................................................................
Decelerating .................................................................................................................................
2021 Ram 5500
The class 5 2021 Ram 5500 was tested
under the lead vehicle stopped, lead
vehicle moving, and lead vehicle
decelerating scenarios at the NHTSA
VRTC in 2022. The tests performed for
these scenarios involved no manual
brake application; and the GVT was
used as the lead vehicle. For the lead
vehicle stopped scenario, the Ram truck
avoided collisions at 10, 20, 30, 40 km/
h, while impact occurred during two of
the five trials in the 50 km/h test,
although there was an approximately 80
percent reduction in speed. In general,
these results seemed to align with
limitations described in the vehicle
owner’s manual that indicated that the
system works up to 50 km/h. Testing up
to 80 km/h was not completed to avoid
damage to the subject vehicle and test
equipment. During the lead vehicle
moving scenario, the truck avoided
contact at 30, 40, 50, 60, 70, and 80 km/
h. Impact did occur at 90 km/h, though
there was a speed reduction of 63
percent. At 50 km/h, the lead vehicle
decelerating scenario resulted in
consecutive impacts with some speed
reduction. Due to the repeated
collisions, testing was discontinued to
prevent damage to the subject vehicle
and the GVT.
0
20
15
35
12
32
40
50
55
80
Subject vehicle
speed
(km/h)
20–95
30–90
40
75
80
80
40
50
55
80
NHTSA also tested The Ram 5500
under the three scenarios with manual
brake application. The lead vehicle
stopped scenario resulted in avoidance
of contact for all trials at 30, 40, and 60
km/h. Collision did occur at 50 km/h,
though there was a speed reduction of
approximately 80 percent. The lead
vehicle moving scenario resulted in
impact avoidance for all 40 to 90 km/
h trials, but impact did occur during the
100 km/h test. For the lead vehicle
decelerating scenario, impact occurred
during the 50 km/h test with an initial
headway of 40, 32, and 23 m. Collision
also occurred for the 80 km/h test with
a headway of 40 m.
TABLE 12—2021 RAM 5500 TEST TRACK SCENARIOS
Lead vehicle
speed
(km/h)
Scenario
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Lead
Lead
Lead
Lead
Vehicle
Vehicle
Vehicle
Vehicle
Stopped .......................................................................................................................................
Moving .........................................................................................................................................
Decelerating .................................................................................................................................
Decelerating .................................................................................................................................
In general, no single vehicle avoided
collisions at all speeds in the tested
scenarios. While one vehicle may have
performed better at lower speeds and
the other better at higher speeds, the
combination of results from the
individual vehicles showed positive
results over a range of speeds. Overall,
the performance demonstrated that the
AEB technology has improved over
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0
20
50
80
Subject vehicle
speed
(km/h)
10–60
30–100
50
80
time, as shown in Tables 13 and
14.71 72 73 74
71 Phase 1—Boday, C., et al., ‘‘Class 8 TruckTractor and Motorcoach Forward Collision Warning
and Automatic Emergency Braking Test Track
Research—Phase I,’’ Washington, DC: National
Highway Traffic Safety Administration (June 2016).
Docket No. NHTSA-2015–0024–0004.
72 Phase II- U.S. DOT/NHTSA- Class 8 TruckTractor and Motorcoach Forward Collision Warning
and Automatic Emergency Braking System Test
Track Research- Draft Report. Docket No. NHTSA–
2015–0024–0006.
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Fmt 4701
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73 Phase III—Salaani, M.K., Elsasser, D., Boday,
C., ‘‘NHTSA’s 2018 Heavy Vehicle Automatic
Emergency Braking Test Track Research Results,’’
SAE International. J Advances & Current Practices
in Mobility 2(3):1685–1704, 2020, doi:10.4271/
2020–01–1001.
74 This information is available in the report titled
‘‘NHTSA Heavy Vehicle AEB Test Track
Performance Data Summary Report—2022,’’ placed
in the docket identified in the heading of this
NPRM.
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TABLE 13—TECHNOLOGY IMPROVEMENT OVER TIME
[Class 7–8]
Class 7–8 heavy vehicle capability
1st period—
introduction
2nd period—
2nd
generation
(2015)
FCW and AEB activate for moving vehicles .................................................................................
AEB can avoid contact at test speeds up to 80 km/h in lead vehicle moving scenarios .............
AEB can avoid contact at test speeds greater than 80 km/h in lead vehicle moving scenarios
FCW alerts for stopped vehicles ...................................................................................................
AEB activates for stopped vehicles ...............................................................................................
AEB can avoid contact at test speeds up to 80 km/h in lead vehicle stopped scenarios ............
AEB can avoid contact at test speeds greater than 80 km/h .......................................................
Yes .................
No ..................
No ..................
Yes .................
No ..................
No ..................
No ..................
Yes .................
Yes .................
N/A .................
Yes .................
Yes .................
No ..................
No ..................
Current
(2022)
Yes.
Yes.
Yes.
Yes.
Yes.
Yes.
Yes.
TABLE 14—TECHNOLOGY IMPROVEMENT OVER TIME
[Class 3–6]
Class 3–6 heavy vehicle AEB capability
Up to 2015
FCW and AEB activate for moving vehicles .............................................................................................................
AEB can avoid contact at test speeds up to 80 km/h in lead vehicle moving scenarios .........................................
AEB can avoid contact at test speeds greater than 80 km/h in lead vehicle moving scenarios ..............................
FCW alerts for stopped vehicles ...............................................................................................................................
AEB activates for stopped vehicles ...........................................................................................................................
AEB can avoid contact at test speeds up to 80 km/h in lead vehicle stopped scenarios ........................................
AEB can avoid contact at test speeds greater than 80 km/h ...................................................................................
Yes .................
No ..................
No ..................
Yes .................
No ..................
No ..................
No ..................
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C. NHTSA Field Study of a New
Generation Heavy Vehicle AEB System
NHTSA has an ongoing field study
with VTTI that aims to collect
naturalistic driving data of at least 150
heavy vehicles over a one-year
timeframe. The goal is to collect data
from each driver participant for a threemonth segment of the year. This
research has very similar parameters
and objectives as those described above
for the ‘‘Field Study of Heavy-Vehicle
Crash Avoidance Systems’’ study.
However, several years have elapsed
since the data were collected for the
prior study; and the trucks included in
this ongoing research project are
equipped with newer generation AEB
systems, including stationary object
braking and system integration into
instrument clusters.
The data acquisition systems installed
on the heavy vehicles will allow VTTI
to sample various system activations
including AEB, stationary object alerts
and FCWs. The focus of the study’s realworld data collection and analysis is to
ascertain an understanding of vehicle
performance, driver behavior, and
driver adaptation. VTTI is evaluating
Bendix Commercial Vehicle Systems
and Detroit Assurance (Daimler)
systems and the five objectives include
evaluation of system reliability,
assessment of driver performance over
time, assessment of overall driving
behavior, collection of data on realworld conflicts, and generation of
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inputs to a safety benefits simulation
model.
Preliminary results from the driver
survey responses indicate that many
drivers agree that collision mitigation
technology makes drivers safer.
Approximately 50 percent of drivers
surveyed at least slightly agree that AEB
is beneficial and helps drivers avoid a
crash.75
V. Need for This Proposed Rule and
Guiding Principles
A. Estimating AEB System Effectiveness
In developing this NPRM, NHTSA has
examined the effectiveness of AEB,
proposing only those amendments that
contribute to improved crash safety, and
have considered the principles for
regulatory decision-making set forth in
Executive Order 12866 (as amended),
Regulatory Planning and Review.
The effectiveness of AEB indicates the
efficacy of the system in avoiding a rearend crash. This NPRM proposes to
require heavy vehicles to have AEB
systems that enable the vehicle to
completely avoid an imminent rear-end
collision under a set of test scenarios.
One method of estimating effectiveness
would be to perform a statistical
analysis of real-world crash data and
observe the differences in statistics
between heavy vehicles equipped with
AEB and those not equipped with AEB.
information is available in a report titled
‘‘HV AEB Driver Exit Survey Summary as of August
31, 2022,’’ which has been placed in the docket for
this rulemaking.
PO 00000
75 This
Frm 00026
Fmt 4701
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2016–2022
Yes.
Yes.
Yes.
Yes.
Yes.
No.
No.
However, this approach is not feasible
currently due to the low penetration rate
of AEB in the on-road vehicle fleet.
Consequently, NHTSA estimated
effectiveness of AEB systems using
performance data from the agency’s
vehicle testing. The agency assessed
effectiveness against all crash severity
levels collectively, rather than for
specific crash severity levels
(i.e.,*COM028* minor injury versus
fatal).
The performance data derived from
four different test vehicles was used to
estimate AEB effectiveness,76 and the
agency is continuing its effort to test a
larger variety of vehicles to further
evaluate AEB system performance.
These vehicles were subject to the same
test scenarios (stopped lead vehicle,
slower-moving lead vehicle,
decelerating lead vehicle) that are
proposed in this NPRM, and
effectiveness estimates are based on
each vehicle’s capacity to avoid a
collision during a test scenario. For
example, if a vehicle avoided colliding
with a stopped lead vehicle in four out
of five test runs, its effectiveness in that
scenario would be 80 percent. The test
results for each vehicle were combined
76 This information is available in the report titled
‘‘NHTSA Heavy Vehicle AEB Test Track
Performance Data Summary Report—2022,’’ placed
in the docket identified in the heading of this
NPRM.
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into an aggregate effectiveness value by
vehicle class range and crash scenario,
as displayed in Table 15.
TABLE 15—AEB ESTIMATED EFFECTIVENESS (PERCENT)
[By vehicle class range and crash scenario]
Stopped lead
vehicle
Vehicle class range
7–8 .............................................................................................................................................
3–6 .............................................................................................................................................
As shown in Table 15, after
aggregating class 7 and class 8 together,
the agency has estimated AEB would
avoid 38.5 percent of rear-end crashes
for the stopped lead vehicle scenario,
and 49.2 percent of slower-moving and
decelerating lead vehicle crashes. For
class 3–6, AEB is estimated to be 43.0
percent effective against stopped lead
vehicle crashes and 47.8 percent against
slower-moving and decelerating lead
vehicle crashes. These effectiveness
values are the values NHTSA used for
assessing the benefits of this proposed
rule.
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B. AEB Performance Over a Range of
Speeds Is Necessary and Practicable
The performance requirements
proposed in this NPRM are designed
around the goal of realizing as much of
the safety potential of AEB systems,
while remaining realistic and
practicable both economically and
technically. AEB performance
guidelines created outside of the
agency’s rulemaking process appear not
to have been created with these same
goals, and thus may not represent the
optimal balance of safety and
practicability. Several AEB performance
tests developed in the private sector are
limited to a maximum test speed of
around 40 km/h (25 mph), and do not
test the capability of AEB system at
highway speeds.77 78
NHTSA considered two primary
factors in selecting the proposed test
speed ranges. The first factor is the
practical ability of AEB technology to
consistently operate and avoid contact
with a lead vehicle at the widest
reasonable range of speeds. A larger
range of speeds would likely yield more
safety benefits and would more
77 IIHS Autonomous Emergency Braking Test
Protocol (Version I). Available at https://
www.iihs.org/media/a582abfb-7691-4805-81aa16bbdf622992/REo1sA/Ratings/Protocols/current/
test_protocol_aeb.pdf. (last accessed August 5,
2022).
78 SAE International Forward Collision Warning
and Mitigation Vehicle Test Procedure—Truck and
Bus J3029_201510. (For more details, see https://
www.sae.org/standards/content/j3029_201510) (last
accessed August 5, 2022).
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thoroughly test the capabilities of the
AEB system. Furthermore, as observed
in vehicle testing for NHTSA research,
AEB performance during testing at
higher speeds does not necessarily
indicate what the same system’s
performance will be at lower speeds.
For example, NHTSA’s testing of the
2021 Freightliner Cascadia truck
showed that the AEB system was able to
avoid a collision with the lead vehicle
at test speeds of 40 to 85 km/h, but not
at speeds below 40 km/h. Thus, testing
over a range of speeds is necessary to
more fully assess AEB performance.79
The second factor is the practical
limit of safely conducting vehicle tests
of AEB systems. Test data indicates that
AEB performance is less consistent,
becoming less likely to avoid a collision
when test speeds approach or exceed
the proposed upper limits, indicating
that testing at higher speeds than
proposed would be beyond
technological feasibility.80
NHTSA’s testing must be safe and
repeatable as permitted by track
conditions and testing equipment. For
example, if the AEB system does not
intervene as required, or if test
parameters inadvertently fall outside of
the specified limits, it should be
possible to safely abort the test. In the
event the subject vehicle does collide
with the lead vehicle, it should not
injure the testing personnel nor cause
excessive property damage.
Additionally, test tracks may be
constrained by available space and there
may be insufficient space to accelerate
a heavy vehicle up to a higher speed
and still have sufficient space to
perform a test. Many types of heavy
vehicles are not capable of accelerating
as quickly as lighter vehicles and
reaching higher test speeds may require
longer stretches that exceed available
testing facilities. At approximately 100
79 This information is available in the report titled
‘‘NHTSA Heavy Vehicle AEB Test Track
Performance Data Summary Report—2022,’’ placed
in the docket identified in the heading of this
NPRM.
80 More detail on test data is discussed in the
NHTSA and FMCSA Research and Testing section.
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38.5
43.0
Slower-moving
lead vehicle
49.2
47.8
Decelerating
lead vehicle
49.2
47.8
km/h, the agency found that constraints
with available test track length, in
conjunction with the time required to
accelerate the vehicle to the desired test
speed, made performing these higher
speed tests with heavy vehicles
logistically challenging.81 The agency
has tentatively concluded that at this
time the maximum practicable test
speed is 100 km/h.
The maximum speed of 100 km/h is
included in the test speed range when
manual braking is present; the manual
braking will reduce impact speed if the
FCW issues a warning and the AEB
system does not activate before reaching
the lead vehicle. This would limit
potential damage to the test equipment
and avoid injury to testing personnel.
With no manual braking, the maximum
test speed is 80 km/h so that in the
event that the AEB system does not
provide any braking at all, damage to
the subject vehicle and test equipment
is reduced and potential injuries
avoided.
The stopped lead vehicle test scenario
uses a no-manual-braking test speed
range of 10–80 km/h and a manualbraking test speed range of 70–100 km/
h. Similarly, the slower-moving lead
vehicle test scenario uses subject
vehicle speed ranges of 40–80 km/h for
no manual-braking and 70–100 km/h for
manual braking, while the lead vehicle
travels ahead at a constant speed of 20
km/h. The lower end of the subject
vehicle test speed range is 40 km/h so
that the subject vehicle is traveling
faster than the lead vehicle. The
decelerating lead vehicle tests are run at
either 80 or 50 km/h. This latter test is
performed at two discreet speeds rather
than at ranges of speeds because the
main factors that test AEB performance
are the variation of headway, or the
distance between the subject vehicle
81 During testing of a 2021 Freightliner Cascadia
at speeds approaching 100 km/h, NHTSA
experienced difficulty establishing valid test
conditions due to test facility use restrictions.
Facility use restrictions limited where emergency
braking tests by heavy vehicles and automated lead
vehicle robots could co-operate, thereby reducing
the effective useable track length to less than 1100
meters.
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and lead vehicle, and how hard the lead
vehicle brakes. Also, because these tests
contain a larger number of variables
requiring more complex test
choreography, limiting the test to two
discreet test speeds reduces the number
of potential test conditions and reduces
potential test burden. Together, these
test speed ranges provide good coverage
of the travel speeds at which heavy
vehicle rear-end crashes occur in the
real world, while reducing the potential
risk and damage to test equipment and
vehicles and not exceeding the practical
physical size limits of test tracks.
Additionally, the agency is proposing
that these requirements would not apply
at speeds below 10 km/h. NHTSA
believes that there are real-world cases
where heavy vehicles are being
maneuvered intentionally in proximity
of other objects at low-speed, and AEB
intervention could be in conflict with
the vehicle operator’s intention. For
example, if an operator intends to drive
towards the rear of another vehicle in a
parking lot in order to park the vehicle
near the other, automatic braking during
this parking maneuver would be
unwanted. The agency tentatively
concluded that excluding speeds below
10 km/h from the AEB requirement
would allow these types of low-speed
maneuvers. This proposal does not
require AEB systems to be disabled
below 10 km/h. However, publicly
available literature from at least one
manufacturer shows that some or all of
the AEB system functions are not
available below 15 mph (24 km/h),
indicating that current manufacturers
may have similar considerations about
low-speed AEB functionality.82 A lower
bound for FCW and AEB activation
speed of 10 km/h is also consistent with
the lower bound testing proposed for
light vehicle AEB and the Euro NCAP
rating program.83
During each test run in any of the test
scenarios, the vehicle test speed will be
held constant until the test procedure
specifies a change. NHTSA is proposing
that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of
the specified test value. In NHTSA’s
experience, both the subject vehicle and
lead vehicle speeds can be reliably
controlled within the 1.6 km/h tolerance
range, and speed variation within that
82 Bendix Wingman Fusion Brochure, or SD–61–
4963 Service Data manual for Bendix Wingman
Fusion Driver Assistance System. Available at
https://www.bendix.com/media/documents/
technical_documentsproduct_literature/bulletins/
SD-61-4963_US_005.pdf (last accessed August 23,
2022).
83 Euro NCAP Test Protocol—AEB Car-to-Car
systems v3.0.3 (April 2021). See https://
cdn.euroncap.com/media/62794/euro-ncap-aebc2c-test-protocol-v303.pdf.
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range yields consistent test results. A
tighter speed tolerance is unnecessary
for repeatability and burdensome as it
may result in a higher test-rejection rate,
without any greater assurance of
accuracy of the test track performance.
NHTSA’s vehicle testing suggested
that the selected speed ranges for the
various scenarios are within the
capabilities of at least some recent
model year AEB-equipped production
vehicles.84 While these current AEB
systems perform a bit differently
depending on the vehicle, given that
this notice proposes a lead time for
manufacturers to come into compliance
with the proposed performance
requirement, the agency expects that
future model year performance in
accordance with a final rule schedule
will be achievable.
C. Market Penetration Varies
Significantly Among Classes of Heavy
Vehicles
Though the presence of AEB in heavy
vehicles has increased over the years,
many new heavy vehicles sold in the
U.S. are not equipped with AEB. Market
data obtained by NHTSA indicates that
although AEB is likely equipped on the
majority of class 8 vehicles and is
available on nearly all class 3 and class
4 vehicles, few of class 5 and 6 vehicles
come equipped with any type of AEB
system. In addition, though the
capabilities of these AEB systems have
also improved over time, there has been
no set of standardized performance
metrics in the U.S. that manufacturers
could use as a benchmark to meet. This
NPRM proposes standard performance
metrics that would meet a motor vehicle
safety need.
Among the variety of heavy vehicle
types, class 7 and 8 truck tractors have
been the earliest to voluntarily adopt
AEB systems. These vehicles are (with
some exceptions) already subject to the
electronic stability control requirement
in FMVSS No. 136 and contain fewer
variations in vehicle type, configuration,
and operational pattern. It was
estimated that as of 2013 only 8 to 10
percent of class 8 trucks in the U.S.
were equipped with this technology.85
In 2017 a FMCSA report extrapolated
available information to estimate that
12.8 percent of the entire on-road fleet
of class 8 trucks in the United States
84 This information is available in the report titled
‘‘NHTSA Heavy Vehicle AEB Test Track
Performance Data Summary Report—2022,’’ placed
in the docket identified in the heading of this
NPRM.
85 National Transportation Safety Board. 2015.
‘‘Special Investigation Report: The Use of Forward
Collision Avoidance Systems to Prevent and
Mitigate Rear-End Crashes.’’ Report No. NTSB/SIR–
15/01 PB2015–104098. Washington, DC.
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were equipped with an AEB system,86
while the industry estimated that up to
15 percent of class 8 trucks were
equipped with AEB.87 More recently, a
survey of public information on AEB
availability for heavy vehicles reveals
that this technology is becoming more
prevalent on new trucks. In 2016,
Peterbilt announced the option of AEB
in its class 8 model 579 truck tractor,
and then made the technology standard
in 2019.88 89 As of 2017, Volvo Trucks
made AEB standard equipment on all of
its class 8 truck tractor models, as a part
of its Volvo Active Driver Assist safety
package.90 While several fleets or
manufacturers have made AEB
standard, it remains an option for some
class 8 vehicles, such as the Peterbilt
single-unit truck models 337 and 348.91
Data from a recent study indicates that
the large majority of class 8 vehicles
sold from 2018 until mid-2022 had AEB
as a standard feature, and that the top
ten selling class 8 vehicles all include
standard AEB.92
AEB systems are also available on
nearly all class 3 and 4 trucks that are
relatively similar in size to light trucks,
are manufactured by companies that
also manufacture light vehicles, and
likely have similar component and
component suppliers as light vehicles.
Although these vehicles are not required
to have ESC systems, many of them are
also available with ESC, likely because
these vehicles are similar in size and
use to light trucks. However, while
NHTSA has information on ESC and
AEB system availability, NHTSA has no
86 Grove, K., et al., ‘‘Research and Testing to
Accelerate Voluntary Adoption of Automatic
Emergency Braking (AEB) on Commercial
Vehicles,’’ VTTI (May 2020). Available at https://
rosap.ntl.bts.gov/view/dot/49335 (last accessed June
9, 2022).
87 Cannon, J., ‘‘Automatic emergency braking is
the next generation of driver assist technologies,’’
Commercial Carrier Journal, December 14, 2017.
https://www.ccjdigital.com/business/article/
14936178/future-of-automatic-emergency-brakingdriver-assist-tech.
88 https://www.peterbilt.com/about/news-events/
news-releases/peterbilt-introduces-bendixwingman-fusion-advanced-safety-system (last
accessed August 23, 2022).
89 https://www.peterbilt.com/about/news-events/
peterbilt-trucks-introduce-bendix-wingman-fusionstandard (last accessed August 23, 2022).
90 https://www.volvotrucks.us/news-and-stories/
press-releases/2017/july/volvo-active-driver-assistnow-standard/#:∼:text=Volvo%20Active%20Driver
%20Assist%20is%20now%20
standard%20equipment,is%20fully%20
integrated%20with%20Volvo%E2%80%99s%20
Driver%20Information%20Display (last accessed
August 23, 2022).
91 https://www.peterbilt.com/about/news-events/
peterbilt-announces-bendix-wingman-fusionmedium-duty (last accessed August 23, 2022).
92 This information is available in the S&P
Global’s presentation titled ‘‘MHCV Safety
Technology Study,’’ which has been placed in the
docket identified in the heading of this NPRM.
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information on what percentage of class
3 and 4 vehicle purchases are equipped
with ESC and AEB. For classes 5 and 6,
there is substantially lower ESC and
AEB system availability. However,
NHTSA believes that this slower pace of
voluntary adoption does not imply that
these vehicles are not capable of being
deployed with an AEB system. The
system components are largely the same
and have little to do with a vehicle’s
size. There are also vehicles within
these classes that are available with
ESC, and the availability of ESC has
increased since NHTSA issued FMVSS
No. 136. This market information
indicates that AEB is practicable for all
vehicles included in this proposal.
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D. This NPRM Would Compel
Improvements in AEB
This rulemaking is also needed to
drive improvements in AEB systems.
The performance requirements
proposed in this NPRM are designed
around the goal of realizing as much of
the safety potential of AEB systems as
possible, while remaining realistic and
practicable. Some contemporary AEB
systems are currently designed to detect
and mitigate collision with a vehicle
ahead when travelling at a wide range
of speeds, including interstate speeds.93
While the systems are also functional at
lower speeds, the higher speed
capabilities indicate that AEB will be
capable of reducing the frequency of
interstate rear-end crashes rather than
just slower speed events.
NHTSA has tentatively concluded
that the improvements to AEB systems
by manufacturers in the absence of
regulation have insufficiently addressed
the safety problem associated with rearend crashes. No individual vehicle’s
AEB system tested by NHTSA is
currently capable of avoiding a collision
over the range of test speeds that aligns
with the majority of the safety problem.
However, the range of speeds included
in this proposal is practicable as at least
some vehicles were able to achieve the
desired results at each tested speed.
While manufacturers may continue to
improve AEB systems, only a regulation
would ensure that all heavy vehicles are
equipped with an AEB system that can
avoid a collision at a range of speeds
that targets the majority of the safety
problem. Establishing performance
criteria that meet the safety need of
preventing fatalities and serious injuries
will also ensure that the systems will be
designed to address the serious safety
93 See https://www.bendix.com/media/
documents/technical_documentsproduct_literature/
bulletins/SD-61-4963_US_005.pdf (last accessed
March 1, 2023).
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problem associated with these crashes.
This NPRM proposes that all heavy
vehicles be subject to the same
performance requirements such that the
entire heavy vehicle fleet benefits from
improvements in AEB technology.
E. BIL Section 23010(b)(2)(B)
NHTSA is issuing this NPRM in
accordance with a statutory mandate in
BIL. Section 23010 of BIL requires the
Secretary to prescribe a Federal motor
vehicle safety standard to require all
commercial vehicles subject to FMVSS
No. 136 to be equipped with an AEB
system. The FMVSS is required to
establish performance standards for
AEB systems. BIL directs the Secretary
to prescribe the standard not later than
two years after the date of enactment of
the Act.
Section 23010(b)(2)(B) of BIL states
that prior to prescribing the FMVSS for
heavy vehicle AEB, the Secretary shall
consult with representatives of
commercial motor vehicle drivers
regarding the experiences of drivers
with AEB. Prior to this NPRM, NHTSA
and FMCSA have engaged drivers and
the industry more generally in various
ways. NHTSA has published research
previously that involved surveying the
driving experiences of 18 drivers
driving heavy trucks equipped with a
prototype FCW system over a 10-month
period in May 2011.94 NHTSA has also
been sponsoring studies seeking input
of commercial motor vehicle drivers.
The current ongoing field study with
VTTI aims to collect and analyze
performance and operational data on
newer generation AEB crash avoidance
technologies on new, class 8 tractors by
heavy vehicle original equipment
manufacturers and their suppliers. One
year of naturalistic driving data will be
collected by monitoring the production
systems used in real-world conditions
as deployed by multiple fleets across the
United States. In addition to the
performance and operational data
retrieved from on-board data acquisition
systems for evaluation, the study will
also involve conducting subjective
surveys with drivers and fleet managers
regarding performance, satisfaction, and
overall acceptance of the crash
avoidance technologies.
FMSCA is also engaged consultation
with representatives of drivers through
the Tech-Celerate Now program.95 This
program intends to accelerate the
adoption of advanced crash avoidance
94 ‘‘Integrated Vehicle-Based Safety Systems
Heavy-Truck Field Operational Test Independent
Evaluation,’’ DOT HS 811 464.
95 Tech-Celerate Now. FMCSA. Available at
https://www.fmcsa.dot.gov/Tech-CelerateNow (last
accessed August 8, 2022).
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technologies by the trucking industry.
The first phase initiatives include
national outreach and education. The
outreach element allowed for the
successful creation of training materials
for fleets, drivers, and maintenance
personnel related to AEB technology.
Additionally, the program features other
avenues to reach drivers including
educational videos on braking,
presentations, booth exhibitions, and
webinars. As of January 2023, FMCSA
has compiled the findings from drivers
and/or representatives of drivers in a
final report that is currently undergoing
internal review. However, planning for
the second phase has been initiated and
includes expanding the national
outreach and education campaign.
Building upon this and other
research, NHTSA and FMCSA seek
comment from representatives of
commercial motor vehicle drivers, and
from drivers themselves, about their
experiences with AEB systems,
including whether the AEB system
prevented a crash, whether the FCW
warnings were helpful, and whether any
malfunctions or unwarranted
activations occurred. Although members
of the public should comment on all
aspects of the NPRM they find relevant,
NHTSA also request comments on the
following specific issues:
• This proposal includes
considerations that automatic braking is
needed for safety and crash prevention.
NHTSA seeks comment from driver
experiences with AEB-equipped heavy
vehicles on whether AEB improves
heavy vehicle rear-end crash safety.
• This proposal includes warning
requirements to the driver as part of the
AEB system that braking is needed in a
rear-end crash-imminent situation.
NHTSA seeks comments from driver
experiences on whether AEB is helpful
in getting a driver’s attention back to the
task of driving.
• This proposal includes
requirements that automatic braking
will occur in the event of an imminent
collision on a straight testing path.
NHTSA seeks comment on driver
experiences with the performance of
AEB when it is applied on curved roads.
• This proposal includes
requirements that automatic braking
will be tested under certain weather and
roadway pavement conditions. NHTSA
seeks comment on driver experiences
when AEB is applied at the last moment
in all weather conditions.
• This proposal includes
considerations that automatic braking is
needed because of multiple elements,
including driver misjudgments and
distractions. NHTSA seeks comment on
driver experiences on whether the
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application of AEB causes drivers to pay
less attention to the road; or whether the
application of AEB distracts or annoys
drivers.
F. Vehicles Excluded From Braking
Requirements
The result of this proposal would
require AEB and ESC on nearly all
heavy vehicles. The only vehicles that
would be excluded from AEB and ESC
requirements would be vehicles that are
already excluded from NHTSA’s braking
requirements for vehicles equipped with
pneumatic brakes in FMVSS No. 121.
This braking standard includes
requirements for minimum stopping
distance. For those vehicles, there is no
assurance that their foundational brake
systems would have the capability to
meet the proposed AEB performance
requirements, even if equipped with
sensors capable of detecting another
vehicle. These vehicles are also
presently excluded from FMVSS No.
136 and would continue to be excluded
under this proposal. The vehicles
excluded from the proposed AEB and
ESC requirements are:
• Any vehicle equipped with an air
brake system and equipped with an axle
that has a gross axle weight rating of
13,154 kilograms (29,000 pounds) or
more;
• Any truck or bus that is equipped
with an air brake system and that has a
speed attainable in 3.2 km (2 miles) of
not more than 53 km/h (33 mph);
• Any truck equipped with an air
brake system that has a speed attainable
in 3.2 km (2 miles) of not more than 72
km/h (45 mph), an unloaded vehicle
weight that is not less than 95 percent
of its gross vehicle weight rating, and no
capacity to carry occupants other than
the driver and operating crew.
FMCSA believes that an exemption
from its ESC and AEB regulations is
appropriate for vehicles involved in
driveaway-towaway operations, for
example, vehicles that are being
transported to dealer locations or that
are manufactured exclusively for use
outside of the United States. Although
these vehicles are operated on public
roads in the United States when they are
being transported from the point of
manufacture to a domestic or foreign
destination, these vehicles have not yet
entered commercial service. The
economic burden associated with
requiring these vehicles to be equipped
with AEB or ESC for the one-way trip
out of the United States would certainly
exceed the potential benefits.
The driveaway-towaway exemption
would also be applicable to vehicles
being delivered to the Armed Forces of
the United States. Vehicles operated by
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the military are exempt from the
FMCSRs under § 390.3(f)(2).96
FMCSA seeks comment on other
types of operations for which an
exemption from the AEB or ESC
requirements may be appropriate. For
example, what types of exemptions may
be needed for CMVs with auxiliary
equipment installed that would interfere
with the operation of the AEB system?
VI. Heavy Vehicles Not Currently
Subject to ESC Requirements
A. AEB and ESC Are Less Available on
These Vehicles
NHTSA is proposing to include nearly
all vehicles with a GVWR greater than
4,536 kg (10,000 lbs.). This includes
vehicles that are currently exempted
from FMVSS No. 136 such as trucks
other than truck tractors, school buses,
perimeter-seating buses, transit buses,
passenger cars, and multipurpose
passenger vehicles because about half of
the fatalities and serious injuries
brought about by heavy vehicles are
caused by class 3 through 6 vehicles.
The FMVSSs do not currently require
ESC on class 3 through 6 vehicles or on
class 7 and 8 single unit trucks, school
buses, and certain bus types such as
transit buses. ESC has not been
commercially available for as long on
class 3 through 6 vehicles as it has been
for class 7 and 8 vehicles. However,
examples can be found of manufacturers
who offer ESC as an option on their
class 3 through 6 vehicles. Kenworth
has made AEB optional for the T880
vocational truck as well as for their
T270 and T370 conventional class 6
trucks. Ford made ESC standard on its
F–650 model in the 2018 model year
and has made AEB optional on model
year 2022 F–650 and F–750 class 6
trucks. A number of school bus
manufacturers have made ESC standard
on certain models, including ones that
fall into classes 3 through 6. For
example, Thomas Built offers ESC as
standard equipment on its type C school
buses, which can be configured to be in
class 6. In some cases, ESC technology
originating in hydraulic-brake passenger
cars has moved up into the lower
classes of heavy vehicles. For example,
96 FMCSA notes that the driveaway-towaway
exemption provided in § 393.56 and § 393.57 is
consistent with exceptions provided by NHTSA.
Section 571.7(c) provides an exception for vehicles
and items of equipment manufactured for, and sold
directly to, the Armed Forces of the United States
in conformity with contractual specifications.
Section 571.7(d), through a cross-reference to the
United States Code, indicates the FMVSSs do not
apply to motor vehicles or motor vehicle equipment
intended only for export, labeled for export on the
vehicle or equipment and on the outside of any
container of the vehicle or equipment, and exported
(49 U.S.C. 30112(b)(2)).
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the 2019 Mercedes Sprinter, a cargo van
which can be configured as a class 3
heavy vehicle, has ESC as standard
equipment. Other class 3 and 4 vehicles
that resemble light vehicles, such as
pickup trucks, are available with ESC.
The availability of ESC as an option
across multiple brands and models
within class 3 through 6 leads NHTSA
tentatively to conclude that providing
ESC is technically and economically
feasible. NHTSA believes it is
reasonable and practicable to require
that ESC to be installed on class 3
through 6 vehicles.
B. This NPRM Proposes To Require ESC
NHTSA has tentatively determined
that ESC is necessary for safety to
include as a foundation for an AEB
requirement. Historically, the two
technologies have been thought of as
supplement or complementary rather
joined technologies. That is, while ESC
and AEB share hardware fundamental to
both technologies, such as brake
actuators, ESC is generally not described
or advertised as a component of AEB.
That said, despite this theoretical
separation, in a survey NHTSA has
conducted on the availability of ESC
and AEB systems, NHTSA was unable
to identify any heavy vehicle that could
currently be purchased with an AEB
system, other than an FCW-only system
(i.e., not capable of automatic brake
application), that did not also have an
ESC system.97 In a 2017 white paper
Bendix indicated that collision
mitigation technology is built on a
foundation of full stability. Bendix
stated that as we look to more
automated, autonomous functionality in
the future, all of this is likely to be built
on an ESC foundation as well.98 In a
2018 news release, Bendix stated that
ESC provides the necessary platform for
more advanced driver assistance
systems (ADAS), including collision
mitigation technologies.99
Manufacturers such as Ford have ESC as
a must-have system for installing driver
assist technology on the stripped
commercial chassis, including AEB.100
97 This information is available in NHTSA’s
VRTC class 3 to 6 market scan for ESC–FCW–AEB
spreadsheet, which has been placed in the docket
identified in the heading of this NPRM.
98 Full Stability and the Road Map to The FutureAre we still on the Right Road? https://
www.bendix.com/media/documents/products_1/
absstability/BW8055_US_000.pdf (last accessed
March 3, 2023).
99 October 16, 2018. Bendix News Release,
‘‘WORKING TOGETHER, BENDIX AND NORTH
AMERICA’S SCHOOL BUS MANUFACTURERS
ENHANCE STUDENT TRANSPORTATION
SAFETY’’.
100 2022 Ford Commercial Vehicles, F–59
Commercial Stripped Chassis. ESC is required for
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Also, Ford has ESC and AEB as standard
equipment on other chassis models such
as the E-series models, F–650, and F–
750 truck series. Ram Trucks also offers
ESC and AEB for Chassis Cab models
like RAM 3500 trucks.101 102 Based upon
these factors and its own understanding
of the capabilities of AEB and ESC
systems, NHTSA has tentatively
concluded that there may be safety risks
associated with the installation of an
AEB system without an ESC system. For
example, a driver who responds to an
imminent collision by steering to avoid
a collision while an AEB system is
simultaneously applying braking may
induce a lateral instability event that is
not addressed by ABS, but that may be
prevented with an ESC system. Thus,
this NPRM proposes to require both
AEB and ESC for the class 3 through 8
vehicles not currently subject to FMVSS
No. 136.
NHTSA requests comment on this
tentative conclusion that ESC is
necessary to ensure safe AEB operation
or whether ESC systems are necessary
prerequisites for AEB systems for any
other reason. NHTSA further requests
comments on specific safety scenarios
where ESC systems would be necessary
for safe operation of an AEB system.
Currently, pursuant to FMVSS No.
136, only class 7 and 8 truck tractors
and certain large buses are required to
have ESC systems. FMVSS No. 136
includes both vehicle equipment
requirements and performance
requirements. This proposal would
require nearly all heavy vehicles to have
an ESC system that meets the equipment
requirements, general system
operational capability requirements, and
malfunction detection requirements of
FMVSS No. 136. The general ESC
system operational capability
requirements are the nine capabilities
that are specified in the definition of
ESC system in S4 of FMVSS No. 136,
which include a means to augment
directional stability and enhance
rollover stability by having control over
the brake systems individually at each
wheel position and the means to control
engine torque. However, NHTSA is not
proposing test track performance
requirements at this time because
NHTSA is conscious of the potential
the stripped chassis Driver Assist Technology
Package.
101 ESC equipped standard on E-Series models,
and F–650/F–750 trucks, available at this link
https://www.ford.com/cmslibs/content/dam/vdm_
ford/live/en_us/ford/nameplate/f-650-750/2022/
brochures/BRO_SUF_130E80EB-C9B2-936F-6F5472CA6F5472CA.pdf (last viewed March 3, 2023).
102 https://www.ramtrucks.com/gab.html, ESC
equipped standard on the RAM Chassis cab models
and RAM 3500 trucks, available at this link (last
accessed March 3, 2023).
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testing burden on small businesses and
the multi-stage vehicle manufacturers
involved in class 3 through 6 vehicle
production.
NHTSA’s proposed approach would
provide vehicle manufacturers the
ability to ascertain the ESC system
design most appropriate for their
vehicles. The approach recognizes that
ESC system design is dependent on
vehicle dynamics characteristics, such
as the total vehicle weight and location
of that weight (center of gravity), which
would differ depending on the final
vehicle configuration. Vehicles not
subject to FMVSS No. 136 include a
large variety of vehicle configurations,
which can result in numerous variations
of ESC system design. The approach
provides maximum flexibility to vehicle
manufacturers to evaluate the
characteristics of their vehicles and
design an ESC system.
In Europe, ESC was predicted to
prevent about 3,000 fatalities (14
percent), and about 50,000 injuries (6
percent) per year.103 In Europe, ESC has
been mandatory for new types of
vehicles since 2011, and for all new
vehicles is mandatory since 2014.104
More information about international
regulations can be found in Appendix B.
(a) and (b) of section 30111 of the Safety
Act, and if the Secretary finds that an
FMVSS would meet such requirements,
initiate a rulemaking to prescribe such
an FMVSS.
This NPRM and the accompanying
PRIA fulfils the mandate of section
23010(d)(1) concerning a study on
equipping commercial vehicles not
subject to FMVSS No. 136 with AEB.
Pursuant to the mandate section
23010(d)(3) of BIL, NHTSA seeks
comment on the tentative conclusions
in this NPRM and the PRIA regarding
the feasibility, benefits, and costs
associated with installing AEB on all
heavy vehicles, particularly class 3–6
vehicles and class 7 and 8 single-unit
trucks. Further, as part of this
rulemaking, the agency has considered
whether proceeding with an AEB
mandate for these vehicles meet the
necessary provisions of the Safety Act,
and will continue to do so in any final
rule. Finally, although the agency notes
that paragraph (d) concerns when the
agency would be mandated to initiate a
rulemaking to require AEB for these
vehicles, that section does not affect the
agency’s discretionary ability to issue an
FMVSS when it believes doing so is
compelled by the Safety Act.
C. BIL Section 23010(d)
Section 23010 of BIL requires the
Secretary to prescribe a Federal motor
vehicle safety standard to require any
commercial vehicle subject to FMVSS
No. 136, that is manufactured after the
effective date of an AEB standard, to be
equipped with an AEB system that
meets established performance
standards. In addition, Section 23010(d)
of BIL requires NHTSA to study
equipping AEB on a variety of
commercial motor vehicles not subject
to FMVSS No. 136, including an
assessment of the feasibility, benefits,
and costs associated with installing AEB
systems on a variety of newly
manufactured commercial motor
vehicles with a GVWR greater than
10,000 pounds. Section (d)(3) states that
the Secretary shall issue a notice in the
Federal Register containing the findings
of the study and provide an opportunity
for public comment. After completion of
this study, the Secretary must determine
whether a motor vehicle safety standard
would meet the requirements and
considerations described in paragraphs
D. Multi-Stage Vehicle Manufacturers
and Alterers
Heavy vehicles include many
specialty or vocational vehicles such as
work trucks, delivery box trucks,
motorhomes, and school buses, and the
complexities within this large variety of
special purpose vehicles make
installation of ESC and AEB more
challenging. These specialized vehicles
may be produced in lower volumes with
customized features to suit the specific
needs of individual customers and in
multiple stages by several
manufacturers. Concepts and
terminology relating to the certification
of vehicles built in two or more stages
(multi-stage vehicles) and alters are
described below.
In the typical situation, a vehicle built
in two or more stages is one in which
an incomplete vehicle, such as a
chassis-cab or cut-away chassis built by
one manufacturer, is completed by
another manufacturer who adds workperforming or cargo-carrying
components to the vehicle. For example,
the incomplete vehicle may have a cab,
but nothing built on the frame behind
the cab. As completed, it may be a dry
freight van (box truck), dump truck, tow
truck, or plumber’s truck. Like all
vehicles that are manufactured for sale
in the United States, a multi-stage
vehicle must be certified as complying
with all applicable Federal motor
103 Iombiller, S.F., Prado, W.B., Silva M.A.
(September 15, 2019). Comparative Analysis
between American and European Requirements for
Electronic Stability Control (ESC) Focusing on
Commercial Vehicles. SAE International.
104 July 31, 2009, Official Journal of the European
Union, Regulation (EC) No. 661/2009, Articles 12 &
13, and Annex V.
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vehicle safety standards (FMVSS) before
the vehicle is introduced into interstate
commerce.
Manufacturers involved in the
production of multi-stage vehicles can
include, in addition to the incomplete
vehicle manufacturer, one or more
intermediate manufacturers, who
perform manufacturing operations on
the incomplete vehicle after it has left
the incomplete vehicle manufacturer’s
hands, and a final-stage manufacturer
who completes the vehicle so that it is
capable of performing its intended
function.
In some circumstances, a
manufacturer at an earlier stage in the
chain of production for a multi-stage
vehicle can certify that the vehicle will
comply with one or more FMVSS when
completed, provided specified
conditions are met. This allows what is
commonly referred to as ‘‘pass-through
certification.’’ As long as a subsequent
manufacturer meets the conditions of
the prior certification, that subsequent
manufacturer may rely on this
certification and pass it through when
certifying the completed vehicle.
NHTSA requests comments on how
this proposal may impact multi-stage
manufacturers and alterers. The agency
seeks comment on the specific
challenges that would be faced by the
manufacturers in certifying to the
proposed AEB or ESC or in altering a
vehicle certified to the proposed
requirements, and on whether and how
NHTSA could revise this proposal to
minimize any disproportionate impact.
We believe that small-volume vehicle
manufacturers are not likely to certify
compliance with the proposed AEB and
ESC requirements through their own
testing but will use a combination of
component testing by brake system
suppliers and engineering judgment.
Already much of the braking
development work, including for ABS
and ESC, for these small-volume vehicle
manufacturers is done by brake
suppliers. That is, small-volume
manufacturers already must certify their
vehicles to FMVSS Nos. 136, 105, and
121. NHTSA believes that small-volume
manufacturers would certify to the
proposed ESC and AEB requirements
using the means they use now to certify
to those braking requirements, which
involves collaborating with their brake
system suppliers, first and second stage
manufacturers, etc. This NPRM would
also provide one year after the last
applicable date for manufacturer
certification of compliance, in
accordance with 49 CFR 571.8(b).
NHTSA’s regulations governing
vehicles manufactured in two or more
stages at 49 CFR part 568 require
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incomplete vehicle manufacturers to
provide with each incomplete vehicle
an incomplete vehicle document (IVD).
This document details, with varying
degrees of specificity, the types of future
manufacturing contemplated by the
incomplete vehicle manufacturer and
must provide, for each applicable safety
standard, one of the following three
statements that a subsequent
manufacturer can rely on when
certifying compliance of the vehicle, as
finally manufactured, to some or all of
all applicable FMVSS.
First, the IVD may state, with respect
to a particular safety standard, that the
vehicle, when completed, will conform
to the standard if no alterations are
made in identified components of the
incomplete vehicle. This representation,
which is referred to as a ‘‘Type 1
statement,’’ is most often made with
respect to chassis-cabs, since a
significant portion of the occupant
compartment in incomplete vehicles of
that type is already complete.
Second, the IVD may provide a
statement of specific conditions of final
manufacture under which the
completed vehicle will conform to a
particular standard or set of standards.
This statement, which is referred to as
a ‘‘Type 2 statement,’’ is applicable in
those instances in which the incomplete
vehicle manufacturer has provided all
or a portion of the equipment needed to
comply with the standard, but
subsequent manufacturing might be
expected to change the vehicle such that
it may not comply with the standard
once finally manufactured. For example,
the incomplete vehicle could be
equipped with a brake system that
would, in many instances, enable the
vehicle to comply with the applicable
brake standard once the vehicle was
complete, but that would not enable it
to comply if the completed vehicle’s
weight or center of gravity height were
altered from those specified in the IVD.
Third, the IVD may identify those
standards for which no representation of
conformity is made because conformity
with the standard is not substantially
affected by the design of the incomplete
vehicle. This is referred to as a ‘‘Type
3 statement.’’ A statement of this kind
could be made, for example, by a
manufacturer of a stripped chassis who
may be unable to make any
representations about conformity to any
crashworthiness standards if the
incomplete vehicle does not contain an
occupant compartment. When it issued
the original set of regulations regarding
certification of vehicles built in two or
more stages, the agency indicated that it
believed final-stage manufacturers
would be able to rely on the
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representations made in the IVDs when
certifying the completed vehicle’s
compliance with all applicable FMVSS.
Although the final-stage manufacturer
normally certifies the completed
vehicle’s compliance with all applicable
FMVSS, this responsibility can be
assumed by any other manufacturer in
the production chain. To take on this
responsibility, the other manufacturer
must ensure that it is identified as the
vehicle manufacturer on the
certification label that is permanently
affixed to the vehicle. The identified
manufacturer also has legal
responsibility to provide NHTSA and
vehicle owners with notification of any
defect related to motor vehicle safety or
noncompliance with an FMVSS that is
found to exist in the vehicle, and to
remedy any such defect or
noncompliance without charge to the
vehicle’s owner.
An altered vehicle is one that is
completed and certified in accordance
with the agency’s regulations and then
altered, other than by the addition,
substitution, or removal of readily
attachable components, such as mirrors
or tire and rim assemblies, or by minor
finishing operations such as painting,
before the first retail sale of the vehicle,
in such a manner as may affect the
vehicle’s compliance with one or more
FMVSS or the validity of the vehicle’s
stated weight ratings or vehicle type
classification. The person who performs
such operations on a completed vehicle
is referred to as a vehicle ‘‘alterer.’’ An
alterer must certify that the vehicle
remains in compliance with all
applicable FMVSS affected by the
alteration.
NHTSA seeks comment on the
impacts of this NPRM on multi-stage
manufacturers and alterers and requests
comments on the following questions.
• Are certain multi-stage or altered
vehicles manufactured or altered in a
manner that makes it impracticable to
comply with this proposed rule? If so,
please explain which vehicles and why
it is impracticable.
• If an incomplete vehicle were
equipped with sensors for AEB that
could become obstructed by equipment
added in later manufacturing steps, how
should NHTSA apply an AEB
requirement to that vehicle?
• Are there any changes needed to 49
CFR part 567 or part 568 to facilitate
certification to the proposed
requirements? If so, what would those
changes be? Would a final-stage
manufacturer be able to certify a vehicle
based on the information provided by
an intermediate or incomplete vehicle
manufacturer, or is additional
information needed in IVDs? If
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additional information is needed, please
describe the needed information.
• Are there any requirements in this
proposal that ought not to apply to
multi-stage vehicles or altered vehicles?
Are there proposed requirements that
should be lowered in stringency to
better enable pass-through certification?
Please provide details on those
requirements and provide associated
rationale.
• Would intermediate manufacturers,
final-stage manufacturers, and alterers
have sufficient information to identify
when an impermissible change has been
made? Please explain why or why not.
• Assuming there would be cases
where it may not be practical to comply
with the proposed requirements, are the
existing exemption processes detailed in
49 CFR 555, ‘‘Temporary exemption
from motor vehicle safety and bumper
standards,’’ sufficient to accommodate
unique vehicles, or should NHTSA
explicitly consider applicability
exclusions for certain multi-stage
vehicles? If applicability exclusions are
needed, please explain what they
include and why the exclusion is
needed. For example, should there be
exclusions for vehicles with
permanently installed work-performing
equipment installed on the front of or
extending past the front of the vehicle
(e.g., auger trucks, bucket trucks, cable
reel trucks, certain car carriers, etc.) or
vehicles with a GVWR equal to or
greater than 120,000 pounds (i.e., heavy
haulers)?
VII. Proposed Performance
Requirements
This NPRM proposes that all heavy
vehicles, class 3–8, are subject to the
same performance requirements such
that the entire heavy vehicle fleet
benefits from improvements in AEB
technology. The proposed set of
requirements would compel AEB
technology to operate at its highest
safety potential, while at the same time
being objective and practicable. In order
to establish these requirements, the
agency considered the key aspects of the
technology and how they would best be
applied to address the safety problem.
For example, requiring AEB systems to
perform only at lower speeds may
address a significant portion of the rearend crash problem, but it would not
address the rear-end crash fatalities that
mostly occur at higher speeds. Thus,
NHTSA is proposing that AEB systems
must be capable of activating across a
wide spectrum of speeds. Similarly, the
agency is aware that some current AEB
systems may occasionally cause
unwarranted braking events, or ‘‘false
activations,’’ which could lead to
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unwanted consequences; we are thus
proposing two test scenarios which
vehicles must pass without false
activation of the AEB system.
While creating the proposed
performance requirements, NHTSA
considered the capabilities and
limitations of current AEB technologies.
Using information from vehicle testing,
this proposal includes test scenarios and
parameters that the agency found to be
within the potential of current
production vehicles. This means that at
least one vehicle model demonstrated
the ability to avoid impacting a lead
vehicle, represented by a vehicle test
device, or that it so nearly avoided the
impact that we expect that the
additional development time allowed by
this proposal would enable the required
improvement in performance.
While certain requirements can be
assessed without vehicle tests, a large
portion of this proposal has
performance requirements that are
evaluated through vehicle tests. These
tests, discussed in this section, simulate
real-world scenarios and are run
according to specified conditions and
test parameters. NHTSA believes that
these test scenarios will realistically
evaluate how AEB systems perform
while the vehicle is travelling at normal
driving speeds.
Several of the vehicle test scenarios
test involve multiple moving vehicles.
In these test scenarios, the heavy vehicle
being evaluated with AEB is referred to
as the ‘‘subject vehicle.’’ Other vehicles
involved in the test are represented by
a vehicle test device. When a vehicle
test device is used ahead of the subject
vehicle in the same lane, in the path of
the moving subject vehicle, it is referred
to as a ‘‘lead vehicle.’’ When moving, a
lead vehicle moves in the same
direction as the subject vehicle. The
speeds and relative motions of the
subject vehicle and lead vehicle are
choreographed in a variety of ways to
represent the most common scenarios
which lead to heavy vehicle rear-end
crashes, and the test procedures
measure whether the AEB system is able
to avoid impacting the lead vehicle.
The other vehicle tests are two false
activation scenarios. A false activation
refers to an unwarranted brake
activation by the AEB system when
there is no object present in the path of
the vehicle with which the vehicle
would collide. These two test scenarios
use objects, including VTDs and a steel
trench plate, arranged in realistic ways
in or near the travel path but without
obstructing the path. In these scenarios,
the subject vehicle and AEB system are
required to move past these objects
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without making a substantial automatic
application of the service brakes.
This proposal also includes system
requirements that are not accompanied
by vehicle tests. Vehicles with AEB
systems must mitigate collision at
speeds beyond the those covered by the
track testing, ensuring robustness of the
system’s range of performance. The AEB
system must include a forward collision
warning (FCW) system that alerts the
vehicle operator of an impending
collision with a lead vehicle. Also, the
system must indicate an AEB
malfunction to the vehicle operator.
A. Proposed Requirements When
Approaching a Lead Vehicle
1. Automatic Emergency Brake
Application Requirements
The agency is proposing that vehicles
be required to have a forward collision
warning system and an automatic
emergency braking system that are able
to function continuously to apply the
service brakes automatically when a
collision with a vehicle or object is
imminent. The system must operate
when the vehicle is traveling at any
forward speed greater than 10 km/h (6.2
mph). This is a general system
equipment requirement with no
associated performance test. No specific
speed reduction or crash avoidance
would be required. However, this
requirement is included to ensure that
AEB systems are able to function at all
times, including at speeds above those
NHTSA is proposing as part of the
performance test requirements.
This requirement complements the
performance requirements in several
ways. While the track testing described
below provides a representation of realworld crash events, no amount of track
testing can fully duplicate the real
world. This requirement ensures that
the AEB’s perception system identifies
and automatically detects a vehicle,
warns the driver, and applies braking
when a collision is imminent. This
requirement also ensures that AEB
systems continue to function in
environments that are not as controlled
as the test track environment. For
example, unlike during track testing,
other vehicles, road users, and buildings
may be present within the view of the
sensors. Finally, track test equipment
limitations and safety considerations
limit the ability to test at high speeds.
However, crashes still occur at higher
travel speeds. Although generally the
number of rear-end crashes decreases at
higher travel speeds, these high-speed
crashes are the ones that more often
result in fatalities, as shown in Figure 3.
The automatic braking requirement
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ensures that AEB systems continue to
provide safety benefits at speeds above
those for which a track-testing
requirement is currently not practicable,
either because of performance
capabilities or track test limitations.
Where a performance standard is not
practical or does not sufficiently meet
BILLING CODE 4910–59–C
h would allow these types of low-speed
maneuvers. This proposal would not
require AEB systems to be disabled
below 10 km/h.
Enforcement of such a performance
requirement can be based on evidence
obtained by engineering investigation
that might include a post-crash
investigation and/or system design
investigation. For instance, if a crash
occurs in which the vehicle under
examination has collided with a lead
vehicle, NHTSA could investigate the
details surrounding the crash to
determine if a warning was provided
and the automatic emergency braking
system applied the service brakes
automatically. In appropriate cases in
the context of an enforcement
proceeding, NHTSA could also use its
information-gathering authority to
obtain information from a manufacturer
on the basis for its certification that its
FCW and AEB systems meet this
proposed requirement.
headlamps constitutes an objective performance
standard under the Safety Act).
106 SD–61–4963 Bendix Wingman Fusion Driver
Assistance System Brochure, available at https://
www.bendix.com/media/documents/technical_
documentsproduct_literature/bulletins/SD-614963_US_005.pdf (last accessed June 21, 2023).
These requirements would not apply
at speeds below 10 km/h. NHTSA
believes that there are real-world cases
where heavy vehicles are being
maneuvered at low-speed and
intentionally in proximity of other
objects, and AEB intervention could be
in conflict with the vehicle operator’s
intention. For example, if an operator
intends to drive towards the rear of
another vehicle in a parking lot in order
to park the vehicle near the other,
automatic braking during this parking
maneuver would be unwanted. Publicly
available literature from at least one
AEB manufacturer shows that some or
all of the AEB system functions are not
available below 15 mph (24 km/h),
indicating that current manufacturers
may have similar considerations about
low-speed AEB functionality.106
NHTSA tentatively concludes that a
minimum operational speed of 10 km/
105 See 72 FR 17235, 17299 (Apr. 6, 2007)
(discussing the understeer requirement in FMVSS
No. 126); Chrysler Corp. v. DOT, 515 F.2d 1053 (6th
Cir. 1975) (holding that NHTSA’s specification of
dimensional requirements for rectangular
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the need for safety, NHTSA may specify
an equipment requirement as part of an
FMVSS.105
BILLING CODE 4910–59–P
2. Forward Collision Warning
Requirement
NHTSA is proposing that AEBequipped vehicles must have forward
collision warning functionality that
provides a warning to the vehicle
operator if a forward collision with a
lead vehicle is imminent. The proposal
defines FCW as an auditory and visual
warning provided to the vehicle
operator that is designed to elicit an
immediate crash avoidance response by
the vehicle operator. The system must
operate when the vehicle is traveling at
any forward speed greater than 10 km/
h (6.2 mph).
While some vehicles are equipped
with alerts that precede the FCW and
research has examined their use,
NHTSA’s proposal is not specifying an
advisory or preliminary alert that would
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precede the FCW. Lerner, Kotwal,
Lyons, and Gardner-Bonneau (1996b)
differentiated between an imminent
alert, which ‘‘requires an immediate
corrective action’’ and a cautionary
alert, which ‘‘alerts the operator to a
situation which requires immediate
attention and may require a corrective
action.’’ 107 A 2004 NHTSA report titled
‘‘Safety Vehicles using adaptive
Interface Technology (Task 9): A
Literature Review of Safety Warning
Countermeasures,’’ examined the
question of whether to include a
cautionary alert level in an FCW system.
Although the two FCW algorithms in
the Automotive Collision Avoidance
System Field Operational Test
algorithms included a cautionary phase,
the Collision Avoidance Metrics
Partnership (1999) program
recommended that only single
(imminent) stage warnings be used.
Unlike the FCW required as part of
the track testing, NHTSA is not
specifically requiring that FCW
presentation occur prior to the onset of
braking in instances that are not tested
on the track. This is to provide
manufacturers with the flexibility to
design systems that are most
appropriate for the complexities of
various crash situations, some of which
may provide very little time for a driver
to take action to avoid a crash. A
requirement that FCW occur prior to
automatic braking could suppress the
automatic braking function in some
actual driving scenarios, such as a lead
vehicle cutting immediately in front of
an AEB-equipped vehicle, where
immediate automatic braking should not
wait for a driver warning.
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i. FCW Modalities
Since approximately 1994, NHTSA
has completed research and published
related reports for more than 35 research
efforts related to crash avoidance
warnings or forward collision warnings.
These research efforts, along with other
published research and existing ISO
standards (15623 and 22839) and SAE
International (SAE) documents (J3029
and J2400) provide a basis for the
proposed requirements.108
107 Lerner, Kotwal, Lyons, and Gardner-Bonneau
(1996). Preliminary Human Factors Guidelines for
Crash Avoidance Warning Devices. DOT HS 808
342. National Highway Traffic Safety
Administration.
108 ISO 15623—Forward vehicle collision
warning systems—Performance requirements and
test procedures; ISO 22839—Forward vehicle
collision mitigation systems—Operation,
performance, and verification requirements (applies
to light and heavy vehicles); SAE J3029: Forward
Collision Warning and Mitigation Vehicle Test
Procedure and Minimum Performance
Requirements—Truck and Bus (2015–10; WIP
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NHTSA NCAP and Euro NCAP
information relating to FCW was also
considered. Since model year 2011, the
agency has included FCW as a
recommended technology in NCAP and
identifies to consumers which light
vehicles have FCW systems that meet
NCAP’s performance tests. NHTSA’s
March 2022 request for comments
notice on proposed changes to NCAP
sought comment on which FCW
modalities or modality combinations
should be necessary to receive NHTSA’s
NCAP recommendation.109 Commenters
generally supported the use of a
multimodal FCW strategy. The Alliance
for Automotive Innovation and Intel
both advocated allowing credit for any
effective FCW signal type. Multiple
commenters supported allowing NCAP
credit for FCW having either auditory or
haptic signals. BMW and Stellantis
supported use of FCW auditory or
haptic signals in addition to a visual
signal. NTSB and Advocates for
Highway and Auto Safety recommended
that NHTSA conduct research
examining the human-machine interface
and examine the effectiveness of haptic
warning signals presented in different
locations (e.g., seat belt, seat pan, brake
pulse). Dynamic Research, Inc.
advocated allowing NCAP credit for
implementation of a FCW haptic brake
pulse, while ZF supported use of a
haptic signal presented via the seat belt.
Bosch warned that use of a haptic signal
presented via the steering wheel for lane
keeping or blind spot warning and FCW
should be avoided as it may confuse the
driver. The Alliance for Automotive
Innovation raised the potential benefits
of standardizing the warning
characteristics to improve effectiveness
as individuals move from vehicle to
vehicle.
All current U.S. vehicle models with
FCW systems appear to provide
auditory and visual FCW signals, while
only a few manufacturers also provide
a haptic signal (e.g., seat pan vibration
or a brake pulse). Visual FCW signals in
current models consist of either a
symbol or word (e.g., ‘‘BRAKE!’’),
presented on the instrument panel or
head-up display, and most are red.
For this NPRM, NHTSA proposes that
the FCW be presented to the vehicle
operator via at least two sensory
modalities, auditory and visual. Use of
a multimodal warning ensures that most
drivers will perceive the warning as
soon as its presented, allowing the most
currently); SAE J2400 2003–08 (Information report).
Human Factors in Forward Collision Warning
Systems: Operating Characteristics and User
Interface Requirements.
109 87 FR 13452 (Mar. 9, 2022).
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43207
time for the driver to take evasive action
to avoid a crash. As a vehicle operator
who is not looking toward the location
of a visual warning at the time it is
presented may not see it, NHTSA’s
proposal views the auditory warning
signal as the primary modality and the
visual signal as a secondary,
confirmatory indication that explains to
the driver what the warning was
intended to communicate (i.e., a
forward crash-imminent situation).
However, because hearing-impaired
drivers may not perceive an FCW
auditory signal, a visual signal is
important for presenting the FCW to
hearing-impaired individuals.
A multimodal FCW strategy is
consistent with recommendations of
multiple U.S. and international
organizations including ISO, SAE
International, and Euro NCAP. ISO
recommends a multimodal approach in
both ISO 15623, ‘‘Forward vehicle
collision warning systems—
Performance requirements and test
procedures’’ and ISO 22839, ‘‘Forward
vehicle collision mitigation systems—
Operation, performance, and
verification requirements’’ (which
applies to light and heavy vehicles).
SAE addresses the topic of a multimodal
FCW strategy in both information report
J2400 2003–08, ‘‘Human Factors in
Forward Collision Warning Systems:
Operating Characteristics and User
Interface Requirements,’’ and J3029,
‘‘Forward Collision Warning and
Mitigation Vehicle Test Procedure and
Minimum Performance Requirements—
Truck and Bus (2015–10; Work in
Progress currently).’’ Most of these
recommendations specify an FCW
consisting of auditory and visual
signals, while ISO 15623 specifies that
an FCW include a visual warning, as
well as an auditory or haptic signal.
ii. FCW Auditory Signal Characteristics
The proposed FCW auditory signal
would be the primary means used to
direct the vehicle operator’s attention to
the forward roadway and should be
designed to be conspicuous to quickly
capture the driver’s attention, convey a
high level of urgency, and be
discriminable from other auditory
signals presented within the vehicle.110
Some specifications from NHTSA’s
‘‘Human Factors Design Guidance For
Driver—Vehicle Interfaces’’ are
proposed as forward collision warning
specifications to meet these criteria.111
110 DOT HS 810 697, Crash Warning System
Interfaces: Human Factors Insights and Lessons
Learned—Final Report.
111 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
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As the FCW auditory signal would be
the primary warning mode, this signal
would not be permitted to be disabled.
To be conspicuous and quickly
capture the driver’s attention, the FCW
auditory signal must ensure that the
driver will readily detect the warning
under typical driving conditions (e.g.,
ambient noise). The auditory signal
must be clearly perceptible and quickly
focus the driver’s attention on the
forward roadway. To ensure that the
FCW auditory signal is conspicuous to
the vehicle operator, any in-vehicle
system or device that produces sound
that may conflict with the FCW
presentation would be required to be
muted, or substantially reduced in
volume, during the presentation of the
FCW.112 In order for the warning to be
detectable, a minimum intensity of 15–
30 dB above the masked threshold (MT)
should be used.113 114 115 116 Because
sound levels inside a vehicle can vary
based on any number of different
factors, such as vehicle speed and
pavement condition, NHTSA is not
proposing a specific sound level at this
time, but requests comments on suitable
and reasonable approaches for ensuring
that the FCW auditory signal can be
detected by drivers under typical
driving conditions.
For communicating urgency and
ensuring comprehension of auditory
messages, fundamental frequency, the
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
112 DOT HS 810 697, Crash Warning System
Interfaces: Human Factors Insights and Lessons
Learned—Final Report.
113 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
‘‘The amplitude of auditory signals is in the range
of 10–30 dB above the masked threshold (MT), with
a recommended minimum level of 15 dB above the
MT (e.g., [1, 2, 3]). Alternatively, the signal is at
least 15 dB above the ambient noise [3].’’
114 Campbell, J.L., Richman, J.B., Carney, C., and
Lee, J.D. (2002). In-vehicle display icons and other
information elements. Task F: Final in-vehicle
symbol guidelines (FHWA–RD–03–065).
Washington, DC: Federal Highway Administration.
115 International Organization for
Standardization. (2005). Road vehicles—Ergonomic
aspects of in-vehicle presentation for transport
information and control systems—Warning systems
(ISO/TR 16532). Geneva, Switzerland: International
Organization of Standards.
116 MIL–STD–1472F. (1998). Human engineering.
Washington, DC: Department of Defense.
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lowest frequency in a periodic signal, is
a key design parameter.117 Research has
shown that auditory warning signals
with a high fundamental frequency of at
least 800 Hz more effectively
communicate urgency.118 119 Greater
perceived urgency of a warning is
associated with faster reaction times,
which would mean a quicker crash
avoidance response by the
driver.120 121 122 Therefore, NHTSA
proposes that the FCW auditory signal’s
fundamental frequency must be at least
800 Hz.123 Additional proposed FCW
auditory signal requirements that
support communication of the urgency
of the situation include a duty cycle,124
or percentage of time sound is present,
of 0.25–0.95, and faster auditory signals
with a tempo in the range of 6–12 pulses
per second to be perceived as urgent
and elicit rapid driver response.125
117 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
118 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
119 Guilluame, A., Drake, C., Rivenez, M.,
Pellieux, L., & Chastres, V. (2002). Perception of
urgency and alarm design. Proceedings of the 8th
International Conference on Auditory Display.
120 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
121 Campbell, J.L., Richman, J.B., Carney, C., &
Lee, J.D. (2004). In-vehicle display icons and other
information elements, Volume I: Guidelines (Report
No. FHWA–RD–03–065). Washington, DC: Federal
Highway Administration. Available at
www.fhwa.dot.gov/publications/research/safety/
03065/index.cfm.
122 Suied, C., Susini, P., & McAdams, S. (2008).
Evaluating warning sound urgency with reaction
times. Journal of Experimental Psychology:
Applied, 14(3), 201–212.
123 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
124 Duty cycle, or percentage of time sound is
present, is equal to the total pulse duration divided
by the sum of the total pulse duration and the sum
of the inter-pulse intervals.
125 Gonzalez, C., Lewis, B.A., Roberts, D.M., Pratt,
S.M., & Baldwin, C.L. (2012). Perceived urgency
and annoyance of auditory alerts in a driving
context. Proceedings of the Human Factors and
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The FCW auditory signal needs to be
easily discriminable from other auditory
signals in the vehicle. Therefore,
vehicles equipped with more than one
crash warning type should use FCW
auditory signals that are distinguishable
from other warnings.126 This proposed
requirement is consistent with ISO
15623 5.5.2.6.127 Standardization of
FCW auditory signals would likely be
beneficial in ensuring driver
comprehension of the warning
condition across vehicle makes and
models. NHTSA invites comments on
the feasibility of specifying a common
FCW auditory signal. While this
proposal contains no specific
requirements ensuring that the FCW
auditory signal is distinguishable from
other auditory warnings in the vehicles,
NHTSA believes that industry is likely
to consider this in their vehicle designs
as part of their due diligence and safety
assurance.
iii. FCW Visual Signal Characteristics
Current FCWs in the U.S. vehicle fleet
use a mix of symbols and words as a
visual forward collision warning. Use of
a common FCW symbol across makes
and models would help to improve
consumer understanding of the meaning
of FCWs and encourage more
appropriate driver responses in forward
crash-imminent situations.
ISO 7000, ‘‘Graphical symbols for use
on equipment—Registered symbols’’ 128
and the SAE J2400 (2003–08) 129
information report, ‘‘Human Factors in
Forward Collision Warning Systems:
Operating Characteristics and User
Interface Requirements,’’ contain
recommended FCW symbols shown in
Figure 4. These symbols are similar as
they both communicate a forward
impact, while the ISO symbol portrays
the forward impact as being specifically
with another vehicle.
Ergonomics Society Annual Meeting, 56(1), 1684–
1687.
126 DOT HS 810 697, Crash Warning System
Interfaces: Human Factors Insights and Lessons
Learned—Final Report.
127 ISO 15623—Forward vehicle collision
warning systems—Performance requirements and
test procedures.
128 ISO 7000—Graphical symbols for use on
equipment—Registered symbols.
129 SAE J2400 (info. report, not RP or standard),
2003–08. Human Factors in Forward Collision
Warning Systems: Operating Characteristics and
User Interface Requirements.
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Because the symbol in SAE J2400
relates the idea of a frontal crash
without depicting a particular forward
object, this symbol could visually
represent and apply to scenarios when
approaching a lead vehicle but also
scenarios approaching pedestrians or
other objects which may be relevant to
AEB systems. To prevent different
vehicle types from having different FCW
alerts, NHTSA proposes the same FCW
characteristics and reasoning in both the
light vehicle NPRM and this NPRM.
Therefore, NHTSA has taken account of
considerations for pedestrian scenarios,
because the light vehicle proposed rule
contains a requirement that FCW and
AEB systems function in the case of an
imminent collision with a pedestrian.
NHTSA finds the SAE J2400 symbol to
be most applicable to the FCW
requirements in this proposal. NHTSA
proposes that FCW visual signals using
a symbol must use the SAE J2400
(2003–08) symbol.
Some other vehicle models employ a
word-based visual warning, such as
‘‘STOP!’’ or ‘‘BRAKE!’’ SAE J2400 also
includes a word-based visual warning
recommendation consisting of the word,
‘‘WARNING.’’ A well-designed warning
should instruct people about what to do
or what not to do to avoid a hazard. The
potential benefit of a word-based
warning for FCW is that it can
communicate to the driver an
instruction about what to do to avoid or
mitigate the crash, thereby expediting
the driver’s initiation of an appropriate
crash avoidance response. However,
Consumer Reports noted in its online
‘‘Guide to forward collision warning’’
that for some models, visual warning
word use was found to be confusing to
some drivers surveyed.130 Respondents
reported a common complaint that
‘‘their vehicle would issue a visual
130 ‘‘Guide to forward collision warning: How
FCW helps drivers avoid accidents.’’ Consumer
Reports. https://www.consumerreports.org/carsafety/forward-collision-warning-guide/ (last
accessed April 2022).
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‘‘BRAKE’’ alert on the dash, but it
wouldn’t bring the car to a stop . . .’’
This confusion as to whether the word
is meant to communicate what the
driver should do or what the vehicle is
doing may stem from drivers assuming
that any information presented within
the instrument panel area is
communicating something relating to
the vehicle’s condition or state, as
symbols presented in that location
generally do. Presenting a word-based
warning in a higher location away from
the instrument panel, as recommended
by SAE J2400, may be interpreted more
accurately by drivers as well as increase
the likelihood of FCW visual warning
perception by drivers.131 NHTSA
requests comments on this issue and
any available objective research data
that relates to the effectiveness of wordbased FCW visual signals in instrument
panel versus head-up display locations.
NHTSA also requests comments
regarding whether permitting wordbased warnings that are customizable in
terms of language settings is necessary
to ensure warning comprehension by all
drivers.
One plausible benefit of a word-based
visual warning is that some word
choices that instruct the driver to
initiate a particular action, such as
‘‘STOP!,’’ would be fully applicable to
lead vehicles and other obstacles or
pedestrians, whereas a symbol
containing an image of a lead vehicle
would not be directly applicable to
other crash-imminent scenarios.
Although this NPRM does not propose
requiring pedestrian AEB, NHTSA
believes the warning should not be
directed specifically at lead vehicle
AEB. As the response desired from the
driver, to apply the brakes, the content
of the visual warning need not be
specific to the type of forward obstacle,
but needs simply to communicate the
131 SAE J2400 2003–08 (Information report).
Human Factors in Forward Collision Warning
Systems: Operating Characteristics and User
Interface Requirements.
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43209
idea of an impending forward crash.
NHTSA requests comments and any
available research data regarding the use
and effectiveness of obstacle-specific
symbols and word-based visual
warnings and the relative effectiveness
of word-based visual warnings
compared to symbols.
While many current vehicle models
present a visual FCW signal within the
instrument panel, drawing a driver’s
eyes downward away from the roadway
to the instrument panel during a
forward crash-imminent situation is
likely to have a negative impact on the
effectiveness of the driver’s response to
the FCW. Research indicates that a
visual FCW signal presented in the
instrument panel can slow driver
response.132 The research findings
support the SAE J2400 recommendation
advising against the use of instrument
panel based visual FCWs.133 SAE J2400
(2003–08) states:
Visual warnings shall be located within a
10-degree cone of the driver’s line of sight.
Qualitatively, this generally implies a top-ofdashboard or head-up display location. A
conventional dashboard location shall not be
used for the visual warning. The rationale for
this is based on the possibility that an
instrument panel-based visual warning may
distract the driver from the hazard ahead.
This FCW visual signal location
guidance is also consistent with ISO
15623, which states that the FCW visual
signal shall be presented in the ‘‘main
glance direction.’’ Current vehicles
equipped with head-up displays have
the ability to present a FCW visual
signal within the driver’s forward field
of view. Furthermore, some GM vehicles
not equipped with head-up displays
currently have the ability to present a
FCW visual signal reflected onto the
132 ‘‘Evaluation of Forward Collision Warning
System Visual Alert Candidates and SAE J2400,’’
SAE Paper No. 2009–01–0547, https://trid.trb.org/
view/1430473.
133 SAE J2400 2003–08 (Information report).
Human Factors in Forward Collision Warning
Systems: Operating Characteristics and User
Interface Requirements.
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windshield in the driver’s forward lineof-sight. Despite the FCW visual signal
being considered secondary to the
auditory signal, NHTSA agrees that the
effectiveness of a FCW visual signal
would be maximized for both hearing
and hearing-impaired drivers if the
signal is presented at a location within
the driver’s forward field of view above
the instrument panel. To ensure
maximum conspicuity of the FCW
visual signal (be it word-based or a
symbol), NHTSA proposes that it be
presented within a 10-degree cone of the
driver’s line of sight. The line of sight
would be based on the forward-looking
eye midpoint (Mf) as described in
FMVSS No. 111, ‘‘Rear visibility,’’
S14.1.5.
The FCW visual signal would be
required to be red as is generally used
to communicate a dangerous condition
and as recommended by ISO 15623 and
SAE J2400 (2003–08). Because the FCW
visual signal is intended to be
confirmatory for the majority of drivers,
the symbol would be required to be
steady burning.
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iv. FCW Haptic Signal Discussion
NHTSA considered also specifying a
complementary haptic FCW signal as
part of the proposed FCW
specifications. Currently, only a portion
of U.S. vehicles equipped with forward
collision warning include a haptic
warning component. For example,
General Motors vehicles equipped with
the haptic warning feature can present
either a haptic seat pulse (vibration) or
auditory warning based on a driverselectable setting. Some other vehicle
manufacturers, such as Stellantis and
Audi, use a brake pulse, or brief
deceleration of the vehicle, as part of the
FCW. Some Hyundai/Kia models
incorporate a haptic steering wheel
vibration into the FCW. As haptic
steering wheel signals are used by many
lane keeping features of current vehicles
to encourage drivers to steer the vehicle
back toward the center of the lane,
providing a haptic FCW signal via the
steering wheel may result in driver
confusion and be less effective in
eliciting a timely and beneficial driver
response.
ISO 15623 allows a haptic signal as an
alternative to an auditory signal.134 It
permits a haptic brake pulse warning
with a duration of less than 1 second
when the driver is not already applying
the brakes. ISO 15623 also allows
134 ISO 15623—Forward vehicle collision
warning systems—Performance requirements and
test procedures.
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actuation of a seat belt pretensioner as
a haptic FCW signal.
Some research has shown that haptic
FCW signals can improve crash
avoidance response. NHTSA research
on ‘‘Driver-Vehicle Interfaces for
Advanced Crash Warning Systems’’
found that a haptic signal delivered via
the seat belt pretensioner would be
beneficial in eliciting an effective crash
avoidance response from the vehicle
operator. The research showed for FCWs
issued at 2.1-s time to collision (TTC)
that seat belt pretensioner-based FCW
signals elicited the most effective crash
avoidance performance.135 Haptic FCW
signals led to faster driver response
times than did auditory tonal signals.
FCW modality had a significant effect
on participant reaction times and on the
speed reductions resulting from
participants’ avoidance maneuvers
(regardless of whether a collision
ultimately occurred). Brake pulsing or
seat belt tensioning were found to be
effective for returning distracted drivers’
attention to the forward roadway and
eliciting desirable vehicle control
responses; seat vibration similar to a
virtual rumble strip (vibrating the front
of the seat) was not found to rapidly and
reliably return driver attention to the
forward roadway within the research.
Similarly, research by Aust (2014) found
that ‘‘combining sound with seat belt
jerks or a brake pulse leads to
significantly faster response times than
combining the sound with a visual
warning’’ and stated, ‘‘these results
suggest that future FCWs should include
a haptic modality to improve driver
performance.’’ 136 Aust (2014) also
found use of a haptic seat belt FCW
signal to be slightly more effective (100
ms faster driver response) than a haptic
brake pulse in one of two scenarios
(response times were equal in a second
scenario). Despite these promising
research results associated with use of a
seat belt based FCW haptic component,
NHTSA was unable to identify any
current U.S. vehicle models equipped
with a haptic seat belt FCW component.
Other studies found FCW haptic brake
pulses effective at getting a driver’s
attention and that drivers are more
likely to detect a brake pulse if it
produces a sensation of ‘‘jerk’’ or ‘‘self135 Lerner, N., Singer, J., Huey, R., Brown, T.,
Marshall, D., Chrysler, S., . . . & Chiang, D.P. (2015,
November). Driver-vehicle interfaces for advanced
crash warning systems: Research on evaluation
methods and warning signals. (Report No. DOT HS
812 208). Washington, DC: National Highway
Traffic Safety Administration.
136 Aust, M. (2014) Effects of Haptic Versus Visual
Modalities When Combined With Sound in
Forward Collision Warnings. Driving Simulation
Conference 2014, Paper number 36. Paris, France,
September 4–5, 2014.
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motion.’’ 137 138 Kolke reported reaction
times shortened by one-third
(approximately 0.3 s, non-significant)
when a brake pulse was added to an
audio-visual warning.139 One usability
drawback is that drivers tend to report
that vehicle brake pulses are too
disruptive, which can lead to
unfavorable annoyance.140
Presentation of a FCW haptic signal
via the driver’s seat pan has also been
investigated. NHTSA’s ‘‘Human factors
design guidance for driver-vehicle
interfaces’’ contains best practice
information for implementation of
haptic displays, including ‘‘Generating a
Detectable Signal in a Vibrotactile
Seat.’’ 141 In a large-scale field test of
FCW and LDW systems on model year
2013 Chevrolet and Cadillac vehicles,
the University of Michigan
Transportation Research Institute and
GM found that GM’s Safety Alert Seat,
which provides haptic seat vibration
pulses, increases driver acceptance of
both FCW and LDW systems compared
to auditory signals.142
NHTSA’s March 2022 request for
comments notice on the NCAP sought
comment on which FCW modalities or
modality combinations should receive
credit and asked specific questions
regarding haptic signals and whether
certain types should be excluded from
consideration (e.g., because they may be
such a nuisance to drivers that they are
more likely to disable the FCW or AEB
system). A preliminary review of
comments on that notice found multiple
comments highlighting a need for more
137 Lee, J.D., McGehee, D.V., Brown, T.L., &
Nakamoto, J. (2012). Driver sensitivity to brake
pulse duration and magnitude. Ergonomics, 50(6),
828–836.
138 Brown, S.B., Lee, S.E., Perez, M.A., Doerzaph,
Z.R., Neale, V.L., & Dingus, T.A. (2005). Effects of
haptic brake pulse warnings on driver behavior
during an intersection approach. Proceedings of the
Human Factors and Ergonomics Society 49th
Annual Meeting, 1892–1896.
139 Kolke, Gauss, and Silvestro (2012). Accident
reduction through emergency braking systems in
passenger cars. Presentation at the 8th ADAC/BAStSymposium ‘‘Driving Safely in Europe.’’ October 5,
2012, Workshop B.
140 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
141 Campbell, J.L., Brown. J.L., Graving, J.S.,
Richard, C.M., Lichty, M.G., Sanquist, T., . . . &
Morgan, J.L. (2016, December). Human factors
design guidance for driver-vehicle interfaces
(Report No. DOT HS 812 360). Washington, DC:
National Highway Traffic Safety Administration.
142 Flannagan, C., LeBlanc, D., Bogard, S.,
Nobukawa, K., Narayanaswamy, P., Leslie, A.,
Kiefer, R., Marchione, M., Beck, C., and Lobes, K.
(2016, February), Large-scale field test of forward
collision alert and lane departure warning systems
(Report No. DOT HS 812 247), Washington, DC:
National Highway Traffic Safety Administration.
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Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 / Proposed Rules
research relating to FCW signals. The
National Transportation Safety Board
highlighted a need for additional
information regarding haptic signals
presented in different locations stating
‘‘[w]ithout examining the efficacy of
different means of providing haptic
alerts and defining appropriate,
research-supported implementations, a
prudent approach would give credit
only for audible unimodal alerts or for
bi-modal alerts that include audible
alerts.’’ Rivian stated ‘‘[t]he agency
should award credit to systems that
provide both audible and haptic alerts
and provide the option to turn either of
them OFF based on driver preference.
These audible or haptic alerts should be
in sync with providing a visual alert of
an impending collision. The agency
should recommend the decibel level
and the haptic feedback location and
type as a baseline and based on research
on reducing nuisance to the driver.’’
Given the lack of consensus within
available research as to the best location
for a FCW haptic signal (seat belt, seat
pan, steering wheel, or brake pulse), and
NHTSA’s ongoing review of comments
submitted in response to the March
2022 request for comments, NHTSA is
not at this time proposing to require a
haptic FCW component, but invites
comment on whether requiring FCW to
contain a haptic component presented
via any location may increase FCW
effectiveness or whether a FCW haptic
signal presented in only one specific,
standardized location should be
allowed.
While the FCW auditory signal is
envisioned as being the primary means
of warning the driver, providing a
haptic FCW signal that would
complement or supplant the auditory
warning signal would likely improve
FCW perception for hearing-impaired
drivers. Some drivers also may prefer an
alternative modality to auditory
warnings (e.g., due to annoyance caused
by the auditory warning). However, the
degree of additional benefit that may be
accrued by requiring a haptic FCW
signal in addition to a well-designed
auditory and visual FCW that meets the
specifications proposed is not known.
A haptic FCW signal, to be effective,
would necessarily require the driver to
be in physical contact with the vehicle
component through which the haptic
signal is presented in order to perceive
the warning. For example, if the driver
is not wearing a seat belt, a haptic FCW
signal presented via the seat belt would
not be effectively received. A seat pan
based haptic FCW signal would be
unlikely to have such a non-contact
issue. NHTSA is interested in research
data documenting the comparison of a
compliant auditory-visual FCW to that
same FCW with an added haptic
component. NHTSA also welcomes any
objective data documenting the relative
effectiveness of different haptic signal
presentation locations for FCW use.
143 Woodrooffe, J., et al. ‘‘Performance
Characterization and Safety Effectiveness Estimates
of Forward Collision Avoidance and Mitigation
Systems for Medium/Heavy Commercial Vehicles,’’
Pg. 12. Report No. UMTRI–2011–36, UMTRI
(August 2012). Available at https://
www.regulations.gov/document/NHTSA-2013-00670001 (last accessed June 9, 2022).
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3. Performance Test Requirements
This NPRM would require that, when
approaching a lead vehicle during
testing, the subject vehicle must provide
a forward collision warning and
subsequently apply the brakes to avoid
a collision. This performance
requirement is conducted under a
defined set of conditions, parameters
(e.g., relative vehicle speeds and
distances), and test procedures.
For all vehicle tests where the subject
vehicle approaches a lead vehicle,
NHTSA is proposing that the minimum
performance requirement is complete
avoidance of the lead vehicle. NHTSA
chose the performance criterion of
collision avoidance because it
maximizes the safety benefits of the rule
as compared to a metric that might
permit a reduced speed collision.
NHTSA has tentatively concluded that a
no-contact criterion for the performance
test requirements is practicable to
achieve, consistent with the need for
safety, and may be necessary to ensure
test repeatability.
NHTSA also seeks comment on the
potential consequences if vehicle
contact were allowed during testing.
First, NHTSA seeks comment on how
allowing contact during testing would
affect the safety benefits of AEB
systems. Second, NHTSA seeks
comment on whether allowing contact
during testing would create additional
testing burdens. Specifically, NHTSA is
concerned that any performance test
requirement that allows for vehicle
contact not resulting in immediate test
failure could result in the nonrepeatability of testing without
expensive or time-consuming
interruptions to testing, and seeks
comment on this concern. For instance,
if a test vehicle were to strike the lead
vehicle test device, even at a low speed,
sensors on the vehicle could become
misaligned or the vehicle test device
may be damaged, including in ways that
are not immediately observable. For
example, damage to the test device
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might affect the radar cross section that
requires a long verification procedure to
discover.
4. Performance Test Scenarios
NHTSA is proposing three track test
scenarios to evaluate AEB performance.
The test scenarios have the subject
vehicle travelling toward a lead vehicle
which is ahead in the same lane.
However, the lead vehicle may be either
stopped, moving at a constant but
slower speed, or decelerating to a stop.
These three tests were chosen because
they represent the three most common
pre-crash scenarios involving a lead
vehicle. A NHTSA research study of
heavy vehicles comprising the striking
vehicle in rear-end crashes in the
United States determined that four precrash scenarios exist in data of both fatal
and non-fatal crashes.143 These four
scenarios include the three listed above,
and also a ‘‘cut-in’’ case in which a lead
vehicle changed lanes or merged into
the path of the heavy vehicle just prior
to the crash. The cut-in scenario was
excluded from the test scenarios for this
proposal because the research study
shows that it was much less likely to
occur than the other three scenarios.144
i. Stopped Lead Vehicle
This test recreates a roadway scenario
where the subject vehicle encounters a
lead vehicle which is stopped ahead in
the same lane. Figure 5 shows the basic
setup for the stopped lead vehicle
scenario. The subject vehicle is driven
toward the stationary lead vehicle at a
constant speed, and the accelerator is
only released if a forward collision
warning is issued. The test ends when
the subject vehicle either automatically
stops without impact, or proceeds to
strike the lead vehicle.
NHTSA proposes testing under two
conditions for the subject vehicle:
testing without any manual brake
application (to test the CIB component)
and testing with manual brake
application (to ensure that the driver’s
application of the brake pedal does not
inhibit the functionality of the AEB
system). Testing with no brake
application simulates a driver who does
not intervene in response to an FCW
alert prior to a crash. Testing with brake
application simulates a driver who
applies the brakes, but the manual brake
application is insufficient to prevent a
collision.
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144 The cut-in scenario represents less than 5% of
the pre-crash scenarios.
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ii. Slower-Moving Lead Vehicle
This test recreates a roadway scenario
where the subject vehicle encounters a
lead vehicle that is moving at a constant
but slower speed ahead in the same
lane. Figure 6 shows the basic setup for
the slower-moving lead vehicle
iii. Decelerating Lead Vehicle
predetermined relative distance, or
headway. The lead vehicle then begins
to decelerate, reducing the headway.
Once the AEB system in the subject
vehicle issues a forward collision
warning, the subject vehicle’s
accelerator is released. The test ends
when the subject vehicle either
automatically stops without impact or
strikes the lead vehicle. As with the
prior two tests, NHTSA proposes testing
under two conditions for the subject
vehicle: without any manual brake
application and with manual brake
application. Figure 7 shows the basic
setup for the decelerating lead vehicle
scenario.
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vehicle’s speed without impact or
strikes the lead vehicle. As with the
stopped lead vehicle test, NHTSA
proposes testing under two conditions
for the subject vehicle: without any
manual brake application and with
manual brake application.
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This test recreates a roadway scenario
where the subject vehicles encounter a
lead vehicle that is slowing down ahead
in the same lane. At the start of the test,
both the subject vehicle and lead
vehicle travel at the same constant
speed, while maintaining a
scenario. The subject vehicle is driven
toward the lead vehicle at a constant
speed, and its accelerator is then
released after the AEB system in the
subject vehicle issues a forward
collision warning. The test ends when
the subject vehicle either slows down to
a speed less than or equal to the lead
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5. Parameters for Vehicle Tests
The test procedures for each scenario
reference a set of parameters. These
parameters are presented in Table 16,
where each row represents a potential
combination of parameters to be used
for a test run. The parameters define the
speeds, decelerations, headways, and
manual brake applications used for the
• Headway—the distance between the
subject vehicle and the lead vehicle
• Lead Vehicle Deceleration—the rate at
which the lead vehicle reduces its
speed
• Manual Brake Application—specifies
whether or not the service brakes of
the subject vehicle will be applied
‘‘manually,’’ or via a brake controller
choreography of the vehicle test
scenarios. Specifically, these include:
• Subject Vehicle Speed (VSV)—speed
at which the subject vehicle travels
toward the lead vehicle
• Lead Vehicle Travel Speed (VLV)—
speed at which the lead vehicle
travels in the same direction as the
subject vehicle
TABLE 16—TEST PARAMETERS WHEN APPROACHING A LEAD VEHICLE
Speed
(km/h)
Test scenarios
Slower-Moving Lead Vehicle ..............................................
Decelerating Lead Vehicle ..................................................
Some of these parameters are
proposed as ranges.145 The use of ranges
allows NHTSA to ensure AEB system
performance remains consistent under a
variety of conditions and that no
substantial degradation in performance
occurs at any point within the range.
NHTSA tentatively concludes that
requiring a minimum performance only
at discreet, predetermined values within
these proposed ranges may not ensure
that AEB system performance is
sufficiently robust to meet the need for
safety.
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i. Vehicle Speed Parameters
The proposed test speed ranges were
selected considering two primary
factors. The first factor is the practical
ability of AEB technology to
consistently operate and avoid contact
with a lead vehicle at the widest
reasonable range of speeds. A larger
range of speeds could yield more safety
benefits. Also, a larger range of speeds
will more thoroughly test the
capabilities of the AEB system. NHTSA,
through its understanding of vehicle
braking systems described in
established standards such as FMVSS
Nos. 105 and 121, knows that testing
stopping distance at 60 mph is
indicative of the service brake
performance over a range of speeds, and
in those cases testing at a single speed
is acceptable. However, as observed in
vehicle testing for NHTSA research,
AEB performance during testing at
145 In instances where an FMVSS includes a range
of values for testing and/or performance
requirements, the use of the word ‘‘any’’ is
consistent with 49 CFR 571.4.
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Lead vehicle
decel.
(g)
........................
........................
........................
........................
Any 21–40 .....
Any 21–40 .....
Any 28–40 .....
Any 28–40 .....
........................
........................
........................
........................
Any 0.3–0.4 ...
Any 0.3–0.4 ...
Any 0.3–0.4 ...
Any 0.3–0.4 ...
VLV
VSV
Stopped Lead Vehicle ........................................................
Headway
(m)
Any 10–80 .....
Any 70–100 ...
Any 40–80 .....
Any 70–100 ...
50 ...................
50 ...................
80 ...................
80 ...................
0
0
20
20
50
50
80
80
interstate speeds does not necessarily
indicate what the same system’s
performance will be at lower speeds.
Thus, NHTSA tentatively concludes that
testing over a range of speeds is
necessary to fully assess AEB
performance.
The second factor is the practical
limit of safely conducting vehicle tests
of AEB systems. NHTSA’s testing must
be safe and repeatable as permitted by
track conditions and testing equipment.
For example, if the AEB system does not
intervene as required or if test
parameters inadvertently fall outside of
the specified limits, it should be
possible to safely abort the test. In the
event the subject vehicle does collide
with the lead vehicle, the test should be
designed so that it does so in a manner
that will not injure the testing personnel
nor cause excessive property damage.
Additionally, test tracks may be
constrained by available space and there
may be insufficient space to accelerate
a heavy vehicle up to a high speed and
still have sufficient space to perform a
test. Many types of heavy vehicles are
not capable of accelerating as quickly as
lighter vehicles and reaching high test
speeds may require long distances that
exceed what is available at many
vehicle testing facilities. At
approximately 100 km/h, the agency
found that constraints with available
test track length, in conjunction with
the time required to accelerate the
vehicle to the desired test speed, made
performing these high speed tests with
heavy vehicles logistically
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Manual brake
application
no.
yes.
no.
yes.
no.
yes.
no.
yes.
challenging.146 The agency has
tentatively concluded that at this time
the maximum practicable test speed is
100 km/h.
The maximum speed of 100 km/h is
included in the test speed range when
manual braking is present; the manual
braking will guarantee a speed
reduction even if the AEB system does
not activate before reaching the lead
vehicle, which would limit potential
damage to the test equipment and
reduce other potential risks. When no
manual braking is allowed, the
maximum test speed would be 80 km/
h so that, in the event the AEB system
does not provide any braking at all, risk
to personnel and damage to test
equipment are reduced. Over 82 percent
of rear-end crashes where the heavy
vehicle is the striking vehicle occur at
speeds below 80 km/h.147 However, the
majority of fatal crashes occur at speeds
above 80 km/h, and approximately 40
percent of these occur at travel speeds
between 80 and 100 km/h. The stopped
lead vehicle test scenario uses a nomanual-braking test speed range of 10 to
80 km/h and a manual-braking test
speed range of 70 to 100 km/h.
Together, these test speed ranges
overlap with the travel speeds at which
heavy vehicle rear-end crashes occur in
the real world, while reducing the
potential risk and damage to test
equipment and vehicles and not
146 During testing of a 2021 Freightliner Cascadia
at speeds approaching 100 km/h, NHTSA
experienced difficulty establishing valid test
conditions due to insufficient track length.
147 This is based on analysis of 2017–2019 crash
data.
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exceeding the practical physical size
limits of test tracks.
Similarly, the slower-moving lead
vehicle test scenario uses speed ranges
of 40 to 80 km/h and 70 to 100 km/h
for the subject vehicle, while the lead
vehicle travels ahead at a constant speed
of 20 km/h. The lower end of the subject
vehicle test speed range is 40 km/h so
that the subject vehicle is traveling
faster than the lead vehicle. The
decelerating lead vehicle tests are run at
either 50 or 80 km/h. This test is
performed at two discreet speeds rather
than at ranges of speeds because the
main factors that test AEB performance
are the variation of headway, or the
distance between the subject vehicle
and lead vehicle, and how hard the lead
vehicle brakes. Additionally, because
these tests contain a larger number of
variables requiring more complex test
choreography, limiting the test to two
discreet test speeds reduces the number
of potential test conditions and reduces
potential test burden.
During each test run in any of the test
scenarios, the vehicle test speed will be
held constant until the test procedure
specifies a change. NHTSA is proposing
that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of
the chosen test value. This is important
for test consistency. Vehicle speed
determines the time to collision, which
is a critical variable in AEB tests. In
NHTSA’s experience, both the subject
vehicle and lead vehicle speeds can be
reliably controlled within the 1.6 km/h
tolerance range, and speed variation
within that range yields consistent test
results. A tighter speed tolerance is
burdensome and unnecessary for
repeatability as it may result in a higher
test-rejection rate, without any greater
assurance of accuracy of the test track
performance.
NHTSA’s vehicle testing suggested
that the selected speed ranges for the
various scenarios are within the
capabilities of at least some recent
model year AEB-equipped production
vehicles. For example, the 2021
Freightliner Cascadia avoided collision
in the stopped lead vehicle test at all
speeds between 40 and 85 km/h, most
speeds between 30 and 90 km/h (except
30 and 60 km/h) in the slower-moving
lead vehicle test, and in all decelerating
lead vehicle tests that were run at the
proposed parameters. This vehicle’s
AEB system did not prevent a collision
at lower speeds between 20 and 35 km/
h for the stopped lead vehicle test.
However, the 2021 Dodge Ram 550
avoided collision in all stopped lead
vehicle tests from 10 to 40 km/h. In
many test cases where current AEB
systems did not prevent a collision, the
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AEB significantly reduced the speed
before the collision. While these current
AEB systems perform a bit differently
depending on the vehicle, given that
this notice proposes a lead time for
manufacturers to come into compliance
with the proposed performance
requirement, the agency expects that
compliance with these requirements
would be achievable.
ii. Headway
The decelerating lead vehicle test
scenario includes a parameter defining
how far ahead the lead vehicle is from
the subject vehicle at the beginning of
the test, which is referred to as
headway. Headway and lead vehicle
deceleration are the main factors for the
dynamics of the decelerating lead
vehicle test since both the lead and
subject vehicles start the test at the same
constant speed. At the start of the test,
when the vehicles are both travelling at
50 km/h, the proposed headway
specification is any distance between 21
m and 40 m.148 When the vehicles are
both travelling at 80 km/h, the proposed
headway specification is any distance
between 28 m and 40 m. Headways are
proposed as a range in order to assure
AEB functionality over a wider range of
driving scenarios. A basic kinematic
simulation of heavy vehicle AEB
braking under the proposed test
parameters, assuming factors such as
AEB response time and foundation
brake reaction time/deceleration similar
to what was observed in testing,
indicated that headways shorter than 21
and 28 m would not be realistic to
achieve and would inevitably result in
a collision.
The upper limit of 40 m was chosen
because testing at longer headways does
not provide additional insight into AEB
performance with regard to decelerating
lead vehicles. At headways greater than
40 m, the lead vehicle decelerating may
come to a full stop prior to the subject
vehicle actuating the brakes. This
essentially becomes a stopped lead
vehicle test. Allowing for a range of
headways during testing also makes the
choreography of the test possible by
providing a tolerance for the headway.
At the start of the test, the speed of both
the subject vehicle and lead vehicle are
the same and are maintained within the
tolerance specified (plus or minus 1.6
km/h). As each vehicle’s speed
fluctuates a bit differently within these
bounds, in turn the headway between
the vehicles accordingly fluctuates as
148 The bounds of the headway range are
consistent with the headways in the April 2021
European New Car Assessment Programme (Euro
NCAP), Test Protocol—AEB Car-to-Car systems,
Version 3.0.3 for the same scenario.
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well. As long as the headway
fluctuation is within the proposed
range, the test can still be considered
valid, and no headway tolerance needs
to be established.
iii. Lead Vehicle Deceleration Parameter
The decelerating lead vehicle test
scenario includes a deceleration
parameter that dictates how quickly the
lead vehicle will slow down in front of
the subject vehicle. The agency has
tentatively concluded that this
parameter range of 0.3g to 0.4g
represents real-world, manual
application of the service brake.
Previous NHTSA research had
identified 3.0 m/s2 (.306g) as
‘‘reasonably comfortable for passenger
car occupants’’ and that on average,
drivers brake in such a manner that the
vehicle decelerates at an average of
0.48g when presented with a
unexpected obstacle.149 The upper limit
of the lead vehicle braking is proposed
at 0.4g to avoid a test condition in
which the lead vehicle would provide
greater brake inputs than those
necessary to meet the minimum
stopping distance requirements. NHTSA
took into consideration the stopping
distance requirements for heavy
vehicles under FMVSS Nos. 105 and
121 and the resulting average
decelerations that those vehicles would
be required to achieve. For example, an
air-braked tractor trailer under FMVSS
No. 121 would need to brake at 0.41g to
meet the stopping distance of 310 ft
from 60 mph.150 Given the headway
parameters and vehicle speeds in this
proposal, the agency believes a lead
vehicle deceleration above 0.4g would
create a requirement that could
effectively reduce the minimum
stopping distance requirements for
vehicles generally.
6. Manual Brake Application in the
Subject Vehicle
Each of the three lead vehicle test
scenarios includes tests that are
conducted with manual brake
application in the subject vehicle. The
process for testing with manual brake
application is identical to what is
considered a test for dynamic brake
support or DBS in NHTSA’s NCAP for
light vehicles. While the term DBS is
149 Gregory M. Fitch, Myra Blanco, Justin F.
Morgan, Jeanne C. Rice, Amy Wharton, Walter W.
Wierwille, and Richard J. Hanowski (April 2010).
Human Performance Evaluation of Light Vehicle
Brake Assist Systems: Final Report (Report No. DOT
HS 811 251) Washington, DC: National Highway
Traffic Safety Administration, pgs. 13 and 101.
150 This assumes an average deceleration that is
achieved after an initial brake actuation time of 0.45
seconds, as this is the maximum actuation time
allowed by FMVSS No. 121.
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not usually associated with heavy
vehicles, NHTSA is including this
requirement in this proposal to ensure
that the driver’s application of the brake
pedal does not inhibit the functionality
of the AEB system if the driver’s brake
application is insufficient to avoid a
crash. The manual brake application
procedure specifies that the subject
vehicle’s service brakes are applied by
using a robotic brake controller to
ensure accurate and consistent test
conduct.
A NHTSA study that examined light
vehicle drivers’ behavior in response to
potential frontal crash situations found
that they typically exhibit multi-stage
braking behavior.151 This means that the
drivers initially applied and held the
brake moderately, and then continued to
a full application if perceived to be
necessary. A subsequent NHTSA study
concluded that a significant portion of
heavy vehicle operators display the
same multi-stage braking behavior.152
The agency believes that in real world
cases where the operator may apply
insufficient brake force to avoid a rearend collision, an AEB system should
apply the necessary supplemental
braking necessary to avoid a collision.
Furthermore, by using manual brake
application in the test scenarios,
NHTSA is able to test AEB performance
at higher test speeds.
In real world cases, the brake pedal
can be applied by a heavy vehicle
operator in an infinite number of ways
(varying force, reaction time, duration,
etc.). Since the manual brake
application represents an operator’s
response to an unexpected obstacle and
the forward collision warning, the
agency is proposing a brake pedal
application that results in a mean
deceleration of 0.3g. A heavy vehicle
field study by NHTSA indicated that
when presented with an FCW triggered
by a valid object and requiring a crash
avoidance maneuver, the operators
braked on average at a maximum of
0.3g.153 Manually applying the brake at
0.3g also is a low enough value to
improve the capability of observing an
AEB automatic braking intervention that
is occurring simultaneously on top of
that. The minimum stopping distance
requirements for heavy vehicles in
existing FMVSSs require braking at
around 0.4g. Thus hypothetically, if a
heavy vehicle’s service brakes were
manually applied at a higher
deceleration of 0.4g for example, and
the brakes were only capable of a
maximum of 0.4g of deceleration, AEB
intervention would be incapable of
producing additional deceleration and
would not be observable.
There are two methods to perform the
manual brake application—using either
displacement feedback or hybrid
feedback. Both methods are intended to
be carried out by a robotic brake pedal
controller in closed loop operation, and
the method that is most suitable to the
subject vehicle is chosen. Regardless of
the method, it is necessary initially to
determine a pedal position which, in
the absence of any automatic braking
from the AEB system, results in an
average vehicle deceleration of 0.3g. The
displacement feedback method then
simply requires moving the brake pedal
to the 0.3g position quickly, at a rate of
254 mm/s,154 and then maintaining that
position. However, automatic braking in
certain vehicles requires the pedal
position to move further toward the
floor, and can cause conflict with the
displacement feedback method’s control
of pedal position, in turn adversely
affecting test results.155 The hybrid
feedback pedal control method provides
a solution to this conflict. The hybrid
method initially requires the same pedal
position control, but then almost
immediately begins to control the force
on the pedal (and not the position) to
maintain the 0.3g deceleration. If the
AEB system thereafter requires further
movement of the pedal, the brake
controller is able to ‘‘follow’’ the pedal
while still applying the appropriate
force.156 NHTSA is proposing that the
brake will be applied 1.0 second after
the vehicle has provided a FCW; this is
based on the average time it takes a
driver to react when presented with an
151 Mazzae, E., Barickman, F., Scott Baldwin, G.,
and Forkenbrock G., ‘‘Driver Crash Avoidance
Behavior with ABS in an Intersection Incursion
Scenario on Dry Versus Wet Pavement,’’ SAE
Technical Paper 1999–01–1288, 1999, doi:10.4271/
1999–01–1288.
152 Every, J., Salaani, M., Barickman, F., Elsasser,
D., et al., ‘‘Braking Behavior of Truck Drivers in
Crash Imminent Scenarios,’’ SAE International
Journal of Commercial Vehicles, 7(2):2014,
doi:10.4271/2014–01–2380.
153 Grove, K., Atwood, J., Hill, P., Fitch, G.,
Blanco, M., Guo, F., . . . & Richards, T. (2016,
June). Field study of heavy-vehicle crash avoidance
systems. (Final report. Report No. DOT HS 812
280). Washington, DC: National Highway Traffic
Safety Administration.
154 Previous NHTSA research related to AEB
examined pedal application rates by drivers in
emergency and non-emergency situations, and
determined that pedal application rate is important
in AEB testing with manual braking, and that the
appropriate application rate is 254 mm/s. NHTSA,
August 2014. Automatic Emergency Braking System
(AEB) Research Report, An Update of the June 2012
Research Report Titled, ‘‘Forward-Looking
Advanced Braking Technologies Research Report.’’
Docket NHTSA–2012–0057–0037.
155 NHTSA, August 2014. Automatic Emergency
Braking System (AEB) Research Report, An Update
of the June 2012 Research Report Titled, ‘‘ForwardLooking Advanced Braking Technologies Research
Report.’’ Docket No. NHTSA–2012–0057–0037.
156 Id.
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obstacle.157 Although these average
decelerations and reaction times are
based on behavior of light vehicle
drivers, we feel that it is sufficient basis
to simulate a scenario in which a heavy
vehicle operator brakes partially and
insufficiently to fully avoid a rear-end
collision.
B. Conditions for Vehicle Tests
The test conditions are used to control
the environmental, road surface, subject
vehicle, and equipment conditions to
ensure consistency both to define
potential variabilities in conditions
under which an AEB system would be
expected to operate while also
providing consistent conditions to
reduce test variability due to extraneous
factors. NHTSA recognizes that there are
an unlimited number of non-ideal
environmental conditions present in the
real world, and it would be
unreasonable to attempt to reproduce
most of them within practical
constraints in the testing environment.
Thus, in many cases, the proposed test
conditions were chosen to represent
near-ideal conditions with the goal of
reducing variability in the test results.
For example, if testing were conducted
at below-freezing temperatures with
snowfall, it would be difficult to
interpret whether poor test results were
due to the AEB system or reduced road
surface friction.
Many of the proposed conditions
were selected based on research data
and engineering practices, and
reasonable deduction. In some cases, as
appropriate, the agency considered that
conditions should be the same or
similar to what is specified in other
heavy vehicle brake-related FMVSS.
This usage of pre-established conditions
may help reduce testing burden, since
fewer testing conditions would need to
be adjusted between different FMVSS
brake-related compliance tests. It also
ensures that the minimum stopping
distance requirements in the braking
standards would be achievable during
an AEB test.
Each test procedure for the three
scenarios specifies a point at which
thereafter the test conditions described
in this section apply and will be
maintained. For the stopped lead
vehicle and slower-moving lead vehicle
157 Previous NHTSA research has shown that on
average, it takes drivers 1.04 s to begin pressing the
brake when presented with an unexpected obstacle
and 0.8 s when presented with an anticipated
obstacle. Gregory M. Fitch, Myra Blanco, Justin F.
Morgan, Jeanne C. Rice, Amy Wharton, Walter W.
Wierwille, and Richard J. Hanowski (2010, April)
‘‘Human Performance Evaluation of Light Vehicle
Brake Assist Systems: Final Report’’ (Report No.
DOT HS 811 251), Washington, DC: National
Highway Traffic Safety Administration, p. 101.
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test scenarios, this point is at a 5 second
time to collision. For the decelerating
lead vehicle test scenario, this point is
1 second prior to the onset of lead
vehicle deceleration.
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1. Environmental Conditions
repeatability and also aligns with many
real-world, rear-end crash conditions. A
review of NHTSA’s crash data indicates
that 81 percent of those occur when the
weather conditions are clear or cloudy
and with no precipitation.163
The ambient temperature range
specified in this proposal is 2 to 40
degrees Celsius; this is the same range
as specified in FMVSS No. 136, which
avoided testing at 0 degrees Celsius
because it could impact tire
performance and in turn the variability
of test results.
The maximum wind speed is 5 m/s,
which is the same as what is specified
in FMVSS No. 136. This value was
chosen to reduce the potential lateral
displacement of certain heavy vehicles.
NHTSA considered that certain
environmental conditions should be
near-ideal to prevent sensor
performance degradation and maintain
repeatability of vehicle testing. First,
ambient illumination would be at or
above 2,000 lux. This represents
daytime illumination that is at a
minimum equivalent to an overcast
day.158 A NHTSA study has shown that
darkness can cause degradation of
sensor performance.159 NHTSA analysis
shows that 87 percent of heavy vehicle
rear-end crashes occur during daylight
conditions.160 Therefore, NHTSA
tentatively concludes that daylight
testing is necessary to ensure that AEB
systems address the rear-end crash
safety problem.
Second, during testing, the sun would
not be below 15 degrees of elevation and
within 25 degrees laterally from the
center plane of the subject vehicle. This
specification reduces the likelihood of
glare or washout for camera-based
sensors that could lead to degradation of
sensor and AEB system performance.161
Visibility also would not be affected
by fog, smoke, ash or other particulate,
as recommended in previous agency
research findings.162 This improves test
2. Road Surface Conditions
The road surface upon which vehicle
tests will be conducted must also be in
a defined condition to help achieve
repeatable testing. The proposed
conditions specify that the road surface
is free of debris, irregularities, or
undulations, such as loose pavement,
large cracks, or dips. These could affect
the vehicle’s ability to brake properly or
maintain its heading, and ultimately
reduce the repeatability of a test. The
test surface is also required to be level,
with a slope between 0 and 1 degrees,
because the slope of a road surface can
affect the performance of an AEBequipped vehicle.164 A surface that
slopes up and down could obstruct a
sensor’s view of an object ahead. It
could also influence the dynamics and
layout involved in the proposed AEB
test scenarios, as travelling up or down
a slope makes braking to a stop more or
less difficult. In order to have
predictable tire adherence under
braking, the surface must also be dry
and have a controlled coefficient of
friction. NHTSA is proposing that the
test track surface have a peak friction
coefficient of 1.02 when measured in
accordance with ASTM International
(ASTM) E1337 165 using an ASTM
F2493 standard reference test tire and
without water delivery.166 Surface
friction is a critical factor in brake
system performance testing, including
AEB, since it correlates with tire grip
and the achievable stopping distance.
The presence of moisture will
significantly change the measured
performance of a braking system. A dry
surface is more consistent and provides
for greater test repeatability. Also, the
proposed peak friction coefficient is the
158 During an overcast day (no sun), when the
solar altitude is around 6 degrees, the light intensity
on a horizontal surface is around 2,000 lux.
Illuminating Engineering Society of North America.
1979. ‘‘Recommended Practice of Daylighting.’’
159 NHTSA, August 2014. ‘‘Automatic Emergency
Braking System (AEB) Research Report—An Update
of the June 2012 Research Report Titled, ‘ForwardLooking Advanced Braking Technologies Research
Report.’ ’’ Docket NHTSA–2012–0057–0037.
160 Data are from 2017–2019 FARS and CRSS
crash databases, as discussed in the PRIA section
on initial AEB target population.
161 NHTSA, August 2014. ‘‘Automatic Emergency
Braking System (AEB) Research Report—An Update
of the June 2012 Research Report Titled, ‘ForwardLooking Advanced Braking Technologies Research
Report.’ ’’ Docket NHTSA–2012–0057–0037.
162 NHTSA, August 2014. ‘‘Automatic Emergency
Braking System (AEB) Research Report—An Update
of the June 2012 Research Report Titled, ‘ForwardLooking Advanced Braking Technologies Research
Report.’ ’’ Docket NHTSA–2012–0057–0037.
163 This is also supported by another study
(Grove, Atwood, Fitch and Blanco, M, 2016, ‘‘Field
Study of Heavy-Vehicle Crash Avoidance Systems’’)
which concluded that over 88 percent of heavy
vehicle crashes occurred when the conditions were,
clear, partly cloudy, or overcast.
164 Kim, H. et al., ‘‘Autonomous Emergency
Braking Considering Road Slope and Friction
Coefficient,’’ International Journal of Automotive
Technology, 19, 1013–1022 (2018).
165 ASTM International, ASTM E1337, ‘‘Standard
Test Method for Determining Longitudinal Peak
Braking Coefficient (PBC) of Paved Surfaces Using
Standard Reference Test Tire.’’
166 See 87 FR 34800 (June 8, 2022), Final Rule,
Federal Motor Vehicle Safety Standards, Consumer
Information; Standard Reference Test Tire.
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same value that NHTSA uses for brake
performance testing.
This proposal specifies up to two
straight lines be marked on the test
surface to simulate lane markings. In
order to provide flexibility for different
road configurations at a variety of test
track facilities, lane markings may or
may not be present during testing. If
present, the lines would be of any color
or configuration (e.g., solid, dashed,
double-line, etc.). If two lines are used,
they would be parallel to each other and
between 2.7 to 4.5 m apart, which is
representative of typical lane widths.
Lastly, the environment would not
contain obstructions that could interfere
with detection of a lead vehicle or other
test equipment ahead and have an
unintentional effect on the field of view
of the AEB system, in turn
compromising test repeatability. Thus,
the subject vehicle during testing would
not travel beneath overhead structures
such as signs, bridges, or gantries, and
each compliance test would be
conducted without any vehicles,
obstructions, or stationary objects
within one lane width of either side of
the subject vehicle path unless called
for in the test procedure.
3. Subject Vehicle Conditions
Many of the subject vehicle
conditions exist to ensure that a vehicle
chosen for testing is in a working
condition that represents the vehicle as
it is sold into the market, and capable
of performing as intended by the
manufacturer. Thus, the vehicle
conditions specify that no AEB
malfunction telltale is active, vehicle
components ahead of AEB sensors are
clean and do not obstruct the sensors,
the original tires are installed and
properly inflated, and non-consumable
fluids (e.g., brake fluid, engine coolant,
etc.) are full.
Other conditions exist to ensure that
vehicle performance is comparable to
that found in the real world. Prior to
testing, the vehicle’s service brakes are
burnished according to the burnishing
procedures already used in FMVSS No.
121 or 105 testing, as appropriate for the
vehicle prior to the beginning of testing.
Burnishing helps to gradually seat and
condition new brake components,
particularly the brake pads and rotors/
drums, which come into contact and
provide friction under braking.
Burnishing helps achieve optimal and
repeatable brake performance. If
burnishing was done previously, for
example due to the running of
compliance tests for other FMVSS, it
would not be repeated.
The agency also proposes that the
brake temperatures be between 66 and
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204 degrees Celsius prior to the
beginning of a test, which is the same
as specified in FMVSS No. 136. In the
agency’s experience, this initial
temperature range allows the brakes to
perform well without being under or
over heated during testing, and the
upper end of 204 degree Celsius does
not require unreasonably long cooldown time between test runs.
The agency has also considered that
vehicles may have adjustable
characteristics or configurable systems
that a vehicle operator may choose to
adjust, and some of these are factors that
could affect the outcome of an AEB test.
Since each vehicle operator could
potentially choose different settings for
these systems, the testing would ensure
that AEB systems are capable of meeting
the test requirements regardless of
which choices were made. Accordingly,
this proposal specifies that these
adjustable factors will be nearly in any
configurable level during testing.
Consumable fluids (e.g., fuel, diesel
exhaust fluid, etc.) and propulsion
battery charge will be between 5–100
percent of their capacity. Cruise control
systems would be tested in any
available setting, including adaptive
cruise control modes. In the event that
adaptive cruise control is engaged and
remains engaged during the event, the
FCW would not be required. This is
because an adaptive cruise control
system is intended to slow the vehicle
to avoid a collision prior to a collision
being imminent and without
notification to the driver.167
Forward collision warnings would be
tested in any configurable setting. If the
vehicle is equipped with an enginebraking system, tests would be
conducted with the system either
engaged or disengaged. The controls for
the headlamps and regenerative braking
would be tested in any available
position.
Regarding the weight of the subject
vehicle during testing, this proposal
specifies that the vehicle is loaded to its
gross vehicle weight rating. Truck
tractors will be loaded to its GVWR by
connecting a control trailer. The
specifications for this control trailer,
which is an unbraked, single-axle
flatbed, are equivalent to those found in
FMVSS No. 136. The agency believes it
is important to test the performance of
AEB systems when the vehicle is at its
heaviest allowable condition, because
heavy vehicles often travel in a fully
loaded condition and it generally
presents the most challenging scenario
167 Adaptive cruise control is a driver assistance
technology that automatically adjusts vehicle speed
to maintain a certain distance from a vehicle ahead.
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for braking (i.e., stopping a heavier
vehicle is more difficult). This loading
condition is identical to the loaded
condition specified for FMVSS stopping
distance assessment. This may improve
testing efficiency for NHTSA by having
fewer loading conditions specified
among FMVSS.
Finally, because a vehicle will be
tested at its GVWR, this proposal
specifies that, if a vehicle is equipped
with a liftable axle, it will be placed in
the down position during testing.
C. Proposed Requirements for False
Activation
1. No Automatic Braking Requirement
NHTSA proposes a requirement that
the subject vehicle, when presented
with two false activation test scenarios,
must not automatically apply braking
that results in a peak deceleration of
more than 0.25g when manual braking
is not applied, nor a peak deceleration
of more than 0.45g when manual
braking is applied. False activation
refers to cases where the AEB systems
automatically activates the service
brakes although there is no object
present in the path of the vehicle with
which it would collide. The associated
vehicle tests are run both with and
without manual braking. During test
runs without manual braking, the AEB
system must not initiate braking that
results in a peak deceleration of more
than 0.25g. A 0.25g deceleration is
below the 0.3g threshold described
earlier as a comfortable deceleration
which has a low probability of creating
safety concerns such as rear-end crashes
(if the subject vehicle would brake too
hard).168 Also, 0.25g is an easily
measurable deceleration when testing.
During test runs when manual braking
is being applied, the AEB system must
not initiate braking that results in a peak
deceleration of more than 0.45g. When
testing using manual braking, the goal is
to have a manual braking deceleration of
0.3g, and so the AEB system must not
cause more than approximately 0.15g of
additional deceleration. This 0.15g
amount is less than the 0.25g of peak
deceleration permitted in tests without
manual braking—however, allowing the
same 0.25g above manual braking would
mean that up to a total peak
deceleration of 0.55g would be
permitted. Because 0.55g could exceed
the maximum deceleration capacity of
certain heavy vehicles, it would, in turn,
168 Gregory M. Fitch, Myra Blanco, Justin F.
Morgan, Jeanne C. Rice, Amy Wharton, Walter W.
Wierwille, and Richard J. Hanowski (2010, April)
Human Performance Evaluation of Light Vehicle
Brake Assist Systems: Final Report (Report No. DOT
HS 811 251) Washington, DC: National Highway
Traffic Safety Administration, p. 13.
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render the test impossible to fail for
those vehicles. Therefore, the lower
threshold of additional deceleration is
proposed for false activation tests with
manual braking.
2. Vehicle Test Scenarios
Under this proposal, the false
activation requirement would be
evaluated by executing two vehicle test
scenarios—a steel trench plate test and
a pass-through test. The steel trench
plate test was chosen because in
previous agency testing that included
eight different false activation test
scenarios, the steel trench plate scenario
was the only one that produced false
activation of the AEB system.169 The
pass-through test is similar to the
United Nations Economic Commission
for Europe (UNECE) Regulation 131
pass-through test.170
The proposed false activation tests
establish only a baseline for system
functionality. For practical reasons they
are not comprehensive, nor sufficient to
eliminate susceptibility to false
activations in the myriad of
circumstances in the real world.
However, the proposed tests are a
practicable means to establish a
minimum threshold of performance.
The agency expects that vehicle
manufacturers will design AEB systems
to thoroughly address the potential for
false activations.171 Manufacturers have
a strong market incentive to mitigate
false positives and have been successful
even in the absence of specific
requirements.
i. Steel Trench Plate
This test recreates a roadway scenario
where the subject vehicles encounter a
steel trench plate which is placed on the
road surface ahead in the same lane.
The subject vehicle is driven at 80 km/
h toward the steel trench plate at a
constant speed.
169 Snyder, A., Martin, J., & Forkenbrock, G.
(2013, July). ‘‘Evaluation of CIB system
susceptibility to non-threatening driving scenarios
on the test track.’’ (Report No. DOT HS 811 795).
Washington, DC: National Highway Traffic Safety
Administration.
170 UNECE Regulation 131, ‘‘Uniform provisions
concerning the approval of motor vehicles with
regard to the Advanced Emergency Braking Systems
(AEBS),’’ see 6.8 False reaction test, U.N. Regulation
No. 131 (Feb. 27, 2020), available at https://
unece.org/fileadmin/DAM/trans/main/wp29/
wp29regs/2015/R131r1e.pdf.
171 From NHTSA’s NCAP Request for Comments
notice regarding AEB: ‘‘Specifically, the Alliance
stated that vehicle manufacturers will optimize
their systems to minimize false positive activations
for consumer acceptance purposes, and thus such
tests will not be necessary. Similarly, Honda stated
that vehicle manufacturers must already account for
false positives when considering marketability and
HMI.’’ 87 FR 13452 at 13460.
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The tests would be conducted either
with or without manual brake
application. Manual braking is included
in these scenarios to ensure that even
when a vehicle’s service brake is
actuated, false activation would not
occur. For tests without manual braking,
the accelerator is only released if a
forward collision warning is issued. For
test with manual braking, the
accelerator is released at either the
forward collision warning or 1 second
prior to the manual braking, whichever
occurs first. Manual braking begins
when the subject vehicle is 1.1 seconds
away from the steel trench plate. The
test ends when the subject vehicle either
comes to a stop prior to crossing over
the leading edge of the steel trench
plate, or it proceeds to drive over the
steel trench plate. Figure 8 shows the
basic setup for the steel trench plate
scenario.
Unlike the test scenarios in which the
subject vehicle approaches a lead
vehicle, the agency proposes that the
false activation tests be run at a single
speed rather than over a range of speeds.
False activations occurring at interstate
speeds would create the most severe
unintended consequences of AEB
braking. Therefore, the proposal
includes only a test at a single speed of
80 km/h.
ii. Pass-Through
This test recreates a roadway scenario
where the subject vehicle must travel
between two parked cars that are
adjacent to the left and right sides of the
subject vehicle’s travel lane. The parked
cars are represented by two vehicle test
devices. The lateral distance between
the parked cars is 4.5 m, which is
sufficient to give the subject vehicle
enough space to pass between them and
yet be close enough to be in the field of
view of AEB sensors. The subject
vehicle is driven along the center of the
travel lane and toward the gap between
the parked cars at a speed of 80 km/h.
For tests without manual braking, the
accelerator is only released if a forward
collision warning is issued. For tests
with manual braking, the accelerator is
released at either the forward collision
warning or 1 second prior to the manual
braking, whichever occurs first; manual
braking begins when the front plane of
the subject vehicle is 1.1 seconds away
from the rear plane of the two parked
cars).
D. Conditions for False Activation Tests
conditions which apply specifically to
these false activation tests.
The equipment conditions that apply
to the two false positive scenarios in
this proposal relate to the steel trench
plate and the vehicles used for the pass-
through test. The steel trench plate is a
piece of equipment that represents a
steel plate typically used to cover
excavation holes or irregularities in the
road surface during construction work,
and which is meant to be driven over by
The false activation requirement is
conducted under a set test conditions
identical to those used for AEB tests.
However, there are equipment
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vehicles. The steel trench plate
specified in this proposal is made of
ASTM A36 steel, a common structural
steel alloy, and has the dimensions 2.4
m x 3.7 m x 25 mm. Any metallic
fasteners used to secure the steel trench
plate are flush with the top surface of
the plate, to avoid effectively increasing
the profile height and radar crosssection of the plate. The two vehicles
used for the pass-through test are
vehicle test devices identical to those
that would be used in the lead vehicle
testing.
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E. Potential Alternatives to False
Activation Tests
As alternatives to these two false
activation tests, NHTSA is considering
requiring a robust documentation
process, or specifying a data storage
requirement. NHTSA is considering
requiring this documentation and data
in addition to or in place of the
proposed false activation tests. First,
NHTSA seeks comment on the
anticipated impacts on safety and the
certification burden if the agency were
to finalize a rule that did not contain
one or both of the proposed false
positive tests.
The agency is considering requiring
that manufacturers maintain
documentation demonstrating that
process standards were followed
specific to the consideration of false
application of automatic braking. Other
industries where safety-critical
software-controlled equipment failures
may be life threatening (e.g., aviation,172
medical devices 173) are regulated in
some respects via process controls
ensuring that software development
engineering best practices are followed.
This approach recognizes that system
tests are limited in their ability to
evaluate complex, and constantly
changing software driven control
systems.
Software development lifecycle
practices that include risk management,
configuration management, and quality
systems are used in various safetycritical industries. ISO 26262 Road
vehicles—Functional safety and related
standards are examples of methods for
172 14 CFR 33.201(a) The engine must be designed
using a design quality process acceptable to the
Federal Aviation Administration, that ensures the
design features of the engine minimize the
occurrence of failures, malfunctions, defects, and
maintenance errors that could result in an in-flight
shutdown, loss of thrust control, or other power
loss.
173 21 CFR 920.30(a)(1) Each manufacturer of any
class III or class II device, and the class I devices
listed in paragraph (a)(2) of this section, shall
establish and maintain procedures to control the
design of the device in order to ensure that
specified design requirements are met.
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overseeing software development
practices. The agency is considering that
a process standards approach could be
a viable and practical way of regulating
the risk of false positives, as false
activation of braking is a complex
engineering problem with multiple
factors and conditions that must be
considered in the real world. The
agency seeks public comment on all
aspects of requiring that manufacturers
document that they have followed
process standards in the consideration
of the real-world false activation
performance of the AEB system.
Finally, the agency considered
requiring targeted data recording and
storage of significant AEB activations.
These data could then be used by
manufacturers to improve system
performance, or by the agency to review
if a particular alleged false activation is
part of a safety defect investigation. The
agency is considering requiring that an
AEB event that results in a speed
reduction of greater than 20 km/h
should activate the recording and
storage of the following key information:
date, time, engine hours (the time as
measured in hours and minutes during
which an engine is operated), AEB
activation speed, AEB exit speed
(vehicle speed at which the automatic
braking is completely released), AEB
exit reason (e.g. driver override with
throttle, or brake, or system decision),
location, and camera image data. This
information could be used by
investigators to analyze the source of the
activation and determine if an activation
was falsely applied. Such data would
need to be accessible by the agency and
potentially the vehicle operator for a full
and transparent analysis. The agency
seeks comment on all aspects of this
data collection approach as an
alternative to false positive testing,
including whether this list of potential
elements is incomplete, overinclusive,
or impractical.
F. Proposed Requirements for
Malfunction Indication
NHTSA is proposing that AEB
systems must continuously detect
system malfunctions. If an AEB system
detects a malfunction that prevents it
from performing its required safety
function, the vehicle would be required
to provide the vehicle operator with a
warning. The warning would be
required to remain active as long as the
malfunction exists while the vehicle’s
starting system is on. NHTSA would
consider a malfunction to include any
condition in which the AEB system fails
to meet the proposed performance
requirements. NHTSA is proposing that
the driver must be warned in all
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instances of component or system
failures, sensor obstructions,
environmental limitations (like heavy
precipitation), or other situations that
would prevent a vehicle from meeting
the proposed AEB performance
requirements. While NHTSA is not
proposing the specifics of the telltale,
NHTSA anticipates that the
characteristics of the alert will be
documented in the vehicle owner’s
manual and provide sufficient
information to the vehicle operator to
identify it as an AEB malfunction.
NHTSA considered proposing
requirements pertaining to specific
failures and including an accompanying
test procedure. For instance, the agency
could develop or use available tests that
specify disconnecting sensor wires,
removing fuses, or covering sensors to
simulate field malfunctions. Such
requirements are not included in the
proposed regulatory text, but NHTSA is
interested in comments on this issue.
NHTSA also considered proposing
minimum requirements for the
malfunction telltale, to standardize
ways of communicating to the vehicle
operator. NHTSA understands that some
malfunctions of the AEB system require
repair (loose wires, broken sensors, etc.)
while other malfunctions are temporary
and will correct themselves over time
(ice buildup on a camera). The agency
considered requiring that the
malfunction telltale convey the actions
that a driver should take when a
malfunction is detected. Such
requirements are not included in the
proposed regulatory text, but NHTSA is
interested in comments on this issue.
NHTSA seeks comment, including cost
and benefit data, on the potential
advantages of specifying test procedures
that would describe how the agency
would test a malfunction telltale and on
the level of detail that this regulation
should require of a malfunction telltale.
Additionally, the agency considered
requiring more details for the telltale
itself, such as a standardized
appearance (color, size, shape,
illuminance). The agency seeks
comment on the need and potential
safety benefits of requiring a
standardized appearance of the
malfunction telltale and what
standardized characteristics would
achieve the best safety outcomes.
G. Deactivation Switch
The proposed regulatory text does not
permit vehicle manufacturers to install
a manual deactivation switch that
would enable the vehicle operator to
switch off the AEB. The text is silent
regarding the permissibility of a switch
but, under the framework of the FMVSS
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and NHTSA’s interpretations of the
standards, a deactivation switch would
be prohibited if it would allow an AEB
system to be deactivated in any
circumstance in which the standard
requires an AEB system to function.
This is consistent with other FMVSS,
such as FMVSS No. 108, ‘‘Lamps,
reflective devices, and associated
equipment,’’ which is silent about a
switch deactivating the stop lamps but
where NHTSA has interpreted the
standard as prohibiting such a
switch.174 Standards in which a
deactivation switch is permitted
expressly permit the switch in the
regulatory text, for example, FMVSS No.
126, ‘‘Electronic stability control
systems for light vehicles,’’ where the
standard specifically permits and
regulates the performance of a
deactivation switch,175 and FMVSS No.
208, ‘‘Occupant crash protection,’’
where the standard permitted an on-off
switch for the air bag for the front
passenger seat on particular vehicles.176
NHTSA and FMCSA realize a switch
or other method that could deactivate a
vehicle’s AEB system could be useful in
some circumstances. There might be
some heavy vehicle design or
aftermarket equipment installations
where the configuration of the vehicle
could potentially interfere with the AEB
sensing system. For example, a
snowplow might be attached in a
manner that obstructs an AEB sensor.
Some vehicles may have uses where an
AEB system may be incompatible with
its operating environment, for example,
logging operations or other on/off road
environments.
Special conditions could be addressed
by drafting the standard to allow
manual deactivation under limited
circumstances when the system is
compromised. However, an FMVSS in
which deactivation of the system is
easily accomplished would likely
reduce the safety benefit of the proposed
rule. NHTSA seeks comments on the
merits of and need for manual
deactivations of AEB systems. If the
standard were to permit a deactivation
mechanism of some sort, how could
174 https://isearch.nhtsa.gov/files/23833.ztv.html
(last accessed August 31, 2022).
175 FMVSS No. 126, ‘‘ESC systems for light
vehicles,’’ S5.4: The manufacturer may include an
‘‘ESC Off’’ control whose only purpose is to place
the ESC system in a mode or modes in which it will
no longer satisfy the performance requirements of
S5.2.1, S5.2.2, and S5.2.3.
176 FMVSS No. 208, ‘‘Occupant crash protection.’’
FMVSS No. 208 was written such that it permited
such switches only on vehicles configured with no
back seat or a back seat too small to accommodate
a rear-facing child restraint system. This was an
interim step to allow advanced air bag technology
to mature and be fully implemented.
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NHTSA allow for deactivations while
ensuring the mechanism would not be
abused or misused by users?
Alternatively, NHTSA is interested in
comments on the approach of the
standard’s restricting the automatic
deactivation of the AEB system
generally but providing for special
conditions in which the vehicle is
permitted to automatically deactivate or
otherwise restrict braking authority
given to the AEB system.
NHTSA seeks comment on the merits
of various performance requirements
related to manual deactivation switches
for AEB systems. The agency seeks
comment on the appropriate
performance requirements if the agency
were to permit the installation of a
manually operated deactivation switch.
Such requirements might include
limitations such that the default
position of the switch be ‘‘AEB ON’’
with each cycle of the starting system or
that the deactivation functionality be
limited to specific speeds.
H. System Documentation
NHTSA seeks comment on alternate
regulatory approaches that might be
appropriate for regulating complex
systems that depend heavily on software
performance. FMVSS have historically
included requirements that can be
inspected or tested by the agency to
verify compliance. In some cases, such
as in FMVSS No. 126, the agency has
required manufacturers to maintain
technical documentation available for
agency review upon request to ensure
that electronic stability control systems
were designed to mitigate vehicle
understeer (49 CFR 571.126 S5.6). The
agency established this requirement in
the absence of suitable test procedures
for evaluating understeer.
In the case of AEB, there are similar
limits to testing systems in controlled
environments. AEB systems operating
on roadways will be subject to many
scenes and stimuli that are not present
on a test track—e.g., precipitation,
lighting, roadway curvature and
elevation changes, signage, other road
users, animals, debris, etc.—and these
scenes and stimuli could potentially
influence real world effectiveness of
AEB systems. The agency seeks
comment on documentation
requirements that may be effective in
encouraging real world effectiveness
(e.g., maximizing true positive rate and
minimizing false positive rate) and in
ensuring that AEB systems are
developed and maintained in a manner
that minimizes performance risks.
The agency is considering
requirements for manufacturers to
document a risk-based design approach
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identifying and mitigating reasonably
foreseeable risks alongside configuration
management records of all software/
hardware updates performed by the
manufacturer. Manufacturers would
also need to disclose certain servicing
and system limitation requirements and
make AEB-related data stored in
vehicles available. Examples of
requirements under consideration
include:
• Manufacturers must establish and
maintain procedures that provide a riskbased approach in designing,
implementing, and (if applicable)
updating each system required under
this standard. Manufacturers must
maintain documentation over the
system lifetime detailing the outcome of
the risk-based approach taken to ensure
the safety of such systems.
• Where servicing is required to
maintain system performance, each
manufacturer must establish and
maintain instructions and procedures
for performing and verifying that the
servicing meets the specified
requirements.
• Certain information must be
disclosed to consumers at the time of
first sale in a single document such as
an owner’s manual:
Æ If servicing requirements include
periodic maintenance, the maintenance
schedule must be identified.
Æ Manufacturers must include a
statement describing the limitations of
AEB and explaining that AEB is an
emergency system that does not replace
the need for normal actuation of the
service brakes.
• Each manufacturer must maintain
documentation that captures the full
system configuration, including all
hardware, software, and firmware, for
each vehicle at the time of first sale and
at the time of any update to the system
configuration by the manufacturer.
• Each AEB system or a system that
communicates with the AEB system
must store information logging at least
the last three AEB activation events or
all AEB activation events occurring
within the past three drive cycles.
• The vehicle must store the status of
the AEB system (active, inactive,
disabled, warning, engaged, disengaged,
malfunctioning, etc.).
NHTSA believes that manufacturers
that have installed AEB systems in their
fleet may already be meeting many of
the documentation requirements above.
The agency seeks comment on the
suitability of these requirements and on
any changes that manufacturers would
have to introduce in their internal
processes and consumer-facing
documentation (e.g., owner’s manuals).
NHTSA is interested in learning
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whether manufacturers find
discrepancies between real-world
performance and data collected on test
tracks with surrogate vehicles.
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I. ESC Performance Test
This proposal would require nearly
all heavy vehicles to have an ESC
system that meets the equipment
requirements, general system
operational capability requirements, and
malfunction detection requirements of
FMVSS No. 136. However, this proposal
would not require vehicles not currently
required to have ESC systems to meet
any test track performance requirements
for ESC systems because NHTSA is
conscious of the potential testing
burden on small businesses and the
multi-stage vehicle manufacturers
involved in class 3 through 6 vehicle
production. NHTSA requests comments
on whether the agency should establish
performance requirements for ESC for
all vehicles covered by this proposal. If
ESC performance requirements would
be appropriate, NHTSA seeks comment
on which regulatory tests and
requirements would be appropriate for
the class 3–8 vehicles which this notice
proposes to make applicable to FMVSS
No. 136. NHTSA also seeks comment on
whether manufacturers of these vehicles
should have the option to certify to
FMVSS No. 126 or FMVSS No. 136,
whether a new ESC test procedure
should be developed for some or all of
these vehicles, or whether NHTSA
should give the manufacturer the option
to choose the ESC standard to which to
certify.
NHTSA conducted some limited ESC
testing for class 3–6 vehicles, as part of
research efforts during the development
of FMVSS No. 136, which was
established in 2015, and as part of its
recent AEB testing.177 The ESC testing
performed has however been sufficient
to indicate that the test procedures
currently established in FMVSS Nos.
126 and 136 would require modification
in order to better suit class 3 through 6
vehicles. For example, the vehicle test
speeds specified in FMVSS No. 136,
which are designed to induce ESC
activation in class 7 and 8 trucks and
buses at speeds under 48 km/h (30
mph), did not induce ESC activation in
the vehicles that were tested. This
testing indicates that the maximum test
speeds and speed reduction
requirements would likely need to be
modified.
177 This information is available in ‘‘ESC Track
Test Data for Class 3–6 Vehicles,’’ which has been
placed in the docket identified in the heading of
this NPRM.
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J. Severability
The issue of severability of FMVSSs is
addressed in 49 CFR 571.9. It provides
that if any FMVSS or its application to
any person or circumstance is held
invalid, the remainder of the part and
the application of that standard to other
persons or circumstances is unaffected.
NHTSA seeks comment on the issue of
severability.
VIII. Vehicle Test Device
NHTSA has proposed the same
vehicle test device described below for
use in the proposed requirements for
AEB for light vehicles. An identical
discussion of the vehicle test device
appears in the NPRM proposing the
FMVSS for light vehicles.
A. Description and Development
To ensure repeatable and
reproducible testing that reflects how a
subject vehicle would be expected to
respond to an actual vehicle in the real
world, this proposal includes broad
specifications for a vehicle test device to
be used as a lead vehicle or pass
through vehicle during testing. NHTSA
is proposing that the vehicle test device
be based on certain specifications
defined in ISO 19206–3:2021, ‘‘Road
vehicles—Test devices for target
vehicles, vulnerable road users and
other objects, for assessment of active
safety functions—Part 3: Requirements
for passenger vehicle 3D targets.’’ 178
The vehicle test device is a tool that
NHTSA proposes to use to facilitate the
agency’s compliance tests to measure
the performance of AEB systems
required by the proposed FMVSS. This
NPRM describes the vehicle test device
that NHTSA would use.
The surrogate vehicle NHTSA
currently uses in its research testing is
the Global Vehicle Target (GVT). The
GVT is a full-sized, harmonized
surrogate vehicle developed to test crash
avoidance systems while addressing the
limitations of earlier generation
surrogate vehicles. To obtain input from
the public and from industry
stakeholders, NHTSA participated in a
series of five public workshops and
three radar tuning meetings between
August 2015 and December 2016. These
workshops and meetings provided
representatives from the automotive
industry with an opportunity to inspect,
measure, and assess the realism of
prototype surrogates during the various
stages of development. Workshop and
meeting participants were permitted to
take measurements and collect data
with their own test equipment, which
178 https://www.iso.org/standard/70133.html.
May 2021.
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they could then use to provide specific
recommendations about how the
surrogate vehicle’s appearance, to any
sensor, could be improved to increase
realism.
After feedback from automotive
vehicle manufacturers and suppliers
was incorporated into an earlier design
of the GVT, a series of high-resolution
radar scans were performed by the
Michigan Tech Research Institute
(MTRI) under NHTSA contract. These
measurements provided an independent
assessment of how the radar
characteristics of the GVT compared to
those from four real passenger cars.179
This study found that the GVT has
generally less radar scatter than the real
vehicles to which it was compared.
However, MTRI found that ‘‘even
though the [GVT] may more often reflect
a greater amount of energy than the
[real] vehicles, it is not exceeding the
maximum energy of the returns from the
vehicles. Thus, a sensor intended for the
purpose of detecting vehicles should
perform well with the [GVT].’’ 180
NHTSA also performed tests to
determine the practicality of using the
GVT for test-track performance
evaluations by examining how difficult
it was to reassemble the GVT after it was
struck in a test. Using a randomized
matrix designed to minimize the effect
of learning, these tests were performed
with teams of three or five members
familiar with the GVT reassembly
process. NHTSA found that reassembly
of the GVT on the robotic platform takes
approximately 10 minutes to complete;
however, additional time is often
required to re-initialize the robotic
platform GPS afterwards.181
Finally, NHTSA conducted its own
crash imminent braking tests to compare
the speed reduction achieved by three
passenger cars as they approached the
GVT, compared to the Strikable
Surrogate Vehicle (SSV), the surrogate
vehicle NHTSA currently uses for its
NCAP AEB tests. These tests found that
any differences that might exist between
the GVT and the SSV were small
enough to not appreciably influence the
outcome of vehicle testing.182
When used during AEB testing, the
GVT is secured to the top of a low179 The comparison passenger cars used were a
2008 Hyundai Accent, a 2004 Toyota Camry, a 2016
Ford Fiesta hatchback, and a 2013 Subaru Impreza.
180 Buller, W., Hart, B., Aden, S., and Wilson, B.
(2017, May) ‘‘Comparison of RADAR Returns from
Vehicles and Guided Soft Target (GST),’’ Michigan
Technological University, Michigan Tech Research
Institute. Docket NHTSA–2015–0002–0007.
181 Snyder, Andrew C. et al., ‘‘A Test Track
Comparison of the Global Vehicle Target (GVT) and
NHTSA’s Strikeable Surrogate Vehicle (SSV),’’ July
2019. https://rosap.ntl.bts.gov/view/dot/41936.
182 Id.
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profile robotic platform. The robotic
platform is essentially flat and is
movable and programmable. The
vehicle test device’s movement can be
accurately and repeatably defined and
choreographed with the subject vehicle
and testing lane through the use of data
from the robotic platform’s on-board
inertial measurement unit, GPS, and
closed-loop control facilitated by
communication with the subject
vehicle’s instrumentation. The shallow
design of the robotic platform allows the
test vehicle to drive over it. The GVT is
secured to the top of the robotic
platform using hook-and-loop fastener
attachment points, which allow the
pieces of the GVT to easily and safely
break away without significant harm to
the vehicle being tested if struck.
The internal frame of the GVT is
constructed primarily of vinyl-covered
foam segments held together with hookand-loop fasteners. The GVT’s exterior
is comprised of multiple vinyl ‘‘skin’’
sections designed to provide the
dimensional, optical, and radar
characteristics of a real vehicle that can
be recognized as such by camera and
radar sensors.183 If the subject vehicle
impacts the GVT at low speed, the GVT
is typically pushed off and away from
the robotic platform without breaking
apart. At higher impact speeds, the GVT
breaks apart as the subject vehicle
essentially drives through it.
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B. Specifications
The most recent, widely-accepted
iteration of vehicle test device
specifications is contained in ISO
19206–3:2021.184 Using data collected
by measuring the fixed-angle/variablerange radar cross section for several real
vehicles, ISO developed generic
‘‘acceptability corridors,’’ which are
essentially boundaries that the vehicle
test device’s radar cross section must fit
within to be deemed representative of a
real vehicle.185 All vehicles that ISO
tested have radar cross section
measurements that fit within the
boundaries set forth in the ISO standard.
This proposal would incorporate by
reference ISO 19206–3:2021 into
NHTSA’s regulations and specify that
the vehicle test device meets several
specifications in ISO 19206–3:2021, in
addition to other specifications
183 ‘‘A Test Track Comparison of the Global
Vehicle Target (GVT) and NHTSA’s Strikeable
Surrogate Vehicle,’’ DOT HS 812–698.
184 Road vehicles—Test devices for target
vehicles, vulnerable road users and other objects,
for assessment of active safety functions—Part 3:
Requirements for passenger vehicle 3D targets.
185 The vehicles tested to develop the ISO
standard are: 2016 BMW M235i, 2006 Acura RL,
2019 Tesla Model 3, 2017 Nissan Versa, 2018
Toyota Corolla, 2019 Ford Fiesta.
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identified by NHTSA. Because the GVT
was considered during the development
of ISO 19206–3:2021, the GVT would
meet the standard’s specifications.
However, should the design of the GVT
change or a new vehicle test device be
developed, reference to the more general
specifications of ISO 19206–3:2021
should ensure that NHTSA is able to
test with such other vehicle test devices
and should also ensure that such
vehicle test devices have properties
needed by an AEB system to identify it
as a motor vehicle.
The vehicle test device’s physical
dimensions are proposed to be
consistent with those of the subcompact
and compact car vehicle class. The
specific range of dimensions in this
proposal for individual surfaces of the
vehicle test device are incorporated
from ISO 19206–3:2021, Annex A, Table
A.4. These include specifications for the
test device’s width and the placement of
the license plate, lights, and reflectors
relative to the rear end of the vehicle
test device.
The vehicle test device is proposed to
have features printed on its surface to
represent features that are identifiable
on the rear of a typical passenger
vehicle, such as tail lamps, reflex
reflectors, windows, and the rear license
plate. The proposed color ranges for the
various surface features, including tires,
windows, and reflex reflectors are
incorporated from ISO 19206–3:2021,
Annex B, Tables B.2 and B.3. Table B.2
specifies the colors of the tires,
windows, and reflectors, which reflect
the colors observed the in the real
world. The color of the exterior of the
vehicle is specified to be a range
representing the color white, which
provides a high color contrast to the
other identifiable features. White is also
a common color for motor vehicles.186
The proposed reflectivity ranges for the
various features on the vehicle test
device are incorporated from ISO
19206–3:2021, Annex B, Table B.1.
Table B.3 specifies the recommended
minimum, mean, and maximum color
range for the white body, specifically
the outer cover.
Because many AEB systems rely on
radar sensors in some capacity to
identify the presence of other vehicles,
the vehicle test device must have a radar
cross section that would be recognized
as a real vehicle by an AEB system. In
particular, the vehicle test device must
have a radar cross section consistent
186 Globally, white was the most popular color for
light vehicles in 2021. https://gmauthority.com/
blog/2022/02/white-was-the-most-popular-carcolor-again-in-2021/#
:∼:text=According%20to%20PPG%2C%2035%20
percent,by%20silver%20at%2011%20percent.
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with a real vehicle when approached
from the rear over a range of distances.
NHTSA is proposing that the radar
cross section of the vehicle test device
fall within an ‘‘acceptability corridor’’
when measured using an automotivegrade radar sensor. This acceptability
corridor would be defined by the upper
and lower boundaries specified by ISO
19206–3:2021, Annex C, Equations C.1
and C.2, using the radar cross section
boundary parameters defined in ISO
19206–3:2021, Annex C, Table C.3 for a
fixed viewing angle of 180 degrees.
NHTSA is aware that, unlike some
predecessor specification documents
such as Euro NCAP Technical Bulletin
025 from May 2018, ISO 19206–3:2021
does not specify that the radar cross
section measurements be verified using
a specific model of radar. Rather, the
ISO standard specifies that the radar
sensor used have certain specifications
and operational characteristics.
NHTSA’s proposal similarly does not
specify that the vehicle test device’s
initial radar cross section be measured
with a specific model or brand of radar.
NHTSA only proposes that the radar
sensor used to validate the radar cross
section operate within the 76–81 GHz
bandwidth, have a horizontal field of
view of at least 10 degrees, a vertical
field of view of at least 5 degrees, and
a range greater than 100 m.
Additionally, NHTSA’s proposal does
not specify that the VTD’s radar cross
section during in-the-field verifications
be performed to objectively assess
whether the radar cross section still falls
within the acceptability corridor.
NHTSA seeks comment about whether
use of the optional field verification
procedure provided in ISO 19206–
3:2021, Annex E, section E.3 should be
used.
Because the test procedures proposed
in this rule only involve rear-end
approaches by the subject vehicle,
NHTSA is at this time only proposing to
establish specifications applicable for
the rear end of the vehicle test device.
NHTSA seeks comment on whether the
specifications for the vehicle test device
should include all sides of the vehicle.
If NHTSA were to include, in a final
rule, specifications for all sides of a
vehicle test device, NHTSA anticipates
that those specifications would also be
incorporated from ISO 19206–3:2021.
C. Alternatives Considered
One alternative test device that
NHTSA considered for use in this
proposal was the agency’s selfdeveloped Strikable Surrogate Vehicle
(SSV) device, which NHTSA currently
uses in its NCAP testing of AEB
performance. NHTSA adopted the use of
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the SSV as part of its 2015 NCAP
upgrade, under which the agency began
testing AEB performance.187 The SSV
resembles the rear section of a 2011
Ford Fiesta hatchback. The SSV is
constructed primarily from a rigid
carbon fiber mesh, which allows it to
maintain a consistent shape over time
(unless damaged during testing). To
maximize visual realism, the SSV shell
is wrapped with a vinyl material that
simulates paint on the body panels and
rear bumper, and a tinted glass rear
window. The SSV is also equipped with
a simulated United States specification
rear license plate. The taillights, rear
bumper reflectors, and third brake light
installed on the SSV are actual original
equipment from a production vehicle.
NHTSA testing shows that AEB systems
will recognize the SSV and will respond
in a way that is comparable to how they
would respond to an actual vehicle.188
While the SSV and GVT are both
recognized as real vehicles by AEB
systems from the rear approach aspect,
the SSV has several disadvantages. The
foremost disadvantage of the SSV is
how easily it can be irreparably
damaged when struck by a subject
vehicle during testing, particularly at
high relative velocities. While NHTSA
has tried to address this issue by
attaching a foam bumper to the rear of
the SSV to reduce the peak forces
resulting from an impact by the subject
vehicle, the SSV can still easily be
damaged to a point where it can no
longer be used if the relative impact
speed is sufficiently high (greater than
40 km/h (25 mph)); this speed is much
lower than the maximum relative
impact speed of 80 km/h (50 mph)
potentially encountered during the AEB
tests performed at the maximum relative
speeds proposed in this notice). Also,
unlike the GVT, which has its
movement controlled by precise
programming and closed loop control,
the SSV moves along a monorail
secured to the test surface, which may
be visible to a camera-based AEB
system.
In addition to the vehicle test device
specifications, NHTSA seeks comment
on specifying a set of real vehicles to be
used as vehicle test devices in AEB
testing. UN ECE Regulation No. 152
specifies that the lead vehicle be either
a regular high-volume passenger sedan
or a ‘‘soft target’’ meeting the
specifications of ISO 19206–1:2018.189
UN ECE regulation does not require the
187 80
FR 68604.
FR 68607.
189 U.N. Regulation No. 152, E/ECE/TRANS/505/
Rev.3/Add.151/Amend.1 (Nov. 4, 2020), available
at https://unece.org/fileadmin/DAM/trans/main/
wp29/wp29regs/2020/R152am1e.pdf.
188 80
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use of real vehicles as targets, but rather
offers them as an alternative to
manufacturers to homologate their
systems, at their choice. Although
NHTSA has tentatively concluded that
the specification in UN ECE Regulation
No. 152 of any high-volume passenger
sedan is not sufficiently specific for an
FMVSS, NHTSA seeks comment on
whether it should create a list of
vehicles from which NHTSA could
choose a lead vehicle for testing. Unlike
the UN ECE regulation, which provides
flexibility to manufacturers, inclusion of
a list of vehicles would provide
flexibility to the agency in the
assessment of the performance of AEB
systems. Such a list would be in
addition to the vehicle test device
proposed in this document, to provide
assurance of vehicle performance with a
wider array of lead vehicles. For
example, the list could include the
highest selling vehicle models in 2020.
Using actual vehicles has various
challenges, including the potential for
risk to individuals conducting the tests
and damage to the vehicles involved,
and assuring a safe testing environment
that could encounter high energy
collisions between real vehicles in cases
of poor AEB system performance or AEB
or test equipment malfunctions. NHTSA
seeks comment on the utility and
feasibility of test laboratories safely
conducting AEB tests with real vehicles,
such as through removing humans from
test vehicles and automating scenario
execution, and how laboratories would
adjust testing costs to factor in the risk
of damaged vehicles.
Beyond the practical safety limits and
cost of testing described above,
managing a list of relevant lead vehicles
would require the standard to be
updated periodically to keep pace with
the vehicle fleet and to ensure that lead
vehicles are available years after a final
rule. NHTSA seeks comments on the
merits and potential need for testing
using real vehicles, in addition to using
a vehicle test device, as well as
challenges, limitations, and incremental
costs of such.
IX. Proposed Compliance Date
Schedule
NHTSA proposes a two-tiered phasein schedule for meeting the new
standard. For heavy vehicles currently
subject to FMVSS No. 136, any vehicle
manufactured on or after the first
September 1 that is three years after the
date of publication of the final rule must
meet the proposed heavy vehicle AEB
standard. To illustrate, if the final rule
were published on October 1, 2023, the
compliance date would be September 1,
2027. For heavy vehicles not currently
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43223
subject to FMVSS No. 136, with some
exclusions, those manufactured on or
after the first September 1 that is four
years after the date of publication of the
final rule must meet the amendments to
FMVSS No. 136 that would require ESC
systems and the proposed AEB
requirements. In the provided example
of a final rule published on October 1,
2023, that date would be September 1,
2028. Small-volume manufacturers,
final-stage manufacturers, and alterers
would be provided an additional year,
added to the dates above, to meet the
requirements of this proposal.
Consistent with 49 U.S.C. 30111(d),
NHTSA has tentatively concluded that
good cause exists for this proposal to
take effect more than one year after
publication of a final rule because it
would not be feasible for all heavy
vehicles to be equipped with AEB
systems that meet the proposed
performance requirements within one
year. Furthermore, NHTSA seeks
comments on whether this proposed
phase-in schedule appropriately
addresses challenges to the
implementation of AEB for specific
categories of heavy vehicles. The agency
is particularly interested in information
about single-unit trucks with
permanently installed work-performing
equipment installed on the front of or
extending past the front of the vehicle
(e.g., auger trucks, bucket trucks, cable
reel trucks, certain car carriers, etc.),
where AEB sensors may be located.
NHTSA seeks comments to discern the
best way to implement the applicability
of AEB on class 3–6 single-unit trucks,
considering all scenarios such as vehicle
configuration, vehicle service
applicability, and cargo type, which,
among other factors, can affect vehicle
dynamics and drivability. The
manufacture of single-unit trucks is
more complex than that of truck tractors
due to wider variations in vehicle
weight, wheelbase, number of axles,
center of gravity height, and cargo type.
These factors, and others, bear on the
calibration and performance of ESC. For
example, ESC system design depends on
vehicle dynamics characteristics, such
as the total vehicle weight and location
of that weight (center of gravity), which
will differ depending on the final
vehicle configuration. Because ESC has
been a prerequisite for voluntary
adoption of AEB, single-unit trucks not
having had ESC requirements suggests
that AEB implementation has been
slower and that there is a need for
effective date flexibility.
NHTSA is also aware that many, if not
most, manufacturers of single-unit
trucks are final-stage manufacturers,
which are typically small businesses. To
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provide more flexibility to small
businesses to meet the proposed rule,
this NPRM proposes to permit smallvolume manufacturers, final-stage
manufacturers, and alterers an
additional year to meet the requirements
of the final rule. The additional time
would provide flexibility to the
manufacturers to install ESC and
collaborate with AEB suppliers to meet
the proposed requirements.
FMCSA proposes that vehicles
currently subject to FMVSS No. 136
(i.e., those manufactured on or after
August 1, 2019, the initial compliance
date for FMVSS No. 136) would be
required to comply with FMCSA’s
proposed ESC regulation on the final
rule’s effective date. Vehicles with a
GVWR greater than 4,536 kilograms
(10,000 pounds) not currently subject to
FMVSS No. 136 would be required to
meet the proposed ESC regulation on or
after the first September 1 that is five
years after the date of publication of the
final rule.
FMCSA proposes that, for vehicles
currently subject to FMVSS No. 136,
any vehicle manufactured on or after the
first September 1 that is three years after
the date of publication of the final rule
would be required to meet the proposed
heavy vehicle AEB standard. FMCSA
proposes that vehicles with a gross
vehicle weight rating greater than 4,536
kilograms (10,000 pounds) not currently
subject to FMVSS No. 136 and vehicles
supplied to motor carriers by smallvolume manufacturers, final-stage
manufacturers, and alterers would be
required to meet the proposed heavy
vehicle AEB standard on or after the
first September 1 that is five years after
the date of publication of the final rule.
This proposed implementation
timeframe simplifies FMCSR training
and enforcement because the Agency
expects a large number of final stage
manufacturers supplying vehicles to
motor carriers in the category of
vehicles with a gross vehicle weight
rating greater than 4,536 kilograms
(10,000 pounds).
FMCSA will require the ESC and AEB
systems to be inspected and maintained
in accordance with § 396.3.
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X. Retrofitting
The Secretary has the statutory
authority to promulgate safety standards
for commercial motor vehicles and
equipment subsequent to initial
manufacture. The Secretary has
delegated authority to NHTSA, in
coordination with FMCSA, to
promulgate safety standards for
commercial motor vehicles and
equipment subsequent to initial
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manufacture when the standards are
based upon and similar to an FMVSS.190
NHTSA considered, but decided
against, proposing to require retrofitting
of in-service vehicles with GVWR
greater than 4,536 kg (10,000 lbs.) with
AEB systems. NHTSA believes that
retrofitting in-service vehicles with AEB
systems could be very complex and
costly because of the integration
between an AEB system and the
vehicles’ chassis, engine, and braking
systems. There may be changes that
would have to be made to an originally
manufactured vehicle’s systems that
interface with an AEB system, such as
plumbing for new air brake valves and
lines and a new electronic control unit
for a revised antilock braking system
and a new electronic stability control
system. NHTSA might also have to
develop and establish additional
requirements to ensure that AEB control
components on in-service (used)
vehicles are at an acceptable level of
performance for a compliance test of
AEB. This would be likely given the
uniqueness of each vehicle’s
maintenance condition, particularly for
items such as tires and brake
components, which are foundational for
AEB performance (and which are
subject to high demands of wear-andtear).
Nonetheless, although this NPRM
does not propose requiring heavy
vehicles to be equipped with AEB
subsequent to initial manufacture,
NHTSA requests comment on the
following issues related to retrofitting to
learn more about the technical and
economic feasibility of a retrofit
requirement going forward.
• The complexity, cost, and burdens
of a requirement to retrofit in-service
vehicles with AEB.
• The changes that would be needed
to an originally manufactured vehicle’s
systems that interface with an AEB
system, such as plumbing for new air
brake valves and lines and a new
electronic control unit for a revised ABS
and a new ESC system.
• Approaches NHTSA could take to
identify portions of the on-road fleet to
which a retrofit requirement could
apply. For a retrofitting requirement,
should the requirement distinguish
among in-service vehicles based on the
vehicles’ date of manufacture? Is it
reasonable to assume that older inservice vehicles would have greater
challenges to meet a retrofit
requirement? What should, for example,
the original manufacture date be of
190 Sec. 101(f) of Motor Carrier Safety
Improvement Act of 1999 (Pub. L. 106–159; Dec. 9,
1999). 49 CFR 1.95(c).
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vehicles that should be subject to a
retrofit requirement?
• Should there be provisions to
ensure that the various components
related to AEB performance (e.g., brakes
and tires) are at an acceptable level of
performance for a compliance test, given
the uniqueness of the maintenance
condition for vehicles in service,
especially for items particularly subject
to wear-and-tear (e.g., brake components
and tires)?
• Relatedly, would it be warranted to
vary the performance requirements for
retrofitted vehicles, so that the
requirements would be less stringent for
used vehicles? If yes, what would be
appropriate level of stringency? If not,
how can the requirements be adjusted
for in-service vehicles?
• NHTSA requests comment on other
options the agency could take to
identify portions of the on-road fleet to
which a retrofit requirement should
apply. Are there other voluntary
improvements that heavy vehicle
operators would consider in attaining
the benefits provided by AEB for their
in-service vehicles?
XI. Summary of Estimated
Effectiveness, Cost, Benefits, and
Comparison of Regulatory Alternatives
A. Crash Problem
NHTSA’s assessment of available
safety data indicates that between 2017
and 2019, an average of approximately
60,000 crashes occurred annually in
which a heavy vehicle rear-ended
another vehicle. These crashes resulted
in an annual average of 388 fatalities,
approximately 30,000 non-fatal injuries,
and 84,000 property-damage-only
vehicles. Additionally, class 3–6 heavy
vehicles were involved in
approximately 17,000 rollover and loss
of control crashes annually. These
crashes resulted in 178 fatalities,
approximately 4,000 non-fatal injuries,
and 13,000 property-damage-only
vehicles annually. In total, these rearend, rollover, and loss of control crashes
add up to 77,000 annually, which
represent 1.2 percent of all policereported crashes and over 14 percent of
all crashes involving heavy vehicles. In
total, these crashes resulted in 566
fatalities and 34,000 non-fatal injuries.
These crashes also damaged 97,000
vehicles in property-damage-only
crashes.
B. AEB System Effectiveness
NHTSA evaluated the effectiveness of
AEB indicates based on the efficacy of
the system in avoiding a rear-end crash.
This relates to the proposed requirement
that a vehicle avoid an imminent rear-
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end collision under a set of test
scenarios. One method of estimating
effectiveness would be to perform a
statistical analysis of real-world crash
data and observe the differences in
statistics between heavy vehicles
equipped with AEB and those not
equipped with AEB. However, this
approach is not feasible currently due to
the low penetration rate of AEB in the
on-road vehicle fleet. Consequently,
NHTSA estimated the effectiveness of
AEB systems using performance data
from the agency’s vehicle testing.
Effectiveness was assessed against all
crash severity levels collectively, rather
than for specific crash severity levels
(i.e., minor injury versus fatal).
The AEB effectiveness estimates were
derived from performance data from
four vehicles tested by NHTSA, and the
agency is continuing its effort to test a
larger variety of vehicles to further
evaluate AEB system performance.
These vehicles were subject to the same
test scenarios (stopped lead vehicle,
slower-moving lead vehicle, and
43225
decelerating lead vehicle) that are
proposed in this notice, and
effectiveness estimates are based on
each vehicle’s capacity to avoid a
collision during a test scenario. For
example, if a vehicle avoided colliding
with a stopped lead vehicle in four out
of five test runs, its effectiveness in that
scenario would be 80 percent. The test
results for each vehicle were combined
into an aggregate effectiveness value by
vehicle class range and crash scenario,
as displayed in Table 17.
TABLE 17—AEB EFFECTIVENESS (%) BY VEHICLE CLASS RANGE AND CRASH SCENARIO
Stopped
lead vehicle
Vehicle class range
7–8 .............................................................................................................................
3–6 .............................................................................................................................
As shown in Table 17, after
aggregating class 7 and class 8 together,
AEB would avoid 38.5 percent of rearend crashes for the stopped lead vehicle
scenario, and 49.2 percent of slowermoving and decelerating lead vehicle
target crashes. For class 3–6, AEB is 43.0
percent effective against stopped lead
vehicle crashes and 47.8 percent against
slower-moving and decelerating lead
vehicle target crashes. These
effectiveness values are the values used
for assessing the benefits of this
proposed rule. Further detail on the
derivation of AEB effectiveness can be
found in the PRIA accompanying this
proposal.
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C. ESC System Effectiveness
ESC effectiveness rates were adopted
from those estimated in the final
regulatory impact analysis for the final
rule implementing heavy vehicle ESC
requirements in FMVSS No. 136.191 In
that final rule, a range of ESC crash
avoidance effectiveness was established
for the first-event rollover crashes but
only a single-point estimate was
established for loss of control crashes.
ESC was estimated to be 40 to 56
percent effective at preventing rollover
crashes and 14 percent effective at
preventing loss-of-control crashes. For
simplicity, and to correspond with the
single-point estimate for loss of control
crashes, the PRIA used the mid-point
between the lower and upper bounds of
191 Final Regulatory Impact Analysis, FMVSS No.
136 Electronic Stability Control on Heavy Vehicles,
June 2014, Docket No. NHTSA–2015–0056.
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38.5
43.0
the estimated range as the effectiveness
for rollovers.
The propensity for vehicles to
experience rollover and loss-of-control
crashes is influenced by their body type
and center of gravity, and the
implementation of ESC varies. ESC was
estimated to be less effective on class 7
and 8 vehicles than it was on light
vehicles, especially for rollover
crashes.192 Vehicle characteristics for
class 3 through 6 vehicles range
between that of light trucks and vans
and class 7 and 8 vehicles, it would be
plausible to assume that ESC
effectiveness would be between the
effectiveness estimated in the FMVSS
No. 126 and FMVSS No. 136 final rules.
Nevertheless, this NPRM uses the
effectiveness estimates from the FMVSS
No. 136 final rule.
TABLE 18—ESC EFFECTIVENESS (%)
BY CRASH SCENARIO
Vehicle class range
Rollover
Loss of
control
3–6 ............................
48.0
14.0
D. Avoided Crashes and Related
Benefits
Considering the annual heavy vehicle
rear-end, rollover, and loss of control
crashes, as well as the effectiveness of
AEB and ESC at avoiding these crashes,
the proposed rule would prevent an
estimated 19,118 crashes, 155 fatalities,
192 Dang, J. (July 2007) Statistical Analyzing of the
Effectiveness of Electronic Stability Control (ESC)
Systems—Final Report, DOT HS 810 794,
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Slower-moving
lead vehicle
49.2
47.8
Decelerating
lead vehicle
49.2
47.8
and 8,814 non-fatal injuries annually. In
addition, the proposed rule would
eliminate an estimated 24,828 PDOVs
annually. The benefit estimates include
assumptions that likely result in the
underestimation of the benefits of this
proposal because it only reflects the
benefits from crash avoidance. That is,
the benefits only reflect those resulting
from crashes that are avoided as a result
of the AEB and ESC performance
proposed. It is likely that AEB will also
reduce the severity of crashes that are
not prevented. Some of these crashes
may include fatalities and significant
injuries that will be prevented or
mitigated by AEB.
Table 19 tabulates these benefits in
two ways, one by vehicle class and one
by technology. These benefits are
measured for the portion of the vehicle
fleet that has not voluntarily adopted
AEB prior to the NPRM. These benefits
also assume reduced performance under
dark or hazardous weather conditions.
The estimated annual benefits would be
the undiscounted lifetime benefits once
the proposal is fully implemented (four
years after publication of a final rule).
The undiscounted lifetime benefits for
each new model year of vehicles would
equal the annual benefits of the on-road
fleet when that fleet has been fully
equipped with this technology. The
actual annual benefits will increase each
year as the on-road vehicle fleet is
replaced with vehicles that would be
subject to the proposed requirements.
Washington, DC, https://crashstats.nhtsa.dot.gov/
Api/Public/ViewPublication/810794.
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TABLE 19—UNDISCOUNTED ESTIMATED ANNUAL BENEFITS OF THE PROPOSED RULE
Crashes
By Vehicle Class:
Class 7–8 ..................................................................................................
Class 3–6 ..................................................................................................
Fatalities
Non-fatal
injuries
PDOVs
5,691
13,427
40
115
2,822
5,992
7,958
16,870
Total ...................................................................................................
By Technology:
AEB ...........................................................................................................
ESC ..........................................................................................................
19,118
155
8,814
24,828
16,224
2,894
106
49
8,058
756
22,713
2,115
Total ...................................................................................................
19,118
155
8,814
24,828
E. Technology Costs
The AEB system is estimated to cost
$396 per vehicle. The unit cost includes
all the components, labor cost for
training customers, tuning the system to
ensure the performance of AEB, and the
AEB malfunction telltale. The
component unit costs were based on the
agency’s 2018 weight and teardown
study, which accounted for scale
efficiencies in production and labor.193
The cost for an ESC system would range
from $320 to $687, which was
calculated by adjusting the assumed
unit cost for ESC in the FMVSS No. 136
final rule for inflation.194 Therefore, for
vehicles that need both AEB and ESC,
the total unit cost would range from
$716 to $1,083 per affected vehicle.195
The total number of affected vehicles
including trucks and buses are
estimated to be 569,792 units annually:
164,405 units for class 7–8 and 405,387
units for class 3–6 vehicles. The total
cost corresponding to the estimated
annual benefits is estimated to be $353
million ($288 million for class 7–8 and
$65 million for class 3–6). The affected
vehicle units were based on the 10 year
average of units sold between 2011 and
2020.196
F. Monetized Benefits
Table 20 summarizes the primary
benefit cost estimates, which include
the annual total cost, total monetized
savings, cost per equivalent life saved,
and net benefits of the proposed rule
under three and seven percent discount
rates. Monetized savings are measured
by comprehensive costs, which include
the tangible costs of reducing fatalities
and injuries such as savings from
medical care, emergency services,
insurance administration, workplace
costs, legal costs, congestion and
property damage, lost productivity as
well as nontangible cost of quality life
lost. The nontangible cost components
were based on the value of statistical life
of $11.8 million.197
The proposed rule would generate a
net benefit of $1.81 billion to $2.58
billion, annually under 3 and 7 percent
discount rates. The proposed rule would
be cost-effective given that the highest
estimated net cost per fatal equivalent
would be $0.50 million, a value less
than $12.2 million (the comprehensive
cost of a fatality). The negative net cost
per fatal equivalent for the 3 percent
discount rate indicates that the savings
from reducing traffic congestion and
property damage is greater than the total
cost of the proposed rule. Net benefits
are likely to be even higher given that
the estimates only include benefits from
crashes prevented by AEB, but do not
include benefits from crashes for which
AEB mitigates the severity of, but does
not prevent.
TABLE 20—ESTIMATED ANNUAL COST, MONETIZED BENEFITS, COST-EFFECTIVENESS, AND NET BENEFITS OF THE
PROPOSED RULE
[2021 dollars in millions]
Discount rates
Annual cost *
3 Percent .................................................................................
7 Percent .................................................................................
$353.3
353.3
Monetized savings
Net cost per fatal
equivalent
$2,937.0
2,160.4
**¥$0.12
0.50
Net benefits
$2,583.7
1,807.1
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the cost, resulting in negative net
cost per equivalent life. The negative value indicates cost-effectiveness.
G. Alternatives
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NHTSA has identified and assessed
alternatives to the preferred alternative
set forth in the proposed regulatory text.
193 ‘‘Cost and Weight Analysis of Heavy Vehicle
Forward Collision Warning (FCW) and Automatic
Emergency Braking (AEB) Systems for Heavy
Trucks,’’ September 27, 2018, Contract number:
DTNH2216D00037, Task Order: DTNH2217F00147.
194 Final Regulatory Impact Analysis, FMVSS No.
136 Electronic Stability Control on Heavy Vehicles,
June 2014, Docket No. NHTSA–2015–0056.
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The agency considered two primary
alternatives to the proposed rule.
The first alternative would not require
AEB or ESC on vehicles not currently
subject to FMVSS No. 136. Eliminating
the requirement would reduce the
burden on heavy vehicle manufacturers
associated with installing AEB and ESC
on vehicles with different body types,
but would result in significantly fewer
195 AEB and ESC unit cost estimates are the
additional component costs for the vehicles without
the systems. Specifically, AEB cost is the additional
hardware to those vehicles that already had ESC.
196 Due to data constraints, the average is only
available for trucks and school buses. The annual
sales volume for motorcoaches and transit buses
was based on the agency’s estimate for earlier final
rules and other sources. Please consult Appendix B
of the PRIA for details.
197 Departmental Guidance on Valuation of a
Statistical Life in Economic Analysis, Effective
Date: Friday, March 4, 2022, https://
www.transportation.gov/office-policy/
transportation-policy/revised-departmentalguidance-on-valuation-of-a-statistical-life-ineconomic-analysis.
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safety benefits and lives saved. A
summary of the costs, benefits, and cost-
effectiveness associated with
Alternative 1 is in Table 21.
TABLE 21—DISCOUNTED BENEFITS OF ALTERNATIVE 1
[Millions of 2021$]
Annual cost *
3 Percent Discount ..................................................................
7 Percent Discount ..................................................................
Net cost
per fatal
equivalent
Monetized savings
$65.10
65.10
$874.59
662.23
Net benefits
**¥$1.00
¥0.66
$809.50
597.10
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the cost, resulting in negative net
cost per equivalent life. The negative value indicates cost-effectiveness.
The second alternative would require
all class 3–6 heavy vehicles to have AEB
and ESC within four years, as with the
primary agency proposal. However, this
alternative would include a one-year
phase-in period beginning three years
after publication of the final rule in
which 50 percent of class 3–6 vehicles
would be required to install AEB and
ESC. This alternative was considered
because it has the potential to save more
lives sooner. This alternative would
have the same annual cost, savings, net
cost per fatal equivalent, and net
benefits as the primary proposal.
However, this alternative would result
in added benefits from vehicles
manufactured in the phase-in period.
The estimated total additional benefits
associated with alternative 2 above the
primary estimate are summarized in
Table 22.
TABLE 22—DISCOUNTED ADDITIONAL
BENEFITS OF ALTERNATIVE 2 ABOVE
THE PRIMARY PROPOSAL
[Millions of 2021$]
Percent discount
3
7
Net Additional Benefit
$830.5
$566.4
Detailed benefit-cost calculations of
these alternatives are discussed in the
PRIA. The agency seeks comment on the
feasibility of the second alternative.
Because of the significant safety
benefits that accrue by including Class
3–6 vehicles, and to allow time for the
Class 3–6 vehicle manufactures to
optimize implementations of both ESC
and AEB into their vehicles, the agency
decided not to select either alternative.
XII. Regulatory Notices and Analyses
Executive Orders 12866, 13563, and
14094 and DOT Regulatory Policies and
Procedures
NHTSA and FMCSA have considered
the impact of this rulemaking action
under Executive Order 12866, as
amended by Executive Order 14094,
Executive Order 13563, and the
Department of Transportation’s
regulatory procedures. This rulemaking
is considered significant under section
3(f)(1) of Executive Order 12866, as
amended, and was reviewed by the
Office of Management and Budget under
that Executive Order. NHTSA and
FMCSA have prepared a preliminary
regulatory impact analysis (PRIA) that
assesses the cost and benefits of this
proposed rule. The benefits, costs and
other impacts of this NPRM are
discussed in the prior section.
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility
Act of 1980, Public Law 96–354, 94 Stat.
1164 (5 U.S.C. 601 et seq., as amended),
whenever an agency is required to
publish an NPRM or a final rule, it must
prepare and make available for public
comment a regulatory flexibility
analysis that describes the effect of the
rule on small entities (i.e., small
businesses, small not-for-profit
organizations, and small governmental
jurisdictions). I certify that this NPRM
would not have a significant economic
impact on a substantial number of small
entities.
NHTSA’s proposal would directly
affect manufacturers of class 3- through
8 trucks, buses, and multipurpose
passenger vehicles. Of the more than 20
companies who are sole manufacturers
or first-stage manufacturers of class 3
through 8 vehicles in the United States,
NHTSA found two companies (Proterra
and Workhorse Group, Inc.) that qualify
as a small entities.198 Table 23. Below
show the list of heavy duty truck
manufacturers.
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TABLE 23—HEAVY DUTY TRUCK MANUFACTURERS
Company
Trucks .........................................
Autocar company .......................
Brightdrop ...................................
Ford ............................................
GM .............................................
International ...............................
Freightliner .................................
Hendrickson International ..........
Mack ...........................................
Navistar ......................................
Oshkosh Corp ............................
PACCAR ....................................
487
252
186,000
167,000
2,760
15,000
6,000
2,000
14,500
15,000
31,100
$126
138
158,060
156,700
721
450
1,600
671
3,900
8,300
28,800
Ram ............................................
200,000
180,000
198 NHTSA researched MD and HD vehicle
manufacturing companies and found their
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# Employees
Annual revenue
(millions)
Type
estimated number of employees and annual revenue
(as of Dec 2022) from the following sources:
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Notes
Parent Company: GVW Group.
Parent Company: GM.
Parent Company: Navistar.
Parent Company: Daimler.
Parent Company: Volvo.
Subsidiaries:
Kenworth,
Peterbilt.
Parent Company: Stellantis.
zoominfo.com, macrotrends.net, zippia.com,
statista.com, and linkedin.com.
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TABLE 23—HEAVY DUTY TRUCK MANUFACTURERS—Continued
Type
Company
Buses ..........................................
# Employees
Annual revenue
(millions)
Shyft Group ................................
Western Star ..............................
Workhorse ..................................
Bluebird ......................................
Forest River ...............................
4,200
3,221
331
1,702
11,000
1,000
680
5
726
3,300
Gillig ...........................................
900
267
IC Bus ........................................
Nikola .........................................
Proterra ......................................
REV group .................................
Thomas Built Buses ...................
219
1,500
938
6,800
1,276
44
51
247
2,300
288
Workhorse Group, Inc. currently has
about 330 employees. Its vehicles are
already equipped with ESC and AEB
and are unlikely to be affected by this
proposal. Proterra is a manufacturer of
large electric transit buses and falls into
the small business threshold with about
9,400 employees. Although its vehicles
are not currently equipped with AEB, its
vehicles sell for approximately
$750,000. With such a high sale price,
NHTSA considers the effect of this rule
on the price of the vehicle to be de
minimis. Accordingly, NHTSA has
concluded that this proposal would not
have a significant economic impact
upon these small entities. However,
NHTSA seeks comment on this
conclusion.
Final stage manufacturers are also
affected by this proposal, and final stage
manufacturers would be considered
small entities. According to the U.S.
Census, there are 570 small businesses
in body manufacturing for light,
medium, and heavy-duty classes.199
This proposal likely would affect a
substantial number of final stage
manufacturers that are small businesses.
It is NHTSA’s understanding that these
small entities rarely make modifications
to a vehicle’s braking system and
instead rely upon the pass-through
certification provided by the first-stage
manufacturer, which is not typically a
small business.. More information about
multi-stage vehicle manufacturing can
be found in section VI.E of this
proposal. Additionally, this proposal
would further accommodate final-stage
manufacturers by providing them an
additional year before compliance is
required. Therefore, NHTSA does not
believe at this time that the impacts of
this proposal on small entities would be
significant.
This rule may also affect purchasers
of class 3 through 8 vehicles. It is
assumed that the incremental costs of
this proposal would be passed on to
Notes
Parent Company: Daimler.
Small Business.
Parent Company: Berkshire
Hathaway.
Parent Company: Henry Crown
& Co.
Parent Company: Navistar.
Small Business.
Subsidiary: El Dorado.
Parent Company: Daimler.
these purchasers. Class 7 through 8
vehicles are primarily purchased by
motor carriers, an industry composed of
approximately 757,652 interstate,
intrastate, and hazardous materials
motor carriers, in which over ninety
percent of its companies (687,139) are
considered small.200 Class 3–6 vehicles
consisting of work pickup trucks, small
buses, and moving/cargo vans are
purchased and utilized in industries
where small businesses are not
uncommon as well. It is not known
precisely how frequently small
businesses purchase new vehicles
(instead of used vehicles) affected by the
proposed rule, however, small entities
usually have the option to finance or
lease these vehicles to mitigate financial
burden by spreading out cost over time.
Table 24 below shows a list of
industries, where small businesses may
be affected by the proposed rule.
TABLE 24—SBA SIZE STANDARDS OF INDIRECTLY AFFECTED INDUSTRIES
NAICS Code
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484110
484122
484122
484210
484220
484230
485113
485210
485410
485510
485991
488410
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
....................................
General Freight Trucking, Local ...............................................................................................
General Freight Trucking, Long-Distance, Truckload ..............................................................
General Freight Trucking, Long-Distance, Less Than Truckload ............................................
Used Household and Office Goods Moving ............................................................................
Specialized Freight (except Used Goods) Trucking, Local .....................................................
Specialized Freight (except Used Goods) Trucking, Long-Distance .......................................
Bus and Other Motor Vehicle Transit Systems .......................................................................
Interurban and Rural Bus Transportation ................................................................................
School & Employee Bus Transportation ..................................................................................
Charter Bus Industry ................................................................................................................
Special Needs Transportation ..................................................................................................
Motor Vehicle Towing ...............................................................................................................
199 2020 SUSB Annual Data Tables by
Establishment Industry, ‘‘U.S. and states, NAICS,
detailed employment sizes.’’ https://
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in millions
of dollars
NAICS Industry description
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200 Assume a motor carrier of 10 or less power
units is considered a small entity, which is very
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30
30
38
30
30
30
28.5
28
26.5
17
16.5
8
conservative given an SBA size standard of $30
million in annual revenue. 2022 Pocket Guide to
Large Truck and Bus Statistics (December 2022),
Federal Motor Carrier Safety Administration, p.13.
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FMCSA’s proposed requirement
would ensure that the benefits resulting
from CMVs equipped with AEBs are
sustained through proper maintenance
and operation. The cost of maintaining
AEB systems is minimal and may be
covered by regular annual maintenance.
Therefore, FMCSA does not expect this
requirement to have a significant
economic impact on a substantial
number of small entities.
Additional information concerning
the potential impacts of this proposal on
small businesses is presented in the
PRIA accompanying this proposal. The
agencies seek comment on the effects
this NPRM would have on small
businesses.
National Environmental Policy Act
The National Environmental Policy
Act of 1969 (NEPA) 201 requires Federal
agencies to analyze the environmental
impacts of proposed major Federal
actions significantly affecting the
quality of the human environment, as
well as the impacts of alternatives to the
proposed action.202 The Council on
Environmental Quality (CEQ)’s NEPA
implementing regulations direct federal
agencies to determine the appropriate
level of NEPA review for a proposed
action; an agency can determine that a
proposed action normally does not have
significant effects and is categorically
excluded,203 or can prepare an
environmental assessment for a
proposed action ‘‘that is not likely to
have significant effects or when the
significance of the effects is
unknown.’’ 204 When a Federal agency
prepares an environmental assessment,
CEQ’s NEPA implementing regulations
require it to (1) ‘‘[b]riefly provide
sufficient evidence and analysis for
determining whether to prepare an
environmental impact statement or a
finding of no significant impact;’’ and
(2) ‘‘[b]riefly discuss the purpose and
need for the proposed action,
alternatives . . . , and the
environmental impacts of the proposed
action and alternatives, and include a
listing of agencies and persons
consulted.’’ 205
As discussed further below, FMCSA
has determined that its proposed action
is categorically excluded from further
analysis and documentation in
accordance with FMCSA Order
5610.1.206 NHTSA determined that
there is no similarly applicable
201 42
U.S.C. 4321–4347.
U.S.C. 4332(2)(C).
203 40 CFR 1501.4.
204 40 CFR 1501.5(a).
205 40 CFR 1501.5(c).
206 69 FR 9680 (Mar. 1, 2004).
202 42
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categorical exclusion for its proposed
action and has therefore determined that
it is appropriate to prepare a Draft
Environmental Assessment (EA). The
preamble provides additional
information about the distinction
between NHTSA and FMCSA’s
proposed requirements based on each
agency’s statutory authority.
This section serves as NHTSA’s Draft
EA. In this Draft EA, NHTSA outlines
the purpose and need for the proposed
rulemaking, a reasonable range of
alternative actions the agency could
adopt through rulemaking, and the
projected environmental impacts of
these alternatives.
Purpose and Need
This NPRM preamble and the
accompanying PRIA set forth the
purpose of and need for this action. The
preamble and PRIA outline the safety
need for this proposal, in particular to
address safety problems associated with
heavy vehicles, i.e., vehicles with a
GVWR greater than 4,536 kilograms
(10,000 pounds). These heavy vehicles,
also referred to as Class 3–8 vehicles,207
include single unit straight trucks,
combination trucks, truck tractors,
motorcoaches, transit buses, school
buses, and certain pickup trucks. An
annualized average of 2017 to 2019 data
from NHTSA’s FARS and CRSS shows
heavy vehicles were involved in around
60,000 rear-end crashes in which the
heavy vehicle was the striking vehicle
annually, which represents 11 percent
of all crashes involving heavy
vehicles.208 These rear-end crashes
resulted in 388 fatalities annually,
which comprises 7.4 percent of all
fatalities in heavy vehicle crashes.
These crashes resulted in approximately
30,000 injuries annually, or 14.4 percent
of all injuries in heavy vehicle crashes,
and 84,000 damaged vehicles with no
injuries or fatalities. Considering vehicle
size, approximately half of the rear-end
crashes, injuries, and fatalities resulting
from rear-end crashes where the heavy
vehicle was the striking vehicle
207 Class is a vehicle classification system used by
the Federal Highway Administration of Department
of Transportation to categorize vehicles into 8
Classes based on vehicle size, weight, and number
of wheels. The following lists the GVWR for Class
3–8 heavy vehicles. A complete vehicle class
categorization table is included in 49 CFR part 565.
Class GVWR
Class 3: 4,536–6,350 kg (10,001–14,000 pounds)
Class 4: 6,351–7,257 kg (14,001–16,000 pounds)
Class 5: 7,258–8,845 kg (16,001–19,500 pounds)
Class 6: 8,846–11,793 kg (19,501–26,000 pounds)
Class 7: 11,794–14,969 kg (26,001–33,000
pounds)
Class 8: 14,969 kg (33,001 pounds) and above
208 These rear-end crashes are cases where the
heavy vehicle was the striking vehicle.
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involved vehicles with a GVWR above
4,536 kilograms (10,000 pounds) up to
11,793 kilograms (26,000 pounds).
Similarly, half of all rear-end crashes
and the fatalities and injuries resulting
from those crashes where the heavy
vehicle was the striking vehicle
involved vehicles with a GVWR of
greater than 11.793 kilograms (26,000
pounds).
To address this safety need, NHTSA
proposes to adopt a new FMVSS to
require AEB systems on certain heavy
vehicles.209 Current AEB systems use
radar and camera-based sensors or
combinations thereof and build upon
older FCW-only systems. An FCW-only
system provides an alert to a driver of
an impending rear-end collision with a
lead vehicle to induce the driver to take
action to avoid the crash but does not
automatically apply the brakes. This
proposal would require both FCW and
AEB systems. For simplicity, when
referring to AEB systems in general, this
proposal is referring to both FCW and
AEB unless the context suggests
otherwise. NHTSA also proposes to
amend FMVSS No. 136 to require nearly
all heavy vehicles to have an ESC
system that meets the equipment
requirements, general system
operational capability requirements, and
malfunction detection requirements of
FMVSS No. 136. In addition to requiring
certain heavy vehicles be equipped with
AEB/ESC, the proposed rule requires
the heavy vehicles to be able to avoid
a collision in various rear-end crash
scenarios at different speeds.
As explained earlier in this preamble,
the AEB system improves safety by
using various sensor technologies and
sub-systems that work together to detect
when the vehicle is in a crash imminent
situation, to automatically apply the
vehicle brakes if the driver has not done
so, or to apply more braking force to
supplement the driver’s braking, thereby
detecting and reacting to an imminent
crash. This proposed rule is anticipated
to address the safety need by mitigating
the amount of fatalities, non-fatal
injuries, and property damage that
would result from crashes that could
potentially be prevented or mitigated
because of AEB and ESC. This proposed
rule is expected to substantially
decrease risks associated with rear-end,
rollover, and loss of control crashes.
This NPRM follows NHTSA’s 2015
grant of a petition for rulemaking from
the Truck Safety Coalition, the Center
for Auto Safety, Advocates for Highway
209 Some heavy vehicles are excluded from the
proposed rule. These include those vehicles that are
excluded from FMVSS No. 121 and FMVSS No.
136.
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and Auto Safety and Road Safe America,
requesting that NHTSA establish a
safety standard to require AEB on
certain heavy vehicles. This NPRM also
responds to a mandate under the
Bipartisan Infrastructure Law, enacted
as the Infrastructure Investment and
Jobs Act, directing the Department to
prescribe an FMVSS that requires heavy
commercial vehicles with FMVSSrequired ESC systems to be equipped
with an AEB system, and also promotes
DOT’s January 2022 National Roadway
Safety Strategy to initiate a rulemaking
to require AEB on heavy trucks. This
NPRM also proposes Federal Motor
Carrier Safety Regulations requiring the
ESC and AEB systems to be on during
vehicle operation.
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Alternatives
NHTSA has considered three
regulatory alternatives for the proposed
action and a ‘‘no action alternative.’’
Under the no action alternative, NHTSA
would not issue a final rule requiring
that vehicles be equipped (installation
standards) with systems that meet
minimum specified performance
standards, and manufacturers would
continue to add these systems
voluntarily. However, since the BIL
directs NHTSA to promulgate a rule that
would require heavy vehicles subject to
FMVSS No. 136 to be equipped with an
AEB system, the no action alternative is
not a permissible option. The proposed
standard (the preferred alternative)
requires specific AEB/ESC installation
and performance standards for certain
Class 3–8 heavy vehicles with a twotiered phase-in schedule based on
whether the heavy vehicle is currently
subject to FMVSS No. 136. Alternative
1, which is considered less stringent
than the preferred alternative, would set
AEB/ESC installation and performance
standards only for vehicles currently
subject to FMVSS No. 136. Alternative
2, which is considered more stringent
than the preferred alternative, would
require a more aggressive phase-in
schedule for the AEB/ESC installation
requirements for Class 3–6 heavy
vehicles.
Although these regulatory alternatives
differ in phase-in schedule and heavy
vehicle Class applicability, the
functional AEB/ESC installation and
performance requirements would be the
same. Please see the preamble and PRIA
Chapter 11, Regulatory Alternatives, for
more information about the preferred
alternative and other regulatory
alternatives, and the proposed
standards’ requirements.
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Environmental Impacts of the Proposed
Action and Alternatives
Based on the purpose and need for the
proposed action and the regulatory
alternatives described above, the
primary environmental impacts that
could potentially result from this
rulemaking are associated with
greenhouse gas (GHG) emissions and air
quality, socioeconomics, public health
and safety, solid waste/property
damage/congestion, and hazardous
materials.210 Consistent with CEQ
regulations and guidance, this EA
discusses impacts in proportion to their
potential significance. The effects of the
proposed rulemaking that were
analyzed further are summarized below.
Greenhouse Gas Emissions and Air
Quality
NHTSA has previously recognized
that additional weight required by
FMVSS could potentially negatively
impact the amount of fuel consumed by
a vehicle, and accordingly result in GHG
emissions or air quality impacts from
criteria pollutant emissions.211
Atmospheric GHGs affect Earth’s surface
temperature by absorbing solar radiation
that would otherwise be reflected back
into space. Carbon dioxide (CO2) is the
most significant GHG resulting from
human activity. Motor vehicles emit
CO2 as well as other GHGs, including
methane and nitrous oxides, in addition
to criteria pollutant emissions that
negatively affect public health and
welfare.
Additional weight added to a vehicle,
like added hardware from safety
systems, can potentially cause an
increase in vehicle fuel consumption
and emissions. NHTSA analyzed in
PRIA Chapter 9.1, Technology Unit
Costs and Added Weights, the cost
associated with meeting the
performance requirements in the
proposed rule, including the potential
weight added to the vehicle. An AEB
system for heavy vehicles requires the
following hardware: sensors (radar
210 NHTSA anticipates that the proposed action
and alternatives would have negligible or no impact
on the following resources and impact categories,
and therefore has not analyzed them further:
topography, geology, soils, water resources
(including wetlands and floodplains), biological
resources, resources protected under the
Endangered Species Act, historical and
archeological resources, farmland resources,
environmental justice, and Section 4(f) properties.
211 Criteria pollutants is a term used to describe
the six common air pollutants for which the Clean
Air Act (CAA) requires the Environmental
Protection Agency (EPA) to set National Ambient
Air Quality Standards (NAAQS). EPA calls these
pollutants criteria air pollutants because it regulates
them by developing human health-based or
environmentally based criteria (i.e., science-based
guidelines) for setting permissible levels.
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mounted at front bumper and, in some
cases, camera located at top, inside
portion of windshield), control units
(electronic control unit), display (in
some cases integrated with existing dash
cluster, in other cases, a separate
display), associated wiring harnesses,
mounting hardware specific to FCW/
AEB system, and other materials and
scrap (for electronic parts, this category
includes labels, soldering materials,
flux, and fasteners).212 Although AEB
and ESC have some shared system
components, NHTSA also estimated that
a limited amount of additional hardware
would be required for ESC systems
depending on the vehicle class,
including accelerometers, yaw rate
sensors, and steer angle sensors.213
Based on a study conducted for NHTSA
on the cost and weight of heavy vehicle
FCW and AEB systems,214 NHTSA
concluded that the added weight for the
installation of AEB is estimated to be up
to 3.10 kg (∼ 7 lbs) and AEB and ESC
combined is up to 6.70 kg (∼ 15 lbs).
These weights are considered negligible
compared to the 4,536 kg (10,000 lbs) or
greater curb weight of Class 3–8
vehicles. NHTSA tentatively concluded
in the PRIA that the proposed rule is not
expected to impact the fuel
consumption of Class 3–8 vehicles, and
therefore none of the regulatory
alternatives would be presumed to
result in GHG or criteria pollutant
impacts.
NHTSA also analyzed this action for
purposes of the Clean Air Act (CAA)’s
General Conformity Rule.215 The
212 PRIA,
at 141.
Regulatory Impact Analysis, FMVSS No.
136, Electronic Stability Control Systems on Heavy
Vehicles; Docket No. NHTSA–2015–0056–0002, at
VI–5.
214 Department of Transportation National
Highway Traffic Safety Administration Office of
Acquisition Management (NPO–320) West Building
51–117 1200 New Jersey Avenue SE Washington,
DC 20590 Contract Number: DTNH2216D00037
Task Order: DTNH2217F00147 Cost and Weight
Analysis of Heavy Vehicle Forward Collision
Warning (FCW) and Automatic Emergency Braking
(AEB) Systems for Heavy Trucks Ricardo Inc.
Detroit Technical Center Van Buren Twp., MI 48111
USA September 27, 2018.
215 Section 176(c) of the CAA, codified at 42
U.S.C. 7506(c); To implement CAA Section 176(c),
EPA issued the General Conformity Rule (40 CFR
part 51, subpart W and part 93, subpart B). Pursuant
to the CAA, the U.S. Environmental Protection
Agency (EPA) has established a set of National
Ambient Air Quality Standards (NAAQS) for the
following criteria pollutants: carbon monoxide
(CO), nitrogen dioxide (NO2), ozone, particulate
matter (PM) less than 10 micrometers in diameter
(PM10), PM less than 2.5 micrometers in diameter
(PM2.5), sulfur dioxide (SO2), and lead (Pb). EPA
requires a ‘‘conformity determination’’ when a
Federal action would result in total direct and
indirect emissions of a criteria pollutant or
precursor originating in nonattainment or
maintenance areas equaling or exceeding the
213 Final
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General Conformity Rule does not
require a conformity determination for
Federal actions that are ‘‘rulemaking
and policy development and issuance,’’
such as this action.216 Therefore,
NHTSA has determined it is not
required to perform a conformity
analysis for this action.
Socioeconomics
The socioeconomic impacts of the
proposed rule would be primarily felt
by heavy vehicle and equipment
manufacturers, heavy vehicle drivers,
and other road users that would
otherwise be killed or injured as a result
of heavy vehicle crashes. NHTSA
conducted a detailed assessment of the
economic costs and benefits of
establishing the new rule in its PRIA.
The main economic benefits come
primarily from the reduction in fatalities
and non-fatal injuries (safety benefits).
Reductions in the severity of heavy
vehicle crashes would be anticipated to
have corresponding reductions in costs
for medical care, emergency services,
insurance administrative costs,
workplace costs, and legal costs due to
the fatalities and injuries avoided. Other
socioeconomic factors discussed in the
PRIA that would affect these parties
include quantified property damage
savings, and additional quantified and
unquantified impacts like less
disruptions to commodity flow and
improved traffic conditions. Most of
these socioeconomic benefits are related
to public health and safety and are
discussed in more detail below.
TABLE 25—COMPARISON OF REGULATORY ALTERNATIVES
[2021 dollars]
Net cost per equivalent live saved
Regulatory option
3%
7%
3%
7%
Proposed Rule ......................
...............................................
¥$118,922
$496,746
$2,583,652,432
$1,807,064,498
Alternative 1: AEB Requirements only for Class 7–8.
Less Stringent .......................
¥1,003,884
¥662,217
809,485,467
597,125,719
Alternative 2: More Aggressive Phase in Schedule for
Class 3–6.
More Stringent ......................
¥118,922
496,746
2,583,652,432
1,807,064,498
The total annual cost, considering the
implementation of both AEB and ESC
technologies proposed in this rule, is
estimated to be $353 million. The
proposed rule would generate a net
benefit of $2.58 to $1.81 billion,
annually under 3 and 7 percent
discount rates. The proposed rule would
be cost-effective given that the highest
estimated net cost per fatal equivalent
would be $0.50 million. Maintenance
costs are considered de minimis and
therefore not included in the cost
estimate. Please see PRIA for additional
information about the annual cost,
monetized benefits, cost-effectiveness,
and net benefits of this proposal.
Public Health and Safety
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Net benefits
Relative to the proposed rule
The affected environment for public
health and safety includes roads,
highways and other driving locations
used by heavy vehicle drivers, drivers
and passengers in light vehicles and
other motor vehicles, and pedestrians or
other individuals who could be injured
or killed in crashes involving the
vehicles regulated by the proposed
action. In the PRIA, the agency
determined the impacts on public
health and safety by estimating the
reduction in fatalities and injuries
resulting from the decreased crash
severity due to the use of AEB systems
emissions thresholds specified in 40 CFR
93.153(b)(1) and (2).
216 40 CFR 93.153(c)(2)(iii).
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Vehicle crashes can generate solid
wastes and release hazardous materials
into the environment. The chassis and
engines, as well as associated fluids and
components of automobiles and the
contents of the vehicles, can all be
deemed waste and/or hazardous
materials. Solid waste can also include
damage to the roadway infrastructure,
including road surface, barriers, bridges,
and signage. Hazardous materials are
substances that may pose a threat to
public safety or the environment
because of their physical, chemical, or
radioactive properties when they are
released into the environment, in this
case as a result of a crash. Vehicle
crashes also generate socioeconomic
and environmental effects from
congestion as engines idle while drivers
are caught in traffic jams and
slowdowns, in particular from wasted
fuel and the resulting increased
greenhouse gas emissions.217
The proposal is projected to reduce
the amount and severity of heavy
vehicle crashes, and therefore is
expected to reduce the quantity of solid
waste, hazardous materials, and other
property damage generated by vehicle
crashes in the United States, in addition
to reducing the traffic congestion that
occurs as a consequence of a crash. Less
solid waste translates into cost and
environmental savings from reductions
in the following areas: (1) transport of
waste material, (2) energy required for
recycling efforts, and (3) landfill or
217 Blincoe, L.J., Miller, T.R., Zaloshnja, E., &
Lawrence, B.A. (2015, May). The economic and
societal impact of motor vehicle crashes, 2010.
(Revised) (Report No. DOT HS 812 013).
Washington, DC: National Highway Traffic Safety
Administration.
under the regulatory alternatives. Under
the proposed standard (the preferred
alternative), it is expected that the
addition of a requirement for specific
AEB/ESC installation and performance
standards for certain Class 3–8 heavy
vehicles with a two-tiered phase-in
schedule, would result each year in 151
to 206 equivalent lives saved. Under
Alternative 1, it is expected that the
addition of a less stringent requirement
that would set AEB/ESC installation and
performance standards only for Class 7–
8 heavy vehicles, with the same phasein schedule as the preferred alternative,
would result each year in 45 to 60
equivalent lives saved. Under
Alternative 2, it is expected that the
addition of a more stringent requirement
that would require a more aggressive
phase-in schedule for the AEB/ESC
installation requirements for Class 3–6
heavy vehicles, would result in 94 to
128 equivalent lives saved in 2024 and
151 to 206 equivalent lives saved in
2025 onwards. The PRIA discusses this
information in further detail.
Solid Waste/Property Damage/
Congestion
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incinerator fees. Less waste will result
in beneficial environmental effects
through less GHG emissions used in the
transport of it to a landfill, less energy
used to recycle the waste, less emissions
through the incineration of waste, and
less point source pollution at the scene
of the crash that would result in
increased emissions levels or increased
toxins leaking from the crashed vehicles
into the surrounding environment.
Similarly, as mentioned above, less
congestion translates into economic and
environmental benefits from fuel
savings and reduced GHG emissions, in
addition to benefits from the time that
drivers are not caught in additional
traffic congestion.
As discussed in the PRIA, NHTSA’s
monetized benefits are calculated by
multiplying the number of non-fatal
injuries and fatalities mitigated by their
corresponding ‘‘comprehensive costs.’’
The comprehensive costs include
economic costs that are external to the
value of a statistical life (VSL) costs,
such as emergency management services
or legal costs, and congestion costs.
NHTSA calculated the monetized
benefits attributable to reduced traffic
congestion and property damage in the
PRIA accompanying this proposed rule
for the proposed action and the
regulatory alternatives. As shown in
Table 26, the monetized benefits from
reduced traffic congestion and property
damage increase as the regulatory
alternatives increase the heavy vehicle
classes covered by the proposal and the
proposal’s phase-in year. Please see
PRIA for additional information about
the comprehensive cost values used in
this proposal.
TABLE 26—CONGESTION AND PROPERTY DAMAGE SAVINGS
Alternative 1
3% Discount
Preferred alternative
7% Discount
$125,337,423 ....
$94,904,159
3% Discount
$377,815,690
While NHTSA did not quantify
impacts aside from the monetized
benefits from congestion and property
damage savings, like the specific
quantity of solid waste avoided from
reduced crashes, NHTSA believes the
benefits would increase relative to the
crashes avoided and would be relative
across the different alternatives. This is
based in part on NHTSA and FMCSA’s
previously conducted Draft EA on heavy
vehicle speed limiting devices.218 While
that Draft EA analyzed the effects of
reduced crash severity, there would be
similar, if not increasing benefits to
avoided crashes as a result of the
addition of AEB to heavy vehicles.219
The PRIA discusses information related
to quantified costs and benefits of
crashes, and in particular property
damage due to crashes, for each
regulatory alternative in further detail.
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Cumulative Impacts
In addition to direct and indirect
effects, CEQ regulations require agencies
to consider cumulative impacts of major
Federal actions. CEQ regulations define
cumulative impacts as the impact ‘‘on
the environment that result from the
incremental [impact] of the action when
added to . . . other past, present, and
reasonably foreseeable future actions
regardless of what agency (Federal or
non-Federal) or person undertakes such
other actions.’’ 220 NHTSA notes that the
public health and safety, solid waste/
218 Speed
Limiting Devices Draft Environmental
Assessment, DOT HS 812 324 (August 2016).
219 Id. at 33 (‘‘Using this procedure, the results in
this section are expected to be more conservative
than if presented in terms of crash avoidance.’’
220 40 CFR 1508.1(g)(3).
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Alternative 2
7% Discount
$278,309,156
3% Discount
7% Discount
2024: $243,518,740 ...............
2025 Onwards: $377,815,690
2024: $180,753,307.
2025 Onwards: $278,309,156.
property damage/congestion, air quality
and GHG emissions, socioeconomic,
and hazardous material benefits
identified in this EA were based on
calculations described in the PRIA, in
addition to other NHTSA actions and
studies on motor vehicle safety. That
methodology required the agency to
adjust historical figures to reflect
vehicle safety rulemakings that have
recently become effective. As a result,
many of the calculations in this EA
already reflect the incremental impact of
this action when added to other past
actions.
NHTSA’s and other parties’ past
actions that improve the safety of heavy
vehicles, as well as future actions taken
by the agency or other parties that
improve the safety of heavy vehicles,
could further reduce the severity or
number of crashes involving these
vehicles. Any such cumulative
improvement in the safety of heavy
vehicles would have an additional effect
in reducing injuries and fatalities and
could reduce the quantity of solid and
hazardous materials generated by
crashes. Additional federal actions like
NHTSA’s fuel efficiency standards for
heavy vehicles, and EPA’s GHG and
criteria pollutant emissions standards
for heavy vehicles, could also result in
additional decreased fuel use and
emissions reductions in the future.
Agencies and Persons Consulted
This preamble describes the various
materials, persons, and agencies
consulted in the development of the
proposal.
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Finding of No Significant Impact
Although this rule is anticipated to
result in increased FMVSS requirements
for heavy vehicle manufacturers,
NHTSA’s analysis indicates that it
would likely result in environmental
and other socioeconomic benefits. The
addition of regulatory requirements to
standardize heavy vehicle AEB is
anticipated to result in no additional
fuel consumption (and accordingly, no
additional GHG or criteria pollutant
emissions impacts), increasing
socioeconomic and public safety
benefits depending on the regulatory
alternative phase-in year and vehicle
class applicability requirements from
the no-action alternative, and an
increase in benefits from the reduction
in solid waste, property damage, and
congestion (including associated trafficlevel impacts like a reduction in energy
consumption and tailpipe pollutant
emissions from congestion) from fewer
crashes.
Based on the information in this Draft
EA and assuming no additional
information or changed circumstances,
NHTSA expects to issue a Finding of No
Significant Impact (FONSI).221 NHTSA
has tentatively concluded that none of
the impacts anticipated to result from
the proposed action and alternatives
under consideration will have a
significant effect on the human
environment. Such a finding will be
made only after careful review of all
public comments received. A Final EA
and a FONSI, if appropriate, will be
issued as part of the final rule.
221 40
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FMCSA
FMCSA analyzed this rule pursuant to
the National Environmental Policy Act
and determined this action is
categorically excluded from further
analysis and documentation in an
environmental assessment or
environmental impact statement under
FMCSA Order 5610.1 (69 FR 9680, Mar.
1, 2004), Appendix 2, paragraph 6(aa).
The Categorical Exclusion in paragraph
6(aa) covers regulations requiring motor
carriers, their officers, drivers, agents,
representatives, and employees directly
in control of CMVs to inspect, repair,
and provide maintenance for every CMV
used on a public road. In addition, this
rule does not have any effect on the
quality of environment.
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Executive Order 13132 (Federalism)
NHTSA has examined this NPRM
pursuant to Executive Order 13132 (64
FR 43255, August 10, 1999) and
concludes that no additional
consultation with States, local
governments or their representatives is
mandated beyond the rulemaking
process. The agency has concluded that
the rulemaking would not have
sufficient federalism implications to
warrant consultation with State and
local officials or the preparation of a
federalism summary impact statement.
The NPRM would not have ‘‘substantial
direct effects on the States, on the
relationship between the national
government and the States, or on the
distribution of power and
responsibilities among the various
levels of government.’’
NHTSA rules can preempt in two
ways. First, the National Traffic and
Motor Vehicle Safety Act contains an
express preemption provision: When a
motor vehicle safety standard is in effect
under this chapter, a State or a political
subdivision of a State may prescribe or
continue in effect a standard applicable
to the same aspect of performance of a
motor vehicle or motor vehicle
equipment only if the standard is
identical to the standard prescribed
under this chapter. 49 U.S.C.
30103(b)(1). It is this statutory command
by Congress that preempts any nonidentical State legislative and
administrative law addressing the same
aspect of performance.
The express preemption provision
described above is subject to a savings
clause under which ‘‘[c]ompliance with
a motor vehicle safety standard
prescribed under this chapter does not
exempt a person from liability at
common law.’’ 49 U.S.C. 30103(e).
Pursuant to this provision, State
common law tort causes of action
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against motor vehicle manufacturers
that might otherwise be preempted by
the express preemption provision are
generally preserved.
However, the Supreme Court has
recognized the possibility, in some
instances, of implied preemption of
such State common law tort causes of
action by virtue of NHTSA’s rules, even
if not expressly preempted. This second
way that NHTSA rules can preempt is
dependent upon there being an actual
conflict between an FMVSS and the
higher standard that would effectively
be imposed on motor vehicle
manufacturers if someone obtained a
State common law tort judgment against
the manufacturer, notwithstanding the
manufacturer’s compliance with the
NHTSA standard. Because most NHTSA
standards established by an FMVSS are
minimum standards, a State common
law tort cause of action that seeks to
impose a higher standard on motor
vehicle manufacturers will generally not
be preempted. However, if and when
such a conflict does exist—for example,
when the standard at issue is both a
minimum and a maximum standard—
the State common law tort cause of
action is impliedly preempted. See
Geier v. American Honda Motor Co.,
529 U.S. 861 (2000).
Pursuant to Executive Order 13132
and 12988, NHTSA has considered
whether this proposed rule could or
should preempt State common law
causes of action. The agency’s ability to
announce its conclusion regarding the
preemptive effect of one of its rules
reduces the likelihood that preemption
will be an issue in any subsequent tort
litigation. To this end, the agency has
examined the nature (e.g., the language
and structure of the regulatory text) and
objectives of this final rule and finds
that this rule, like many NHTSA rules,
would prescribe only a minimum safety
standard. As such, NHTSA does not
intend this NPRM to preempt State tort
law that would effectively impose a
higher standard on motor vehicle
manufacturers than that established by
a final rule. Establishment of a higher
standard by means of State tort law will
not conflict with the minimum standard
adopted here. Without any conflict,
there could not be any implied
preemption of a State common law tort
cause of action.
FMCSA has determined that this
proposed rule would not have
substantial direct costs on or for States
concerning the adoption and
enforcement of compatible motor carrier
safety rules for intrastate motor carriers,
nor would it limit the policymaking
discretion of States. Nothing in this
document would preempt any State
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motor carrier safety law or regulation.
Therefore, this proposed rule would not
have sufficient federalism implications
to warrant the preparation of a
Federalism Impact Statement related to
the delivery of FMCSA’s programs.
Civil Justice Reform
With respect to the review of the
promulgation of a new regulation,
section 3(b) of Executive Order 12988,
‘‘Civil Justice Reform’’ (61 FR 4729,
February 7, 1996) requires that
Executive agencies make every
reasonable effort to ensure that the
regulation: (1) Clearly specifies the
preemptive effect; (2) clearly specifies
the effect on existing Federal law or
regulation; (3) provides a clear legal
standard for affected conduct, while
promoting simplification and burden
reduction; (4) clearly specifies the
retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses
other important issues affecting clarity
and general draftsmanship under any
guidelines issued by the Attorney
General. This document is consistent
with that requirement.
Pursuant to this Order, NHTSA notes
as follows. The preemptive effect of this
rulemaking is discussed above. NHTSA
notes further that there is no
requirement that individuals submit a
petition for reconsideration or pursue
other administrative proceeding before
they may file suit in court.
Paperwork Reduction Act (PRA)
Under the PRA of 1995, a person is
not required to respond to a collection
of information by a Federal agency
unless the collection displays a valid
OMB control number. There are no
‘‘collections of information’’ (as defined
at 5 CFR 1320.3(c)) in this proposed
rule.
National Technology Transfer and
Advancement Act
Under the National Technology
Transfer and Advancement Act of 1995
(NTTAA) (Public Law 104–113), all
Federal agencies and departments shall
use technical standards that are
developed or adopted by voluntary
consensus standards bodies, using such
technical standards as a means to carry
out policy objectives or activities
determined by the agencies and
departments. Voluntary consensus
standards are technical standards (e.g.,
materials specifications, test methods,
sampling procedures, and business
practices) that are developed or adopted
by voluntary consensus standards
bodies, such as the International
Organization for Standardization (ISO)
and SAE International. The NTTAA
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directs Federal agencies to provide
Congress, through OMB, explanations
when a Federal agency decides not to
use available and applicable voluntary
consensus standards.
NHTSA is proposing to incorporate by
reference ISO and ASTM standards into
this proposed rule. NHTSA considered
several ISO standards and has proposed
to use ISO 19206–3:2021 to specify the
vehicle test device. NHTSA is
incorporating by reference ASTM
E1337–19, which is already
incorporated by reference into many
FMVSSs, to measure the peak braking
coefficient of the testing surface.
NHTSA considered SAE J3029,
Forward Collision Warning and
Mitigation Vehicle Test Procedure—
Truck and Bus, which defines the
conditions for testing AEB and FCW
systems. This document outlines a basic
test procedure to be performed under
specified operating and environmental
conditions. It does not define tests for
all possible operating and
environmental conditions. The
procedures in this SAE recommended
practice are substantially similar to this
proposal. Minimum performance
requirements are not addressed in SAE
J3029.
In Appendix B of this preamble,
NHTSA describes several international
test procedures and regulations the
agency considered for use in this NPRM.
This proposed rule also has substantial
technical overlap with the UNECE No.
131 described in the appendix. First,
this proposed rule and UNECE No. 131
specify a warning and automatic
emergency braking in lead vehicle crash
situations. Several lead vehicle
scenarios are nearly identical, including
the stopped lead vehicle and lead
vehicle moving scenarios. Finally,
NHTSA has based its test target for the
lead vehicle test device on the ‘‘soft
target option’’ condition contained in
UNECE No. 152. As discussed in the
appendix, this proposed rule differs
from the UNECE standards in the areas
of maximum test speed and the basic
performance criteria. This proposed rule
uses higher test speeds to better match
the safety problem in the United States.
This proposed rule includes a
requirement that the test vehicle avoid
contact. This approach would increase
the repeatability of the test and
maximize the realized safety benefits of
the rule.
Incorporation by Reference
Under regulations issued by the Office
of the Federal Register (1 CFR 51.5(a)),
an agency, as part of a proposed rule
that includes material incorporated by
reference, must summarize material that
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is proposed to be incorporated by
reference and discuss the ways the
material is reasonably available to
interested parties or how the agency
worked to make materials available to
interested parties.
In this NPRM, NHTSA proposes to
incorporate by reference three
documents into the Code of Federal
Regulations, one of which is already
incorporated by reference. The
document already incorporated by
reference into 49 CFR part 571 is ASTM
E1337, ‘‘Standard Test Method for
Determining Longitudinal Peak Braking
Coefficient (PBC) of Paved Surfaces
Using Standard Reference Test Tire.’’
ASTM E1337 is a standard test method
for evaluating peak braking coefficient
of a test surface using a standard
reference test tire using a trailer towed
by a vehicle. NHTSA uses this method
in all of its braking and electronic
stability control standards to evaluate
the test surfaces for conducting
compliance test procedures.
NHTSA is also proposing to
incorporate by reference into part 571
SAE J2400, ‘‘Human Factors in Forward
Collision Warning System: Operating
Characteristics and User Interface
Requirements.’’ SAE J2400 is an
information report that is intended as a
starting point of reference for designers
of forward collision warning systems.
NHTSA would incorporate this
document by reference solely to specify
the location specification and symbol
for a visual forward collision warning.
NHTSA is proposing to incorporate by
reference ISO 19206–3:2021(E), ‘‘Test
devices for target vehicles, vulnerable
road users and other objects, for
assessment of active safety functions
—Part 3: Requirements for passenger
vehicle 3D targets.’’ This document
provides specification of threedimensional test devices that resemble
real vehicles. It is designed to ensure the
safety of the test operators and to
prevent damage to subject vehicles in
the event of a collision during testing.
NHTSA is referencing many, but not all,
of the specifications of ISO 19206–
3:2021(E), as discussed in section VIII.B
of this NPRM.
All standards proposed to be
incorporated by reference in this NPRM
are available for review at NHTSA’s
headquarters in Washington, DC, and
for purchase from the organizations
promulgating the standards. The ASTM
standard presently incorporated by
reference into other NHTSA regulations
is also available for review at ASTM’s
online reading room.222
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Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act
of 1995 (Pub. L. 104–4) requires
agencies to prepare a written assessment
of the costs, benefits, and other effects
of proposed or final rules that include
a Federal mandate likely to result in the
expenditures by States, local or tribal
governments, in the aggregate, or by the
private sector, $100 million or more
(adjusted annually for inflation with
base year of 1995) in any one year.
Adjusting this amount by the Consumer
Price Index for All-Urban Consumers
(CPI–U) for the year 2021 and 1995
results in an estimated current value of
$178 million (= 2021 index value of
270.970/1995 index value of 152.400).
This proposed rule is not likely to result
in expenditures by State, local, or tribal
governments of more than $178 million
in any one year. However, it is
estimated to result in the expenditures
by motor vehicle manufacturers of more
than $178 million. The prior section of
this NPRM contains a summary of the
costs and benefits of this proposed rule,
and the PRIA discusses the costs and
benefits of this proposed rule in detail.
Executive Order 13609 (Promoting
International Regulatory Cooperation)
The policy statement in section 1 of
E.O. 13609 states, in part, that the
regulatory approaches taken by foreign
governments may differ from those
taken by U.S. regulatory agencies to
address similar issues and that, in some
cases, the differences between the
regulatory approaches of U.S. agencies
and those of their foreign counterparts
might not be necessary and might
impair the ability of American
businesses to export and compete
internationally. The E.O. states that, in
meeting shared challenges involving
health, safety, labor, security,
environmental, and other issues,
international regulatory cooperation can
identify approaches that are at least as
protective as those that are or would be
adopted in the absence of such
cooperation and that international
regulatory cooperation can also reduce,
eliminate, or prevent unnecessary
differences in regulatory requirements.
NHTSA requests public comment on the
‘‘regulatory approaches taken by foreign
governments’’ concerning the subject
matter of this rulemaking.
Regulation Identifier Number
The Department of Transportation
assigns a regulation identifier number
(RIN) to each regulatory action listed in
the Unified Agenda of Federal
Regulations. The Regulatory Information
Service Center publishes the Unified
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Agenda in April and October of each
year. You may use the RINs contained
in the heading at the beginning of this
document to find this action in the
Unified Agenda.
Plain Language
Executive Order 12866 requires each
agency to write all rules in plain
language. Application of the principles
of plain language includes consideration
of the following questions:
• Have we organized the material to
suit the public’s needs?
• Are the requirements in the rule
clearly stated?
• Does the rule contain technical
language or jargon that isn’t clear?
• Would a different format (grouping
and order of sections, use of headings,
paragraphing) make the rule easier to
understand?
• Would more (but shorter) sections
be better?
• Could we improve clarity by adding
tables, lists, or diagrams?
• What else could we do to make the
rule easier to understand?
If you have any responses to these
questions, please write to us with your
views.
XV. Public Participation
How long do I have to submit
comments?
Please see the DATES section at the
beginning of this document.
lotter on DSK11XQN23PROD with PROPOSALS2
• Your comments must be written in
English.
• To ensure that your comments are
correctly filed in the Docket, please
include the Docket Number shown at
the beginning of this document in your
comments.
• Your comments must not be more
than 15 pages long. (49 CFR 553.21).
NHTSA established this limit to
encourage you to write your primary
comments in a concise fashion.
However, you may attach necessary
additional documents to your
comments. There is no limit on the
length of the attachments. FMCSA does
not impose a page limit on docket
comments, but like NHTSA, it
appreciates a concise statement of the
issues addressed by commenters.
• If you are submitting comments
electronically as a PDF (Adobe) File,
NHTSA asks that the documents be
submitted using the Optical Character
Recognition (OCR) process, thus
allowing NHTSA to search and copy
certain portions of your submissions.
Comments may be submitted to the
18:50 Jul 05, 2023
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How can I be sure that my comments
were received?
If you wish Docket Management to
notify you upon its receipt of your
comments, enclose a self-addressed,
stamped postcard in the envelope
containing your comments. Upon
receiving your comments, Docket
Management will return the postcard by
mail.
How do I submit confidential business
information?
How do I prepare and submit
comments?
VerDate Sep<11>2014
docket electronically by logging onto the
Docket Management System website at
https://www.regulations.gov. Follow the
online instructions for submitting
comments.
• You may also submit two copies of
your comments, including the
attachments, to Docket Management at
the address given above under
ADDRESSES.
Please note that pursuant to the Data
Quality Act, in order for substantive
data to be relied upon and used by the
agency, it must meet the information
quality standards set forth in the OMB
and DOT Data Quality Act guidelines.
Accordingly, we encourage you to
consult the guidelines in preparing your
comments. OMB’s guidelines may be
accessed at https://
www.whitehouse.gov/omb/fedreg/
reproducible.html. DOT’s guidelines
may be accessed at https://www.bts.gov/
programs/statistical_policy_and_
research/data_quality_guidelines.
NHTSA
If you wish to submit any information
under a claim of confidentiality, you
should submit three copies of your
complete submission, including the
information you claim to be confidential
business information (CBI), to the Chief
Counsel, NHTSA, at the address given
above under FOR FURTHER INFORMATION
CONTACT. In addition, you should
submit two copies, from which you
have deleted the claimed confidential
business information, to Docket
Management at the address given above
under ADDRESSES. When you send a
comment containing information
claimed to be confidential business
information, you should include a cover
letter setting forth the information
specified in our confidential business
information regulation. (49 CFR part
512). To facilitate social distancing
during COVID–19, NHTSA is
temporarily accepting confidential
business information electronically.
Please see https://www.nhtsa.gov/
coronavirus/submission-confidentialbusiness-information for details.
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FMCSA
CBI is commercial or financial
information that is both customarily and
actually treated as private by its owner.
Under the Freedom of Information Act
(5 U.S.C. 552), CBI is exempt from
public disclosure. If your comments
responsive to the NPRM contain
commercial or financial information
that is customarily treated as private,
that you actually treat as private, and
that is relevant or responsive to the
NPRM, it is important that you clearly
designate the submitted comments as
CBI. Please mark each page of your
submission that constitutes CBI as
‘‘PROPIN’’ to indicate it contains
proprietary information. FMCSA will
treat such marked submissions as
confidential under the Freedom of
Information Act, and they will not be
placed in the public docket of the
NPRM. Submissions containing CBI
should be sent to Mr. Brian Dahlin,
Chief, Regulatory Evaluation Division,
Office of Policy, FMCSA, 1200 New
Jersey Avenue SE, Washington, DC
20590–0001. Any comments FMCSA
receives not specifically designated as
CBI will be placed in the public docket
for this rulemaking.
Will the agency consider late
comments?
NHTSA will consider all comments
that Docket Management receives before
the close of business on the comment
closing date indicated above under
DATES. To the extent possible, we will
also consider comments that Docket
Management receives after that date. If
Docket Management receives a comment
too late for us to consider in developing
the final rule, we will consider that
comment as an informal suggestion for
future rulemaking action. FMCSA will
consider all comments and material
received during the comment period
and through the closing date up to
11:59:59 p.m. ET.
How can I read the comments submitted
by other people?
You may read the comments received
by Docket Management at the address
given above under ADDRESSES. The
hours of the Docket are indicated above
in the same location. You may also see
the comments on the internet. To read
the comments on the internet, go to
https://www.regulations.gov. Follow the
online instructions for accessing the
dockets.
Please note that, even after the
comment closing date, we will continue
to file relevant information in the
Docket as it becomes available. Further,
some people may submit late comments.
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Accordingly, we recommend that you
periodically check the Docket for new
material.
XIV. Appendices to the Preamble
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Appendix A: Description of
Technologies
For the convenience of readers, this section
describes various technologies of an AEB
system. An AEB system employs multiple
sensor technologies and sub-systems that
work together to sense a crash imminent
scenario and, where applicable,
automatically apply the vehicle brakes to
avoid or mitigate a crash. Current systems
utilize radar- and camera-based sensors. AEB
has been implemented in vehicles having
electronic stability control technology, which
itself leverages antilock braking system
technologies. It also builds upon older
forward collision warning-only systems.
Radar-Based Sensors
At its simplest form, radar is a time-offlight sensor that measures the time between
when a radio wave is transmitted and its
reflection is recorded. This time-of-flight is
then used to calculate the distance to the
object that caused the reflection. More
information about the reflecting object, such
as speed, can be determined by comparing
the output signal to the input signal. Typical
automotive applications use a type of radar
called Frequency Modulated Continuous
Wave radar. This radar system sends out a
radio pulse where the pulse frequency rises
through the duration of the pulse. This pulse
is reflected off the object and the radar sensor
compares the reflected signal to the original
pulse to determine the range and relative
speed.
Radar sensors are widely used in AEB
application, for many reasons. These sensors
can have a wide range of applicability, with
automotive grade radars sensing ranges on
the order of 1 meter (3 ft) up to over 200
meters (656 ft). Radar sensors are also
relatively unaffected by time of day,
precipitation, fog, and many other adverse
weather conditions. Automotive radar
systems typically operate on millimeter wave
lengths, easily reflecting off even the smallest
metallic surfaces found on vehicles. Radio
waves tend to penetrate soft materials, such
as rubber and plastic, allowing these sensors
to be mounted in the front ends of vehicles
behind protective, and visually appealing,
grilles and bumper fascia.
Radar-based sensors have limitations that
impact their effectiveness. Radar is a line-ofsight sensor, in that they only operate in the
direction the receiving antenna is pointed
and therefore have a limited angular view.
Also, while radar is excellent at identifying
radar-reflective objects, the nature of the
radar reflection makes classification of that
object difficult. In addition, objects that do
not reflect radio waves easily, such as rubber,
plastic, humans, and other soft objects, are
difficult for radar-based sensors to detect.
Lastly, because forward facing radar sensors
are usually mounted inside the front end of
equipped vehicles, damage caused from
front-end collisions can lead to alignment
issues and reduced effectiveness.
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Camera Sensors
Cameras are passive sensors in which
optical data are recorded by digital imaging
chips, which are then processed to allow for
object detection and classification. They are
an important part of most automotive AEB
systems and one or more cameras are
typically mounted behind the front
windshield, often high up near the rearview
mirror. This provides a good view of the
road, plus the windshield wipers provide
protection from debris and grease, dirt and
the like that can cover the sensor.
Camera-based imaging systems are one of
the few sensor types that can determine both
color and contrast information. This makes
them able to recognize and classify objects
such as road signs, other vehicles, and
pedestrians, much in the same way the
human eye does. In addition, systems that
utilize two or more cameras can see
stereoscopically, allowing the processing
system to determine range information along
with detection and classification.
Like all sensor systems, camera-based
sensors have their benefits and limitations.
Monocular camera systems lack depth
perception and are poor at determining
range, and even stereoscopic camera systems
are not ideal for determining speed. Because
cameras rely on the visible spectrum of light,
conditions that make it difficult to see such
as rain, snow, sleet, fog, and even dark unlit
areas, decrease the effectiveness of
perception checks of these systems. It is also
possible for the imaging sensor to saturate
when exposed to excessive light, such as
driving towards the sun. For these reasons,
camera sensors are often used in conjunction
with other sensors like radar.
Electronically Modulated Braking Systems
Automatic actuation of the vehicle brakes
requires more than just systems to sense
when a collision is imminent. Regardless of
how good a sensing system is, hardware is
needed to physically apply the brakes
without relying on the driver to modulate the
brake pedal. The automatic braking system
leverages two foundational braking
technologies, antilock braking systems and
electronic safety control.
Antilock brakes are a foundational
technology that automatically controls the
degree of wheel slip during braking to
prevent wheel lock and minimize skidding,
by sensing the rate of angular rotation of the
wheels and modulating the braking force at
the wheels to keep the wheels from slipping.
Modern ABS systems have wheel speed
sensors and independent brake modulation at
each wheel and can increase and decrease
braking pressures as needed.
ESC builds upon the antilock brakes and
increases their capability with the addition of
at least two sensors, a steering wheel angle
sensor and an inertial measurement unit.
These sensors allow the ESC controller to
determine intended steering direction (from
the steering wheel angle sensor), compare it
to the actual vehicle direction, and then
apply appropriate braking forces at each
wheel to induce a counter yaw when the
vehicle starts to lose lateral stability. AEB
uses the hardware needed for ESC and
automatically applies the brakes to avoid
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certain scenarios where a crash with a
vehicle is imminent.
Forward Collision Warning
Using the sensors described above, coupled
with an alert mechanism and perception
calculations, a FCW system is able to monitor
a vehicle’s speed, the speed of the vehicle in
front of it, and the distance between the two
vehicles. If the FCW system determines that
the distance from the driver’s vehicle to the
vehicle in front of it is too short, and the
closing velocity between the two vehicles is
too high, the system warns the driver of an
impending rear-end collision.
Typically, FCW systems are comprised of
two components: a sensing system, which
can detect a vehicle in front of the driver’s
vehicle, and a warning system, which alerts
the driver to a potential crash threat. The
sensing portion of the system may consist of
forward-looking radar, camera systems, lidar
or a combination of these. Warning systems
in use today provide drivers with a visual
display, such as an illuminated telltale on the
instrument panel, an auditory signal (e.g.,
beeping tone or chime), and/or a haptic
signal that provides tactile feedback to the
driver (e.g., rapid vibrations of the seat pan
or steering wheel or a momentary brake
pulse) to alert the driver of an impending
crash so that they may manually intervene
(e.g., apply the vehicle’s brakes or make an
evasive steering maneuver) to avoid or
mitigate the crash.
FCW systems alone are designed to warn
the driver, but do not provide automatic
braking of the vehicle (some FCW systems
use haptic brake pulses to alert the driver of
a crash-imminent driving situation, but they
are not intended to effectively slow the
vehicle). Since the first introduction of FCW
systems, the technology has advanced such
that it is now possible to couple those
sensors, software, and alerts with the
vehicles service brake system to provide
additional functionality covering a broader
portion of the safety problem.
From a functional perspective, research
suggests that active braking systems, such as
AEB, provide greater safety benefits than
warning systems, such as FCW systems.
However, NHTSA has found that current
AEB systems often integrate the
functionalities of FCW and AEB into one
frontal crash prevention system to deliver
improved real-world safety performance and
high consumer acceptance. FCW can now be
considered a component of AEB. As such,
this NPRM integrates FCW directly into the
performance requirements for AEB. This
integration would also enable the agency to
assess vehicles’ compliance with the
proposed FCW and AEB requirements at the
same time in a single test.
Automatic Emergency Braking
Unlike systems that only alert, AEB
systems (systems that automatically apply
the brakes), are designed to actively help
drivers avoid or mitigate the severity of rearend crashes. AEB has been previously broken
into two primary functions, crash imminent
braking and dynamic brake support. CIB
systems provide automatic braking when
forward-looking sensors indicate that a crash
is imminent and the driver has not applied
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the brakes, whereas DBS systems use the
same forward-looking sensors, but provides
supplemental braking after the driver applies
the brakes when sensors determine that
driver-applied braking is insufficient to avoid
an imminent rear-end crash. This NPRM does
not split the terminology of these
functionalities and instead discusses them
together as ‘‘AEB.’’ In some crash situations,
AEB functions independently of the driver’s
use of the brake pedal (CIB), while in other
situations, the vehicle uses the driver’s pedal
input to better evaluate the situation and
avoid the crash (in the light vehicle context,
this is called DBS). This proposal considers
each function necessary to address the safety
need and presents a performance-based
regulatory approach that can permit the
detailed application of each function to be
based on the specific vehicle application and
the manufacturer’s approach to meeting the
standard.
In response to an FCW alert or a driver
noticing an imminent crash scenario, a driver
may initiate braking to avoid a rear-end
crash. In situations where the driver’s
braking is insufficient to prevent a collision,
the AEB system can automatically
supplement the driver’s braking action to
prevent or mitigate the crash. Similar to FCW
systems, AEB systems employ forwardlooking sensors such as radar and visionbased sensors to detect vehicles in the path
directly ahead and monitor a vehicle’s
operating conditions such as speed or brake
application. However, AEB systems can also
actively supplement braking to assist the
driver whereas FCW systems serve only to
warn the driver of a potential crash threat.
If a driver does not take any action to brake
when a rear-end crash is imminent, AEB
systems utilize the same types of forwardlooking sensors to apply the vehicle’s brakes
automatically to slow or stop the vehicle. The
amount of braking applied varies by
manufacturer, and several systems are
designed to achieve maximum vehicle
deceleration just prior to impact. This NPRM
would not directly require a particular
deceleration capability but specifies
situations in which crash avoidance must be
achieved. Avoidance may be produced by a
combination of warnings, vehicle
deceleration, and AEB application timing.
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Appendix B: International Regulatory
Requirements and Other Standards
European Union (EU)
UNECE 131: Uniform provisions
concerning the approval of motor vehicles
regarding the Advanced Emergency Braking
Systems (AEBS).
Europe mandated AEBS for nearly all
heavy vehicles starting in November 2013.
The mandate requires warning and automatic
braking on Lead Vehicle Moving (LVM) and
Stopped lead vehicle (LVS), but it does not
require Dynamic Braking Support (DBS). It
also requires Forward Collision Warning
(FCW) in 2 of 3 modes (audio, visual, haptic).
This mandate was implemented into two
phases. Phase 1, which is for new types (i.e.,
an all-new vehicle configuration) was
mandated in November 2013, and new
vehicles in November 2015. Phase 2 which
covers more stringent implementations, was
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put in place for the new types in November
2016 and all new heavy vehicles in
November 2018. The requirements apply to
buses and trucks over 3,500 kg (7,716 lbs.).
EU regulations include an electronic stability
control (ESC) requirement for all heavy-duty
vehicle segments.
The United Nations Economic Commission
for Europe (UNECE) is the main entity that
regulates vehicle safety in the European
Union. UNECE has developed regulations for
the implementation of AEBS (using a type
approval process) in motor vehicles, as
described below (UNECE Regulation 131).
Regarding AEBS test procedures, the leadvehicle-moving scenario in UNECE
regulations has a subject vehicle speed of 80
km/h (50 mph). For the lead-vehicle-stopped
scenario, the subject vehicle speed is also 80
km/h (50 mph).
In addition, it also has false positive test
requirements for vehicle speeds of 50 km/h
(31 mph). However, these false positive test
requirements are different from the ones in
NHTSA’s proposal, because NHTSA uses a
steel trench plate and pass-through vehicles,
as opposed to UNECE, which only uses passthrough vehicles.
There are similarities between the
performance requirements of the UNECE
regulation and proposed FMVSS No. 128 as
the speeds of the subject vehicle in the
scenarios of stopped lead vehicle as well as
slow moving lead vehicle are the same.
However, the UNECE regulation does not
have performance requirements for
decelerating lead vehicle scenarios, which
NHTSA does have. Because NHTSA has
tentatively determined it is important to have
a decelerating lead vehicle test scenario,
NHTSA decided not to completely base its
requirements on the UNECE regulation
parameters.
We note that UNECE 131 is considering the
implementation of Automatic Emergency
Braking-Pedestrian (PAEB) into its existing
regulation. NHTSA is not proposing PAEB
for heavy vehicles in this NPRM. NHTSA
believes there are unknowns at this time
about the performance of PAEB on heavy
vehicles in the U.S., as well as cost and other
technical and practicability considerations to
support a proposed implementation of PAEB
for heavy vehicles. Rather than delay this
NPRM to obtain this information, we have
decided to proceed with the rulemaking as
set forth in this NPRM.
Japan
In January 2017, the Japanese government,
under the Ministry of Land, Infrastructure,
Transport and Tourism (MLIT) presented a
proposal for UN Regulation on AEBS for M1/
N1 vehicles.223 As part of the harmonization
efforts under consideration by the UNECE
working group (WP.29), MLIT proposed a
new United Nations regulation on AEBS in
September 2008, initially including M2, N2,
M3 and N3 vehicles, and having as a future
target M1 and N1 vehicles. NHTSA’s
consideration of UNECE Regulation 131 is
discussed above.
223 https://unece.org/DAM/trans/doc/2017/
wp29grrf/GRRF-83-17e.pdf.
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South Korea
The Republic of Korea (ROK), under the
Ministry of Land, Infrastructure and
Transport (MOLIT), in January 2019 required
all passenger vehicles to have AEBS and lane
departure warning systems. Those
requirements were applied to trucks and
other vehicles in July 2021. Article 90–3
(Advanced Emergency Braking System
(AEBS)) from the Korean standard applies to
buses and trucks/special purpose vehicle
with a gross vehicle weight more than 3.5
tons (over 3,500 kg) (7,716 lbs.).224 The
majority of the performance requirements
from the Korean standard is derived from
UNECE Regulation 131. NHTSA’s
consideration of ECE Regulation 131 is
discussed above.
SAE International (SAE)
SAE J3029: Forward Collision Warning and
Mitigation Vehicle Test Procedure—Truck
and Bus.
This SAE Recommended Practice (RP)
establishes uniform powered vehicle level
test procedures for Forward Collision
Avoidance and Mitigation (FCAM) systems
(also identified as AEB systems) used in
highway commercial vehicles and coaches
greater than 4,535 kg (10,000 lbs.) GVWR.
This document outlines a basic test
procedure to be performed under specified
operating and environmental conditions. It
does not define tests for all possible
operating and environmental conditions.
Minimum performance requirements are not
addressed in this document.
When comparing the SAE test procedure
with proposed FMVSS No. 128, the SAE
procedure specifies lower test conditions
than NHTSA’s proposal. The SAE subject
vehicle speed for the stopped lead vehicle
scenario is 40.2 km/h (25 mph), compared to
80 km/h (50 mph) in this NPRM. For the case
of false activation test parameters, SAE uses
50.7 km/h (32 mph), compared to 80 km/h
(50 mph) used in the NHTSA proposed
performance requirements. NHTSA is not
proposing to use the performance
requirements from the SAE tests because the
agency believes they are not stringent enough
to provide the level of safety benefit the
agency seeks for this NPRM.
International Organization for
Standardization (ISO)
ISO 19377: Heavy commercial vehicles and
buses—Emergency braking on a defined
path—Test method for trajectory
measurement.
This standard describes test methods for
determining the deviation of the path
travelled by a vehicle during a braking
maneuver induced by an emergency braking
system from a pre-defined desired path. The
standard evaluates the vehicle path during
and following the system intervention. The
corrective steering actions for keeping the
vehicle on the desired path can be applied
either by the driver or by a steering machine
or by a driver assistance system.
This document applies to heavy vehicles
equipped with an advanced emergency
224 Regulations for Performance sand Safety
Standards of Motor Vehicle and Vehicle Parts:
Article 90–3 and Table 7–8.
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braking system, including commercial
vehicles, commercial vehicle combinations,
buses and articulated buses as defined in ISO
3833 225 (trucks and trailers with maximum
weight above 3,5 tonnes (3,500 kg or 7,716
lbs.) and buses and articulated buses with
maximum weight above 5 tonnes (5,000 kg or
11,023 lbs.), according to ECE and European
Commission on vehicle classification,
categories M3, N2, N3, O3 and O4).
NHTSA considered the ISO test procedure
but decided it is limited because the ISO
standard tests braking on a defined path on
a straight line as well as braking in a constant
radius curve, which NHTSA does not.
Therefore, NHTSA is not proposing
performance requirements based on the ISO
standard.
Proposed Regulatory Text
List of Subjects
49 CFR Part 393
Highways and roads, Motor carriers,
Motor vehicle equipment, Motor vehicle
safety.
49 CFR Part 396
Highway safety, Motor carriers, Motor
vehicle safety, Reporting and
recordkeeping requirements.
49 CFR Part 571
Imports, Incorporation by reference,
Motor vehicle safety, Reporting and
recordkeeping requirements, Tires.
49 CFR Part 596
Motor vehicle safety, Automatic
emergency braking, Incorporation by
reference, Motor vehicle safety, Test
devices.
In consideration of the foregoing,
FMCSA proposes to amend 49 CFR
parts 393 and 396, and NHTSA
proposes to amend part 571 and add
part 596 as follows:
PART 393—PARTS AND
ACCESSORIES NECESSARY FOR
SAFE OPERATION
1. The authority citation for 49 CFR
part 393 is amended to read as follows:
■
lotter on DSK11XQN23PROD with PROPOSALS2
Authority: 49 U.S.C. 31136, 31151, and
31502; sec. 1041(b) of Pub. L. 102–240, 105
Stat. 1914, 1993 (1991); sec. 5301 and 5524
of Pub. L. 114–94, 129 Stat. 1312, 1543, 1560;
sec. 23010, Pub. L. 117–58, 135 Stat. 429,
766–767, and 49 CFR 1.87.
§ 393.5
Definitions.
*
*
*
*
*
Automatic emergency braking (AEB)
system is a system that detects an
imminent collision with vehicles,
objects, and road users in or near the
path of a vehicle and automatically
controls the vehicle’s service brakes to
avoid or mitigate the collision.
Electronic stability control system or
ESC system means a system that has all
of the following attributes:
(1) It augments vehicle directional
stability by having the means to apply
and adjust the vehicle brake torques
individually at each wheel position on
at least one front and at least one rear
axle of the vehicle to induce correcting
yaw moment to limit vehicle oversteer
and to limit vehicle understeer;
(2) It enhances rollover stability by
having the means to apply and adjust
the vehicle brake torques individually at
each wheel position on at least one front
and at least one rear axle of the vehicle
to reduce lateral acceleration of a
vehicle;
(3) It is computer-controlled with the
computer using a closed-loop algorithm
to induce correcting yaw moment and
enhance rollover stability;
(4) It has a means to determine the
vehicle’s lateral acceleration;
(5) It has a means to determine the
vehicle’s yaw rate and to estimate its
side slip or side slip derivative with
respect to time;
(6) It has a means to estimate vehicle
mass or, if applicable, combination
vehicle mass;
(7) It has a means to monitor driver
steering inputs;
(8) It has a means to modify engine
torque, as necessary, to assist the driver
in maintaining control of the vehicle
and/or combination vehicle; and
(9) When installed on a truck tractor,
it has the means to provide brake
pressure to automatically apply and
modulate the brake torques of a towed
trailer.
*
*
*
*
*
■ 3. Add § 393.56 to read as follows:
§ 393.56 Electronic Stability Control
Systems.
(a) Truck tractors manufactured
between August 1, 2019 and [the first
■ 2. Amend § 393.5 by adding, in
September 1 that is 5 years after the
alphabetical order, the definition for
date of publication of a final rule]. Each
‘‘Automatic emergency braking (AEB)
truck tractor (except as provided by 49
system’’ and ‘‘Electronic stability control CFR 571.136, paragraph S3.1 or truck
system or ESC system’’ to read as
tractors engaged in driveaway-towaway
follows:
operations) with a gross vehicle weight
rating of greater than 11,793 kilograms
225 ISO 3833, ‘‘Road vehicles—Types—Terms and
(26,000 pounds) manufactured on or
Definitions,’’ ISO 3833 defines terms relating to
after August 1, 2019, but before [the first
some types of road vehicles designated according to
September 1 that is 5 years after the
certain design and technical characteristics. ISO
3833—European Standards (en-standard.eu).
date of publication of a final rule], must
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be equipped with an electronic stability
control (ESC) system that meets the
requirements of Federal Motor Vehicle
Safety Standard No. 136 (49 CFR
571.136).
(b) Buses manufactured between
August 1, 2019 and [the first September
1 that is 5 years after the date of
publication of a final rule]. Each bus
(except as provided by 49 CFR 571.136,
paragraph S3.1 or buses engaged in
driveaway-towaway operations) with a
gross vehicle weight rating of greater
than 11,793 kilograms (26,000 pounds)
manufactured on or after August 1,
2019, but before [the first September 1
that is 5 years after the date of
publication of a final rule], must be
equipped with an ESC system that
meets the requirements of FMVSS No.
136.
(c) Commercial motor vehicles
manufactured on and after [the first
September 1 that is 5 years after the
date of publication of a final rule].
Trucks and buses, with a GVWR greater
than 4,536 kilograms (10,000 pounds)
and truck tractors manufactured on or
after [the first September 1 that is 5
years after the date of publication of a
final rule] (except trucks, buses, and
truck tractors engaged in driveawaytowaway operations), must be equipped
with an electronic stability control
(ESC) system that meets the
requirements of Federal Motor Vehicle
Safety Standard No. 136 (49 CFR
571.136).
(d) ESC Malfunction Detection. Each
truck, truck tractor and bus must be
equipped with an indicator lamp,
mounted in front of and in clear view
of the driver, which is activated
whenever there is a malfunction that
affects the generation or transmission of
control or response signals in the
vehicle’s electronic stability control
system.
■ 4. Add § 393.57 to read as follows:
§ 393.57 Automatic Emergency Braking
Systems.
(a) Truck tractors manufactured on or
after [the first September 1 that is 3
years after the date of publication of a
final rule]. Each truck tractor (except as
provided by 49 CFR 571.136, paragraph
S3.1 or truck tractors engaged in
driveaway-towaway operations) with a
gross vehicle weight rating of greater
than 11,793 kilograms (26,000 pounds)
manufactured on or after the first
September 1 that is 3 years after the
date of publication of a final rule], must
be equipped with an automatic
emergency brake (AEB) system that
meets the requirements of Federal Motor
Vehicle Safety Standard No. 128 (49
CFR 571.128).
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(b) Buses manufactured on or after
[the first September 1 that is 3 years
after the date of publication of a final
rule]. Each bus (except as provided by
49 CFR 571.136, paragraph S3.1 or
buses engaged in driveaway-towaway
operations) with a gross vehicle weight
rating of greater than 11,793 kilograms
(26,000 pounds) manufactured on or
after the first September 1 that is 3 years
after the date of publication of a final
rule], must be equipped with an AEB
system that meets the requirements of
FMVSS No. 128.
(c) Commercial motor vehicles
manufactured on and after [the first
September 1 that is 5 years after the
date of publication of a final rule].
Trucks and buses, with a GVWR greater
than 4,536 kilograms (10,000 pounds)
and truck tractors manufactured on or
after [the first September 1 that is 5
years after the date of publication of a
final rule] (except trucks, buses, and
truck tractors engaged in driveawaytowaway), must be equipped with an
AEB system that meets the requirements
of Federal Motor Vehicle Safety
Standard No. 128 (49 CFR 571.128).
(d) AEB Malfunction Detection. Each
commercial motor vehicle subject to
FMVSS No. 128 must be equipped with
a telltale that meets the requirements of
S5.3 of FMVSS No. 128 (49 CFR
571.128), mounted in front of and in
clear view of the driver, which is
activated whenever there is a
malfunction that affects the generation
or transmission of control or response
signals in the vehicle’s AEB system.
PART 396—INSPECTION, REPAIR,
AND MAINTENANCE
5. The authority citation for 49 CFR
part 396 is amended to read as follows:
■
Authority: 49 U.S.C. 504, 31133, 31136,
31151, 31502; sec. 32934, Pub. L. 112–141,
126 Stat. 405, 830; sec. 5524, Pub. L. 114–94,
129 Stat. 1312, 1560; sec. 23010, Pub. L. 117–
58, 135 Stat. 429, 766–767 and 49 CFR 1.87.
6. Amend Appendix A to Part 396 by
adding paragraphs 1.n. and o to read as
follows:
■
Appendix A to Part 396—Minimum
Periodic Inspection Standards
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*
*
*
*
*
1. Brake System
n. Electronic Stability Control (ESC)
System.
(1) Missing ESC malfunction detection
components.
(2) The ESC malfunction telltale must be
identified by the symbol shown for
‘‘Electronic Stability Control System
Malfunction’’ or the specified words or
abbreviations listed in Table 1 of Standard
No. 101 (§ 571.101).
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(3) The ESC malfunction telltale must be
activated as a check-of-lamp function either
when the ignition locking system is turned to
the ‘‘On’’ (‘‘Run’’) position when the engine
is not running, or when the ignition locking
system is in a position between the ‘‘On’’
(‘‘Run’’) and ‘‘Start’’ that is designated by the
manufacturer as a check-light position.
(4) Other missing or inoperative ESC
system components.
o. Automatic Emergency Braking (AEB).
(1) Missing AEB malfunction telltale
components (e.g., bulb/LED, wiring, etc.).
(2) AEB malfunction telltale that does not
illuminate while power is continuously
applied during initial powerup.
(3) AEB malfunction telltale that stays
illuminated while power is continuously
applied during normal vehicle operation.
(4) Other missing or inoperative AEB
components.
*
*
*
*
*
PART 571—FEDERAL MOTOR
VEHICLE SAFETY STANDARDS
7. The authority citation for part 571
continues to read as follows:
■
Authority: 49 U.S.C. 322, 30111, 30115,
30117 and 30166; delegation of authority at
49 CFR 1.95.
7. Amend § 571.5 by:
a. Revising paragraph (d)(34);
b. Redesignating paragraphs (l)(49)
and (50) as paragraphs (l)(50) and (51),
respectively; and
■ c. Adding new paragraph (l)(49).
The revision and addition read as
follows:
■
■
■
§ 571.5
Matter incorporated by reference
*
*
*
*
*
(d) * * *
(34) ASTM E1337–19, ‘‘Standard Test
Method for Determining Longitudinal
Peak Braking Coefficient (PBC) of Paved
Surfaces Using Standard Reference Test
Tire,’’ approved December 1, 2019, into
§§ 571.105; 571.121; 571.122; 571.126;
571.128; 571.135; 571.136; 571.500.
*
*
*
*
*
(l) * * *
(49) SAE J2400, ‘‘Human Factors in
Forward Collision Warning System:
Operating Characteristics and User
Interface Requirements,’’ August 2003
into § 571.128.
*
*
*
*
*
■ 9. Add § 571.128 to read as follows:
§ 571.128 Standard No. 128; Automatic
emergency braking systems for heavy
vehicles.
S1. Scope. This standard establishes
performance requirements for automatic
emergency braking (AEB) systems for
heavy vehicles.
S2. Purpose. The purpose of this
standard is to reduce the number of
deaths and injuries that result from
crashes in which drivers do not apply
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43239
the brakes or fail to apply sufficient
braking power to avoid or mitigate a
crash.
S3. Application. This standard
applies to multipurpose passenger
vehicles, trucks, and buses with a gross
vehicle weight rating greater than 4,536
kilograms (10,000 pounds) that are
subject to §§ 571.105 or 571.121 of this
part.
S4. Definitions.
Adaptive cruise control system is an
automatic speed control system that
allows the equipped vehicle to follow a
lead vehicle at a pre-selected gap by
controlling the engine, power train, and
service brakes.
Ambient illumination is the
illumination as measured at the test
surface, not including any illumination
provided by the subject vehicle.
Automatic emergency braking (AEB)
system is a system that detects an
imminent collision with vehicles,
objects, and road users in or near the
path of a vehicle and automatically
controls the vehicle’s service brakes to
avoid or mitigate the collision.
Brake pedal application onset is when
the brake controller begins to displace
the brake pedal.
Forward collision warning is an
auditory and visual warning provided to
the vehicle operator by the AEB system
that is designed to induce an immediate
forward crash avoidance response by
the vehicle operator.
Forward collision warning onset is the
first moment in time when a forward
collision warning is provided.
Headway is the distance between the
lead vehicle’s rearmost plane normal to
its centerline and the subject vehicle’s
frontmost plane normal to its centerline.
Lead vehicle is a vehicle test device
facing the same direction and preceding
a subject vehicle within the same travel
lane.
Lead vehicle braking onset is the
point at which the lead vehicle achieves
a deceleration of 0.05g due to brake
application.
Over-the-road bus means a bus
characterized by an elevated passenger
deck located over a baggage
compartment, except a school bus.
Perimeter-seating bus means a bus
with 7 or fewer designated seating
positions rearward of the driver’s
seating position that are forward-facing
or can convert to forward-facing without
the use of tools and is not an over-theroad bus.
Small-volume manufacturer means an
original vehicle manufacturer that
produces or assembles fewer than 5,000
vehicles annually for sales in the United
States.
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Steel trench plate is a rectangular
steel plate often used in road
construction to temporarily cover
sections of pavement unsafe to drive
over directly.
Subject vehicle is the vehicle under
examination for compliance with this
standard.
Transit bus means a bus that is
equipped with a stop-request system
sold for public transportation provided
by, or on behalf of, a State or local
government and that is not an over-theroad bus.
Travel path is the path projected onto
the road surface of a point located at the
intersection of the subject vehicle’s
frontmost vertical plane and
longitudinal vertical center plane, as the
subject vehicle travels forward.
Vehicle test device is a device meeting
the specifications set forth in subpart C
of 49 CFR part 596.
S5. Requirements.
(a) Truck tractors and buses with a
GVWR greater than 11,793 kilograms
(26,000 pounds), other than school
buses, perimeter-seating buses, and
transit buses and which are
manufactured on or after [the first
September 1 that is three years after the
date of publication of a final rule] must
meet the requirements of this standard.
(b) Vehicles with a GVWR greater
than 4,536 kilograms (10,000 pounds)
which are manufactured on or after [the
first September 1 that is four years after
the date of publication of a final rule]
must meet the requirements of this
standard.
(c) The requirements of paragraphs (a)
and (b) of this section S5 do not apply
to small-volume manufacturers, finalstage manufacturers and alterers until
one year after the dates specified in
those paragraphs.
S5.1. Requirements when
approaching a lead vehicle.
S5.1.1. Forward Collision Warning. A
vehicle is required to have a forward
collision warning system, as defined in
S4 of this section, that provides an
auditory and visual signal to the driver
of an impending collision with a lead
vehicle when traveling at any forward
speed greater than 10 km/h (6.2 mph).
The auditory signal must have a high
fundamental frequency of at least 800
Hz, a duty cycle of 0.25—0.95, and
tempo in the range of 6–12 pulses per
second. The visual signal must be
located according to SAE J2400
(incorporated by reference, see § 571.5),
paragraph 4.1.14, and must include the
symbol in the bottom right of paragraph
4.1.16. Line of sight is based on the
forward-looking eye midpoint (Mf) as
described in S14.1.5 of § 571.111. The
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symbol must be red in color and steadyburning.
S5.1.2. Automatic Emergency Braking.
A vehicle is required to have an
automatic emergency braking system, as
defined in S4 of this section, that
applies the service brakes automatically
when a collision with a lead vehicle is
imminent. The system must operate
when the vehicle is traveling at any
forward speed greater than 10 km/h (6.2
mph).
S5.1.3. Performance Test
Requirements. The vehicle must provide
a forward collision warning and
subsequently apply the service brakes
automatically when a collision with a
lead vehicle is imminent such that the
subject vehicle does not collide with the
lead vehicle when tested using the
procedures in S7. The forward collision
warning is not required if adaptive
cruise control is engaged.
S5.2. False Activation. The vehicle
must not automatically apply braking
that results in peak deceleration of 0.25g
or greater when manual braking is not
applied, nor a peak deceleration of 0.45g
or greater when manual braking is
applied, when tested using the
procedures in S8.
S5.3. Malfunction Detection. The
system must continuously detect system
malfunctions, including malfunctions
caused solely by sensor obstructions. If
the system detects a malfunction that
prevents the system from meeting the
requirements specified in S5.1 or S5.2,
the system must provide the vehicle
operator with a telltale that the
malfunction exists.
S6. Test Conditions.
S6.1. Environmental conditions.
S6.1.1. Temperature. The ambient
temperature is any temperature between
2 °C and 40 °C.
S6.1.2. Wind. The maximum wind
speed is no greater than 5 m/s (11 mph)
during tests approaching a lead vehicle.
S6.1.3. Ambient Lighting.
(a) The ambient illumination on the
test surface is any level at or above
2,000 lux.
(b) Testing is not performed while
driving toward or away from the sun
such that the horizontal angle between
the sun and a vertical plane containing
the centerline of the subject vehicle is
less than 25 degrees and the solar
elevation angle is less than 15 degrees.
S6.1.4. Precipitation. Testing is not
conducted during periods of
precipitation or when visibility is
affected by fog, smoke, ash, or other
particulate.
S6.2. Road conditions.
S6.2.1. Test Track Surface and
Construction. The tests are conducted
on a dry, uniform, solid-paved surface.
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Surfaces with debris, irregularities, or
undulations, such as loose pavement,
large cracks, or dips are not used.
S6.2.2. Surface Friction. The road test
surface produces a peak friction
coefficient (PFC) of 1.02 when measured
using an ASTM International (ASTM)
F2493 standard reference test tire, in
accordance with ASTM E1337–19
(incorporated by reference, see § 571.5),
at a speed of 64 km/h (40 mph), without
water delivery.
S6.2.3. Slope. The test surface has any
consistent slope between 0 percent and
1 percent.
S6.2.4. Markings. The road surface
within 2.3 m of the intended travel path
is marked with zero, one, or two lines
of any configuration or color. If one line
is used, it is straight. If two lines are
used, they are straight, parallel to each
other, and at any distance from 2.7 m to
4.5 m apart.
S6.2.5. Obstructions. Testing is
conducted such that the vehicle does
not travel beneath any overhead
structures, including but not limited to
overhead signs, bridges, or gantries. No
vehicles, obstructions, or stationary
objects are within 7.4 m of either side
of the intended travel path except as
specified.
S6.3. Subject vehicle conditions.
S6.3.1. Malfunction notification.
Testing is not conducted while the AEB
malfunction telltale specified in S5.3 is
illuminated.
S6.3.2. Sensor obstruction. All sensors
used by the system and any part of the
vehicle immediately ahead of the
sensors, such as plastic trim, the
windshield, etc., are free of debris or
obstructions.
S6.3.3. Tires. The vehicle is equipped
with the original tires present at the
time of initial sale. The tires are inflated
to the vehicle manufacturer’s
recommended cold tire inflation
pressure(s) specified on the vehicle’s
placard or the tire inflation pressure
label.
S6.3.4. Brake burnish.
(a) Vehicles subject to § 571.105 are
burnished in accordance with S7.4 of
that section.
(b) Vehicles subject to § 571.121 are
burnished in accordance with S6.1.8 of
that section.
S6.3.5. Brake temperature. The
average temperature of the service
brakes on the hottest axle of the vehicle
during testing, measured according to
S6.1.16 of § 571.121, is between 66°C
and 204°C prior to braking.
S6.3.6. Fluids. All non-consumable
fluids for the vehicle are at 100 percent
capacity. All consumable fluids are at
any level from 5 to 100 percent capacity.
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S6.3.7. Propulsion battery charge. The
propulsion batteries are charged at any
level from 5 to 100 percent capacity.
S6.3.8. Cruise control. Cruise control,
including adaptive cruise control, is
configured under any available setting.
S6.3.9. Adjustable forward collision
warning. Forward collision warning is
configured in any operator-configurable
setting.
S6.3.10. Engine braking. A vehicle
equipped with an engine braking system
that is engaged and disengaged by the
operator is tested with the system in any
selectable configuration.
S6.3.11. Regenerative braking.
Regenerative braking is configured
under any available setting.
S6.3.12. Liftable Axles. A vehicle with
one or more liftable axles is tested with
the liftable axles down.
S6.3.13. Headlamps. Testing is
conducted with the headlamp control in
any selectable position.
S6.3.14. Subject vehicle loading.
(a) Except as provided in S6.3.14(b),
the vehicle is loaded to its GVWR so
that the load on each axle, measured at
the tire-ground interface, is most nearly
proportional to the axles’ respective
GAWRs, without exceeding the GAWR
of any axle.
(b) Truck tractors.
(1) A truck tractor is loaded to its
GVWR with the operator and test
instrumentation, and by coupling it to a
control trailer as provided in
S6.3.14(b)(2) of this section and placing
ballast (weight) on the control trailer
which loads the tractor’s non-steer
axles. The control trailer is loaded with
ballast without exceeding the GAWR of
the trailer axle. The location of the
center of gravity of the ballast on the
control trailer is directly above the
kingpin. The height of the center of
gravity of the ballast on the control
trailer is less than 610 mm (24 inches)
above the top of the tractor’s fifth-wheel
hitch (the area where the truck tractor
attaches to the trailer). If the tractor’s
fifth-wheel hitch position is adjustable,
the fifth-wheel hitch is adjusted to
proportionally distribute the load on
each of the tractor’s axle(s), according to
each axle’s GAWR, without exceeding
the GAWR of any axle(s). If the fifthwheel hitch position cannot be adjusted
to prevent the load from exceeding the
GAWR of the tractor’s axle(s), the ballast
is reduced until the axle load is equal
to or less than the GAWR of the tractor’s
rear axle(s), maintaining load
proportioning as close as possible to
specified proportioning.
(2) The control trailer is an unbraked,
flatbed semi-trailer that has a single axle
with a GAWR of 8,165 kilograms
(18,000 pounds). The control trailer has
a length of at least 6,400 mm (252
inches), but no more than 7,010 mm
(276 inches), when measured from the
transverse centerline of the axle to the
centerline of the kingpin (the point
where the trailer attaches to the truck
tractor). At the manufacturer’s option,
truck tractors with four or more axles
may use a control trailer with a length
of more than 7,010 mm (276 inches), but
no more than 13,208 mm (520 inches)
when measured from the transverse
centerline of the axle to the centerline
of the kingpin.
S6.3.15. AEB system initialization.
The vehicle is driven at a speed of 10
km/h or higher for at least one minute
prior to testing, and subsequently the
starting system is not cycled off prior to
testing.
S6.4. Equipment and test Devices.
S6.4.1. The vehicle test device is
specified in 49 CFR part 596 subpart C.
Local fluttering of the lead vehicle’s
external surfaces does not exceed 10
mm perpendicularly from the reference
surface, and distortion of the lead
vehicle’s overall shape does not exceed
25 mm in any direction.
S6.4.2. The steel trench plate used for
the false activation test has the
dimensions 2.4 m x 3.7 m x 25 mm and
is made of ASTM A36 steel. Any
metallic fasteners used to secure the
steel trench plate are flush with the top
surface of the steel trench plate.
S7. Testing when approaching a lead
vehicle.
S7.1. Setup.
(a) The testing area is set up in
accordance with Figure 1 to this section.
(b) Testing is conducted during
daylight.
(c) For reference, Table 1 to S7.1
specifies the subject vehicle speed
(VSV), lead vehicle speed (VLV),
headway, and lead vehicle deceleration
for each test that may be conducted.
(d) The intended travel path of the
vehicle is a straight line toward the lead
vehicle from the location corresponding
to a headway of L0.
(e) If the road surface is marked with
a single or double lane line, the
intended travel path is parallel to and
1.8 m from the inside of the closest line.
If the road surface is marked with two
lane lines bordering the lane, the
intended travel path is centered
between the two lines.
(f) For each test run conducted, the
subject vehicle speed (VSV), lead vehicle
speed (VLV), headway, and lead vehicle
deceleration will be selected from the
ranges specified.
TABLE 1 TO S7.1—TEST PARAMETERS WHEN APPROACHING A LEAD VEHICLE
Speed
(km/h)
Test scenarios
VSV
Stopped Lead Vehicle ................................................................
Slower-Moving Lead Vehicle .....................................................
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Decelerating Lead Vehicle .........................................................
S7.2. Headway calculation. For each
test run conducted under S7.3 and S7.4,
the headway (L0), in meters, providing
5 seconds time to collision (TTC) is
calculated. L0 is determined with the
following equation where VSV is the
speed of the subject vehicle in m/s and
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0
0
20
20
50
50
80
80
VLV is the speed of the lead vehicle in
m/s:
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S7.3. Stopped lead vehicle.
S7.3.1. Test parameters.
Frm 00069
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Lead vehicle
decel
(g)
......................
......................
......................
......................
Any 21–40 ....
Any 21–40 ....
Any 28–40 ....
Any 28–40 ....
......................
......................
......................
......................
Any 0.3–0.4 ..
Any 0.3–0.4 ..
Any 0.3–0.4 ..
Any 0.3–0.4 ..
VLV
Any 10–80 ....
Any 70–100 ..
Any 40–80 ....
Any 70–100 ..
50 .................
50 .................
80 .................
80 .................
L0 = TTC0 × (VSV¥VLV)
TTC0 = 5
Headway
(m)
Manual brake
application
no.
yes.
no.
yes.
no.
yes.
no.
yes.
(a) For testing with no subject vehicle
manual brake application, the subject
vehicle test speed is any speed between
10 km/h and 80 km/h, and the lead
vehicle speed is 0 km/h.
(b) For testing with manual brake
application of the subject vehicle, the
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subject vehicle test speed is any speed
between 70 km/h and 100 km/h, and the
lead vehicle speed is 0 km/h.
S7.3.2. Test conduct prior to forward
collision warning onset.
(a) The lead vehicle is placed
stationary with its longitudinal
centerline coincident to the intended
travel path.
(b) Before the headway corresponds to
L0, the subject vehicle is driven at any
speed, in any direction, on any road
surface, for any amount of time.
(c) The subject vehicle approaches the
rear of the lead vehicle.
(d) Beginning when the headway
corresponds to L0, the subject vehicle
speed is maintained within 1.6 km/h of
the test speed with minimal and smooth
accelerator pedal inputs.
(e) Beginning when the headway
corresponds to L0, the subject vehicle
heading is maintained with minimal
steering input such that the travel path
does not deviate more than 0.3 m
laterally from the intended travel path
and the subject vehicle’s yaw rate does
not exceed ±1.0 deg/s.
S7.3.3. Test conduct after forward
collision warning onset.
(a) The accelerator pedal is released at
any rate such that it is fully released
within 500 ms. This action is omitted
for vehicles tested with cruise control
active.
(b) For testing conducted with manual
brake application, the service brakes are
applied as specified in S9. The onset of
brake pedal application occurs 1.0 ± 0.1
second after forward collision warning
onset.
(c) For testing conducted without
manual brake application, no manual
brake application is made until the test
completion criteria of S7.3.4 are
satisfied.
S7.3.4. Test completion criteria. The
test run is complete when the subject
vehicle comes to a complete stop
without making contact with the lead
vehicle or when the subject vehicle
makes contact with the lead vehicle.
S7.4. Slower-moving lead vehicle.
S7.4.1. Test parameters.
(a) For testing with no subject vehicle
manual brake application, the subject
vehicle test speed is any speed between
40 km/h and 80 km/h, and the lead
vehicle speed is 20 km/h.
(b) For testing with manual brake
application of the subject vehicle, the
subject vehicle test speed is any speed
between 70 km/h and 100 km/h, and the
lead vehicle speed is 20 km/h.
S7.4.2. Test conduct prior to forward
collision warning onset.
(a) The lead vehicle is propelled
forward in a manner such that the
longitudinal center plane of the lead
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vehicle does not deviate laterally more
than 0.3m from the intended travel path.
(b) The subject vehicle approaches the
lead vehicle.
(c) Beginning when the headway
corresponds to L0, the subject vehicle
and lead vehicle speed is maintained
within 1.6 km/h of the test speed with
minimal and smooth accelerator pedal
inputs.
(d) Beginning when the headway
corresponds to L0, the subject vehicle
and lead vehicle headings are
maintained with minimal steering input
such that the subject vehicle’s travel
path does not deviate more than 0.3 m
laterally from the centerline of the lead
vehicle, and the yaw rate of the subject
vehicle does not exceed ±1.0 deg/s prior
to forward collision warning onset.
S7.4.3. Test conduct after forward
collision warning onset.
(a) The subject vehicle’s accelerator
pedal is released at any rate such that
it is fully released within 500 ms. This
action is omitted for vehicles tested
with cruise control active.
(b) For testing conducted with manual
braking application, the service brakes
are applied as specified in S9. The onset
of brake pedal application is 1.0 ± 0.1
second after the forward collision
warning onset.
(c) For testing conducted without
manual braking application, no manual
brake application is made until the test
completion criteria of S7.4.4 are
satisfied.
S7.4.4. Test completion criteria. The
test run is complete when the subject
vehicle speed is less than or equal to the
lead vehicle speed without making
contact with the lead vehicle or when
the subject vehicle makes contact with
the lead vehicle.
S7.5. Decelerating lead vehicle.
S7.5.1. Test parameters.
(a) The subject vehicle test speed is 50
km/h or 80 km/h, and the lead vehicle
speed is identical to the subject vehicle
test speed.
(b) [Reserved]
S7.5.2. Test conduct prior to lead
vehicle braking onset.
(a) Before the 1 second prior to lead
vehicle braking onset, the subject
vehicle is driven at any speed, in any
direction, on any road surface, for any
amount of time.
(b) Between 1 second prior to lead
vehicle braking onset and lead vehicle
braking onset:
(1) The lead vehicle is propelled
forward in a manner such that the
longitudinal center plane of the vehicle
does not deviate laterally more than 0.3
m from the intended travel path.
(2) The subject vehicle follows the
lead vehicle at a headway of any
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distance between 21 m and 40 m if the
subject vehicle test speed is 50 km/h, or
any distance between 28 m and 40 m if
the subject vehicle test speed is 80 km/
h.
(3) The subject vehicle’s speed is
maintained within 1.6 km/h of the test
speed with minimal and smooth
accelerator pedal inputs prior to forward
collision warning onset.
(4) The lead vehicle’s speed is
maintained within 1.6 km/h.
(5) The subject vehicle and lead
vehicle headings are maintained with
minimal steering input such that their
travel paths do not deviate more than
0.3 m laterally from the centerline of the
lead vehicle, and the yaw rate of the
subject vehicle does not exceed ±1.0
deg/s until forward collision warning
onset.
S7.5.3. Test conduct following lead
vehicle braking onset.
(a) The lead vehicle is decelerated to
a stop with a targeted average
deceleration of any value between 0.3g
and 0.4g. The targeted deceleration
magnitude is achieved within 1.5
seconds of lead vehicle braking onset
and is maintained until 250 ms prior to
coming to a stop.
(b) After forward collision warning
onset, the subject vehicle’s accelerator
pedal is released at any rate such that
it is fully released within 500 ms. This
action is omitted for vehicles with
cruise control active.
(c) For testing conducted with manual
braking application, the service brakes
are applied as specified in S9. The brake
pedal application onset occurs 1.0 ± 0.1
second after the forward collision
warning onset.
(d) For testing conducted without
manual braking application, no manual
brake application is made until the test
completion criteria of S7.5.4 are
satisfied.
S7.5.4. Test completion criteria. The
test run is complete when the subject
vehicle comes to a complete stop
without making contact with the lead
vehicle or when the subject vehicle
makes contact with the lead vehicle.
S8. False AEB activation.
S8.1. Headway calculation. For each
test run to be conducted under S8.2 and
S8.3, the headway (L0, L2.1, L1.1), in
meters, between the front plane of the
subject vehicle and either the steel
trench plate’s leading edge or the
rearmost plane normal to the centerline
of the vehicle test devices providing 5.0
seconds, 2.1 seconds, and 1.1 seconds
time to collision (TTC) is calculated. L0,
L2.1, and L1.1 are determined with the
following equation where VSV is the
speed of the subject vehicle in m/s:
Lx = TTCx × (VSV)
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TTC0 = 5.0
TTC2.1 = 2.1
TTC1.1 = 1.1
S8.2. Steel trench plate.
S8.2.1. Test parameters and setup.
(a) The testing area is set up in
accordance with Figure 2 to this section.
(b) The steel trench plate is secured
flat on the test surface so that its longest
side is parallel to the subject vehicle’s
intended travel path and horizontally
centered on the subject vehicle’s
intended travel path.
(c) The subject vehicle test speed is 80
km/h.
S8.2.2. Test conduct.
(a) The subject vehicle approaches the
steel trench plate.
(b) Beginning when the headway
corresponds to L0, the subject vehicle
speed is maintained within 1.6 km/h of
the test speed with minimal and smooth
accelerator pedal inputs.
(c) Beginning when the headway
corresponds to L0, the subject vehicle
heading is maintained with minimal
steering input such that the travel path
does not deviate more than 0.3 m
laterally from the intended travel path,
and the yaw rate of the subject vehicle
does not exceed ±1.0 deg/s.
(d) If forward collision warning
occurs, the subject vehicle’s accelerator
pedal is released at any rate such that
it is fully released within 500 ms. This
action is omitted for vehicles with
cruise control active.
(e) For tests where no manual brake
application occurs, manual braking is
not applied until the test completion
criteria of S8.2.3 are satisfied.
(f) For tests where manual brake
application occurs, the subject vehicle’s
accelerator pedal, if not already
released, is released when the headway
corresponds to L2.1 at any rate such that
it is fully released within 500 ms.
(g) For tests where manual brake
application occurs, the service brakes
are applied as specified in S9. The brake
application pedal onset occurs at
headway L1.1.
S8.2.3. Test completion criteria. The
test run is complete when the subject
vehicle comes to a stop prior to crossing
over the leading edge of the steel trench
plate or when the subject vehicle
crosses over the leading edge of the steel
trench plate.
S8.3. Pass-through.
S8.3.1. Test parameters and setup.
(a) The testing area is set up in
accordance with Figure 3 to this section.
(b) Two vehicle test devices are
secured in a stationary position parallel
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to one another with a lateral distance of
4.5 m ±0.1 m between the vehicles’
closest front wheels. The centerline
between the two vehicles is parallel to
the intended travel path.
(c) The subject vehicle test speed is 80
km/h.
(d) Testing may be conducted with
manual subject vehicle pedal
application.
S8.3.2. Test conduct.
(a) The subject vehicle approaches the
gap between the two vehicle test
devices.
(b) Beginning when the headway
corresponds to L0, the subject vehicle
speed is maintained within 1.6 km/h
with minimal and smooth accelerator
pedal inputs.
(c) Beginning when the headway
corresponds to L0, the subject vehicle
heading is maintained with minimal
steering input such that the travel path
does not deviate more than 0.3 m
laterally from the intended travel path,
and the yaw rate of the subject vehicle
does not exceed ±1.0 deg/s.
(d) If forward collision warning
occurs, the subject vehicle’s accelerator
pedal is released at any rate such that
it is fully released within 500 ms.
(e) For tests where no manual brake
application occurs, manual braking is
not applied until the test completion
criteria of S8.3.3 are satisfied.
(f) For tests where manual brake
application occurs, the subject vehicle’s
accelerator pedal, if not already
released, is released when the headway
corresponds to L2.1 at any rate such that
it is fully released within 500 ms.
(g) For tests where manual brake
application occurs, the service brakes
are applied as specified in S9. The brake
application onset occurs when the
headway corresponds to L1.1.
S8.3.3. Test completion criteria. The
test run is complete when the subject
vehicle comes to a stop prior to its
rearmost point passing the vertical
plane connecting the forwardmost point
of the vehicle test devices or when the
rearmost point of the subject vehicle
passes the vertical plane connecting the
forwardmost point of the vehicle test
devices.
S9. Subject Vehicle Brake Application
Procedure.
S9.1. The procedure begins with the
subject vehicle brake pedal in its natural
resting position with no preload or
position offset.
S9.2. At the option of the
manufacturer, either displacement
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43243
feedback or hybrid feedback control is
used.
S9.3. Displacement feedback
procedure. For displacement feedback,
the commanded brake pedal position is
the brake pedal position that results in
a mean deceleration of 0.3g in the
absence of AEB system activation.
(a) The mean deceleration is the
deceleration over the time from the
pedal achieving the commanded
position to 250 ms before the vehicle
comes to a stop.
(b) The pedal displacement controller
depresses the pedal at a rate of 254 mm/
s ±25.4 mm/s to the commanded brake
pedal position.
(c) The pedal displacement controller
may overshoot the commanded position
by any amount up to 20 percent. If such
an overshoot occurs, it is corrected
within 100 ms.
(d) The achieved brake pedal position
is any position within 10 percent of the
commanded position from 100 ms after
pedal displacement occurs and any
overshoot is corrected.
S9.4. Hybrid brake pedal feedback
procedure. For hybrid brake pedal
feedback, the commanded brake pedal
application is the brake pedal position
and a subsequent commanded brake
pedal force that results in a mean
deceleration of 0.3g in the absence of
AEB system activation.
(a) The mean deceleration is the
deceleration over the time from the
pedal achieving the commanded
position to 250 ms before the vehicle
comes to a stop.
(b) The hybrid controller displaces the
pedal at a rate of 254 mm/s ±25.4 mm/
s to the commanded pedal position.
(c) The hybrid controller may
overshoot the commanded position by
any amount up to 20 percent. If such an
overshoot occurs, it is corrected within
100 ms.
(d) The hybrid controller begins to
control the force applied to the pedal
and stops controlling pedal
displacement 100 ms after pedal
displacement occurs and any overshoot
is corrected.
(e) The hybrid controller applies a
pedal force of at least 11.1 N.
(f) The applied pedal force is
maintained within 10 percent of the
commanded brake pedal force from 350
ms after commended pedal
displacement occurs and any overshoot
is corrected until test completion.
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Figure 1 to § 571.128—Setup for Tests
Approaching a Lead Vehicle
BILLING CODE 4910–59–P
Figure 2 to § 571.128—Setup for Steel
Trench Plate False Activation Tests
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Figure 3 to § 571.128—Setup for PassThrough False Activation Tests
Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 / Proposed Rules
9. Amend § 571.136 by revising
paragraphs S3, S3.1, S3.2, and
paragraphs (1) and (2) of the definition
of ‘‘Electronic stability control system or
ESC system’’ in S4, and adding S8.3 to
read as follows:
■
§ 571.136 Standard No. 136; Electronic
stability control systems for heavy vehicles.
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*
*
*
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S3 Application.
S3.1 This standard applies to
passenger cars, multipurpose passenger
vehicles, trucks, and buses, with a
GVWR greater than 4,536 kilograms
(10,000 pounds) except:
(a) Any vehicle equipped with an axle
that has a gross axle weight rating of
13,154 kilograms (29,000 pounds) or
more;
(b) Any truck or bus that has a speed
attainable in 3.2 kilometers (2 miles) of
not more than 53 km/h (33 mph); and
(c) Any truck that has a speed
attainable in 3.2 kilometers (2 miles) of
not more than 72 km/h (45 mph), an
unloaded vehicle weight that is not less
than 95 percent of its gross vehicle
weight rating, and no capacity to carry
occupants other than the driver and
operating crew.
S3.2 The following vehicles are
subject only to the requirements in S5.1,
S5.2, and S5.4 of this standard:
(a) Vehicles with a gross vehicle
weight rating of 11,793 kilograms
(26,000 pounds) or less;
(b) Trucks other than truck tractors;
(c) School buses;
(d) Perimeter-seating buses;
(e) Transit buses;
(f) Passenger cars; and
(g) Multipurpose passenger vehicles.
*
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S4 Definitions
*
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*
*
Electronic stability control system or
ESC system means a system that has all
of the following attributes:
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(1) It augments vehicle directional
stability by having the means to apply
and adjust the vehicle brake torques
individually at each wheel position on
at least one front and at least one rear
axle of the vehicle to induce correcting
yaw moment to limit vehicle oversteer
and to limit vehicle understeer;
(2) It enhances rollover stability by
having the means to apply and adjust
the vehicle brake torques individually at
each wheel position on at least one front
and at least one rear axle of the vehicle
to reduce lateral acceleration of a
vehicle;
*
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*
S8.3 Vehicles with a gross vehicle
weight rating of 11,793 kilograms
(26,000 pounds) or less, trucks other
than truck tractors, school buses,
perimeter-seating buses, transit buses,
passenger cars, and multipurpose
passenger vehicles are not required to
comply this standard before [the first
September 1 that is four years after the
date of publication of a final rule].
*
*
*
*
*
■ 11. Add part 596 to read as follows.
Subpart A—General
§ 596.1
Scope.
This part describes the test devices
that are to be used for compliance
testing of motor vehicles with motor
vehicle safety standards for automatic
emergency braking.
§ 596.2
Purpose.
The design and performance criteria
specified in this part are intended to
describe devices with sufficient
precision such that testing performed
with these test devices will produce
repetitive and correlative results under
similar test conditions to reflect
adequately the automatic emergency
braking performance of a motor vehicle.
§ 596.3
Application.
PART 596—AUTOMATIC EMERGENCY
BRAKING TEST DEVICES
This part does not in itself impose
duties or liabilities on any person. It is
a description of tools that are used in
compliance tests to measure the
performance of automatic emergency
braking systems required by the safety
standards that refer to these tools. This
part is designed to be referenced by, and
become part of, the test procedures
specified in motor vehicle safety
standards.
Subpart A—General
§ 596.4
Sec.
596.1
596.2
596.3
596.4
596.5
All terms defined in section 30102 of
the National Traffic and Motor Vehicle
Safety Act (49 U.S.C. chapter 301, et
seq.) are used in their statutory
meaning.
Vehicle Test Device means a test
device that simulates a passenger
vehicle for the purpose of testing
automatic emergency brake system
performance.
Vehicle Test Device Carrier means a
movable platform on which a Lead
Vehicle Test Device may be attached
during compliance testing.
Scope.
Purpose.
Application
Definitions.
Matter incorporated by reference.
Subpart B—[Reserved]
Subpart C—Vehicle Test Device
596.9 General Description
596.10 Specifications for the Vehicle Test
Device
Authority: 49 U.S.C. 322, 30111, 30115,
30117 and 30166; delegation of authority at
49 CFR 1.95.
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§ 596.5
Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 / Proposed Rules
Matter incorporated by reference.
(a) Certain material is incorporated by
reference into this part with the
approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1
CFR part 51. To enforce any edition
other than that specified in this section,
the National Highway Traffic Safety
Administration (NHTSA) must publish
notice of change in the Federal Register
and the material must be available to the
public. All approved material is
available for inspection at NHTSA at the
National Archives and Records
Administration (NARA). Contact
NHTSA at: NHTSA Office of Technical
Information Services, 1200 New Jersey
Avenue SE, Washington, DC 20590;
(202) 366–2588. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations.html or email
fr.inspection@nara.gov. The material
may be obtained from the source(s) in
the following paragraph of this section.
(b) International Organization for
Standardization (ISO), 1, ch. de la VoieCreuse, CP 56, CH–1211 Geneva 20,
Switzerland; phone: + 41 22 749 01 11;
fax: + 41 22 733 34 30; website:
www.iso.org/.
(1) [Reserved].
(2) [Reserved].
(3) ISO 19206–3:2021(E), ‘‘Test
devices for target vehicles, vulnerable
road users and other objects, for
assessment of active safety functions—
Part 3: Requirements for passenger
vehicle 3D targets,’’ First edition, 2021–
05; into § 596.10.
(4) [Reserved]
Subpart B—[Reserved]
Subpart C—Vehicle Test Device
§ 596.9
General Description.
(a) The Vehicle Test Device provides
a sensor representation of a passenger
motor vehicle.
(b) The rear view of the Vehicle Test
Device contains representations of the
vehicle silhouette, a rear window, a
high-mounted stop lamp, two taillamps,
a rear license plate, two rear reflex
reflectors, and two tires.
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§ 596.10 Specifications for the Vehicle
Test Device.
(a) Word Usage—Recommendations.
The words ‘‘recommended,’’ ‘‘should,’’
‘‘can be,’’ or ‘‘should be’’ appearing in
sections of ISO 19206–3:2021(E)
(incorporated by reference, see § 596.5),
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referenced in this section, are read as
setting forth specifications that are used.
(b) Word Usage—Options. The words
‘‘may be,’’ or ‘‘either,’’ used in
connection with a set of items appearing
in sections of ISO 19206–3:2021(E)
(incorporated by reference, see § 596.5),
referenced in this section, are read as
setting forth the totality of items, any
one of which may be selected by
NHTSA for testing.
(c) Dimensional specifications. (1)
The rear silhouette and the rear window
are symmetrical about a shared vertical
centerline.
(2) Representations of the taillamps,
rear reflex reflectors, and tires are
symmetrical about the surrogate’s
centerline.
(3) The license plate representation
has a width of 300 ± 15 mm and a height
of 150 ± 15 mm and mounted with a
license plate holder angle within the
range described in 49 CFR 571.108
S6.6.3.1.
(4) The Vehicle Test Device
representations are located within the
minimum and maximum measurement
values specified in columns 3 and 4 of
Tables A.4 of ISO 19206–3:2021(E)
Annex A (incorporated by reference, see
§ 596.5). The tire representations are
located within the minimum and
maximum measurement values
specified in columns 3 and 4 of Tables
A.3 of ISO 19206–3:2021(E) Annex A
(incorporated by reference, see § 596.5).
The terms ‘‘rear light’’ means
‘‘taillamp,’’ ‘‘retroreflector’’ means
‘‘reflex reflector,’’ and ‘‘high centre
taillight’’ means ‘‘high-mounted stop
lamp.’’
(d) Visual and near infrared
specification. (1) The Vehicle Test
Device rear representation colors are
within the ranges specified in Tables
B.2 and B.3 of ISO 19206–3:2021(E)
Annex B (incorporated by reference, see
§ 596.5).
(2) The rear representation infrared
properties of the Vehicle Test Device are
within the ranges specified in Table B.1
of ISO 19206–3:2021(E) Annex B
(incorporated by reference, see § 596.5)
for wavelengths of 850 to 950 nm when
measured according to the calibration
and measurement setup specified in
paragraph B.3 of ISO 19206–3:2021(E)
Annex B (incorporated by reference, see
§ 596.5).
(3) The Vehicle Test Device rear reflex
reflectors, and at least 50 cm2 of the
taillamp representations are grade DOT–
C2 reflective sheeting as specified in 49
CFR 571.108 S8.2.
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(e) Radar reflectivity specifications.
(1) The radar cross section of the
Vehicle Test Device is measured with it
attached to the carrier (robotic
platform). The radar reflectivity of the
carrier platform is less than 0 dBm2 for
a viewing angle of 180 degrees and over
a range of 5 to 100 m when measured
according to the radar measurement
procedure specified in C.3 of ISO
19206–3:2021(E) Annex C (incorporated
by reference, see § 596.5) for fixed-angle
scans.
(2) The rear bumper area as shown in
Table C.1 of ISO 19206–3:2021(E)
Annex C (incorporated by reference, see
§ 596.5) contributes to the target radar
cross section.
(3) The radar cross section is assessed
using radar sensor that operates at 76 to
81 GHz and has a range of at least 5 to
100 m, a range gate length smaller than
0.6m, a horizontal field of view of 10
degrees or more (¥3dB amplitude
limit), and an elevation field of view of
5 degrees or more (¥3dB amplitude).
(4) At least 92 percent of the filtered
data points of the surrogate radar cross
section for the fixed vehicle angle,
variable range measurements are within
the RCS boundaries defined in Sections
C.2.2.4 of ISO 19206–3:2021(E) Annex C
(incorporated by reference, see § 596.5)
for a viewing angle of 180 degrees when
measured according to the radar
measurement procedure specified in C.3
of ISO 19206–3:2021(E) Annex C
(incorporated by reference, see § 596.5)
for fixed-angle scans.
(5) Between 86 to 95 percent of the
Vehicle Test Device spatial radar cross
section reflective power is with the
primary reflection region defined in
Section C.2.2.5 of ISO 19206–3:2021(E)
Annex C (incorporated by reference, see
§ 596.5) when measured according to
the radar measurement procedure
specified in C.3 of ISO 19206–3:2021(E)
Annex C (incorporated by reference, see
§ 596.5) using the angle-penetration
method.
Issued under the authority delegated in 49
CFR 1.87.
Robin Hutcheson,
Administrator.
Issued under authority delegated in 49 CFR
part 1.95 and 49 CFR 501.8.
Raymond R. Posten,
Associate Administrator for Rulemaking.
[FR Doc. 2023–13622 Filed 7–5–23; 8:45 am]
BILLING CODE 4910–59–P
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Agencies
[Federal Register Volume 88, Number 128 (Thursday, July 6, 2023)]
[Proposed Rules]
[Pages 43174-43246]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-13622]
[[Page 43173]]
Vol. 88
Thursday,
No. 128
July 6, 2023
Part II
Department of Transportation
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National Highway Traffic Safety Administration
Federal Motor Carrier Safety Administration
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49 CFR Parts 393, 396, 571, et al.
Heavy Vehicle Automatic Emergency Braking; AEB Test Devices; Notice of
Proposed Rule
Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 /
Proposed Rules
[[Page 43174]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Parts 571 and 596
[Docket No. NHTSA-2023-0023]
RIN 2127-AM36
Federal Motor Carrier Safety Administration
49 CFR Parts 393 and 396
[Docket No. FMCSA-2022-0171]
RIN 2126-AC49
Heavy Vehicle Automatic Emergency Braking; AEB Test Devices
AGENCY: National Highway Traffic Safety Administration (NHTSA), Federal
Motor Carrier Safety Administration (FMCSA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This NPRM proposes to adopt a new Federal Motor Vehicle Safety
Standard (FMVSS) to require automatic emergency braking (AEB) systems
on heavy vehicles, i.e., vehicles with a gross vehicle weight rating
greater than 4,536 kilograms (10,000 pounds). This notice also proposes
to amend FMVSS No. 136 to require nearly all heavy vehicles to have an
electronic stability control system that meets the equipment
requirements, general system operational capability requirements, and
malfunction detection requirements of FMVSS No. 136. An AEB system uses
multiple sensor technologies and sub-systems that work together to
sense when the vehicle is in a crash imminent situation and
automatically applies the vehicle brakes if the driver has not done so
or automatically applies more braking force to supplement the driver's
applied braking. This NPRM follows NHTSA's 2015 grant of a petition for
rulemaking from the Truck Safety Coalition, the Center for Auto Safety,
Advocates for Highway and Auto Safety and Road Safe America, requesting
that NHTSA establish a safety standard to require AEB on certain heavy
vehicles. This NPRM also responds to a mandate under the Bipartisan
Infrastructure Law, as enacted as the Infrastructure Investment and
Jobs Act, directing the Department to prescribe an FMVSS that requires
heavy commercial vehicles with FMVSS-required electronic stability
control systems to be equipped with an AEB system, and also promotes
DOT's January 2022 National Roadway Safety Strategy to initiate a
rulemaking to require AEB on heavy trucks. This NPRM also proposes
Federal Motor Carrier Safety Regulations requiring the electronic
stability control and AEB systems to be on during vehicle operation.
DATES: Comments must be received on or before September 5, 2023.
Proposed compliance dates: NHTSA proposes a two-tiered phase-in
schedule for meeting the proposed standard. For vehicles currently
subject to FMVSS No. 136, ``Electronic stability control systems for
heavy vehicles,'' any vehicle manufactured on or after the first
September 1 that is three years after the date of publication of the
final rule would be required to meet the proposed heavy vehicle AEB
standard. For vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136,
any vehicle manufactured on or after the first September 1 that is four
years after the date of publication of the final rule would be required
to meet the proposed AEB requirements and the proposed amendments to
the ESC requirements. Small-volume manufacturers, final-stage
manufacturers, and alterers would be provided an additional year to
comply with this proposal beyond the dates identified above.
FMCSA proposes that vehicles currently subject to FMVSS No. 136
would be required to comply with FMCSA's proposed ESC regulation on the
final rule's effective date. Vehicles with a GVWR greater than 4,536
kilograms (10,000 pounds) not currently subject to FMVSS No. 136 would
be required to meet the proposed ESC regulation on or after the first
September 1 that is five years after the date of publication of the
final rule.
FMCSA proposes that, for vehicles currently subject to FMVSS No.
136, any vehicle manufactured on or after the first September 1 that is
three years after the date of publication of the final rule would be
required to meet FMCSA's proposed AEB regulation. FMCSA proposes that
vehicles with a gross vehicle weight rating greater than 4,536
kilograms (10,000 pounds) not currently subject to FMVSS No. 136 and
vehicles supplied to motor carriers by small-volume manufacturers,
final-stage manufacturers, and alterers would be required to meet the
proposed AEB regulation on or after the first September 1 that is five
years after the date of publication of the final rule.
This proposed implementation timeframe simplifies FMCSR training
and enforcement because the Agency expects a large number of final
stage manufacturers supplying vehicles to motor carriers in the
category of vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds).
FMCSA's phase-in schedule would require the ESC and AEB systems to
be inspected and maintained in accordance with Sec. 396.3.
Early compliance is permitted but optional.
ADDRESSES: You may submit comments to the docket number identified in
the heading of this document by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the online instructions for submitting
comments.
Mail: Docket Management Facility, M-30, U.S. Department of
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery or Courier: West Building, Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m.
Eastern Time, Monday through Friday, except Federal holidays. To be
sure someone is there to help you, please call 202-366-9332 before
coming.
Fax: 202-493-2251.
Regardless of how you submit your comments, please provide the
docket number of this document.
Instructions: For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to https://www.regulations.gov, including any personal information
provided.
Privacy Act: In accordance with 5 U.S.C. 553(c), DOT solicits
comments from the public to better inform its decision-making process.
DOT posts these comments, without edit, including any personal
information the commenter provides, to https://www.regulations.gov, as
described in the system of records notice (DOT/ALL-14 FDMS), which can
be reviewed at https://www.transportation.gov/privacy. In order to
facilitate comment tracking and response, the agency encourages
commenters to provide their name, or the name of their organization;
however, submission of names is completely optional. Whether or not
commenters identify themselves, all timely comments will be fully
considered.
Docket: For access to the docket to read background documents or
[[Page 43175]]
comments received, go to https://www.regulations.gov, or the street
address listed above. To be sure someone is there to help you, please
call 202-366-9322 before coming. Follow the online instructions for
accessing the dockets.
FOR FURTHER INFORMATION CONTACT: NHTSA: For non-legal issues: Hisham
Mohamed, Office of Crash Avoidance Standards (telephone: 202-366-0307).
For legal issues: David Jasinski, Office of the Chief Counsel
(telephone: 202-366-2992, fax: 202-366-3820). The mailing address for
these officials is: National Highway Traffic Safety Administration,
1200 New Jersey Avenue SE, Washington, DC 20590. FMCSA: For FMCSA
issues: David Sutula, Office of Vehicle and Roadside Operations
Division (telephone: 202-366-9209). The mailing address for this
official is: Federal Motor Carrier Safety Administration, 1200 New
Jersey Avenue SE, Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Safety Problem
III. Efforts To Promote AEB Deployment in Heavy Vehicles
A. NHTSA's Foundational AEB Research
B. NHTSA's 2015 Grant of a Petition for Rulemaking
C. Congressional Interest
1. MAP-21
2. Bipartisan Infrastructure Law
D. IIHS Effectiveness Study
E. DOT's National Roadway Safety Strategy (January 2022)
F. National Transportation Safety Board Recommendations
G. FMCSA Initiatives
IV. NHTSA and FMCSA Research and Testing
A. NHTSA-Sponsored Research
1. 2012 Study on Effectiveness of FCW and AEB
2. 2016 Field Study
3. 2017 Target Population Study
4. 2018 Cost and Weight Analysis
B. VRTC Research Report Summaries and Test Track Data
1. Relevance of Research Efforts on AEB for Light Vehicles
2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach
3. Phase II Testing of Class 8 Truck-Tractors
4. NHTSA's 2018 Heavy Vehicle AEB Testing
5. NHTSA's Research Test Track Procedures
6. 2021 VRTC Testing
C. NHTSA Field Study of a New Generation Heavy Vehicle AEB
System
D. FMCSA-Sponsored Research
V. Need for This Proposed Rule and Guiding Principles
A. Estimating AEB System Effectiveness
B. AEB Performance Over a Range of Speeds Is Necessary and
Practicable
C. Market Penetration Varies Significantly Among Classes of
Heavy Vehicles
D. This NPRM Would Compel Improvements in AEB
E. BIL Section 23010(b)(2)(B)
F. Vehicles Excluded From Braking Requirements
VI. Heavy Vehicles Not Currently Subject to ESC Requirements
A. AEB and ESC Are Less Available on These Vehicles
B. This NPRM Proposes To Require ESC
C. BIL Section 23010(d)
D. Multi-Stage Vehicle Manufacturers and Alterers
VII. Proposed Performance Requirements
A. Proposed Requirements When Approaching a Lead Vehicle
1. Automatic Emergency Brake Application Requirements
2. Forward Collision Warning Requirement
i. FCW Modalities
ii. FCW Auditory Signal Characteristics
iii. FCW Visual Signal Characteristics
iv. FCW Haptic Signal Discussion
3. Performance Test Requirements
4. Performance Test Scenarios
i. Stopped Lead Vehicle
ii. Slower-Moving Lead Vehicle
iii. Decelerating Lead Vehicle
5. Parameters for Vehicle Tests
i. Vehicle Speed Parameters
ii. Headway
iii. Lead Vehicle Deceleration Parameter
6. Manual Brake Application in the Subject Vehicle
B. Conditions for Vehicle Tests
1. Environmental Conditions
2. Road Service Conditions
3. Subject Vehicle Conditions
C. Proposed Requirements for False Activation
1. No Automatic Braking Requirement
2. Vehicle Test Scenarios
i. Steel Trench Plate
ii. Pass-Through
D. Conditions for False Activation Tests
E. Potential Alternatives to False Activation Tests
F. Proposed Requirements for Malfunction Indication
G. Deactivation Switch
H. System Documentation
I. ESC Performance Test
J. Severability
VIII. Vehicle Test Device
A. Description and Development
B. Specifications
C. Alternatives Considered
IX. Proposed Compliance Date Schedule
X. Retrofitting
XI. Summary of Estimated Effectiveness, Cost, Benefits, and
Comparison of Regulatory Alternatives
A. Crash Problem
B. AEB System Effectiveness
C. ESC System Effectiveness
D. Avoided Crashes and Related Benefits
E. Technology Costs
F. Monetized Benefits
G. Alternatives
XII. Regulatory Notices and Analyses
XIII. Public Participation
XIV. Appendices to the Preamble
A. Description of Technologies
B. International Regulatory Requirements and Other Standards
Abbreviations Frequently Used in This Document
The following table is provided for the convenience of readers for
illustration purposes only.
Table 1--Abbreviations
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Abbreviation Full term Notes
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ABS................. Antilock Braking Automatically controls the
System. degree of longitudinal wheel
slip during braking to prevent
wheel lock and minimize
skidding by sensing the rate
of angular rotation of each
wheel and modulating the
braking force at the wheels to
keep the wheels from slipping.
AEB................. Automatic Applies a vehicle's brakes
Emergency automatically to avoid or
Braking. mitigate an impending forward
crash.
CIB................. Crash Imminent Applies automatic braking when
Braking. forward-looking sensors
indicate a crash is imminent
and the driver has not applied
the brakes.
CMV................. Commercial Motor Has the meaning given the term
Vehicle. in 49 U.S.C. 31101.
CRSS................ Crash Report A sample of police-reported
Sampling System. crashes involving all types of
motor vehicles, pedestrians,
and cyclists, ranging from
property-damage-only crashes
to those that result in
fatalities.
DBS................. Dynamic Brake Supplements the driver's
Support. application of the brake pedal
with additional braking when
sensors determine the driver-
applied braking is
insufficient to avoid an
imminent crash.
ESC................. Electronic Able to determine intended
Stability steering direction (steering
Control. wheel angle sensor), compare
it to the actual vehicle
direction, and then modulate
braking forces at each wheel
to induce a counter yaw when
the vehicle starts to lose
lateral stability.
FARS................ Fatality Analysis A nationwide census providing
Reporting System. annual data regarding fatal
injuries suffered in motor
vehicle crashes.
[[Page 43176]]
FCW................. Forward Collision An auditory and visual warning
Warning. provided to the vehicle
operator by the AEB system
that is designed to induce an
immediate forward crash
avoidance response by the
vehicle operator.
FMCSR............... Federal Motor 49 CFR parts 350-399.
Carrier Safety
Regulations.
FMVSS............... Federal Motor ...............................
Vehicle Safety
Standards.
GES................. General Estimates Data from a nationally
System. representative sample of
police reported motor vehicle
crashes of all types, from
minor to fatal.
GVWR................ Gross Vehicle The value specified by the
Weight Rating. manufacturer as the maximum
design loaded weight of a
single vehicle.
BIL................. Bipartisan Public Law 117-58 (Nov. 15,
Infrastructure 2021).
Law.
MAIS................ Maximum A means of describing injury
Abbreviated severity based on an ordinal
Injury Scale. scale. An MAIS 1 injury is a
minor injury and an MAIS 5
injury is a critical injury.
MAP-21.............. The Moving Ahead A funding and authorization
for Progress in bill to govern United States
the 21st Century Federal surface transportation
Act. spending. It was enacted into
law on July 6, 2012.
NCAP................ New Car ...............................
Assessment
Program.
PDO................. Property-damage- A police-reported crash
only. involving a motor vehicle in
transport on a trafficway in
which no one involved in the
crash suffered any injuries.
PDOV................ Property-Damage- Damaged vehicles involved in
Only-Vehicles. property-damage-only crashes.
TTC................. Time to collision The theoretical time, given the
current speed of the vehicles,
after which a rear-end
collision with the lead
vehicle would occur if no
corrective action was taken.
VRTC................ Vehicle Research NHTSA's in-house laboratory.
and Test Center.
VTD................. Vehicle Test A test device used to test AEB
Device. system performance.
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I. Executive Summary
There were 38,824 people killed in motor vehicle crashes on U.S.
roadways in 2020 and early estimates put the number of fatalities at
42,915 for 2021.\1\ The Department established the National Roadway
Safety Strategy in January 2022 to address this rising number of
transportation deaths occurring on this country's streets, roads, and
highways.\2\ This NPRM takes a crucial step in implementing this
strategy by proposing to adopt a new Federal motor vehicle safety
standard (FMVSS) that would require heavy vehicles to have automatic
emergency braking (AEB) systems that mitigate the frequency and
severity of rear-end collisions with vehicles.
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\1\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283, https://www.nhtsa.gov/press-releases/early-estimate-2021-
traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\2\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf. Last accessed August
23, 2022.
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The crash problem addressed by heavy vehicle AEB is substantial, as
are the safety benefits to be gained. This NPRM addresses lead vehicle
rear-end, rollover, and loss of control crashes, and their associated
fatalities, injuries, and property damage. The NPRM also proposes new
Federal Motor Carrier Safety Regulations requiring the electronic
stability control and AEB systems to be on during vehicle operation.
Considering the effectiveness of AEB and electronic stability control
technology (ESC) at avoiding these crashes, the proposed rule would
conservatively prevent an estimated 19,118 crashes, save 155 lives, and
reduce 8,814 non-fatal injuries annually once all vehicles covered in
this rule are equipped with AEB and ESC. In addition, it would
eliminate 24,828 property-damage-only crashes annually.
In this NPRM, the term ``heavy vehicles'' refers to vehicles with a
gross vehicle weight rating (GVWR) greater than 4,536 kilograms (10,000
pounds). For application of the FMVSS, it is often necessary to further
categorize these heavy vehicles, as the FMVSS must be appropriate for
the particular type of motor vehicle for which they are
prescribed.3 4 Certain vehicles have common characteristics
relevant to the application of AEB, and categorizing those vehicles
accordingly allows for useful analyses, proposals, or other
considerations that are particularly appropriate for the vehicle group
and application of the safety standards.
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\3\ As required by 49 U.S.C 30111(b)(3), NHTSA shall consider
whether a proposed standard is reasonable, practicable, and
appropriate for the particular type of motor vehicle or motor
vehicle equipment for which it is prescribed.
\4\ This NPRM excludes heavy trailers because they typically do
not have braking components necessary for AEB.
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One useful way to categorize vehicles further is by GVWR. This NPRM
uses vehicle class numbers designed by NHTSA in 49 CFR 565, ``Vehicle
identification number requirements,'' and the Federal Highway
Administration that are based on GVWR.\5\ These class numbers, shown in
Table 2 below, are widely used by industry and States in categorizing
vehicles. In this NPRM, ``heavy vehicle'' and ``class 3 through 8''
both refer to all vehicles with a GVWR greater than 4,536 kg (10,000
lbs.). The term ``class 3 through 6'' refers to vehicles with a GVWR
greater than 4,536 kg (10,000 lbs.) and up to 11,793 kg (26,000 lbs.),
while the term ``class 7 to 8'' refers to vehicles with a GVWR greater
than 11,793 kg (26,000 lbs.).
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\5\ See https://ops.fhwa.dot.gov/publications/fhwahop10014/s5.htm#f21 (Last viewed on May 5, 2022).
[[Page 43177]]
Table 2--Vehicle Class by GVWR
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Vehicle class GVWR
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1............................ Not greater than 2,722 kg (6,000 lbs.).
2a........................... Greater than 2,722 kg (6,000 lbs.) and up
to 3,856 kg (8,500 lbs.).
2b........................... Greater than 3,856 kg (8,500 lbs.) and up
to 4,536 kg (10,000 lbs.).
3............................ Greater than 4,536 kg (10,000 lbs.) and
up to 6,350 kg (14,000 lbs.).
4............................ Greater than 6,350 kg (14,000 lbs.) and
up to 7,257 kg (16,000 lbs.).
5............................ Greater than 7,257 kg (16,000 lbs.) and
up to 8,845 kg (19,500 lbs.).
6............................ Greater than 8,845 kg (19,500 lbs.) and
up to 11,793 kg (26,000 lbs.).
7............................ Greater than 11,793 kg (26,000 lbs.) and
up to 14,969 kg (33,000 lbs.).
8............................ Greater than 14,969 kg (33,000 lbs.).
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NHTSA and FMCSA have jointly developed this NPRM. Both agencies
will have complementary standards that respond to mandates in Section
23010 of the Bipartisan Infrastructure Law (BIL), as enacted as the
Infrastructure Investment and Jobs Act. Section 23010(b) requires the
Secretary to prescribe an FMVSS that requires any commercial motor
vehicle subject to FMVSS No. 136, ``Electronic stability control
systems for heavy vehicles,'' to be equipped with an AEB system meeting
performance requirements established in the new FMVSS not later than
two years after enactment. Section 23010(c) requires the Secretary to
prescribe a Federal Motor Carrier Safety Regulation (FMCSR) that
requires, for commercial motor vehicles subject to FMVSS No. 136, that
an AEB system installed pursuant to the new Federal motor vehicle
safety standard must be used at any time during which the commercial
motor vehicle is in operation. This NPRM sets forth NHTSA's proposed
FMVSS and FMCSA's proposed FMCSR issued pursuant to these provisions of
the BIL. In order to provide the benefits of AEB to a greater number of
vehicles, this proposal would also require that many heavy vehicles not
currently subject to FMVSS No. 136, including vehicles in classes 3
through 6, be equipped with ESC and AEB systems under the authority
provided in the Motor Vehicle Safety Act. Pursuant to section 23010(d)
of the BIL, NHTSA seeks public comment on this proposal.
NHTSA's Statutory Authority
NHTSA is proposing this NPRM under the National Traffic and Motor
Vehicle Safety Act (``Motor Vehicle Safety Act'') and in response to
the Bipartisan Infrastructure Law. Under 49 U.S.C. Chapter 301, Motor
Vehicle Safety (49 U.S.C. 30101 et seq.), the Secretary of
Transportation is responsible for prescribing motor vehicle safety
standards that are practicable, meet the need for motor vehicle safety,
and are stated in objective terms. ``Motor vehicle safety'' is defined
in the Motor Vehicle Safety Act as ``the performance of a motor vehicle
or motor vehicle equipment in a way that protects the public against
unreasonable risk of accidents occurring because of the design,
construction, or performance of a motor vehicle, and against
unreasonable risk of death or injury in a crash, and includes
nonoperational safety of a motor vehicle.'' ``Motor vehicle safety
standard'' means a minimum performance standard for motor vehicles or
motor vehicle equipment. When prescribing such standards, the Secretary
must consider all relevant, available motor vehicle safety information.
The Secretary must also consider whether a proposed standard is
reasonable, practicable, and appropriate for the types of motor
vehicles or motor vehicle equipment for which it is prescribed and the
extent to which the standard will further the statutory purpose of
reducing traffic accidents and associated deaths. The responsibility
for promulgation of Federal motor vehicle safety standards is delegated
to NHTSA.
In developing this NPRM, NHTSA carefully considered these statutory
requirements, and relevant Executive Orders, Departmental Orders, and
administrative laws and procedures. NHTSA is also issuing this NPRM in
response to the Bipartisan Infrastructure Law. Section 23010 of BIL \6\
requires the Secretary to prescribe a Federal motor vehicle safety
standard to require all commercial motor vehicles subject to a
particular brake system standard to be equipped with an AEB system
meeting established performance requirements. BIL directs the Secretary
to prescribe the standard not later than two years after the date of
enactment of the Act.
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\6\ Public Law 117-58, (Nov. 15, 2021).
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FMCSA's Statutory Authority
For purposes of this NPRM, FMCSA's authority is found in the Motor
Carrier Act of 1935 (1935 Act, 49 U.S.C. 31502) and the Motor Carrier
Safety Act of 1984 (1984 Act, 49 U.S.C. 31132 et seq.), both as
amended. The authorities assigned to the Secretary in these two acts
are delegated to the FMCSA Administrator in 49 CFR 1.87(i) and (f),
respectively. In addition, section 23010(c) of the BIL, Public Law 117-
58, 135 Stat. 429, 766-767, Nov. 15, 2021, requires FMCSA to adopt an
AEB regulation consistent with the companion NHTSA AEB regulation.
The 1935 Act authorizes the DOT to ``prescribe requirements for--
(1) qualifications and maximum hours of service of employees of and
safety of operation and equipment of a motor carrier; and (2)
qualifications and maximum hours of service of employees of, and
standards of equipment of, a motor private carrier, when needed to
promote safety of operations'' (49 U.S.C. 31502(b)). FMCSA's proposed
ESC and AEB regulations, which incorporate the ESC and AEB requirements
of the NHTSA rule, will require most motor carriers to maintain and use
the ESC and AEB systems required by the corresponding NHTSA regulations
to promote safety of operations.
The 1984 Act confers on DOT the authority to regulate drivers,
motor carriers, and vehicle equipment. ``At a minimum, the regulations
shall ensure that--(1) commercial motor vehicles are maintained,
equipped, loaded, and operated safely; (2) the responsibilities imposed
on operators of commercial motor vehicles do not impair their ability
to operate the vehicles safely; (3) the physical condition of operators
of commercial motor vehicles is adequate to enable them to operate the
vehicles safely; (4) the operation of commercial motor vehicles does
not have a deleterious effect on the physical condition of the
operators; and (5) an operator of a commercial motor vehicle is not
coerced by a motor carrier, shipper, receiver, or transportation
intermediary to operate a commercial motor vehicle in violation of a
regulation promulgated under this section, or chapter 51 or chapter 313
of this title'' (49 U.S.C. 31136(a)(1)-(5)).
[[Page 43178]]
FMCSA's proposed rule will help to ensure that commercial motor
vehicles (CMVs) equipped with the ESC and AEB systems mandated by NHTSA
are maintained and operated safely, as required by 49 U.S.C.
31136(a)(1). While the FMCSA proposal does not explicitly address the
remaining provisions of section 31136, it will enhance the ability of
drivers to operate safely, consistent with 49 U.S.C. 31136(a)(2)-(4).
Section 23010(c) of BIL requires FMCSA to prescribe a regulation
under 49 U.S.C. 31136 that requires that an automatic emergency braking
system installed in a commercial motor vehicle manufactured after the
effective date of the NHTSA standard that is in operation on or after
that date and is subject to 49 CFR 571.136 be used at any time during
which the commercial motor vehicle is in operation'' (135 Stat. 767).
Consistent with the BIL mandate, part of FMCSA's proposal would require
that motor carriers operating CMVs manufactured subject to FMVSS No.
136 maintain and use the required AEB devices as prescribed by NHTSA
whenever the CMV is operating.
AEB and ESC Systems
An AEB system employs multiple sensor technologies and sub-systems
that work together to sense when a vehicle is in a crash imminent
situation with a lead vehicle and, when necessary, automatically apply
the vehicle brakes if the driver has not done so, or apply the brakes
to supplement the driver's applied braking. Current systems use radar
and camera-based sensors or combinations thereof. AEB builds upon older
forward collision warning-only systems. An FCW-only system provides an
alert to a driver of an impending rear-end collision with a lead
vehicle to induce the driver to take action to avoid the crash but does
not automatically apply the brakes. This proposal would require both
FCW and AEB systems. For simplicity, when referring to AEB systems in
general, this proposal is referring to both FCW and AEB unless the
context suggests otherwise.
This proposal follows up on NHTSA's October 16, 2015 notice
granting a petition for rulemaking submitted by the Truck Safety
Coalition, the Center for Auto Safety, Advocates for Highway and Auto
Safety, and Road Safe America.\7\ The petitioners requested that NHTSA
establish a safety standard to require automatic forward collision
avoidance and mitigation systems on heavy vehicles. This rulemaking
also addresses recommendations made to NHTSA by the National
Transportation Safety Board.
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\7\ 80 FR 62487.
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The safety problem addressed by AEB is substantial. An annualized
average of 2017 to 2019 data from NHTSA's Fatality Analysis Reporting
System (FARS) and the Crash Report Sampling System (CRSS) shows that
heavy vehicles are involved in around 60,000 rear-end crashes in which
the heavy vehicle was the striking vehicle annually, which represents
11 percent of all crashes involving heavy vehicles.\8\ These rear-end
crashes resulted in 388 fatalities annually, which comprises 7.4
percent of all fatalities in heavy vehicle crashes. These crashes
resulted in approximately 30,000 injuries annually, or 14.4 percent of
all injuries in heavy vehicle crashes, and 84,000 damaged vehicles with
no injuries or fatalities.
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\8\ These rear-end crashes are cases where the heavy vehicle was
the striking vehicle.
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Considering vehicle size, approximately half of the rear-end
crashes, injuries, and fatalities resulting from rear-end crashes where
the heavy vehicle was the striking vehicle involved vehicles with a
gross vehicle weight rating above 4,536 kilograms (10,000 pounds) up to
11,793 kilograms (26,000 pounds). Similarly, half of all rear-end
crashes and the fatalities and injuries resulting from those crashes
where the heavy vehicle was the striking vehicle involved vehicles with
a gross vehicle weight rating of greater than 11.793 kilograms (26,000
pounds).
The speed of the striking vehicle is an important factor in the
severity of a crash. For example, in approximately 53 percent of
crashes, the striking vehicle was traveling at or under 30 mph (47 km/
h). Those crashes, though, were responsible for only approximately 1
percent of fatalities. In contrast, in approximately 17 percent of
crashes, the striking vehicle was traveling over 55 mph (89 km/h).
Those crashes resulted in 89 percent of the fatalities from rear-end
crashes involving heavy vehicles. While the majority of crashes occur
at low speeds, the overwhelming majority of fatalities result from
high-speed crashes. For AEB systems to address this safety problem,
they must function at both low and high speeds.
NHTSA has been studying AEB technologies since their conception
over 15 years ago. NHTSA and FMCSA have recognized the potential of
heavy vehicle AEB for many years and continued to research this
technology as it evolved from early generations to its current state.
As part of NHTSA's efforts to better understand these new collision
prevention technologies, NHTSA sponsored and conducted numerous
research projects, including ones focused on AEB and FCW for heavy
trucks. NHTSA conducted testing at its in-house testing facility, the
Vehicle Research and Test Center, to examine the effectiveness of AEB
in different crash scenarios and speeds. NHTSA and FMCSA have also
sponsored or conducted projects with a specific focus on the heavy
vehicle rear-end crash problem.
International standards for the regulation of AEB systems on heavy
vehicles exist and are under development. The European Union and Asian
countries have either already adopted or are considering AEB
regulations for heavy vehicles. More information can be found in
Appendix A of this document.
In 2016, NHTSA published its first report of track testing of heavy
vehicles equipped with AEB systems. NHTSA used its light vehicle test
procedures, similar to those used in NHTSA's New Car Assessment
Program,\9\ as a framework to adapt for use on heavy vehicles. These
scenarios included a stopped lead vehicle scenario, a slower moving
lead vehicle scenario, a decelerating lead vehicle scenario, and a
false positive scenario that consisted of driving over a steel trench
plate. NHTSA's initial testing of AEB systems focused on vehicles
equipped with ESC--primarily Class 8 truck tractors and motorcoaches.
Adjustments had to be made to the scenarios to account for the greater
stopping distances of heavy vehicles compared to light vehicles and to
the surrogate vehicle and towing device to ensure that the systems
performed as they would on the road. Testing of early heavy vehicle
systems indicated that vehicles did not automatically brake when
encountering a stopped lead vehicle. The false positive test also
resulted in FCW alerts, but no automatic braking.
---------------------------------------------------------------------------
\9\ NHTSA's New Car Assessment Program (NCAP) provides
comparative information on the safety performance of new vehicles to
assist consumers with vehicle purchasing decisions and to encourage
safety improvements.
---------------------------------------------------------------------------
Later testing was intended to evaluate the evolution of AEB
systems, to further refine the test procedures, and to test other
vehicle types such as single-unit trucks and class 3 through 6
vehicles. Newer FCW and AEB systems on heavy vehicles generally
performed better than older versions. Testing of these updated systems
exhibited less severe rear-end collisions through velocity reductions
before a collision or avoided contact with a lead vehicle entirely. The
refined test procedures addressed previous
[[Page 43179]]
issues with timing, range parameters, and the vehicle test device.
NHTSA's most recent testing of a 2021 Freightliner Cascadia, a
class 8 truck tractor, indicated that the AEB system was able to
prevent a collision with a lead vehicle at speeds between 40 km/h and
85 km/h. Collisions occurred with the lead vehicle at lower speeds,
although significant speed reductions were still achieved. This
suggests that collision avoidance at lower speed cannot necessarily be
extrapolated to performance outcomes at higher speed and may depend on
the specific ways AEB systems may be programmed. It also indicates that
AEB systems that prevent collisions at higher speeds are practicable.
NHTSA and FMCSA studies have also examined system availability
across all types of heavy vehicles. Across larger (class 7 and 8) air
braked truck tractors and motorcoaches, AEB systems are widely
available. A market analysis of class 3 through 6 heavy vehicles showed
that nearly all manufacturers had at least one vehicle model within
each class available with AEB. Two manufacturers had AEB advertised as
standard equipment on at least one model. All vehicles that were
offered with AEB systems were also equipped with ESC systems. A few
models that offered FCW-only systems (not capable of automatic brake
application) did so without also having ESC.
Based on these factors, and consistent with the Motor Vehicle
Safety Act and the BIL, NHTSA is proposing a new FMVSS that would
require nearly all heavy vehicles to be equipped with AEB systems.\10\
Furthermore, FMCSA is proposing that all commercial vehicles equipped
with ESC and AEB systems required by NHTSA's proposed rule be used any
time the commercial vehicle is in operation. NHTSA is further proposing
minimum performance criteria for AEB systems to meet the need for
safety. These performance criteria would ensure that AEB systems
function at a wide range of speeds that address the safety problem
associated with rear-end crashes, injuries, and fatalities.
---------------------------------------------------------------------------
\10\ The vehicles excluded from this proposal include trailers,
which by definition, are towed by other vehicles, and vehicles
already excluded from NHTSA's braking requirements. For details, see
section V.F.
---------------------------------------------------------------------------
Based on NHTSA's survey of publicly available data on ESC and AEB
system availability, all manufacturers that have equipped vehicles with
AEB systems (other than FCW-only systems) have done so only if the
vehicle is also equipped with an ESC system. Furthermore, NHTSA has
consulted with two AEB system manufacturers for heavy vehicles and both
indicated that they would equip vehicles with AEB only if they were
also equipped with ESC.\11\ An ESC system provides stability under
braking by using differential braking and engine torque reduction to
reduce lateral instability that could induce rollover or loss of
directional control. An ABS system also provides lateral stability
under braking. ABS systems are currently required on all vehicles
subject to this proposal under FMVSS Nos. 105 and 121. However, the
absence of any AEB systems available without ESC leads NHTSA to believe
that manufacturers have identified scenarios in which the operation of
an AEB system without ESC may have adverse safety effects that are not
adequately addressed by ABS systems alone.
---------------------------------------------------------------------------
\11\ On September 29, 2021, NHTSA met with Daimler Truck North
America (DTNA) and on October 22, 2021, NHTSA met with Bendix to
discuss the AEB systems of heavy vehicles.
---------------------------------------------------------------------------
Summary of the Proposal
NHTSA has tentatively concluded based upon this information that a
safety need exists for an ESC system to be installed on a vehicle
equipped with AEB. Consequently, this proposal also requires nearly all
heavy vehicles to be equipped with an ESC system.\12\ Even separate
from the benefits of AEB, the safety problem related to the vehicles
addressed by the FMVSS No. 136 amendments is also substantial. Class 3
through 6 heavy vehicles are involved in approximately 17,000 rollover
and loss of control crashes annually. These crashes resulted in 178
fatalities annually, approximately 4,000 non-fatal injuries, and 13,000
damaged vehicles. Currently, pursuant to FMVSS No. 136, only class 7
and 8 truck tractors and certain large buses are required to have ESC
systems. FMVSS No. 136 includes both vehicle equipment requirements and
performance requirements. This proposal would amend FMVSS No. 136 to
require nearly all heavy vehicles to have an ESC system that meets the
equipment requirements, the general system operational capability
requirements, and malfunction detection requirements of FMVSS No. 136.
It would not, as proposed, require vehicles not currently required to
have ESC systems to meet any test track performance requirements for
ESC systems, though the agency does request comment on whether to
include a performance test and, if so, what that test should be. In
designing any potential test, NHTSA wishes to remain conscious of the
potential testing burden on small businesses and the multi-stage
vehicle manufacturers.
---------------------------------------------------------------------------
\12\ The vehicles excluded from the proposed ESC requirements
are the same vehicles excluded from the proposed AEB requirements.
---------------------------------------------------------------------------
The proposed standard includes certain requirements for AEB
systems. First, vehicles would be required to provide the driver with a
forward collision warning at any forward speed greater than 10 km/h
(6.2 mph). NHTSA is proposing that the forward collision warning be
auditory and visual with limited specifications for each of the warning
modalities. NHTSA has tentatively concluded that no further
specification of the warning is necessary.
Second, vehicles would be required to have an AEB system that
applies the service brakes automatically at any forward speed greater
than 10 km/h (6.2 mph) when a collision with a lead vehicle is
imminent. This requirement serves to ensure that AEB systems operate at
all speeds above 10 km/h, even if they are above the speeds tested by
NHTSA. This requirement also assures at least some level of AEB system
performance in rear-end crashes other than those for which NHTSA has
test procedures.
Third, the AEB system would be required to prevent the vehicle from
colliding with a lead vehicle when tested according to the proposed
standard's test procedures. Vehicles with AEB systems meeting the
proposed standard would have to automatically activate the braking
system when they encounter a stopped lead vehicle, a slower moving lead
vehicle, or a decelerating lead vehicle.
The proposed requirements also include two tests to ensure that the
AEB system does not inappropriately activate when no collision is
actually imminent. These false positive tests provide some assurance
that an AEB system is capable of differentiating between an actual
imminent collision and a non-threat. While these tests are not
comprehensive, they establish a minimum performance for non-activation
of AEB systems. The two scenarios NHTSA proposes to test are driving
over a steel trench plate and driving between two parked vehicles.
The final proposed requirement for AEB systems is that they be
capable of detecting a system malfunction and notify the driver of any
malfunction that causes the AEB system not to operate. This proposed
requirement would include any malfunction solely attributable to sensor
obstruction, such as by accumulated snow or debris, dense fog, or
sunlight glare. The malfunction telltale must remain active as long as
the malfunction exists, and
[[Page 43180]]
the vehicle's starting system is on. The proposal does not include any
specifications for the form of this notification to the driver.
The NPRM also includes proposed test procedures. In this NPRM, the
heavy vehicle being evaluated with AEB is referred to as the ``subject
vehicle.'' Other vehicles involved in the test are referred to as
``vehicle test devices,'' (VTDs) and a specific type of VTD called the
``lead vehicle'' refers to a vehicle which is ahead in the same lane,
in the path of the moving subject vehicle. To ensure repeatable test
conduct that reflects how a subject vehicle might respond in the real
world, this proposal includes broad specifications for a vehicle test
device to be used as a lead vehicle or principal other vehicle during
testing. NHTSA is proposing that the vehicle test device is based on
the specifications in the International Organization for
Standardization (ISO) standard 19206-3:2021.\13\ The vehicle test
device is a tool that NHTSA would use in the agency's compliance tests
to measure the performance of automatic emergency braking systems
required by the FMVSS. For its research testing, NHTSA has been using a
full-size surrogate vehicle, the Global Vehicle Target (GVT). The GVT
falls within the specifications of ISO 19206-3:2021. These
specifications include specifications for the dimensions, color and
reflectivity, and the radar cross section of a vehicle test device that
ensure it appears like a real vehicle to vehicle sensors.
---------------------------------------------------------------------------
\13\ ISO 19206-3:2021, ``Road vehicles--Test devices for target
vehicles, vulnerable road users and other objects, for assessment of
active safety functions--Part 3: Requirements for passenger vehicle
3D targets.'' https://www.iso.org/standard/70133.html. May 2021.
---------------------------------------------------------------------------
NHTSA has included three test scenarios in this proposed rule for
AEB when approaching a lead vehicle--a stopped lead vehicle, a slower
moving lead vehicle, and a decelerating lead vehicle. The stopped lead
vehicle scenario consists of the subject vehicle--that is, the vehicle
being tested--traveling straight at a constant speed approaching a
stopped lead vehicle in the center of its path. To satisfy the proposed
performance requirement, the subject vehicle must provide an FCW and
stop prior to colliding with the lead vehicle. NHTSA proposes to
conduct this scenario both with no manual brake application and with
manual brake application. Testing with manual brake application is
similar to the DBS test procedure that is included in New Car
Assessment Program for light vehicles. While DBS is not generally
advertised as a feature of AEB systems on air braked vehicles, driver-
applied braking should not suppress automatic braking. Testing without
manual brake application would be conducted at any constant speed
between 10 km/h and 80 km/h. The 80 km/h upper bound of testing
reflects safety limitations that would result from any collision
resulting from a failure of an AEB system to activate in the testing
environment. However, with manual brake application, NHTSA proposes to
test vehicles up to 100 km/h. This is possible because the manual brake
application ensures at least some level of speed reduction even in a
test failure where automatic braking does not occur.
The second test scenario is a slower moving lead vehicle. In this
scenario, the subject vehicle is traveling straight at a constant
speed, approaching a lead vehicle traveling at a slower speed in the
subject vehicle's path. To satisfy the proposed performance test
requirement, the subject vehicle must provide an FCW and slow to a
speed equal to or below the lead vehicle's speed without colliding with
the lead vehicle. As with the stopped lead vehicle test, NHTSA proposes
to perform this test with both no manual brake application and manual
brake application. The subject vehicle speed without manual brake
application would be any constant speed between 40 km/h and 80 km/h,
and with manual brake application, testing would be conducted at any
constant speed between 70 km/h and 100 km/h. The lead vehicle would
travel at 20 km/h in all tests.
The third test scenario is a decelerating lead vehicle. In this
scenario, the subject vehicle and lead vehicle are travelling at the
same constant speed in the same path and the lead vehicle begins to
decelerate. To satisfy the proposed performance test requirement, the
subject vehicle must provide an FCW and stop without colliding with the
lead vehicle. As with the other AEB tests approaching a lead vehicle,
this test is performed both with and without manual brake application.
However, the test speeds are the same for both scenarios--either 50 km/
h or 80 km/h. The lead vehicle would decelerate with a magnitude
between 0.3g and 0.4g and the headway between the vehicles would be any
distance between 21 m and 40 m (for 50 km/h tests) or 28 m and 40 m
(for 80 km/h tests). The upper bound of the lead vehicle deceleration
and the lower bound of the headway were chosen to ensure that the
corresponding test scenarios would not require a brake performance
beyond what is necessary to satisfy the minimum stopping distance
requirements in the FMVSS applicable to brake performance.
This proposal would require that all of the NHTSA AEB requirements
be phased in within four years of publication of a final rule. Truck
tractors and certain large buses with a GVWR of greater than 11,793
kilograms (26,000 pounds) that are currently subject to FMVSS No. 136
would be required to meet all requirements within three years. Vehicles
not currently subject to FMVSS No. 136 would be required to have ESC
and AEB systems within four years of publication of a final rule.
Small-volume manufacturers, final-stage manufacturers, and alterers
would be allowed one additional year (five years total) of lead time.
Consistent with the BIL mandate, FMCSA proposes to require that
motor carriers operating CMVs manufactured subject to FMVSS No. 136,
maintain and use the required AEB and ESC systems as prescribed by
NHTSA for the effective life of the CMV. FMCSA's proposed rule is
intended to ensure that commercial motor vehicles equipped with the ESC
and AEB systems mandated by NHTSA are maintained and operated safely,
as required by 49 U.S.C. 31136(a)(1). While the FMCSA proposal does not
explicitly address the remaining provisions of section 31136, it will
enhance the ability of drivers to operate safely, consistent with 49
U.S.C. 31136(a)(2)-(4). FMCSA's proposal would require the ESC and AEB
systems to be inspected and maintained in accordance with 49 CFR part
396, Inspection, Repair, and Maintenance (Sec. 396.3).
The proposed requirements would ensure that the benefits resulting
from CMVs equipped with ESC and AEB systems are sustained through
proper maintenance and operation. The maintenance costs include annual
costs required to keep the ESC and AEB systems operative. FMCSA
believes the cost of maintaining the ESC and AEB systems over their
lifetimes is minimal compared to the cost of equipping trucks with ESC
and AEB systems and may be covered by regular annual maintenance.
NHTSA and FMCSA have jointly determined not to propose retrofitting
requirements AEB for existing heavy vehicles and ESC for vehicles not
currently subject to FMVSS No. 136. For technical reasons, AEB and ESC
retrofits are difficult to apply broadly, generically, or inexpensively
and thus this NPRM does not propose a retrofit requirement.
NHTSA and FMCSA seek comments and suggestions on any aspect of this
[[Page 43181]]
proposal and any alternative requirements to address this safety
problem. NHTSA and FMCSA also request comments on the proposed lead
time for meeting these requirements, and how the lead time can be
structured to maximize the benefits that can be realized most quickly
while ensuring that the standard is practicable. Finally, NHTSA and
FMCSA seek comment on whether and how this proposal may
disproportionately impact small businesses and how NHTSA and FMCSA
could revise this proposal to minimize any disproportionate impact.
Benefits and Costs
NHTSA and FMCSA have issued a Preliminary Regulatory Impact
Analysis (PRIA) that analyzes the potential impacts of this proposed
rule. The PRIA is available in the docket for this NPRM.\14\ This
proposed rule is expected to substantially decrease risks associated
with rear-end, rollover, and loss of control crashes. The effectiveness
of AEB and ESC at avoiding rear-end, rollover, and loss of control
crashes is summarized in Table 3 for AEB and Table 4 for ESC.
---------------------------------------------------------------------------
\14\ The PRIA may be obtained by downloading it or by contacting
Docket Management at the address or telephone number provided at the
beginning of this document.
Table 3--AEB Effectiveness (%) by Vehicle Class Range and Crash Scenario
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving lead Decelerating lead
Vehicle class range vehicle vehicle vehicle
----------------------------------------------------------------------------------------------------------------
7-8................................................. 38.5 49.2 49.2
3-6................................................. 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------
Table 4--ESC Effectiveness (%) by Crash Scenario
------------------------------------------------------------------------
Vehicle class range Rollover Loss of control
------------------------------------------------------------------------
3-6........................... 48.0 14.0
------------------------------------------------------------------------
Considering the annual rear-end, rollover, and loss of control
crashes, as well as the effectiveness of AEB and ESC at avoiding these
crashes, the proposed rule would prevent an estimated 19,118 crashes,
save 155 lives, and reduce 8,814 non-fatal injuries, annually. In
addition, the proposed rule would eliminate an estimated 24,828
property-damage-only-vehicles (PDOVs), annually. Table 5 shows these
estimated benefits also by vehicle class and technology.
Table 5--Estimated Annual Benefits of the Proposed Rule
----------------------------------------------------------------------------------------------------------------
Non-fatal
Crashes Fatalities injuries PDOVs avoided
avoided avoided avoided
----------------------------------------------------------------------------------------------------------------
By Vehicle Class
----------------------------------------------------------------------------------------------------------------
Class 7-8....................................... 5,691 40 2,822 7,958
Class 3-6....................................... 13,427 115 5,992 16,870
---------------------------------------------------------------
Total....................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------
By Technology
----------------------------------------------------------------------------------------------------------------
AEB............................................. 16,224 106 8,058 22,713
ESC............................................. 2,894 49 756 2,115
---------------------------------------------------------------
Total....................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------
There are two potential unintended consequences that cannot be
quantified: the impact of false activations on safety and the potential
impact of sensor degradation over time on AEB performance. However, the
required malfunction indicator combined with FMCSA's proposed AEB and
ESC inspection and maintenance requirements would help vehicle
operators maintain AEB systems and substantially reduce degradation of
AEB sensor performance. We seek comments on these two issues and ask
for any data that can help us to quantify these impacts.
The benefits estimate includes assumptions that likely result in
the underestimation of the benefits of this proposal because it does
not quantify the benefits from crash mitigation. That is, the benefits
only reflect those resulting from crashes that are avoided as a result
of AEB and ESC. It is likely that AEB will also reduce the severity of
crashes that are not prevented. Some of these crashes mitigated may
include fatalities and significant injuries that will be prevented or
mitigated by AEB. Finally, this NPRM does not quantify any potential
benefits that AEB could provide during adverse environmental conditions
(night, wet, etc.). While AEB is likely to be effective in many of
these crashes, NHTSA is not aware of any data to quantify the
performance degradation of AEB in adverse conditions.
The benefits of this proposed rule, monetized and analyzed with the
total annual cost, are summarized in Table 6. The total annual cost,
considering the implementation of both AEB and ESC technologies
proposed in this rule, is
[[Page 43182]]
estimated to be $353 million. The proposed rule would generate a net
benefit of $2.58 to $1.81 billion, annually under 3 and 7 percent
discount rates. The proposed rule would be cost-effective given that
the highest estimated net cost per fatal equivalent would be $0.50
million. Maintenance costs are considered de minimis and therefore not
included in the cost estimate.
Table 6--Estimated Annual Cost, Monetized Benefits, Cost-Effectiveness, and Net Benefits of the Proposed Rule
[2021 Dollars in millions]
----------------------------------------------------------------------------------------------------------------
Monetized Net cost per
Discount rates Annual cost * benefits fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent.................................... $353.3 $2,937.0 \15\ -$0.12 $2,583.7
7 Percent.................................... 353.3 2,158.0 0.50 1,807.1
----------------------------------------------------------------------------------------------------------------
* Paid at purchasing; no need to discount.
NHTSA has issued an NPRM that proposes to adopt an FMVSS for AEB
requirements for light vehicles, including pedestrian AEB. \16\ NHTSA
notes that it may decide to issue final rules adopting the AEB
requirements for light and heavy vehicles in a way that incorporates
the AEB requirements into a single Federal motor vehicle safety
standard for all vehicle classes.
---------------------------------------------------------------------------
\15\ The negative net cost per fatal equivalent reflects the
fact that savings from reducing traffic congestion and damaged
property is greater the total compliance costs of the proposed rule.
\16\ 88 FR 38632 (June 13, 2023).
---------------------------------------------------------------------------
The following is a brief explanation of terms and technologies used
to describe AEB systems. More detailed information can be found in
Appendix A to this preamble.
Radar-Based Sensors
Heavy vehicle AEB systems typically employ radar sensors. At its
simplest, radar is a time-of-flight sensor that measures the time
between when a radio wave is transmitted and its reflection is
recorded. This time-of-flight is then used to calculate how far away
the object is that caused the reflection. Information about the
reflecting object, such as the speed at which it is travelling, can
also be determined. Radar units are compact, relatively easy to mount,
and do not require a line of sight to function properly. Radar can
penetrate most rubbers and plastics, allowing for the units to be
installed behind grilles and bumper fascia, increasing mounting
options. Radar can detect objects in low-light situations and also
works well in environmental conditions like precipitation and fog.
Camera Sensors
Cameras are passive sensors in which optical data are recorded then
processed to allow for object detection and classification. Cameras are
an important part of many automotive AEB systems, and one or more
cameras are typically mounted behind the front windshield and often up
high near the rearview mirror. Cameras at this location provide a good
view of the road and are protected by the windshield from debris,
grease, dirt, and other contaminants that can cover the sensor. Systems
that utilize two or more cameras can see stereoscopically, allowing the
processing system to determine range information along with detection
and classification.
Electronically Modulated Braking Systems
Automatic actuation of the vehicle brakes requires more than just
systems to sense when a collision is imminent. In addition to the
sensing system, hardware is needed to physically apply the brakes
without relying on the driver to apply the brake pedal. AEB leverages
two foundational braking technologies, antilock braking systems (ABS)
and electronic stability control. AEB uses the hardware equipped for
ESC and electronically applies the brakes to avoid certain scenarios
where a crash with a vehicle is imminent.
ABS: Antilock braking systems automatically control the degree of
longitudinal wheel slip during braking to prevent wheel lock and
minimize skidding by sensing the rate of angular rotation of the wheels
and modulating the braking force at the wheels to keep the wheels from
locking. Preventing wheel lock, and therefore skidding, greatly
increases the controllability of the vehicle during a panic stop.
Modern ABS systems have wheel speed sensors, independent brake
modulation at each wheel, and can increase or decrease braking
pressures as needed. During modulation of a brake application, the ABS
system repeatedly relieves and regenerates pressure to quickly release
and reapply, or ``pulse,'' the brake.
ESC: ESC builds upon the antilock brakes system by adding two
sensors, a steering wheel angle sensor and an inertial measurement
unit. These sensors allow the ESC controller to determine intended
steering direction (steering wheel angle sensor), compare it to the
actual vehicle direction, and then modulate braking forces at each
wheel to induce a corrective yaw moment when the vehicle starts to lose
lateral stability. An ESC system can control the brakes even when the
vehicle operator is not pressing the brake pedal.
When an AEB system activates in response to an imminent collision,
much of the same or similar hardware from ESC systems is used to
automatically control and modulate the brakes. Like ESC, an AEB system
includes components that give the vehicle the capacity to automatically
apply the brakes even when the vehicle operator is not pressing the
brake pedal. To do this in hydraulic brake systems, hydraulic brake
pressure is generated by a pump similarly as with ABS. In a pneumatic
brake system, the air pressure is already available via the air
reservoir and air compressor, and the ESC system must direct this
pressure accordingly. Additionally, the safety benefits of ESC enable
an AEB system to operate at its potential. Especially under the high-
speed, heavy-deceleration emergency braking events that potentially
occur during AEB activation, ESC could improve vehicle stability and
reduce the propensity for loss of control or rollover crashes that may
result from a steering response to an impending rear-end collision.
Forward Collision Warning
A forward collision warning (FCW) system uses the camera and radar
sensors described above, and couples them with an alert mechanism. An
FCW system can monitor a vehicle's speed, the speed of the vehicle in
front of it, and the distance between the two vehicles. If the FCW
system determines that the distance from the driver's vehicle to the
vehicle in front of it is too short, and the closing velocity between
[[Page 43183]]
the two vehicles too high, the system warns the driver of an impending
rear-end collision. Warning systems in use today provide drivers with a
visual display, such as a light on the instrument panel, an auditory
signal (e.g., beeping tone or chime), and/or a haptic signal that
provides tactile feedback to the driver (e.g., rapid vibrations of the
seat pan or steering wheel or a momentary brake pulse) to alert the
driver of an impending crash so they may manually intervene. The alerts
provided by FCW systems, even those that include momentary brake
pulses, are not intended to provide significant and sustained vehicle
deceleration. Rather, the FCW system is intended to inform the driver
that they must take corrective action in certain rear-end crash-
imminent driving situations.
Automatic Emergency Braking
An automatic emergency braking system automatically applies the
brakes to help drivers avoid or mitigate the severity of rear-end
crashes. AEB has two primary functions, crash imminent braking (CIB)
and a brake support system that supplements a driver's applied braking,
which is referred to as dynamic brake support (DBS) in the light
vehicle context. CIB systems apply automatic braking when forward-
looking sensors indicate a crash is imminent and the driver has not
applied the brakes, while supplemental brake support systems use the
same forward-looking sensors, but also supplement the driver's
application of the brake pedal with enhanced braking when sensors
determine the driver-applied braking is insufficient to avoid the
imminent crash. This NPRM does not split the terminology of these CIB
and supplemental brake support functionalities, and instead considers
both functions as part of AEB. The proposed standard includes
performance tests that would entail installation of AEB that has both
CIB and supplemental brake support functionalities.
``AEB'' as Used in This NPRM
As used in this NPRM, when we refer to ``AEB,'' we mean a system
that has: (a) a forward collision warning (FCW) component to alert the
driver to an impending collision; (b) a crash imminent braking
component (CIB) that automatically applies the vehicle's brakes if the
driver does not respond to an imminent crash in the forward direction
regardless of whether there's an FCW alert; and, (c) a supplemental
brake support component that automatically supplements the driver's
brake application if the driver applies insufficient manual braking.
II. Safety Problem
Overview
There were 38,824 people killed in motor vehicle crashes on U.S.
roadways in 2020 and 42,939 in 2021.17 18 The 2021 data are
the highest numbers of fatalities since 2005. While the upward trend in
fatalities may be related to increases in risky driving behaviors
during the COVID-19 pandemic,\19\ NHTSA data from 2010 to 2019 show an
increase of approximately 3,000 fatalities since 2010. There has also
been an upward trend since 2010 in the total number of motor vehicle
crashes, which corresponds to an increase in fatalities, injuries, and
property damage. NHTSA uses data from its FARS and the CRSS, to account
for and understand motor vehicle crashes.\20\
---------------------------------------------------------------------------
\17\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266;, https://www.nhtsa.gov/press-releases/early-
estimate-2021-traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\18\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813435; https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283; https://www.nhtsa.gov/press-releases/early-
estimate-2021-traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\19\ These behaviors relate to increases in impaired driving,
the non-use of seat belts, and speeding.
\20\ The Crash Report Sampling System (CRSS) builds on a
previous, long-running National Automotive Sampling System General
Estimates System (NASS GES). CRSS is a sample of police-reported
crashes involving all types of motor vehicles, pedestrians, and
cyclists, ranging from property-damage-only crashes to those that
result in fatalities. CRSS is used to estimate the overall crash
picture, identify highway safety problem areas, measure trends,
drive consumer information initiatives, and form the basis for cost
and benefit analyses of highway safety initiatives and regulations.
FARS contains data on every fatal motor vehicle traffic crash within
the 50 States, the District of Columbia, and Puerto Rico. To be
included in FARS, a traffic crash must involve a motor vehicle
traveling on a public trafficway that results in the death of a
vehicle occupant or a nonoccupant within 30 days of the crash.
---------------------------------------------------------------------------
Rear-End Crashes
As defined in a NHTSA technical manual relating to data entry for
FARS and CRSS, rear-end crashes are incidents where the first event is
defined as the frontal area of one vehicle striking a vehicle ahead in
the same travel lane. In a rear-end crash, as instructed by the FARS/
CRSS Coding and Validation Manual, the vehicle ahead is categorized as
intending to head either straight, left or right, and is either
stopped, travelling at a lower speed, or decelerating.\21\
---------------------------------------------------------------------------
\21\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813251 Category II Configuration D. Rear-End.
---------------------------------------------------------------------------
Heavy Vehicle Rear-End Crashes
On average from 2017 to 2019, there were 6.65 million annual
police-reported crashes resulting in 36,888 fatalities. Of the police-
reported crashes, approximately 550,000 involved a heavy vehicle (a
vehicle with a GVWR greater than 4,536 kg (10,000 pounds)), resulting
in 5,255 fatalities.\22\ Thus, heavy vehicle crashes represented 8.3
percent of the total number of crashes and resulted in 14.2 percent of
all fatalities. Annually, the entire U.S. fleet traveled a total of
3,237,449 million miles, and 9.3 percent of total vehicle miles
traveled were in heavy vehicles.\23\
---------------------------------------------------------------------------
\22\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the accompanying PRIA.
\23\ See the Traffic Safety Report at https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141 (Last
viewed September 22, 2022).
---------------------------------------------------------------------------
A typical heavy vehicle rear-end crash is characterized by a heavy
vehicle travelling on a roadway and colliding with another vehicle
ahead of it travelling in the same direction, but which is stopped,
moving slower, or decelerating, usually within the same lane. While
these crashes occur nationwide on all types of roads and in all
environments, they overwhelmingly take place on straight roadways (99
percent) and in dry conditions (85 percent). Approximately 60,000 (11
percent of heavy vehicle crashes annually), were rear-end crashes in
which the heavy vehicle was the striking vehicle. These rear-end
crashes resulted in 388 fatalities annually (7.4 percent of all
fatalities in heavy vehicle crashes), approximately 30,000 injuries
(14.3 percent of injuries in all heavy vehicle crashes.), and
approximately 84,000 damaged vehicles (without injuries or
fatalities).\24\
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\24\ All data in this paragraph are from 2017-2019 FARS and CRSS
crash databases, and are discussed in the accompanying PRIA.
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The PRIA accompanying this proposal includes a complete review and
analysis of the relevant crash data and provides full details about the
target population of this NPRM. A summary of the PRIA is contained in
section XI. of this proposal.
Rear-End Crashes by Heavy Vehicle Class
Installing AEB on vehicles is related to the installation of ESC on
vehicles. ESC is required by FMVSS No. 136 for truck tractors and
certain large buses with a GVWR greater than 11,793 kg
[[Page 43184]]
(26,000 lbs.). Although the group of heavy vehicles that is not subject
to FMVSS No. 136 and the group of heavy vehicles that is subject to
FMVSS No. 136 are not solely defined by GVWR range, those not subject
to FMVSS No. 136 can be generally characterized as class 3-6 vehicles,
while those that are subject to FMVSS No. 136 can be generally
characterized as class 7-8 vehicles. Accordingly, NHTSA has further
examined rear-end crash data for each of these vehicle class ranges.
The lower weight range of class 3 through 6 includes vehicles such
as delivery vans, utility trucks, and smaller buses. Sales data for
2018 and 2019 show that on average 454,692 class 3-6 vehicles per year
were sold in the U.S.\25\ Approximately 57 percent of these were class
3 vehicles. Based on crash data, NHTSA determined that class 3-6
vehicles are involved in an annual average of 29,493 rear-end crashes
where the heavy vehicle is the striking vehicle. As a result of these
crashes, there were 184 fatalities, 14,675 injuries, and 41,285 PDOVs
per year on average. A NHTSA study also shows that, according to FARS
data, fatalities related to crashes involving these vehicles are on the
rise.\26\ In 2015, trucks and buses in this category were involved in 2
percent of all fatal crashes in the U.S., but that increased to 4
percent in 2019.\27\
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\25\ This information is available in the S&P Global's
presentation titled ``MHCV Safety Technology Study,'' which has been
placed in the docket identified in the heading of this NPRM.
\26\ Mynatt, M., Zhang, F., Brophy, J., Subramanian, R., Morgan,
T. (2022, September). Medium Truck Special Study (Report No. DOT HS
813 371). Washington, DC: National Highway Traffic Safety
Administration.
\27\ In 2015, 655 of the 32,538 total fatalities involved a
class 3-6 truck. In 2019, it increased to 1,301 of the 33,244 total
fatalities.
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The higher weight range of class 7 and 8 includes vehicles such as
larger single-unit trucks, combination tractor-trailers, transit buses,
and motorcoaches (GVWR greater than 11,793 kg (26,000 lbs.)).\28\ Sales
data for 2018 and 2019 shows that on average 332,558 class 7-8 vehicles
per year were sold in the U.S. Approximately 77 percent of these were
class 8 vehicles. NHTSA estimates that class 7 and 8 vehicles are
involved in 30,416 rear-end crashes where the heavy vehicle is the
striking vehicle. As a result of these crashes, there were an annual
average of 204 fatalities, 15,117 injuries, and 42,466 PDOVs. As these
data indicate, the numbers of crashes, fatalities, injuries, and PDOVs
are very similar for both class 3-6 and class 7-8.
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\28\ These vehicles are subject to FMVSS No. 136 and so must
have ESC.
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Rear-End Crashes by Vehicle Travel Speed and Roadway Speed Limit
Pre-crash vehicle travel speed is highly important in understanding
the heavy vehicle rear-end crash problem and is perhaps the most
influential factor in outcome of these crashes. In NHTSA's analysis of
the data, travel speed of the striking vehicle was markedly different
when comparing non-fatal and fatal rear-end truck crashes. As shown in
Figure 1, the percentage of heavy vehicle rear-end crashes with a
fatality is greatest at higher travel speeds.\29\ Approximately 89
percent of fatal heavy vehicle rear-end crashes occur at above 80 km/h
(50 mph). For non-fatal heavy vehicle rear-end crashes, the trend is
more or less reversed, with approximately 83 percent of these crashes
occurring at travel speeds below 80 km/h (50 mph). These data
illustrate the distribution of a crash problem across all travel
speeds.
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\29\ Note that the figure shows percentage of the total number
of fatal or non-fatal crashes. The total number of crashes is much
greater for non-fatal crashes.
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BILLING CODE 4910-59-P
[[Page 43185]]
[GRAPHIC] [TIFF OMITTED] TP06JY23.001
The speed limits in heavy vehicle rear-end crashes also show a
similar trend. NHTSA categorized the fatal and non-fatal crash data
according to posted speed limit at the crash location, as illustrated
in Figure 2.\31\ These data show that over 90 percent of heavy vehicle
rear-end crashes with a fatality occur on roadways with a posted speed
limit higher than 50 mph (80 km/h). This reinforces the association
between higher speeds and fatal crash outcome in these types of
crashes. In contrast, non-fatal rear-end crashes tend to occur most
commonly on roads with lower speed limit, with a peak frequency at
speed limits of 45 mph (72 km/h). These data help in understanding the
conditions under which heavy vehicle rear-end crashes of different
severities occur.
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\30\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on target population.
\31\ These data naturally are clustered around 5 mph intervals
normally assigned for posted speed limits on roadways.
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[[Page 43186]]
[GRAPHIC] [TIFF OMITTED] TP06JY23.002
BILLING CODE 4910-59-C
Safety Problem That Can Be Addressed by AEB
NHTSA identified the set of crashes that might be prevented by AEB
systems equipped on heavy vehicles. To determine these crashes for this
NPRM, NHTSA analyzed 2017 through 2019 crash data for heavy vehicles.
The 2017 through 2019 years were chosen because they provide the most
recent available data, and thus reflect newer model year vehicles,
safety technologies, and crash environments.\33\ The crash-related
statistics discussed in this section, often depicted as annual
averages, are derived from these data.
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\32\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on target population.
\33\ Crash data from 2020, although available, were excluded due
to a significant reduction in weighted cases for CRSS. The 2020 data
was greatly influenced by COVID-19 and might not reflect the long-
term trend of crash outcomes, as described in the accompanying PRIA.
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To develop a target crash population relevant to AEB, the agency
identified crashes that were classified as rear-end crashes as
instructed by the FARS/CRSS manual and in which the striking vehicle
was a heavy vehicle. NHTSA analyzed rear-end crashes in which the
vehicle ahead is categorized as being either stopped, travelling at a
lower speed, or decelerating, and also examined a few other categories
to account for rear-end crashes that did not fit into the three
categories. Additionally, NHTSA included some other cases which,
although not classified as rear-end, were multi-vehicle crashes that
still involved the front end of a heavy vehicle colliding with the
rear-end of another vehicle.
NHTSA believes that AEB will help reduce the severity of rear-end
crashes occurring in a wide variety of real-world situations. However,
the data analysis presented some rear-end crash cases where, due to a
significant sequence of events or other conditions preceding the crash,
the agency had less certainty of the extent to which AEB systems would
be able to reduce the crash severity. For example, if the data
indicated that the heavy vehicle had changed lanes just prior to
colliding with a vehicle ahead, there would potentially not have been
sufficient time and/or space for the AEB system to properly identify
and track that vehicle and brake in time to avoid the crash. As another
example, if the road surface conditions were icy and slippery, the AEB
system may have been less likely to prevent a crash due to the reduced
friction and increased stopping distances. In another example, if the
struck vehicle was a motorcycle, NHTSA is uncertain of the AEB system's
capacity to perform optimally since motorcycles may be more difficult
to detect.\34\
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\34\ NHTSA is currently conducting research tests to understand
AEB performance in light vehicle rear-end crashes with motorcycles.
Two types of AEB sensor types (e.g., camera and camera+radar) were
investigated. See www.regulations.gov, Docket No. NHTSA-2022-0091. A
study by the RDW, the vehicle authority in the Netherlands,
indicated that adaptive cruise control systems (which detect a
vehicle ahead, similar to AEB) had more difficulty detecting
motorcycles. https://www.femamotorcycling.eu/wp-content/uploads/Final%20Report_motorcycle_ADAS_RDW.pdf (last accessed February 10,
2023).
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NHTSA believes that, even in these situations where AEB performance
may be partially degraded, having AEB will still be beneficial. It may
not, for example, prevent a crash but it may reduce its severity by
slowing the
[[Page 43187]]
striking vehicle down. However, the agency took a conservative approach
and excluded cases such as those above from the target crash
population, and included only those cases in which AEB systems would
have the opportunity to perform optimally. This approach gives greater
confidence that the crashes included in the target crash population
would be prevented by having AEB-equipped vehicles.\35\
---------------------------------------------------------------------------
\35\ The PRIA discusses the rear-end crashes that were excluded
from the target population.
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The result is that out of the 550,000 annual police reported
crashes involving heavy vehicles, approximately 60,000 annually are
rear-end crashes in which the heavy vehicle was the striking vehicle.
Thus, if heavy vehicles were equipped with AEB, a portion of these
60,000 crashes could be prevented. These 60,000 crashes, between 2017
and 2019, resulted in an annual average of approximately 388
fatalities, 30,000 injuries, and 84,000 PDOVs.
By requiring ESC for most class 3 through 6 vehicles, the proposed
rule would affect approximately 17,000 rollover and loss of control
crashes. These crashes resulted in 178 fatalities, 4,000 injuries, and
13,000 PDOVs, a portion of which could be prevented if class 3 through
6 heavy vehicles were equipped with ESC. These numbers are set forth in
Table 7.
Table 7--Target Crash Population
----------------------------------------------------------------------------------------------------------------
Crashes Fatalities Injuries PDOVs
----------------------------------------------------------------------------------------------------------------
AEB............................................. 60,000 388 30,000 84,000
ESC............................................. 17,000 178 4,000 13,000
----------------------------------------------------------------------------------------------------------------
III. Efforts To Promote AEB Deployment in Heavy Vehicles
Unlike with light vehicles in the U.S., there is currently no
voluntary commitment by heavy vehicle manufacturers to begin installing
AEB on all new vehicles.\36\ Nor is there a program similar to NHTSA's
New Car Assessment Program (NCAP) for heavy vehicles. However, NHTSA
and FMCSA have researched heavy vehicle AEB. In addition, Congress,
other governmental agencies, and a variety of stakeholders recognize
that this technology has the potential to reduce the fatalities,
injuries, and property damage associated with heavy vehicle rear-end
crashes. The installation rate of AEB in the U.S. vehicle fleet has
gradually increased, and the latest generations of the technology are
higher performing than the original implementations.
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\36\ On March 17, 2016, NHTSA and the Insurance Institute for
Highway Safety (IIHS) announced a commitment by 20 automakers
representing more than 99 percent of the U.S. auto market to make
lower speed AEB a standard feature on virtually all new cars no
later than Sept 1, 2022. https://www.nhtsa.gov/press-releases/us-dot-and-iihs-announce-historic-commitment-20-automakers-make-automatic-emergency.
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A. NHTSA's Foundational AEB Research
NHTSA has been studying emergency braking technologies since
manufacturers first introduced these technologies over fifteen years
ago. NHTSA has recognized the safety potential of heavy vehicle AEB for
many years and continued to research this technology as it evolved from
early generations to its current state. As part of NHTSA's efforts to
better understand these new crash avoidance technologies, NHTSA
sponsored and conducted numerous research projects focused on AEB and
FCW for heavy trucks. NHTSA conducted testing at its in-house testing
facility, the Vehicle Research and Test Center, to examine the
performance of AEB in different combinations of crash scenarios and
speeds.
NHTSA's foundational knowledge of braking technology was built on a
long history of work on FMVSS No. 105, ``Hydraulic and electric brake
systems,'' No. 121, ``Air brake systems,'' and No. 136, ``Electronic
stability control systems for heavy vehicles.''
FMVSS No. 105 applies to multipurpose passenger vehicles, trucks,
and buses with a GVWR greater than 3,500 kg (7,716 lbs.) that are
equipped with hydraulic or electric brake systems. This standard sets
performance requirements for, among other things, maximum stopping
distance, anti-lock braking systems, stability and control under
braking (including a curved and wet road surface), and recovery from
brake fade.\37\
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\37\ Brake fade events are associated with speed control on
roads with steep or gradual but long downgrades. As brake
temperature increases in a drum, its diameter expands as the metal
heats up; this means the brake shoe displacement must also increase
to be effective. Eventually, the shoe reaches the displacement
limit, and then brake effectiveness drops off.
---------------------------------------------------------------------------
FMVSS No. 121 applies to trucks, buses, and trailers equipped with
air (pneumatic) brake systems, with a few exceptions for special
vehicle types. Although NHTSA sets no standards regarding the choice
between using hydraulic, electric, or air brakes, vehicles with a
larger size and load carrying capacity are more likely to have air
brakes. Thus, air brakes are typically installed on some class 6 and
most class 7-8 vehicles. Lower classes often use hydraulic brakes. A
few examples of the requirements in FMVSS No. 121 are maximum stopping
distance, having ABS, maintaining stability and control when braking to
a stop on a curved and wet roadway test surface, recovering from brake
fade, and having an emergency (backup) brake system.
FMVSS No. 136 establishes performance and equipment requirements
for electronic stability control systems on truck tractors and certain
large buses, for the purpose of reducing crashes caused by rollover or
by loss of directional control. This standard currently applies to
truck tractors and certain large buses with a GVWR greater than 11,793
kilograms (26,000 lbs.). FMVSS No. 136 requires vehicles to be equipped
with an ESC system, and to meet several minimum performance
requirements. For example, when driven on a specified J-shaped test
lane under a variety of specified conditions and parameters which
induce ESC activation, the wheels of the heavy vehicle must remain
within the lane.
B. NHTSA's 2015 Grant of a Petition for Rulemaking
In October 2015, NHTSA granted a petition for rulemaking from the
Truck Safety Coalition, the Center for Auto Safety, Advocates for
Highway and Auto Safety, and Road Safe America. This petition requested
``the commencement of a proceeding to establish a safety regulation to
require the use of [FCW and AEB] on all vehicles (trucks and buses)
with a gross vehicle weight rating (GVWR) of 10,000 pounds (lbs.) or
more.'' The petitioners maintained that AEB has important benefits and
is a technology that has been improving in performance, but that a
regulation is needed to optimize the benefits of the
[[Page 43188]]
technology and increase the frequency of installation in heavy
vehicles. The agency granted this petition on October 16, 2015, noting
that NHTSA's research and evaluation were ongoing, and initiated a
rulemaking proceeding with respect to vehicles with a GVWR greater than
4,536 kg (10,000 lbs.).\38\
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\38\ Grant of petition for rulemaking, 80 FR 62487 (October 16,
2015).
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C. Congressional Interest
1. MAP-21
In July 2012, the Moving Ahead for Progress in the 21st Century Act
was enacted. MAP-21 included Subtitle G, the ``Motorcoach Enhanced
Safety Act of 2012.'' \39\ Section 32705 of MAP-21 directed the
Secretary (NHTSA, by delegation) to research and test forward and
lateral crash warning systems for motorcoaches and decide whether a
corresponding safety standard would accord with section 30111 of the
Safety Act. Section 32703(b)(3) directed the Secretary to consider
requiring motorcoaches to be equipped with stability enhancing
technology, such as electronic stability control, to reduce the number
and frequency of rollover crashes, and prescribe a standard if it would
meet the requirements and considerations of sections 30111(a) and (b)
of the Safety Act.\40\ In response, NHTSA issued FMVSS No. 136,
requiring ESC for certain truck tractors and buses (including
motorcoaches) with a GVWR greater than 13,154 kg (26,000 lbs.).
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\39\ Public Law 112-141, Sec. 32705.
\40\ Section 32703(b) required a regulation not later than two
years after the date of enactment of the Act if DOT determined that
such standard met the requirements of the Safety Act.
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2. Bipartisan Infrastructure Law
In November 2021, the Bipartisan Infrastructure Law (BIL) was
signed into law. Section 23010 of BIL is dedicated to AEB. Section
23010(a) of BIL defines an AEB system as a system on a commercial motor
vehicle that, based on a predefined distance and closing rate with
respect to an obstacle in the path of the vehicle, alerts the driver of
an obstacle and, if necessary, applies the brakes automatically to
avoid or mitigate a collision with that obstacle.
Section 23010(b) requires the Secretary to prescribe an FMVSS to
require all commercial motor vehicles \41\ subject to FMVSS No. 136 (or
a successor regulation) to be equipped with an AEB system. The FMVSS is
also required to establish performance standards for AEB systems. BIL
directs the Secretary to prescribe the standard not later than two
years after the date of enactment of the Act.
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\41\ As defined in 49 U.S.C. 31101, ``commercial motor vehicle''
means a self-propelled or towed vehicle used on the highways in
commerce principally to transport passengers or cargo, if the
vehicle has a gross vehicle weight rating or gross vehicle weight of
at least 10,001 pounds, whichever is greater; is designed to
transport more than 10 passengers including the driver; or is used
in transporting material found by the Secretary of Transportation to
be hazardous and transported in a quantity requiring placarding
under regulations.
---------------------------------------------------------------------------
Under Section 23010(b)(2), prior to prescribing the FMVSS, the
Secretary is required to conduct a review of AEB systems in use in
applicable commercial motor vehicles and address any identified
deficiencies in those systems in the rulemaking proceeding, if
practicable. In addition, the Secretary is required to consult with
representatives of commercial motor vehicle drivers to learn about
their experience with AEB (including malfunctions and/or unwarranted
activations).
This NPRM is issued to meet these provisions of the BIL. NHTSA
conducted a review of AEB systems in use in commercial motor vehicles
to identify limits in those systems. A memorandum summarizing this
review has been placed in the docket for this NPRM and has informed the
development of the proposal. NHTSA is also currently conducting
research to study drivers' experiences with collision mitigation
technologies, including AEB. Comments are requested on the feasibility
of mandating AEB for commercial motor vehicles with GVWR greater than
10,000 pounds which are not currently subject to FMVSS No. 136. This
NPRM requests comments from representatives of commercial motor vehicle
drivers, and drivers themselves, regarding the experience with the use
of AEB systems. This NPRM also includes a series of questions in
section VII.E on which NHTSA seeks comment to obtain information about
drivers' experiences with AEB (including malfunctions and/or
unwarranted activations).
Section 23010(c) of the BIL relates to the regulations of FMCSA,
which regulate the operation of commercial motor vehicles. BIL requires
an FMCSR ensuring that the AEB systems required by the FMVSS for new
commercial vehicles subject to FMVSS No. 136 be in use at any time
during which the vehicle is in operation. This NPRM proposes this
FMCSR.\42\
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\42\ FMCSA has also created an apprenticeship program for novice
drivers of commercial motor vehicles pursuant to the BIL. The
program requires novice drivers to operate vehicles that possess an
active braking collision mitigation system, such as AEB. 87 FR 2477,
January 14, 2022.
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Finally, section 23010(d) of BIL requires DOT to complete a study
on equipping a variety of commercial motor vehicles not currently
required to comply with FMVSS No. 136 with AEB. This study is to
include an assessment of the feasibility, benefits, and costs
associated with installing AEB on these vehicles. As discussed in
greater detail later, the analysis accompanying this NPRM fulfills this
requirement.
D. IIHS Effectiveness Study
In a 2020 report, the Insurance Institute for Highway Safety
studied the effectiveness of FCW and AEB technology on class 8 trucks
and concluded that safety will improve if more trucks have these
technologies installed.\43\ IIHS used data extracted from video camera
footage and crash rates of police-reportable crashes. While the study
sample did not contain a large number of severe crashes, FCW and AEB
were still associated with significant reductions in rear-end crashes
involving trucks. On average, between the time of collision and moment
of system intervention, the velocity of the striking vehicle was
reduced by greater than 50 percent. The study concluded that safety
would improve if more trucks had these technologies installed.\44\ The
IIHS study was limited to class 8 trucks and involved certain fleets
and drivers which may not necessarily be representative of the U.S.
fleet as a whole. Because of this limitation, NHTSA could not use the
findings to calculate the potential benefits of this proposal.
---------------------------------------------------------------------------
\43\ Teoh, Eric R. (2020, September). Effectiveness of front
crash prevention systems in reducing large truck crash rates.
Arlington, VA: Insurance Institute for Highway Safety. Available at
https://www.iihs.org/topics/bibliography/ref/
2211#:~:text=Results%3A%20FCW%20was%20associated%20with,%25%20for%20r
ear%2Dend%20crashes. (last accessed August 30, 2022).
\44\ Id.
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E. DOT's National Roadway Safety Strategy (January 2022)
This NPRM takes a crucial step in implementing DOT's January 2022
National Roadway Safety Strategy to address the rising numbers of
transportation deaths occurring on this country's streets, roads, and
highways.\45\ At the core of this strategy is the Department-wide
adoption of the Safe System Approach, which focuses on five key
objectives: safer people, safer roads, safer vehicles, safer speeds,
and post-crash care. The Department will launch new programs,
coordinate and improve existing programs, and adopt a
[[Page 43189]]
foundational set of principles to guide this strategy.
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\45\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf (last accessed August
23, 2022).
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The National Roadway Safety Strategy highlights new priority
actions that target our most significant and urgent problems and are,
therefore, expected to have the most substantial impact. One of the key
Departmental actions to enable safer vehicles is initiating a
rulemaking to require AEB on heavy trucks. This NPRM proposes a Federal
Motor Vehicle Safety Standard to require AEB on heavy trucks and other
heavy vehicles.
F. National Transportation Safety Board Recommendations
The National Transportation Safety Board (NTSB) included AEB for
commercial vehicles in its 2021-2023 Most Wanted List.\46\ Among other
things, NTSB stated that NHTSA should complete standards for AEB in
commercial vehicles and require this technology in all highway vehicles
and all new school buses.
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\46\ NTSB Most Wanted List, https://www.ntsb.gov/Advocacy/mwl/Pages/mwl-21-22/mwl-hs-04.aspx (last accessed August 23, 2022).
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In 2015, NTSB issued a special investigation report,\47\ which
summarized previous, as well as new, findings related to AEB in a
variety of vehicles. Regarding heavy vehicles, this report presented
the following recommendation to NHTSA:
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\47\ National Transportation Safety Board. 2015. The Use of
Forward Collision Avoidance Systems to Prevent and Mitigate Rear-End
Crashes. Special Investigation Report NTSB/SIR-15-01. Washington,
DC. Available at https://www.ntsb.gov/safety/safety-studies/Documents/SIR1501.pdf (last accessed August 22, 2022).
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H-15-05: Complete, as soon as possible, the development
and application of performance standards and protocols for the
assessment of forward collision avoidance systems in commercial
vehicles.
In a 2018 special investigation report,\48\ the NTSB discussed two
severe accidents involving school buses. In the conclusion of the
report, the NTSB stated that AEB could have helped mitigate the
severity of one of the accidents, and that ESC could have helped
mitigate the other. Accordingly, the following safety recommendations
were made or restated to NHTSA:
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\48\ National Transportation Safety Board. 2018. Selective
Issues in School Bus Transportation Safety: Crashes in Baltimore,
Maryland, and Chattanooga, Tennessee. NTSB/SIR-18/02 PB2018-100932.
Washington, DC. Available at https://www.ntsb.gov/investigations/AccidentReports/Reports/SIR1802.pdf (last accessed August 22, 2022).
---------------------------------------------------------------------------
H-18-08: Require all new school buses to be equipped with
collision avoidance systems and automatic emergency braking
technologies.
H-11-7: Develop stability control system performance
standards for all commercial motor vehicles and buses with a gross
vehicle weight rating greater than 10,000 pounds, regardless of whether
the vehicles are equipped with a hydraulic or a pneumatic brake system.
H-11-8: Once the performance standards from Safety
Recommendation H-11-7 have been developed, require the installation of
stability control systems on all newly manufactured commercial vehicles
with a gross vehicle weight rating greater than 10,000 pounds.
G. FMCSA Initiatives
FMCSA has been engaged in activities to advance the voluntary
adoption of AEB for heavy vehicles, primarily through the Tech-Celerate
Now (TCN) program. This program focuses on accelerating the adoption of
Advanced Driver Assistance Systems (ADAS), such as AEB, by the trucking
industry to reduce fatalities and prevent injuries and crashes, in
addition to realizing substantial return-on-investment through reducing
costs associated with such crashes for the motor carrier. Initiated in
September 2019 and completed in February 2022, the first phase of this
program encompassed research into ADAS technology adoption barriers; a
national outreach, educational, and awareness campaign; and data
collection and analysis.
Outreach accomplishments included development of training materials
for fleets, drivers, and maintenance personnel related to AEB
technology and return-on-investment (ROI) guides; educational videos on
ADAS braking, steering, warning, and monitoring technologies; a web-
based TCN ADAS-specific ROI calculator; four articles on ADAS
technologies; and a program website to host the training materials.
As part of the national outreach campaign, the program was promoted
on social media including LinkedIn and Twitter, and FMCSA conducted
presentations and booth exhibitions at conferences, webinars, and
virtual meetings. Recent efforts have included discussion of a safety
effective analysis project that is using two years of naturalistic data
collected from AEB and other ADAS technologies at the American Trucking
Associations Technology and Maintenance Council's 2022 Annual meeting,
the 2022 Midwest Commercial Vehicle Safety Summit, and the 2022
Southeast Commercial Vehicle Safety Summit. The results of this project
are expected be published late in calendar year 2023.
Planning is underway for the second phase of the TCN program, which
includes an expanded national outreach and education campaign,
additional research into the barriers to ADAS adoption by motor
carriers, and evaluation of the outreach campaign.
IV. NHTSA and FMCSA Research and Testing
A. NHTSA-Sponsored Research
The following are brief summaries of some of the research NHTSA
sponsored relating to strategies to avoid heavy vehicle collisions with
lead vehicles. The agency funded several research efforts to assess
collision avoidance systems, including AEB.
1. 2012 Study on Effectiveness of FCW and AEB
On August 2012, the University of Michigan Transportation Research
Institute (UMTRI) conducted a simulation study under a cooperative
agreement between NHTSA and AEB supplier WABCO.\49\ The objective of
the study was to estimate the safety benefits FCW and AEB systems
implemented on heavy trucks, including single-unit and tractor-
semitrailers. The study characterized technology, estimated a target
crash population, created a simulated reference crash database, and
assessed the impact of the technologies in a simulated environment.
These results were then applied to the target crash population. The
study not only simulated benefits for equipping heavy trucks with then-
available technology, but also simulated benefits for next and future
systems that were expected to have enhanced capabilities.
---------------------------------------------------------------------------
\49\ Woodrooffe, J., et al., ``Performance Characterization and
Safety Effectiveness Estimates of Forward Collision Avoidance and
Mitigation Systems for Medium/Heavy Commercial Vehicles,'' Report
No. UMTRI-2011-36, UMTRI (August 2012). Docket No. NHTSA-2013-0067-
0001, available at https://www.regulations.gov/document/NHTSA-2013-0067-0001.
---------------------------------------------------------------------------
The study simulated estimates based on next and future systems that
would utilize radar as the main sensor, and provided haptic, auditory,
and visual warnings to the driver (just as the current in-production
system). The in-production system could decelerate the vehicle up to a
maximum of 0.35g without any driver intervention. However, it could not
react to fixed objects (i.e., objects that were stationary before they
were in the range of the radar). The primary improvements expected for
the next system included the ability to react and brake at about 0.3g
in response to fixed objects and increased braking control authority on
stopped and moving vehicles to engage
[[Page 43190]]
the foundation brakes to produce as much as 0.6g of longitudinal
deceleration. The study used the same increased control authority on
stopped and moving vehicles as the next generation system, but required
the system to more aggressively react to fixed objects with
longitudinal deceleration of up to 0.6g.
Based on these capabilities, the study estimated that equipping all
tractor-semitrailers with AEB and FCW would reduce fatalities relative
to the base population for current, next, and future generation systems
by 24, 44, and 57 percent, respectively. Additionally, the predicted
reduction in injuries compared to the base population for current,
next, and future generation systems was estimated at 25, 47, and 54
percent, respectively. The combined annual benefit for straight truck
and tractor semitrailers, including property damage reduction for
current, next, and future generation systems was estimated at $1.4,
$2.6, and $3.1 billion, respectively.
The study concluded with multiple observations. The enhancements
depicted by the next generation system in comparison to the current
generation system were substantially larger than when comparing the
next generation to the future generation. These improvements were due
mainly to the ability of the system to react to fixed vehicles and the
increased braking. Overall, this evaluation depicted that the collision
mitigation measures studied would achieve significant benefits.
2. 2016 Field Study
NHTSA sponsored a field study with the Virginia Tech Transportation
Institute (VTTI) to assess the performance of heavy-vehicle crash
avoidance systems using 150 Class 8 tractor-trailers.\50\ The vehicles
were each equipped with a collision avoidance system from one of two
companies that included AEB and FCW. The purpose of the study was to
evaluate system reliability, assess driver performance over time,
assess overall driving behavior, provide data on real-world conflicts,
and generate inputs to a safety benefits simulation model.
---------------------------------------------------------------------------
\50\ See ``Field Study of Heavy-Vehicle Crash Avoidance
Systems'' (June 2016), available at https://www.nhtsa.gov/sites/nhtsa.gov/files/812280_fieldstudyheavy-vehiclecas.pdf (last accessed
June 3, 2022).
---------------------------------------------------------------------------
The vehicles were operated by drivers for one year with a total of
over 3 million miles travelled. Each vehicle was equipped with a data
acquisition system that collected roadway-facing video, driver-facing
video, activations, and vehicle network data. About 85,000 hours of
driving and 885,000 activations were collected across all activation
types. Of the sampled 6,000 activations, 264 were AEB activations and
1,965 were impact alerts.
According to the study, safety benefits of collision avoidance
systems could be estimated based on data describing driver use of
systems and their responses to the activations. Since the systems
depict warnings through an audio and visual display, a precise model of
the benefits would show how fast drivers react and if reactions vary
based on warning type. For 84 percent of the AEB activations, the
driver reacted prior to the alert, and 13 percent of the time, the
driver responded to the alert. Drivers did not respond to 3 percent of
the AEB activations. Over 50 percent of the false AEB activations
received driver responses. Average driving speeds and headway distances
at the initiation of AEB activations prior to safety-critical events
were similar to values recorded for other activations. While at the
initiation of many warranted AEB activations, drivers had already
implemented braking, every warranted AEB activation did not receive a
driver reaction.
The analysis included a driver frustration assessment for each AEB
activation. This was a subjective assessment based on whether drivers
appeared to show frustration during an activation. Advisory warnings
resulted in lower percentages of general frustration. The highest
instances of frustration were noted during false activations with
frustration noted 11 percent of the time.
In summary, the study found that crash avoidance systems can be
effective in collision avoidance. Driver performance and behavior
exhibited almost no changes over time, and there was limited
frustration with the AEB activations. There were some limitations in
the study including varied calibration options between the systems, no
control group, different geographical locations, and unequal driving
time amongst participants.
3. 2017 Target Population Study
In 2017, NHTSA completed a study on a target population for AEB in
vehicles with a GVWR over 4,536 kg (10,000 pounds).\51\ The objective
of the study was to determine which forward collisions would
theoretically benefit from AEB if all vehicles over 4,536 kg (10,000
pounds) GVWR were equipped with the system. First, NHTSA reviewed
literature for then-existing AEB systems manufactured by Bendix and
Meritor. Although the systems varied in some ways, they shared a tiered
functionality approach, including the sequential use of auditory and
visible warnings, automatic torque reduction, application of the engine
retarder, and finally automatic brake application as needed.\52\ The
research efforts concentrated on the FCW and CIB elements.
---------------------------------------------------------------------------
\51\ See ``A Target Population for Automatic Emergency Braking
in Heavy Vehicles,'' available at https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390 (last accessed June 7, 2022).
\52\ See page 8 ``A Target Population for Automatic Emergency
Braking in Heavy Vehicles,'' available at https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390 (last
accessed June 7, 2022).
---------------------------------------------------------------------------
Second, collisions were sampled from NHTSA and FMCSA's Large Truck
Crash Causation Study \53\ for an engineering review because this
database provides comprehensive information on heavy vehicle collisions
in the United States. The engineering review focused on 29 crashes from
the Large Truck Crash Causation Study that involved injuries and
fatalities to determine whether FCW and/or CIB would be effective in
preventing the crash. Effectivity was defined as both reviewing
engineers determining that there was a 50 percent chance or greater
that the crash would be prevented. The analysis determined that FCW and
CIB would both be effective in preventing 17 of the 29 crashes, much
more often than cases in which only either was effective or neither was
effective. Considering a summary of the weighted effectiveness, the
combination of FCW and CIB were effective in 50 percent of the cases.
While FCW alone was effective in 23 percent of cases, there was a
significant 21 percent of cases where neither FCW nor CIB was
effective.\54\
---------------------------------------------------------------------------
\53\ See ``Large Truck Crash Causation Study,'' available at
https://www.fmcsa.dot.gov/safety/research-and-analysis/large-truck-crash-causation-study-analysis-brief (last accessed October 19,
2022).
\54\ Additionally, there was at least one case that consensus
was not reached regarding the effectiveness of CIB, and there was no
investigation of crashes of lower severity where only property
damage resulted.
---------------------------------------------------------------------------
Third, the outcomes from the first two phases allowed for the
development of filters to identify the categories of collisions that
AEB would improve. These filters were then implemented to collisions in
NHTSA's crash databases to approximate how many collisions annually AEB
could have prevented. A combination of data from the FARS and the GES
was used for the calculations while ensuring that an overlap in fatal
crashes was removed to prevent duplicate tallies. Vehicle collision
information for the United States
[[Page 43191]]
involving injuries and fatalities for years 2010 to 2012 was utilized
from these databases.\55\ Both injury-related and fatal collisions
totaled 5,457,387, and this total was filtered to determine the target
population. The filtering exclusions were made cautiously in order to
yield a conservative benefit estimate. Crashes during which the subject
vehicle departed from its original travel lane and the lead vehicle
maintained the lane were not included. Similarly, collisions involving
the lead vehicle changing from the original lane and the subject
vehicle remaining in its lane were excluded. Additional exclusions
included collisions on icy and snowy roads, situations where the lead
vehicle turns from a perpendicular street in front of the subject
vehicle, cases involving acceleration maneuvers to avoid collision,
collisions where the lead vehicle was obscured by an object, collisions
into motorcycles, and cases where the subject vehicle was traveling on
a curved road toward an object such as a guardrail.
---------------------------------------------------------------------------
\55\ LTCCS was not selected due to the age of the crash data,
for it is possible heavy vehicle collisions differ tremendously
since 2001. The UMTRI Trucks Involved in Fatal Accidents study
(https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107389/48532_A56.pdf?isAllowed=y&sequence=1, last accessed June 3, 2022)
was excluded because its detailed information regarding vehicle
style and driving time is only provided for collisions involving
fatalities, where data for collisions of less severity involving
only injuries would not be available.
---------------------------------------------------------------------------
Fourth, the target population estimated in the third phase was
modified to reflect recent and probable future regulations. This
modification eliminated collisions that would be avoided based on the
implementation of other required technologies that had not yet
completely proliferated in heavy vehicles. Accounting for safety
equipment including ESC, ABS, and speed limiters allowed for the
overall target population to be modified to reflect the anticipated
number of future collisions. Crashes that were included in the final
future target population were those involving heavy vehicles in which
the rear-end crash resulted in injuries and fatalities. Further, the
crashes were refined to include only crashes where both vehicles
remained in the original lane after the crash was deemed imminent and
collisions where lane changes prior to crash imminency were allowed as
long as only one of the vehicles changed lanes. Additionally,
situations where the driver attempted to steer around the collision or
used insufficient braking were included.
After all adjustments were completed, the study estimated a target
population of 11,499 crashes annually involving 7,703 injured persons
and 173 fatalities. It also discussed possible sampling error as well
as three sources of uncertainty. However, the size of a target
population provided only an estimated upper bound to the benefits at
that time. The report added value in the detailed descriptions of
affected crashes and subpopulation breakouts that have traditionally
fed into benefits estimation.
4. 2018 Cost and Weight Analysis
In 2018, Ricardo Inc. completed a study sponsored by NHTSA that
focused on the cost and weight implications of requiring AEB on heavy
trucks. The study aimed to determine the product price, total system
cost, incremental consumer price, and weight of FCW and AEB systems on
heavy trucks to provide insight into the safety and efficiency benefits
of using the systems.\56\ The initial steps of the study were vehicle
research, vehicle segregation, and vehicle selection. Model year 2015-
2018 heavy vehicles manufactured by Ford, Cascadia, Volvo, Daimler, and
International LT were chosen for teardown examination and ranged in
mean annual sales from approximately 24,000 to 86,542. The associated
FCW and AEB systems installed on these vehicles were manufactured by
Delphi Technologies, Meritor, Bendix Commercial Vehicle Systems, and
Detroit Assurance (Daimler).
---------------------------------------------------------------------------
\56\ Ricardo, Inc. (2018), ``Cost and Weight Analysis of Heavy
Vehicle Forward Collision Warning (FCW) and Automatic Emergency
Braking (AEB) Systems for Heavy Trucks'' Van Buren Township, MI.
---------------------------------------------------------------------------
Service technician consultations, manuals, and OEM parts
descriptions were used to itemize components of the FCW and AEB
systems. Specific assessments of the related displays, sensors,
mounting hardware, and other elements of the FCW and AEB systems were
provided to prevent extraneous parts from being included in the cost
and weight evaluations. The cost and weight evaluations were executed
by a group of automotive system and integration experts, cost modeling
specialists, and procurement personnel. A bill of materials was
compiled using a ``teardown'' process to inventory the parts, define
manufacturing processes, and ascertain materials utilized. Specialized
cost software allowed for calculation of cost and weight.
In general, components that were not distinct to the FCW and AEB
systems were not included in the cost and weight evaluation. Therefore,
shared parts such as electronic control units and wiring harnesses were
not considered as additions if they were already incorporated into the
vehicle configuration without FCW/AEB. The manufacturing costs were
estimated, factoring in research and development, labor, material
costs, machinery, machine occupancy and tooling.
The five selected vehicles were the Ford F-Series Super Duty,
Freightliner M2-106, Freightliner Cascadia, International LT, and Volvo
VNL. While there was some overlap of similar components, the FCW and
AEB systems in the five selected vehicles had substantial variation
amongst the system mechanisms and functionality. Based on these
differences the vehicles were separated into four groups, and the
average manufacturing costs and weights were assessed for each
category. Overall, the average incremental cost to manufacturers for
these FCW/AEB systems ranged from $44.23 to $197.51; and associated
end-user prices ranged from $70.80 to $316.18. Additionally, the
average incremental weights ranged from approximately 0.46 to 3.10 kg.
B. VRTC Research Report Summaries and Test Track Data
1. Relevance of Research Efforts on AEB for Light Vehicles
AEB was first introduced on light vehicles. For this reason,
NHTSA's research and testing of AEB systems began with light vehicles
and was subsequently used to inform NHTSA's work on heavy vehicle AEB.
NHTSA conducted extensive research on AEB systems to support
development of the technology and eventual deployment in vehicles.
There were three main components to this work. Early research was
conducted on FCW systems that warn drivers of potential rear-end
crashes with other vehicles. This was followed by research into AEB
systems designed to prevent or mitigate rear-end collisions through
automatic braking.
NHTSA's earliest research on FCW systems began in the 1990s, at a
time when the systems were under development and evaluation had been
conducted primarily by suppliers and vehicle manufacturers. NHTSA
collaborated with industry stakeholders to identify the specific crash
types that an FCW system could be designed to address, the resulting
minimum functional requirements, and potential objective test
procedures for evaluation.\57\ In the late 1990s, NHTSA
[[Page 43192]]
worked with industry to conduct a field study, the Automotive Collision
Avoidance System Program. NHTSA later contracted with the Volpe
National Transportation Systems Center (Volpe) to conduct data analyses
of data recorded during that field study.\58\ From this work, NHTSA
learned about the detection and alert timing and information about
warning signal modality (auditory, visual, etc.) of FCW systems, and
predominant vehicle crash avoidance scenarios where FCW systems could
most effectively play a role in alerting a driver to brake and avoid a
crash. In 2009, NHTSA synthesized this research in the development and
conduct of controlled track test assessments on three vehicles equipped
with FCW.\59\
---------------------------------------------------------------------------
\57\ This research was documented in a report, ``Development and
Validation of Functional Definitions and Evaluation Procedures for
Collision Warning/Avoidance Systems,'' Kiefer, R., et al., DOT HS
808 964, August 1999. Additional NHTSA FCW research is described in
Zador, P.L., et al., ``Final Report--Automotive Collision Avoidance
System (ACAS) Program,'' DOT HS 809 080, August 2000; and Ference,
J.J., et al., ``Objective Test Scenarios for Integrated Vehicle-
Based Safety Systems,'' Paper No. 07-0183, Proceedings of the 20th
International Conference for the Enhanced Safety of Vehicles, 2007.
\58\ Najm, W.G., Stearns, M.D., Howarth, H., Koopmann, J., and
Hitz, J., ``Evaluation of an Automotive Rear-End Collision Avoidance
System,'' DOT HS 810 569, April 2006 and Najm, W.G., Stearns, M.D.,
and Yanagisawa, M., ``Pre-Crash Scenario Typology for Crash
Avoidance Research,'' DOT HS 810 767, April 2007.
\59\ Forkenbrock, G., O'Harra, B., ``A Forward Collision Warning
(FCW) Program Evaluation, Paper No. 09-0561, Proceedings of the 21st
International Technical Conference for the Enhanced Safety of
Vehicles, 2009.
---------------------------------------------------------------------------
NHTSA's research and test track performance evaluations of AEB
began around 2010. The agency began a thorough examination of the state
of forward-looking advanced braking technologies, analyzing their
performance and identifying areas of concern or uncertainty, to better
understand their safety potential. NHTSA issued a report \60\ and a
request for comments (RFC) seeking feedback on its CIB and DBS research
in July 2012.\61\ Specifically, NHTSA wanted to enhance its knowledge
further and help guide its continued efforts pertaining to AEB
effectiveness, test operation (including how to ensure repeatability
using a target or surrogate vehicle), refinement of performance
criteria, and exploration of the need for ``false positive'' tests to
minimize the unintended negative consequences of automatic braking in
non-critical driving situations where a crash was not imminent.
---------------------------------------------------------------------------
\60\ The agency's initial research and analysis of CIB and DBS
systems were documented in a report, ``Forward-Looking Advanced
Braking Technologies: An analysis of current system performance,
effectiveness, and test protocols'' (June 2012). https://www.regulations.gov, NHTSA 2012-0057-0001.
\61\ 77 FR 39561.
---------------------------------------------------------------------------
NHTSA considered feedback it received on the RFC and conducted
additional testing to support further development of the test
procedures. The agency's work was documented in two additional reports,
``Automatic Emergency Braking System Research Report'' (August 2014)
\62\ and ``NHTSA's 2014 Automatic Emergency Braking (AEB) Test Track
Evaluations'' (May 2015),\63\ and in accompanying draft CIB and DBS
test procedures.\64\
---------------------------------------------------------------------------
\62\ https://www.regulations.gov, NHTSA 2012-0057-0037.
\63\ DOT HS 812 166.
\64\ https://www.regulations.gov, NHTSA 2012-0057-0038.
---------------------------------------------------------------------------
In 2016, NHTSA published a report identifying the most recurrent
AEB-relevant pre-crash scenarios for heavy vehicles. NHTSA identified
the three most recurrent situations as a heavy vehicle moving toward a
stopped lead vehicle, a heavy vehicle moving toward a slower moving
lead vehicle, and a heavy vehicle moving toward a lead vehicle that is
decelerating.\65\ These were the same three crash scenarios that had
been identified as the most prevalent AEB-relevant crash scenarios for
light vehicles.
---------------------------------------------------------------------------
\65\ Boday, C., et al., ``Class 8 Truck-Tractor and Motorcoach
Forward Collision Warning and Automatic Emergency Braking Test Track
Research--Phase I,'' Washington, DC: National Highway Traffic Safety
Administration (June 2016). Docket No. NHTSA[hyphen]2015-0024-0004.
---------------------------------------------------------------------------
2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach
In 2016, NHTSA published its first report on track-testing of AEB
for heavy vehicles. The previous studies describing the test procedures
for light vehicles provided a framework for the establishment of heavy
vehicle test procedures. Since test procedures were not yet developed
for heavy vehicles, the goal of the research was to first adapt
existing testing protocols for light vehicle AEB and then follow these
adapted test procedures to quantify the performance of FCW and AEB
systems on heavy vehicles. The research was conducted in two phases.
NHTSA's Phase I work began with using a combination of the specific
test situations established for NHTSA's NCAP for assessment of FCW and
AEB systems and a modified version of the light vehicle test procedures
to create heavy vehicle draft research test procedures. NCAP tests
involved use of a strikable surrogate vehicle; however, for early heavy
vehicle Phase I work, NHTSA used a surrogate lead vehicle comprised of
canvas-covered foam to exhibit geometric and reflective features of the
rear of a passenger car. The testing for Phase I was performed with
four heavy vehicles outfitted with FCW and AEB, including three Class 8
truck-tractors and one Class 8 motorcoach. Specifically, the four Class
8 vehicles were a 2006 Volvo VNL 64T630 6x4 tractor, a 2006
Freightliner Century Class 6x4 tractor, a 2012 Freightliner Cascadia
6x4 tractor, and a 2007 MCI 56-passenger motorcoach (bus). Each vehicle
was equipped with ABS, ESC, FCW, and AEB systems. The 2006 and 2012
Freightliners and the MCI motorcoach employed a Meritor WABCO system,
and the 2006 Volvo was equipped with a Bendix Wingman Advanced system.
In general, the FCW and AEB systems utilized a front bumper mounted
sensor to detect objects in front of the vehicle and a display to warn
the driver with audio and visual alerts.
For each vehicle, NHTSA planned to run ten tests that are
summarized in Table 8. These situations covered the three most common
AEB-relevant pre-crash scenarios, as well as two false positive tests
and two tests performed at different weighted conditions.
Table 8--Phase I Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Lightly loaded Loaded at GVWR
Scenario speed (km/h) speed (km/h) (number of trials) (number of trials)
----------------------------------------------------------------------------------------------------------------
Lead vehicle Stopped................. 0 40 10 ..................
Lead Vehicle Moving.................. 16 40 10 10
Lead Vehicle Moving.................. 32 72 10 10
Lead Vehicle Decelerating............ 40 40 10 10
Lead Vehicle Decelerating............ 48 48 .................. 10
Lead Vehicle Decelerating............ 56 56 5 5
Steel Trench Plate False Positive.... N/A 40 5 5
[[Page 43193]]
Steel Trench Plate False Positive.... N/A 72 5 5
----------------------------------------------------------------------------------------------------------------
The test scenarios were defined by the initial speeds of the
subject vehicle and lead vehicle, and the starting headway distance
between the vehicle was monitored. For all the tested scenarios, the
test driver was instructed to modulate the accelerator pedal to
maintain the desired test speed until FCW initiated, upon which the
accelerator pedal input was removed. Steering was applied to maintain
lateral position test tolerances to the lead vehicle. Manual brake
pedal applications were only applied in certain scenarios where AEB was
not designed to activate, or an impact occurred with the leading
surrogate vehicle. Additionally, the previously described test
situations were conducted under both a lightly loaded condition and a
fully loaded vehicle weight condition (i.e., loaded up to the vehicle's
GVWR). Based upon potential damage to the subject vehicle, the
feasibility of completing each test scenario with the specific load,
and the fact that there was no discernable difference between the
performance under the lightly loaded and GVWR loaded conditions in the
trials executed, some of the speed combinations were not investigated
under both loads. The false positive tests were conducted by driving
the selected vehicles toward and over a steel trench plate to determine
if these commonly used road construction covers would trigger false
alerts or unintentional automatic braking.
Stationary lead vehicle testing was limited to the 2006 Volvo, as
it was equipped with the only system that would trigger an FCW on
stationary vehicles. At the time these evaluations were performed, none
of the systems tested were designed to activate AEB on stationary
vehicles. During every slower moving lead vehicle test, FCW was
activated. Additionally, every vehicle's AEB activated and avoided
collision during each slower moving test performed with a subject
vehicle speed of 40 km/h, and a lead vehicle speed of 16 km/h.
The lead vehicle decelerating test was used to evaluate all four
heavy vehicles, but multiple test adjustments had to be applied. For
the lead vehicle decelerating test performed with both the subject and
lead vehicle speeds of 40 km/h, the lead vehicle was slowed to 8 km/h
instead of a stop to account for the failure of the subject vehicles to
activate AEB for stopped vehicles. Once the change was implemented,
both the FCW and the AEB systems were activated, and speeds were
reduced. Collisions between the subject and lead vehicle did occur, but
testing of this scenario mainly led to the observation that the test
procedure's headway would also have to be adjusted since heavy vehicles
have different braking capabilities than light vehicles.
The steel trench plate false positive test was performed using the
2006 Volvo, 2006 Freightliner, and 2007 MCI at 40 km/h and 72 km/h.\66\
For both velocities examined, the 2006 Freightliner and 2007 MCI
exhibited no false positives in all five trials. However, the 2006
Volvo triggered unnecessary auditory warnings in all five trials for
both velocities. None of the false positive testing trials resulted in
AEB system activation.
---------------------------------------------------------------------------
\66\ The 2012 Freightliner was not evaluated with steel trench
plate scenario due to the short window that the vehicle was
available for testing.
---------------------------------------------------------------------------
During this early testing, the surrogate lead vehicle was towed
onto the test track and fixed laterally in the test lane via a low-
profile plastic monorail track. Initially, the test system employed a
low-stretch rope to pull the surrogate lead vehicle by a tow vehicle.
This configuration performed well in the slower moving lead vehicle
situation because the lead vehicle moves at a constant velocity,
allowing the tow rope to stay in tension. In contrast, when testing the
lead vehicle decelerating scenario, the tension in the tow rope was not
maintained once the tow vehicle decelerated, and subsequently the tow
rope was prone to becoming stuck under the surrogate lead vehicle. This
issue resulted in a loss of surrogate lead vehicle lateral stability
and consequently decreased the test repeatability.
To address this shortcoming, the foam surrogate lead vehicle was
replaced with a vertical cylinder wrapped with a layer of radar
reflective material secured to the top of a movable platform with more
consistent and stable deceleration properties. However, because the
cylinder was not representative of a real vehicle, this was identified
as needing further development and modification of the test protocols.
A significant portion of this early AEB testing focused on
developing draft research test procedures that could be used to safely
and objectively assess AEB performance. The development history of test
protocols is important for two reasons. First, it explains how NHTSA
came to the conclusion to propose the performance parameters described
in the notice and its basis that the performance requirements are
objective and practicable. Second, it provides some context as to some
of the limitations of early performance evaluations of AEB for heavy
vehicles. In general, this initial phase of research demonstrated that
the scenarios were generally repeatable and practical, and the tests
showed additional development would potentially result in better
controlled deceleration and stability of the lead vehicle.
3. Phase II Testing of Class 8 Truck-Tractors
NHTSA's primary objectives of the Phase II efforts were to continue
to develop the FCW and AEB test procedures executed in Phase I such
that they could be effectively utilized on a closed-course track test
to assess performance of heavy vehicle FCW and AEB systems. For this
testing, NHTSA used four Class 8, truck-tractors, three of which were
from Phase I. The fourth vehicle from Phase I, the MCI motorcoach, was
replaced with a 2016 Freightliner. Specifically, these subject vehicles
were a 2016 Freightliner, a 2012 Freightliner, a 2006 Volvo, and a 2006
Freightliner. Like in Phase I, all vehicles were outfitted with ABS,
ESC, FCW, and AEB systems. Both the 2006 and 2012 Freightliners
employed the Meritor WABCO system, the 2016 Freightliner had the
Detroit Assurance Safety System, and the 2006 Volvo utilized the Bendix
Wingman Advance system. All AEB systems on the selected vehicles
utilized radar installed on the front bumper and each AEB system
provided auditory and visual alerts. For Phase II testing, NHTSA used
the test scenarios from Phase I; however, a second false positive test
scenario was added. Specifically, NHTSA investigated a pass-through
test from
[[Page 43194]]
Europe's AEB requirements \67\ involving a subject vehicle being driven
in a central lane between two parked vehicles.
---------------------------------------------------------------------------
\67\ United Nations, ``Uniform provisions concerning the
approval of motor vehicles with regard to the Advanced Emergency
Braking Systems (AEBS)'' 2013. Available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R131e.pdf (last accessed
February 10, 2023).
---------------------------------------------------------------------------
While other standards \68\ were considered for this research study,
the use of United States collision data and different testing goals led
to establishment of specific test procedures. While vehicle test speeds
were similar, with some overlap, NHTSA's test procedures included
higher velocity tests to be executed at 55 km/h with more
specifications governing the test conditions and test completion.
NHTSA's Phase II test scenario matrix is summarized in Table 9.
---------------------------------------------------------------------------
\68\ The following were among the standards considered:
International Organization for Standardization (ISO) 22839:2013,
``Intelligent transport systems--Forward vehicle collision
mitigation systems--Operation, performance, and verification
requirements; ISO 15623:2013, ``Intelligent transport systems--
Forward vehicle collision warning systems--Performance requirements
and test procedures,'' and SAE International recommended practice
J3029, ``Forward collision warning and mitigation vehicle test
procedure--Truck and bus.''
---------------------------------------------------------------------------
Phase II also further enhanced the testing of Phase I by
implementing a new strikable surrogate vehicle (SSV) system as the lead
vehicle. The SSV system was created for NHTSA's light vehicle AEB
assessment and was engineered to enhance test repeatability and lateral
stability in higher velocity tests.
Table 9--Phase II Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Lightly loaded Loaded at GVWR
Scenario speed (km/h) speed (km/h) (number of trials) (number of trials)
----------------------------------------------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 40 6 8
Lead Vehicle Moving.................. 0 40 8 8
Lead Vehicle Moving.................. 35 75 8 8
Lead Vehicle Decelerating............ 40 40 8 8
Lead Vehicle Decelerating............ 55 55 6 or 8 6 or 8
Steel Trench Plate False Positive.... N/A 40 8 8
Steel Trench Plate False Positive.... N/A 75 8 8
Stationary Vehicle False Positive.... N/A 50 8 8
----------------------------------------------------------------------------------------------------------------
The SSV served as the lead vehicle or the vehicle test device (VTD)
in the AEB tests. The rear of the SSV was designed to depict features
of a typical passenger car. The carbon fiber surrogate exemplified
these aspects, considering physical measurements, reflective
properties, and visual characteristics. Its structure was not only
developed to be detected as a real vehicle by the AEB systems, but it
was also intended to endure wind gusts and recurrent impacts up to
approximately 40 km/h. The required surrogate test velocities and
deceleration of the VTD were achieved by a tow vehicle equipped with a
brake controller in conjunction with a towed two-rail track used to
move the SSV during the test.
NHTSA implemented changes in the test procedures from Phase I to
Phase II. The Phase II test procedures contained more detail as input
from within NHTSA and data collected during both phases of heavy
vehicle research were used to develop and refine the procedures. For
example, the test procedures contained structure for test scenario
descriptions, minimum data channels to collect, and general testing
requirements (e.g., ambient temperature range, wind, speed, brake
burnish, etc.). Definitions were added for when the initial test
conditions started, and more detail was added to the definition of when
a test trial ended. The test conditions were established to be on dry,
straight roadways in the daylight, based on a previous analysis of
crash data and observed safety critical events in field operation
testing. FCW activation, AEB activation, collision detection, and
accelerator pedal release time were measured in the tests. Similar to
Phase I, the testing of each scenario occurred under two different load
conditions.
After reviewing the Phase I test outcomes, NHTSA determined that
the lead vehicle stopped scenario could only be assessed by the latest
model year test vehicle outfitted with a capable AEB system. In Phase
II, the subject vehicle traveled 40 km/h and approached a stationary
lead vehicle in the same lane. Valid trials required the driver to
remain centered in the traveling lane and continue driving at the
target velocity until AEB was triggered. Once AEB was triggered, the
test driver fully released the accelerator pedal, and the driver was
not allowed to use the brake pedal of the test vehicle unless the
vehicle collided with the lead vehicle or if the AEB system completely
stopped the vehicle. The results showed that FCW was activated,
followed by automatic braking by the AEB system in all 8 trials
performed under the GVWR condition.
The lead vehicle moving test situation was evaluated at multiple
velocity combinations for all four test vehicles. During this test, the
subject test vehicle traveled at 40 km/h or 75 km/h and approached a
slower-moving lead vehicle traveling at 15 km/h or 35 km/h,
respectively, in the same lane. Valid trials required the driver to
remain centered in the traveling lane and continue driving at the
target velocity until AEB was triggered. Once AEB was triggered, the
test driver fully released the accelerator pedal. Testing for this
scenario was conducted for both lightly loaded and GVWR conditions. All
of the vehicles tested consistently issued FCW alerts and activated the
AEB systems; however, impacts occurred.
The lead vehicle decelerating situation was executed with all the
test vehicles except the 2006 Volvo due to its Phase I performance. Two
initial velocity and initial headway combinations of the subject and
lead vehicles were tested (i.e., 40 km/h and 80 m; 55 km/h and 23 m).
After a short period of steady state driving using constant speeds and
a constant headway, the lead vehicle was braked at approximately 0.3g
while traveling in the same lane as the subject vehicle. The subject
vehicle driver kept the subject vehicle centered in the traveling lane
and continued driving until AEB was triggered. Under both the lightly
loaded and GVWR load conditions testing was completed.
The lead vehicle decelerating test scenario with initial test
speeds of 55 km/h and 23 m of headway presented the greatest challenges
when compared to other tests. In Phase II, the initial headway was
changed from 30.5 m to 23
[[Page 43195]]
m to keep the lead vehicle from transitioning to a stopped lead vehicle
test scenario near the end of a test trial, as it did in Phase I
testing with a headway of 30.5 m. Testing for this scenario was
conducted for both lightly loaded and GVWR conditions and all four
vehicles. All of the vehicles consistently issued FCW alerts and
activated the AEB systems; however, most tests resulted in impact.
Two false positive test types were also conducted. The steel trench
plate scenario was executed at 40 km/h and 75 km/h for all test
vehicles. Each vehicle was evaluated in the GVWR load condition, but
only the 2016 Freightliner was also assessed in the lightly loaded
condition. Most of the vehicles did not exhibit any FCW or AEB
activations in these tests. However, one vehicle's FCW/AEB system
perceived the steel trench plate as a stationary object on the path of
travel and the reaction to this false positive detection was not
consistent in terms of warning time, brake initiation time, and
deceleration level. The second test involved two stationary vehicles in
lanes on either side of the test vehicle's travel lane; and only the
2012 Freightliner and the 2016 Freightliner were evaluated under the
GVWR load condition. Neither vehicle exhibited any false FCW or AEB
activations in this test.
Overall, the Phase II test results demonstrated the ability of the
vehicles and AEB systems tested to avoid contact in the lead vehicle
stopped and lead vehicle moving test scenarios at the different
velocities and achieve no collisions. These capabilities extended to
the lead vehicle decelerating tests performed at 40 km/h and a headway
of 80 m. In contrast, there was a much lower likelihood of these
vehicles avoiding contact with the lead vehicle using an initial speed
of 55 km/h and a headway of 23 m.
4. NHTSA's 2018 Heavy Vehicle AEB Testing
NHTSA conducted test track research in 2017 and 2018 on heavy
vehicles equipped with FCW and AEB. This section describes the third
phase of NHTSA's heavy vehicle testing and the results from three
single-unit trucks. These trucks included a class 3 2016 Freightliner
3500 Sprinter, a class 6 2017 International 4300 SBA 4x2, and a class 7
2018 Freightliner M2-106. The main goal of this third phase was to
develop objective test procedures for evaluating the performance of
heavy vehicles equipped with FCW and AEB systems on a closed course
test track.
Table 10--Phase III Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Initial
Scenario speed (km/h) speed (km/h) headway (m)
----------------------------------------------------------------------------------------------------------------
Lead Vehicle Stopped............................................ 0 40 55
Lead Vehicle Moving............................................. 15 40 35
Lead Vehicle Moving............................................. 35 75 56
Lead Vehicle Decelerating....................................... 40 40 80
Lead Vehicle Decelerating....................................... 55 55 23
Steel Trench Plate False Positive............................... N/A 40 56
Steel Trench Plate False Positive............................... N/A 75 105
Stationary Vehicle Pass-Through False Positive.................. N/A 50 60
----------------------------------------------------------------------------------------------------------------
In this third phase of research, the newly developed heavy vehicle
AEB test procedures included test conditions where the driver applies
the subject vehicle brakes while approaching a lead vehicle, but with
an input insufficient to prevent a rear-end crash, to complement the
previously developed scenarios.
The 2017 International 4300 was outfitted with a Bendix system
which includes FCW and AEB. This system was enhanced since Phase II of
NHTSA's research where, in Phase III, it used camera and radar to
engage automatic emergency braking and demonstrated the ability to
respond to traveling and stationary vehicles. The FCW provided alerts
at velocities greater than 8 and 15 km/h for moving and stationary
objects, respectively. For the AEB system to be engaged, the vehicle
had to travel above 25 km/h.
The 2018 Freightliner M2-106 was outfitted with an OnGuardACTIVE
Collision Mitigation system which features FCW and AEB. This system
used radar to engage automatic emergency braking and displayed the
ability to respond to traveling and stationary vehicles. The FCW
provided alerts with visual and auditory cues and a braking warning was
issued when the AEB was activated. In order for the AEB system to be
engaged, the vehicle had to travel above 25 km/h.
The study concluded that the test procedures were reproducible and
appropriate for heavy vehicles outfitted with FCW and AEB systems.
After Phase II, the test procedures and scenarios were updated and
applied to heavy vehicles with different weight classifications. The
inclusion of heavy vehicles with updated AEB systems in Phase III
allowed for evaluation of more systems in the lead vehicle stopped
scenario; during the lead vehicle stopped evaluations with no driver
braking, at least one vehicle experienced no collisions for all trials
tested. This showed improvement in comparison to the prior phase, which
was only able to test lead vehicle stopped on one vehicle and resulted
in multiple collisions. The lead vehicle moving scenario test results
also displayed improvement where the percentage of collisions decreased
in comparison to Phase II. Overall, the outcomes showed that the FCW/
AEB systems have the capacity for being able to decrease rear-end
collisions by exhibiting velocity reductions before a collision or
avoiding contact with a lead vehicle entirely. While some FCW false
positives were observed, the overall results depicted that the systems
have the ability to avoid collision on the test track.
The results of this research show that the test procedures are
applicable to many heavy vehicles and indicate that performance
improvements in heavy vehicles equipped with these safety systems can
be objectively measured.\69\ Further, this was the first phase of the
series that was able to apply the test procedures to single-unit trucks
across multiple weight classifications; and new test scenarios were
added.
---------------------------------------------------------------------------
\69\ Salaani, M.K., Elsasser, D., Boday, C., ``NHTSA's 2018
Heavy Vehicle Automatic Emergency Braking Test Track Research
Results,'' SAE International. J Advances & Current Practices in
Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-1001.
---------------------------------------------------------------------------
5. NHTSA's Research Test Track Procedures
NHTSA's most recently published heavy vehicle AEB research test
track
[[Page 43196]]
procedures were published in March 2019 and evaluate AEB performance in
crash-imminent scenarios both with and without manual brake pedal
applications.\70\ These procedures, with some modification, form the
basis for the proposed test procedure in this NPRM.
---------------------------------------------------------------------------
\70\ Elsasser, D., Salaani, M.K., & Boday, C., ``Test track
procedures for heavy-vehicle forward collision warning and automatic
emergency braking systems,'' Report No. DOT HS 812 675, Washington,
DC: National Highway Traffic Safety Administration (March 2019).
Available at https://rosap.ntl.bts.gov/view/dot/42186/dot_42186_DS1.pdf (last accessed June 28, 2022).
---------------------------------------------------------------------------
The test procedures were based upon prior research and include the
lead vehicle stopped, lead vehicle moving, and lead vehicle
decelerating test scenarios, as well as the steel trench plate and
stationary vehicles false positive scenarios. The testing was divided
into three phases. First, the subject vehicle and the lead vehicle are
situated on the test track to the proper location and test velocity.
The second stage involves determining whether the vehicles have met the
proper starting test conditions to achieve valid and reproducible test
outcomes. The third and final stage serves to assess test validity and
system performance as well as response to any FCW or AEB triggers. In
the research test procedure, if an invalid test is detected, the test
is repeated until at least seven valid test attempts are completed.
Testing was executed during daylight, avoiding inclement weather and
irrelevant obstructions such as overhead signs, bridges, overpasses,
etc. For test procedures that include manual brake pedal applications,
the pedal was displaced at a rate of 254 mm/s to achieve a target
longitudinal acceleration of -3.0 m/s\2\, simulating a manual brake
pedal application of a panicked driver. Test procedures for brake pedal
input characterization and verification assessment are described for
checking uniformity and to ensure the set braking magnitude and
response can be achieved.
The lead vehicle stopped test scenario requires the test subject
vehicle to be driven toward the stationary lead vehicle at 40 km/h. The
subject vehicle is to maintain its velocity and relative lateral
position to the straight testing path as it advances toward the lead
vehicle. When the time to collision is equal to 5 seconds there is a
nominal separation distance of 56 m between the front of the subject
vehicle and the rear of the lead vehicle. Once braking is initiated,
the accelerator pedal input of the subject vehicle is discontinued
fully within 0.5 seconds after the start of braking. For lead vehicle
stopped tests performed with insufficient brake pedal applications, the
brake pedal is applied at a time to collision of 1.51 seconds. The
point at which the brake pedal rate exceeds 50 mm/s is used to define
the beginning event of brake pedal input. The conclusion of testing is
marked by a collision between the subject and lead vehicle or the
subject vehicle stopping prior to colliding with the lead vehicle. The
test procedures are repeated until seven valid test trials are obtained
for each lead vehicle stopped test with and without brake pedal
applications, to obtain a total of 14 valid tests.
The test procedure for the lead vehicle moving scenario is similar
for its two vehicle speed combinations. The subject vehicle travels to
reach the target speed of 40 or 75 km/h for a minimum of 1 second; and
the lead vehicle travels at 15 or 35 km/h, respectively. Prior to
approaching the lead vehicle there should be a separation distance of
at least 100 m. Additionally, by a time to collision equal to 5
seconds, the separation range is 35 m for 40 km/h and 56 m for 75 km/h.
Once the subject vehicle encounters the lead vehicle and braking is
automatically initiated, the subject vehicle accelerator pedal was
fully released within 0.5 seconds.
The lead vehicle decelerating test procedure starts with the
subject vehicle traveling toward the lead vehicle while maintaining an
80 m separation distance. Both the subject vehicle and the lead vehicle
are required to reach and maintain a velocity of 40 km/h for at least 1
second while keeping the headway distance. Once the subject vehicle
encounters the lead vehicle and braking is initiated, the subject
vehicle accelerator pedal was fully released within 0.5 seconds. This
test procedure is repeated with similar steps for a 55 km/h velocity
and a 23 m separation distance.
In order to evaluate false positives, the steel trench plate test
scenario was executed at 40 and 75 km/h, and the stationary vehicles
test was completed at 50 km/h. For the seven test trials performed at
40 and 75 km/h, a short edge of the rectangular steel trench plate was
centered on the roadway about the x-axis. The subject vehicle was
driven toward the steel trench plate such that an initial 110.0 m
headway existed, and a nominal velocity of 40 or 75 km/h was maintained
for at least 1.0 second. The test initial test condition began when the
separation distance between the subject vehicle and steel trench plate
was 56 m and 105 m for 40 and 75 km/h, respectively. Once the subject
vehicle encountered the steel trench plate at a headway of 16.83 or
40.88 m for 40 and 75 km/h, respectively, the brakes of the subject
vehicle were engaged. The test ends when either the subject vehicle
drives over the steep trench plate or the subject vehicle stops before
crossing over the steel trench plate.
The preliminary conditions of the stationary vehicles test involved
two vehicles parked with a lateral separation of 4.5 m. These two
vehicles were faced in the forward direction of the test track and were
aligned. The subject vehicle was driven along the test track with a
100.0 m headway from the stationary vehicles. The subject vehicle was
then driven to maintain a velocity of 50 km/h for at least 1.0 second.
The starting test condition is a headway of 60 m where the steering
wheel of the subject vehicle was controlled to center the vehicle along
the test track. Once the subject vehicle encountered the stationary
vehicles at a range of approximately 23.74 m the subject vehicle
accelerator pedal was fully released within 0.5 seconds of the
initiation of braking.
6. 2021 VRTC Testing
The test track data that follows represents vehicle performance
with the latest generation AEB systems and the procedures and
conditions proposed in this NPRM largely match the procedures and
conditions used for this testing.
2021 Freightliner Cascadia
The 2021 Freightliner Cascadia was tested under the lead vehicle
stopped, lead vehicle moving, and lead vehicle decelerating scenarios
at the NHTSA VRTC in 2021. The GVT was used as the lead vehicle in
these test scenarios. The lead vehicle stopped scenario was executed at
multiple initial subject vehicle velocities from 20 km/h up to 95 km/h.
While contact with the VTD occurred at 20, 25, 30, and 35 km/h, there
were measurable speed reductions. At test velocities between 40 and 85
km/h, no collisions were observed. Collisions also occurred at 90 and
95 km/h, but the FCW at both speeds was issued earlier than 2 seconds
before contact. Ten additional test trials were conducted at 40 km/h,
and only one trial resulted in contact. Four additional test trials
were executed at 50, 60, 70, 80, and 85 km/h; in all four trials, there
were no collisions at three speeds and one collision at two speeds
(i.e., 80 and 85 km/h, respectively) which ultimately resulted in a
speed reduction when compared to the other trials.
The lead vehicle moving scenario was performed at several
combinations of subject vehicle and lead vehicle initial speeds. The
first set of eight trials
[[Page 43197]]
involved the subject vehicle at a range of velocities of 30 km/h to 90
km/h and the initial speed of the lead vehicle was 20 km/h for each.
Contact occurred only at the 30 and 60 km/h test velocities. The
initial speeds for the subject vehicle and lead vehicle for the second
set of eight trials was 40 and 15 km/h, respectively. One of these
trials ended in a collision and this run exhibited a notably lower
speed reduction when compared to the other trials. The third and fourth
sets of trials included subject vehicle and lead vehicle initial
velocity combinations of 75 and 35 km/h and 80 and 12 km/h,
respectively, and contact was avoided in all trials. For the lead
vehicle decelerating scenario collision was avoided for all trials
during the 40 km/h test. Impact occurred during four out of five runs
in the 50 km/h test with an initial headway of 18 m. However, at the
longer headway lengths of 21, 23, 25, and 40 m there were no collisions
during the 50 km/h tests. Additionally, contact was avoided for the 80
km/h test with headway lengths of 23, 25, 28, 40, and 45 m.
Table 11--2021 Freightliner Cascadia Test Track Scenarios
------------------------------------------------------------------------
Lead vehicle Subject vehicle
Scenario speed (km/h) speed (km/h)
------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 20-95
Lead Vehicle Moving.................. 20 30-90
Lead Vehicle Moving.................. 15 40
Lead Vehicle Moving.................. 35 75
Lead Vehicle Moving.................. 12 80
Lead Vehicle Moving.................. 32 80
Lead Vehicle Decelerating............ 40 40
Lead Vehicle Decelerating............ 50 50
Lead Vehicle Decelerating............ 55 55
Lead Vehicle Decelerating............ 80 80
------------------------------------------------------------------------
2021 Ram 5500
The class 5 2021 Ram 5500 was tested under the lead vehicle
stopped, lead vehicle moving, and lead vehicle decelerating scenarios
at the NHTSA VRTC in 2022. The tests performed for these scenarios
involved no manual brake application; and the GVT was used as the lead
vehicle. For the lead vehicle stopped scenario, the Ram truck avoided
collisions at 10, 20, 30, 40 km/h, while impact occurred during two of
the five trials in the 50 km/h test, although there was an
approximately 80 percent reduction in speed. In general, these results
seemed to align with limitations described in the vehicle owner's
manual that indicated that the system works up to 50 km/h. Testing up
to 80 km/h was not completed to avoid damage to the subject vehicle and
test equipment. During the lead vehicle moving scenario, the truck
avoided contact at 30, 40, 50, 60, 70, and 80 km/h. Impact did occur at
90 km/h, though there was a speed reduction of 63 percent. At 50 km/h,
the lead vehicle decelerating scenario resulted in consecutive impacts
with some speed reduction. Due to the repeated collisions, testing was
discontinued to prevent damage to the subject vehicle and the GVT.
NHTSA also tested The Ram 5500 under the three scenarios with
manual brake application. The lead vehicle stopped scenario resulted in
avoidance of contact for all trials at 30, 40, and 60 km/h. Collision
did occur at 50 km/h, though there was a speed reduction of
approximately 80 percent. The lead vehicle moving scenario resulted in
impact avoidance for all 40 to 90 km/h trials, but impact did occur
during the 100 km/h test. For the lead vehicle decelerating scenario,
impact occurred during the 50 km/h test with an initial headway of 40,
32, and 23 m. Collision also occurred for the 80 km/h test with a
headway of 40 m.
Table 12--2021 Ram 5500 Test Track Scenarios
------------------------------------------------------------------------
Lead vehicle Subject vehicle
Scenario speed (km/h) speed (km/h)
------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 10-60
Lead Vehicle Moving.................. 20 30-100
Lead Vehicle Decelerating............ 50 50
Lead Vehicle Decelerating............ 80 80
------------------------------------------------------------------------
In general, no single vehicle avoided collisions at all speeds in
the tested scenarios. While one vehicle may have performed better at
lower speeds and the other better at higher speeds, the combination of
results from the individual vehicles showed positive results over a
range of speeds. Overall, the performance demonstrated that the AEB
technology has improved over time, as shown in Tables 13 and
14.71 72 73 74
---------------------------------------------------------------------------
\71\ Phase 1--Boday, C., et al., ``Class 8 Truck-Tractor and
Motorcoach Forward Collision Warning and Automatic Emergency Braking
Test Track Research--Phase I,'' Washington, DC: National Highway
Traffic Safety Administration (June 2016). Docket No.
NHTSA[hyphen]2015-0024-0004.
\72\ Phase II- U.S. DOT/NHTSA- Class 8 Truck- Tractor and
Motorcoach Forward Collision Warning and Automatic Emergency Braking
System Test Track Research- Draft Report. Docket No. NHTSA-2015-
0024-0006.
\73\ Phase III--Salaani, M.K., Elsasser, D., Boday, C.,
``NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track
Research Results,'' SAE International. J Advances & Current
Practices in Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-
1001.
\74\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
[[Page 43198]]
Table 13--Technology Improvement Over Time
[Class 7-8]
----------------------------------------------------------------------------------------------------------------
1st period-- 2nd period--2nd
Class 7-8 heavy vehicle capability introduction generation (2015) Current (2022)
----------------------------------------------------------------------------------------------------------------
FCW and AEB activate for moving Yes...................... Yes..................... Yes.
vehicles.
AEB can avoid contact at test No....................... Yes..................... Yes.
speeds up to 80 km/h in lead
vehicle moving scenarios.
AEB can avoid contact at test No....................... N/A..................... Yes.
speeds greater than 80 km/h in
lead vehicle moving scenarios.
FCW alerts for stopped vehicles.... Yes...................... Yes..................... Yes.
AEB activates for stopped vehicles. No....................... Yes..................... Yes.
AEB can avoid contact at test No....................... No...................... Yes.
speeds up to 80 km/h in lead
vehicle stopped scenarios.
AEB can avoid contact at test No....................... No...................... Yes.
speeds greater than 80 km/h.
----------------------------------------------------------------------------------------------------------------
Table 14--Technology Improvement Over Time
[Class 3-6]
------------------------------------------------------------------------
Class 3-6 heavy vehicle AEB
capability Up to 2015 2016-2022
------------------------------------------------------------------------
FCW and AEB activate for Yes................. Yes.
moving vehicles.
AEB can avoid contact at test No.................. Yes.
speeds up to 80 km/h in lead
vehicle moving scenarios.
AEB can avoid contact at test No.................. Yes.
speeds greater than 80 km/h
in lead vehicle moving
scenarios.
FCW alerts for stopped Yes................. Yes.
vehicles.
AEB activates for stopped No.................. Yes.
vehicles.
AEB can avoid contact at test No.................. No.
speeds up to 80 km/h in lead
vehicle stopped scenarios.
AEB can avoid contact at test No.................. No.
speeds greater than 80 km/h.
------------------------------------------------------------------------
C. NHTSA Field Study of a New Generation Heavy Vehicle AEB System
NHTSA has an ongoing field study with VTTI that aims to collect
naturalistic driving data of at least 150 heavy vehicles over a one-
year timeframe. The goal is to collect data from each driver
participant for a three-month segment of the year. This research has
very similar parameters and objectives as those described above for the
``Field Study of Heavy-Vehicle Crash Avoidance Systems'' study.
However, several years have elapsed since the data were collected for
the prior study; and the trucks included in this ongoing research
project are equipped with newer generation AEB systems, including
stationary object braking and system integration into instrument
clusters.
The data acquisition systems installed on the heavy vehicles will
allow VTTI to sample various system activations including AEB,
stationary object alerts and FCWs. The focus of the study's real-world
data collection and analysis is to ascertain an understanding of
vehicle performance, driver behavior, and driver adaptation. VTTI is
evaluating Bendix Commercial Vehicle Systems and Detroit Assurance
(Daimler) systems and the five objectives include evaluation of system
reliability, assessment of driver performance over time, assessment of
overall driving behavior, collection of data on real-world conflicts,
and generation of inputs to a safety benefits simulation model.
Preliminary results from the driver survey responses indicate that
many drivers agree that collision mitigation technology makes drivers
safer. Approximately 50 percent of drivers surveyed at least slightly
agree that AEB is beneficial and helps drivers avoid a crash.\75\
---------------------------------------------------------------------------
\75\ This information is available in a report titled ``HV AEB
Driver Exit Survey Summary as of August 31, 2022,'' which has been
placed in the docket for this rulemaking.
---------------------------------------------------------------------------
V. Need for This Proposed Rule and Guiding Principles
A. Estimating AEB System Effectiveness
In developing this NPRM, NHTSA has examined the effectiveness of
AEB, proposing only those amendments that contribute to improved crash
safety, and have considered the principles for regulatory decision-
making set forth in Executive Order 12866 (as amended), Regulatory
Planning and Review.
The effectiveness of AEB indicates the efficacy of the system in
avoiding a rear-end crash. This NPRM proposes to require heavy vehicles
to have AEB systems that enable the vehicle to completely avoid an
imminent rear-end collision under a set of test scenarios. One method
of estimating effectiveness would be to perform a statistical analysis
of real-world crash data and observe the differences in statistics
between heavy vehicles equipped with AEB and those not equipped with
AEB. However, this approach is not feasible currently due to the low
penetration rate of AEB in the on-road vehicle fleet. Consequently,
NHTSA estimated effectiveness of AEB systems using performance data
from the agency's vehicle testing. The agency assessed effectiveness
against all crash severity levels collectively, rather than for
specific crash severity levels (i.e., minor injury versus fatal).
The performance data derived from four different test vehicles was
used to estimate AEB effectiveness,\76\ and the agency is continuing
its effort to test a larger variety of vehicles to further evaluate AEB
system performance. These vehicles were subject to the same test
scenarios (stopped lead vehicle, slower-moving lead vehicle,
decelerating lead vehicle) that are proposed in this NPRM, and
effectiveness estimates are based on each vehicle's capacity to avoid a
collision during a test scenario. For example, if a vehicle avoided
colliding with a stopped lead vehicle in four out of five test runs,
its effectiveness in that scenario would be 80 percent. The test
results for each vehicle were combined
---------------------------------------------------------------------------
\76\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------
[[Page 43199]]
into an aggregate effectiveness value by vehicle class range and crash
scenario, as displayed in Table 15.
Table 15--AEB Estimated Effectiveness (Percent)
[By vehicle class range and crash scenario]
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving Decelerating
Vehicle class range vehicle lead vehicle lead vehicle
----------------------------------------------------------------------------------------------------------------
7-8............................................................ 38.5 49.2 49.2
3-6............................................................ 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------
As shown in Table 15, after aggregating class 7 and class 8
together, the agency has estimated AEB would avoid 38.5 percent of
rear-end crashes for the stopped lead vehicle scenario, and 49.2
percent of slower-moving and decelerating lead vehicle crashes. For
class 3-6, AEB is estimated to be 43.0 percent effective against
stopped lead vehicle crashes and 47.8 percent against slower-moving and
decelerating lead vehicle crashes. These effectiveness values are the
values NHTSA used for assessing the benefits of this proposed rule.
B. AEB Performance Over a Range of Speeds Is Necessary and Practicable
The performance requirements proposed in this NPRM are designed
around the goal of realizing as much of the safety potential of AEB
systems, while remaining realistic and practicable both economically
and technically. AEB performance guidelines created outside of the
agency's rulemaking process appear not to have been created with these
same goals, and thus may not represent the optimal balance of safety
and practicability. Several AEB performance tests developed in the
private sector are limited to a maximum test speed of around 40 km/h
(25 mph), and do not test the capability of AEB system at highway
speeds.77 78
---------------------------------------------------------------------------
\77\ IIHS Autonomous Emergency Braking Test Protocol (Version
I). Available at https://www.iihs.org/media/a582abfb-7691-4805-81aa-16bbdf622992/REo1sA/Ratings/Protocols/current/test_protocol_aeb.pdf.
(last accessed August 5, 2022).
\78\ SAE International Forward Collision Warning and Mitigation
Vehicle Test Procedure--Truck and Bus J3029_201510. (For more
details, see https://www.sae.org/standards/content/j3029_201510)
(last accessed August 5, 2022).
---------------------------------------------------------------------------
NHTSA considered two primary factors in selecting the proposed test
speed ranges. The first factor is the practical ability of AEB
technology to consistently operate and avoid contact with a lead
vehicle at the widest reasonable range of speeds. A larger range of
speeds would likely yield more safety benefits and would more
thoroughly test the capabilities of the AEB system. Furthermore, as
observed in vehicle testing for NHTSA research, AEB performance during
testing at higher speeds does not necessarily indicate what the same
system's performance will be at lower speeds. For example, NHTSA's
testing of the 2021 Freightliner Cascadia truck showed that the AEB
system was able to avoid a collision with the lead vehicle at test
speeds of 40 to 85 km/h, but not at speeds below 40 km/h. Thus, testing
over a range of speeds is necessary to more fully assess AEB
performance.\79\
---------------------------------------------------------------------------
\79\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------
The second factor is the practical limit of safely conducting
vehicle tests of AEB systems. Test data indicates that AEB performance
is less consistent, becoming less likely to avoid a collision when test
speeds approach or exceed the proposed upper limits, indicating that
testing at higher speeds than proposed would be beyond technological
feasibility.\80\
---------------------------------------------------------------------------
\80\ More detail on test data is discussed in the NHTSA and
FMCSA Research and Testing section.
---------------------------------------------------------------------------
NHTSA's testing must be safe and repeatable as permitted by track
conditions and testing equipment. For example, if the AEB system does
not intervene as required, or if test parameters inadvertently fall
outside of the specified limits, it should be possible to safely abort
the test. In the event the subject vehicle does collide with the lead
vehicle, it should not injure the testing personnel nor cause excessive
property damage. Additionally, test tracks may be constrained by
available space and there may be insufficient space to accelerate a
heavy vehicle up to a higher speed and still have sufficient space to
perform a test. Many types of heavy vehicles are not capable of
accelerating as quickly as lighter vehicles and reaching higher test
speeds may require longer stretches that exceed available testing
facilities. At approximately 100 km/h, the agency found that
constraints with available test track length, in conjunction with the
time required to accelerate the vehicle to the desired test speed, made
performing these higher speed tests with heavy vehicles logistically
challenging.\81\ The agency has tentatively concluded that at this time
the maximum practicable test speed is 100 km/h.
---------------------------------------------------------------------------
\81\ During testing of a 2021 Freightliner Cascadia at speeds
approaching 100 km/h, NHTSA experienced difficulty establishing
valid test conditions due to test facility use restrictions.
Facility use restrictions limited where emergency braking tests by
heavy vehicles and automated lead vehicle robots could co-operate,
thereby reducing the effective useable track length to less than
1100 meters.
---------------------------------------------------------------------------
The maximum speed of 100 km/h is included in the test speed range
when manual braking is present; the manual braking will reduce impact
speed if the FCW issues a warning and the AEB system does not activate
before reaching the lead vehicle. This would limit potential damage to
the test equipment and avoid injury to testing personnel. With no
manual braking, the maximum test speed is 80 km/h so that in the event
that the AEB system does not provide any braking at all, damage to the
subject vehicle and test equipment is reduced and potential injuries
avoided.
The stopped lead vehicle test scenario uses a no-manual-braking
test speed range of 10-80 km/h and a manual-braking test speed range of
70-100 km/h. Similarly, the slower-moving lead vehicle test scenario
uses subject vehicle speed ranges of 40-80 km/h for no manual-braking
and 70-100 km/h for manual braking, while the lead vehicle travels
ahead at a constant speed of 20 km/h. The lower end of the subject
vehicle test speed range is 40 km/h so that the subject vehicle is
traveling faster than the lead vehicle. The decelerating lead vehicle
tests are run at either 80 or 50 km/h. This latter test is performed at
two discreet speeds rather than at ranges of speeds because the main
factors that test AEB performance are the variation of headway, or the
distance between the subject vehicle
[[Page 43200]]
and lead vehicle, and how hard the lead vehicle brakes. Also, because
these tests contain a larger number of variables requiring more complex
test choreography, limiting the test to two discreet test speeds
reduces the number of potential test conditions and reduces potential
test burden. Together, these test speed ranges provide good coverage of
the travel speeds at which heavy vehicle rear-end crashes occur in the
real world, while reducing the potential risk and damage to test
equipment and vehicles and not exceeding the practical physical size
limits of test tracks.
Additionally, the agency is proposing that these requirements would
not apply at speeds below 10 km/h. NHTSA believes that there are real-
world cases where heavy vehicles are being maneuvered intentionally in
proximity of other objects at low-speed, and AEB intervention could be
in conflict with the vehicle operator's intention. For example, if an
operator intends to drive towards the rear of another vehicle in a
parking lot in order to park the vehicle near the other, automatic
braking during this parking maneuver would be unwanted. The agency
tentatively concluded that excluding speeds below 10 km/h from the AEB
requirement would allow these types of low-speed maneuvers. This
proposal does not require AEB systems to be disabled below 10 km/h.
However, publicly available literature from at least one manufacturer
shows that some or all of the AEB system functions are not available
below 15 mph (24 km/h), indicating that current manufacturers may have
similar considerations about low-speed AEB functionality.\82\ A lower
bound for FCW and AEB activation speed of 10 km/h is also consistent
with the lower bound testing proposed for light vehicle AEB and the
Euro NCAP rating program.\83\
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\82\ Bendix Wingman Fusion Brochure, or SD-61-4963 Service Data
manual for Bendix Wingman Fusion Driver Assistance System. Available
at https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed August 23, 2022).
\83\ Euro NCAP Test Protocol--AEB Car-to-Car systems v3.0.3
(April 2021). See https://cdn.euroncap.com/media/62794/euro-ncap-aeb-c2c-test-protocol-v303.pdf.
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During each test run in any of the test scenarios, the vehicle test
speed will be held constant until the test procedure specifies a
change. NHTSA is proposing that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of the specified test value. In
NHTSA's experience, both the subject vehicle and lead vehicle speeds
can be reliably controlled within the 1.6 km/h tolerance range, and
speed variation within that range yields consistent test results. A
tighter speed tolerance is unnecessary for repeatability and burdensome
as it may result in a higher test-rejection rate, without any greater
assurance of accuracy of the test track performance.
NHTSA's vehicle testing suggested that the selected speed ranges
for the various scenarios are within the capabilities of at least some
recent model year AEB-equipped production vehicles.\84\ While these
current AEB systems perform a bit differently depending on the vehicle,
given that this notice proposes a lead time for manufacturers to come
into compliance with the proposed performance requirement, the agency
expects that future model year performance in accordance with a final
rule schedule will be achievable.
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\84\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------
C. Market Penetration Varies Significantly Among Classes of Heavy
Vehicles
Though the presence of AEB in heavy vehicles has increased over the
years, many new heavy vehicles sold in the U.S. are not equipped with
AEB. Market data obtained by NHTSA indicates that although AEB is
likely equipped on the majority of class 8 vehicles and is available on
nearly all class 3 and class 4 vehicles, few of class 5 and 6 vehicles
come equipped with any type of AEB system. In addition, though the
capabilities of these AEB systems have also improved over time, there
has been no set of standardized performance metrics in the U.S. that
manufacturers could use as a benchmark to meet. This NPRM proposes
standard performance metrics that would meet a motor vehicle safety
need.
Among the variety of heavy vehicle types, class 7 and 8 truck
tractors have been the earliest to voluntarily adopt AEB systems. These
vehicles are (with some exceptions) already subject to the electronic
stability control requirement in FMVSS No. 136 and contain fewer
variations in vehicle type, configuration, and operational pattern. It
was estimated that as of 2013 only 8 to 10 percent of class 8 trucks in
the U.S. were equipped with this technology.\85\ In 2017 a FMCSA report
extrapolated available information to estimate that 12.8 percent of the
entire on-road fleet of class 8 trucks in the United States were
equipped with an AEB system,\86\ while the industry estimated that up
to 15 percent of class 8 trucks were equipped with AEB.\87\ More
recently, a survey of public information on AEB availability for heavy
vehicles reveals that this technology is becoming more prevalent on new
trucks. In 2016, Peterbilt announced the option of AEB in its class 8
model 579 truck tractor, and then made the technology standard in
2019.88 89 As of 2017, Volvo Trucks made AEB standard
equipment on all of its class 8 truck tractor models, as a part of its
Volvo Active Driver Assist safety package.\90\ While several fleets or
manufacturers have made AEB standard, it remains an option for some
class 8 vehicles, such as the Peterbilt single-unit truck models 337
and 348.\91\ Data from a recent study indicates that the large majority
of class 8 vehicles sold from 2018 until mid-2022 had AEB as a standard
feature, and that the top ten selling class 8 vehicles all include
standard AEB.\92\
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\85\ National Transportation Safety Board. 2015. ``Special
Investigation Report: The Use of Forward Collision Avoidance Systems
to Prevent and Mitigate Rear-End Crashes.'' Report No. NTSB/SIR-15/
01 PB2015-104098. Washington, DC.
\86\ Grove, K., et al., ``Research and Testing to Accelerate
Voluntary Adoption of Automatic Emergency Braking (AEB) on
Commercial Vehicles,'' VTTI (May 2020). Available at https://rosap.ntl.bts.gov/view/dot/49335 (last accessed June 9, 2022).
\87\ Cannon, J., ``Automatic emergency braking is the next
generation of driver assist technologies,'' Commercial Carrier
Journal, December 14, 2017. https://www.ccjdigital.com/business/article/14936178/future-of-automatic-emergency-braking-driver-assist-tech.
\88\ https://www.peterbilt.com/about/news-events/news-releases/peterbilt-introduces-bendix-wingman-fusion-advanced-safety-system
(last accessed August 23, 2022).
\89\ https://www.peterbilt.com/about/news-events/peterbilt-trucks-introduce-bendix-wingman-fusion-standard (last accessed
August 23, 2022).
\90\ https://www.volvotrucks.us/news-and-stories/press-releases/
2017/july/volvo-active-driver-assist-now-standard/
#:~:text=Volvo%20Active%20Driver%20Assist%20is%20now%20standard%20equ
ipment,is%20fully%20integrated%20with%20Volvo%E2%80%99s%20Driver%20In
formation%20Display (last accessed August 23, 2022).
\91\ https://www.peterbilt.com/about/news-events/peterbilt-announces-bendix-wingman-fusion-medium-duty (last accessed August
23, 2022).
\92\ This information is available in the S&P Global's
presentation titled ``MHCV Safety Technology Study,'' which has been
placed in the docket identified in the heading of this NPRM.
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AEB systems are also available on nearly all class 3 and 4 trucks
that are relatively similar in size to light trucks, are manufactured
by companies that also manufacture light vehicles, and likely have
similar component and component suppliers as light vehicles. Although
these vehicles are not required to have ESC systems, many of them are
also available with ESC, likely because these vehicles are similar in
size and use to light trucks. However, while NHTSA has information on
ESC and AEB system availability, NHTSA has no
[[Page 43201]]
information on what percentage of class 3 and 4 vehicle purchases are
equipped with ESC and AEB. For classes 5 and 6, there is substantially
lower ESC and AEB system availability. However, NHTSA believes that
this slower pace of voluntary adoption does not imply that these
vehicles are not capable of being deployed with an AEB system. The
system components are largely the same and have little to do with a
vehicle's size. There are also vehicles within these classes that are
available with ESC, and the availability of ESC has increased since
NHTSA issued FMVSS No. 136. This market information indicates that AEB
is practicable for all vehicles included in this proposal.
D. This NPRM Would Compel Improvements in AEB
This rulemaking is also needed to drive improvements in AEB
systems. The performance requirements proposed in this NPRM are
designed around the goal of realizing as much of the safety potential
of AEB systems as possible, while remaining realistic and practicable.
Some contemporary AEB systems are currently designed to detect and
mitigate collision with a vehicle ahead when travelling at a wide range
of speeds, including interstate speeds.\93\ While the systems are also
functional at lower speeds, the higher speed capabilities indicate that
AEB will be capable of reducing the frequency of interstate rear-end
crashes rather than just slower speed events.
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\93\ See https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed March 1, 2023).
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NHTSA has tentatively concluded that the improvements to AEB
systems by manufacturers in the absence of regulation have
insufficiently addressed the safety problem associated with rear-end
crashes. No individual vehicle's AEB system tested by NHTSA is
currently capable of avoiding a collision over the range of test speeds
that aligns with the majority of the safety problem. However, the range
of speeds included in this proposal is practicable as at least some
vehicles were able to achieve the desired results at each tested speed.
While manufacturers may continue to improve AEB systems, only a
regulation would ensure that all heavy vehicles are equipped with an
AEB system that can avoid a collision at a range of speeds that targets
the majority of the safety problem. Establishing performance criteria
that meet the safety need of preventing fatalities and serious injuries
will also ensure that the systems will be designed to address the
serious safety problem associated with these crashes. This NPRM
proposes that all heavy vehicles be subject to the same performance
requirements such that the entire heavy vehicle fleet benefits from
improvements in AEB technology.
E. BIL Section 23010(b)(2)(B)
NHTSA is issuing this NPRM in accordance with a statutory mandate
in BIL. Section 23010 of BIL requires the Secretary to prescribe a
Federal motor vehicle safety standard to require all commercial
vehicles subject to FMVSS No. 136 to be equipped with an AEB system.
The FMVSS is required to establish performance standards for AEB
systems. BIL directs the Secretary to prescribe the standard not later
than two years after the date of enactment of the Act.
Section 23010(b)(2)(B) of BIL states that prior to prescribing the
FMVSS for heavy vehicle AEB, the Secretary shall consult with
representatives of commercial motor vehicle drivers regarding the
experiences of drivers with AEB. Prior to this NPRM, NHTSA and FMCSA
have engaged drivers and the industry more generally in various ways.
NHTSA has published research previously that involved surveying the
driving experiences of 18 drivers driving heavy trucks equipped with a
prototype FCW system over a 10-month period in May 2011.\94\ NHTSA has
also been sponsoring studies seeking input of commercial motor vehicle
drivers. The current ongoing field study with VTTI aims to collect and
analyze performance and operational data on newer generation AEB crash
avoidance technologies on new, class 8 tractors by heavy vehicle
original equipment manufacturers and their suppliers. One year of
naturalistic driving data will be collected by monitoring the
production systems used in real-world conditions as deployed by
multiple fleets across the United States. In addition to the
performance and operational data retrieved from on-board data
acquisition systems for evaluation, the study will also involve
conducting subjective surveys with drivers and fleet managers regarding
performance, satisfaction, and overall acceptance of the crash
avoidance technologies.
---------------------------------------------------------------------------
\94\ ``Integrated Vehicle-Based Safety Systems Heavy-Truck Field
Operational Test Independent Evaluation,'' DOT HS 811 464.
---------------------------------------------------------------------------
FMSCA is also engaged consultation with representatives of drivers
through the Tech-Celerate Now program.\95\ This program intends to
accelerate the adoption of advanced crash avoidance technologies by the
trucking industry. The first phase initiatives include national
outreach and education. The outreach element allowed for the successful
creation of training materials for fleets, drivers, and maintenance
personnel related to AEB technology. Additionally, the program features
other avenues to reach drivers including educational videos on braking,
presentations, booth exhibitions, and webinars. As of January 2023,
FMCSA has compiled the findings from drivers and/or representatives of
drivers in a final report that is currently undergoing internal review.
However, planning for the second phase has been initiated and includes
expanding the national outreach and education campaign.
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\95\ Tech-Celerate Now. FMCSA. Available at https://www.fmcsa.dot.gov/Tech-CelerateNow (last accessed August 8, 2022).
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Building upon this and other research, NHTSA and FMCSA seek comment
from representatives of commercial motor vehicle drivers, and from
drivers themselves, about their experiences with AEB systems, including
whether the AEB system prevented a crash, whether the FCW warnings were
helpful, and whether any malfunctions or unwarranted activations
occurred. Although members of the public should comment on all aspects
of the NPRM they find relevant, NHTSA also request comments on the
following specific issues:
This proposal includes considerations that automatic
braking is needed for safety and crash prevention. NHTSA seeks comment
from driver experiences with AEB-equipped heavy vehicles on whether AEB
improves heavy vehicle rear-end crash safety.
This proposal includes warning requirements to the driver
as part of the AEB system that braking is needed in a rear-end crash-
imminent situation. NHTSA seeks comments from driver experiences on
whether AEB is helpful in getting a driver's attention back to the task
of driving.
This proposal includes requirements that automatic braking
will occur in the event of an imminent collision on a straight testing
path. NHTSA seeks comment on driver experiences with the performance of
AEB when it is applied on curved roads.
This proposal includes requirements that automatic braking
will be tested under certain weather and roadway pavement conditions.
NHTSA seeks comment on driver experiences when AEB is applied at the
last moment in all weather conditions.
This proposal includes considerations that automatic
braking is needed because of multiple elements, including driver
misjudgments and distractions. NHTSA seeks comment on driver
experiences on whether the
[[Page 43202]]
application of AEB causes drivers to pay less attention to the road; or
whether the application of AEB distracts or annoys drivers.
F. Vehicles Excluded From Braking Requirements
The result of this proposal would require AEB and ESC on nearly all
heavy vehicles. The only vehicles that would be excluded from AEB and
ESC requirements would be vehicles that are already excluded from
NHTSA's braking requirements for vehicles equipped with pneumatic
brakes in FMVSS No. 121. This braking standard includes requirements
for minimum stopping distance. For those vehicles, there is no
assurance that their foundational brake systems would have the
capability to meet the proposed AEB performance requirements, even if
equipped with sensors capable of detecting another vehicle. These
vehicles are also presently excluded from FMVSS No. 136 and would
continue to be excluded under this proposal. The vehicles excluded from
the proposed AEB and ESC requirements are:
Any vehicle equipped with an air brake system and equipped
with an axle that has a gross axle weight rating of 13,154 kilograms
(29,000 pounds) or more;
Any truck or bus that is equipped with an air brake system
and that has a speed attainable in 3.2 km (2 miles) of not more than 53
km/h (33 mph);
Any truck equipped with an air brake system that has a
speed attainable in 3.2 km (2 miles) of not more than 72 km/h (45 mph),
an unloaded vehicle weight that is not less than 95 percent of its
gross vehicle weight rating, and no capacity to carry occupants other
than the driver and operating crew.
FMCSA believes that an exemption from its ESC and AEB regulations
is appropriate for vehicles involved in driveaway-towaway operations,
for example, vehicles that are being transported to dealer locations or
that are manufactured exclusively for use outside of the United States.
Although these vehicles are operated on public roads in the United
States when they are being transported from the point of manufacture to
a domestic or foreign destination, these vehicles have not yet entered
commercial service. The economic burden associated with requiring these
vehicles to be equipped with AEB or ESC for the one-way trip out of the
United States would certainly exceed the potential benefits.
The driveaway-towaway exemption would also be applicable to
vehicles being delivered to the Armed Forces of the United States.
Vehicles operated by the military are exempt from the FMCSRs under
Sec. 390.3(f)(2).\96\
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\96\ FMCSA notes that the driveaway-towaway exemption provided
in Sec. 393.56 and Sec. 393.57 is consistent with exceptions
provided by NHTSA. Section 571.7(c) provides an exception for
vehicles and items of equipment manufactured for, and sold directly
to, the Armed Forces of the United States in conformity with
contractual specifications. Section 571.7(d), through a cross-
reference to the United States Code, indicates the FMVSSs do not
apply to motor vehicles or motor vehicle equipment intended only for
export, labeled for export on the vehicle or equipment and on the
outside of any container of the vehicle or equipment, and exported
(49 U.S.C. 30112(b)(2)).
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FMCSA seeks comment on other types of operations for which an
exemption from the AEB or ESC requirements may be appropriate. For
example, what types of exemptions may be needed for CMVs with auxiliary
equipment installed that would interfere with the operation of the AEB
system?
VI. Heavy Vehicles Not Currently Subject to ESC Requirements
A. AEB and ESC Are Less Available on These Vehicles
NHTSA is proposing to include nearly all vehicles with a GVWR
greater than 4,536 kg (10,000 lbs.). This includes vehicles that are
currently exempted from FMVSS No. 136 such as trucks other than truck
tractors, school buses, perimeter-seating buses, transit buses,
passenger cars, and multipurpose passenger vehicles because about half
of the fatalities and serious injuries brought about by heavy vehicles
are caused by class 3 through 6 vehicles.
The FMVSSs do not currently require ESC on class 3 through 6
vehicles or on class 7 and 8 single unit trucks, school buses, and
certain bus types such as transit buses. ESC has not been commercially
available for as long on class 3 through 6 vehicles as it has been for
class 7 and 8 vehicles. However, examples can be found of manufacturers
who offer ESC as an option on their class 3 through 6 vehicles.
Kenworth has made AEB optional for the T880 vocational truck as well as
for their T270 and T370 conventional class 6 trucks. Ford made ESC
standard on its F-650 model in the 2018 model year and has made AEB
optional on model year 2022 F-650 and F-750 class 6 trucks. A number of
school bus manufacturers have made ESC standard on certain models,
including ones that fall into classes 3 through 6. For example, Thomas
Built offers ESC as standard equipment on its type C school buses,
which can be configured to be in class 6. In some cases, ESC technology
originating in hydraulic-brake passenger cars has moved up into the
lower classes of heavy vehicles. For example, the 2019 Mercedes
Sprinter, a cargo van which can be configured as a class 3 heavy
vehicle, has ESC as standard equipment. Other class 3 and 4 vehicles
that resemble light vehicles, such as pickup trucks, are available with
ESC.
The availability of ESC as an option across multiple brands and
models within class 3 through 6 leads NHTSA tentatively to conclude
that providing ESC is technically and economically feasible. NHTSA
believes it is reasonable and practicable to require that ESC to be
installed on class 3 through 6 vehicles.
B. This NPRM Proposes To Require ESC
NHTSA has tentatively determined that ESC is necessary for safety
to include as a foundation for an AEB requirement. Historically, the
two technologies have been thought of as supplement or complementary
rather joined technologies. That is, while ESC and AEB share hardware
fundamental to both technologies, such as brake actuators, ESC is
generally not described or advertised as a component of AEB.
That said, despite this theoretical separation, in a survey NHTSA
has conducted on the availability of ESC and AEB systems, NHTSA was
unable to identify any heavy vehicle that could currently be purchased
with an AEB system, other than an FCW-only system (i.e., not capable of
automatic brake application), that did not also have an ESC system.\97\
In a 2017 white paper Bendix indicated that collision mitigation
technology is built on a foundation of full stability. Bendix stated
that as we look to more automated, autonomous functionality in the
future, all of this is likely to be built on an ESC foundation as
well.\98\ In a 2018 news release, Bendix stated that ESC provides the
necessary platform for more advanced driver assistance systems (ADAS),
including collision mitigation technologies.\99\ Manufacturers such as
Ford have ESC as a must-have system for installing driver assist
technology on the stripped commercial chassis, including AEB.\100\
[[Page 43203]]
Also, Ford has ESC and AEB as standard equipment on other chassis
models such as the E-series models, F-650, and F-750 truck series. Ram
Trucks also offers ESC and AEB for Chassis Cab models like RAM 3500
trucks.101 102 Based upon these factors and its own
understanding of the capabilities of AEB and ESC systems, NHTSA has
tentatively concluded that there may be safety risks associated with
the installation of an AEB system without an ESC system. For example, a
driver who responds to an imminent collision by steering to avoid a
collision while an AEB system is simultaneously applying braking may
induce a lateral instability event that is not addressed by ABS, but
that may be prevented with an ESC system. Thus, this NPRM proposes to
require both AEB and ESC for the class 3 through 8 vehicles not
currently subject to FMVSS No. 136.
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\97\ This information is available in NHTSA's VRTC class 3 to 6
market scan for ESC-FCW-AEB spreadsheet, which has been placed in
the docket identified in the heading of this NPRM.
\98\ Full Stability and the Road Map to The Future- Are we still
on the Right Road? https://www.bendix.com/media/documents/products_1/absstability/BW8055_US_000.pdf (last accessed March 3,
2023).
\99\ October 16, 2018. Bendix News Release, ``WORKING TOGETHER,
BENDIX AND NORTH AMERICA'S SCHOOL BUS MANUFACTURERS ENHANCE STUDENT
TRANSPORTATION SAFETY''.
\100\ 2022 Ford Commercial Vehicles, F-59 Commercial Stripped
Chassis. ESC is required for the stripped chassis Driver Assist
Technology Package.
\101\ ESC equipped standard on E-Series models, and F-650/F-750
trucks, available at this link https://www.ford.com/cmslibs/content/dam/vdm_ford/live/en_us/ford/nameplate/f-650-750/2022/brochures/BRO_SUF_130E80EB-C9B2-936F-6F54-72CA6F5472CA.pdf (last viewed March
3, 2023).
\102\ https://www.ramtrucks.com/gab.html, ESC equipped standard
on the RAM Chassis cab models and RAM 3500 trucks, available at this
link (last accessed March 3, 2023).
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NHTSA requests comment on this tentative conclusion that ESC is
necessary to ensure safe AEB operation or whether ESC systems are
necessary prerequisites for AEB systems for any other reason. NHTSA
further requests comments on specific safety scenarios where ESC
systems would be necessary for safe operation of an AEB system.
Currently, pursuant to FMVSS No. 136, only class 7 and 8 truck
tractors and certain large buses are required to have ESC systems.
FMVSS No. 136 includes both vehicle equipment requirements and
performance requirements. This proposal would require nearly all heavy
vehicles to have an ESC system that meets the equipment requirements,
general system operational capability requirements, and malfunction
detection requirements of FMVSS No. 136. The general ESC system
operational capability requirements are the nine capabilities that are
specified in the definition of ESC system in S4 of FMVSS No. 136, which
include a means to augment directional stability and enhance rollover
stability by having control over the brake systems individually at each
wheel position and the means to control engine torque. However, NHTSA
is not proposing test track performance requirements at this time
because NHTSA is conscious of the potential testing burden on small
businesses and the multi-stage vehicle manufacturers involved in class
3 through 6 vehicle production.
NHTSA's proposed approach would provide vehicle manufacturers the
ability to ascertain the ESC system design most appropriate for their
vehicles. The approach recognizes that ESC system design is dependent
on vehicle dynamics characteristics, such as the total vehicle weight
and location of that weight (center of gravity), which would differ
depending on the final vehicle configuration. Vehicles not subject to
FMVSS No. 136 include a large variety of vehicle configurations, which
can result in numerous variations of ESC system design. The approach
provides maximum flexibility to vehicle manufacturers to evaluate the
characteristics of their vehicles and design an ESC system.
In Europe, ESC was predicted to prevent about 3,000 fatalities (14
percent), and about 50,000 injuries (6 percent) per year.\103\ In
Europe, ESC has been mandatory for new types of vehicles since 2011,
and for all new vehicles is mandatory since 2014.\104\ More information
about international regulations can be found in Appendix B.
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\103\ Iombiller, S.F., Prado, W.B., Silva M.A. (September 15,
2019). Comparative Analysis between American and European
Requirements for Electronic Stability Control (ESC) Focusing on
Commercial Vehicles. SAE International.
\104\ July 31, 2009, Official Journal of the European Union,
Regulation (EC) No. 661/2009, Articles 12 & 13, and Annex V.
---------------------------------------------------------------------------
C. BIL Section 23010(d)
Section 23010 of BIL requires the Secretary to prescribe a Federal
motor vehicle safety standard to require any commercial vehicle subject
to FMVSS No. 136, that is manufactured after the effective date of an
AEB standard, to be equipped with an AEB system that meets established
performance standards. In addition, Section 23010(d) of BIL requires
NHTSA to study equipping AEB on a variety of commercial motor vehicles
not subject to FMVSS No. 136, including an assessment of the
feasibility, benefits, and costs associated with installing AEB systems
on a variety of newly manufactured commercial motor vehicles with a
GVWR greater than 10,000 pounds. Section (d)(3) states that the
Secretary shall issue a notice in the Federal Register containing the
findings of the study and provide an opportunity for public comment.
After completion of this study, the Secretary must determine whether a
motor vehicle safety standard would meet the requirements and
considerations described in paragraphs (a) and (b) of section 30111 of
the Safety Act, and if the Secretary finds that an FMVSS would meet
such requirements, initiate a rulemaking to prescribe such an FMVSS.
This NPRM and the accompanying PRIA fulfils the mandate of section
23010(d)(1) concerning a study on equipping commercial vehicles not
subject to FMVSS No. 136 with AEB. Pursuant to the mandate section
23010(d)(3) of BIL, NHTSA seeks comment on the tentative conclusions in
this NPRM and the PRIA regarding the feasibility, benefits, and costs
associated with installing AEB on all heavy vehicles, particularly
class 3-6 vehicles and class 7 and 8 single-unit trucks. Further, as
part of this rulemaking, the agency has considered whether proceeding
with an AEB mandate for these vehicles meet the necessary provisions of
the Safety Act, and will continue to do so in any final rule. Finally,
although the agency notes that paragraph (d) concerns when the agency
would be mandated to initiate a rulemaking to require AEB for these
vehicles, that section does not affect the agency's discretionary
ability to issue an FMVSS when it believes doing so is compelled by the
Safety Act.
D. Multi-Stage Vehicle Manufacturers and Alterers
Heavy vehicles include many specialty or vocational vehicles such
as work trucks, delivery box trucks, motorhomes, and school buses, and
the complexities within this large variety of special purpose vehicles
make installation of ESC and AEB more challenging. These specialized
vehicles may be produced in lower volumes with customized features to
suit the specific needs of individual customers and in multiple stages
by several manufacturers. Concepts and terminology relating to the
certification of vehicles built in two or more stages (multi-stage
vehicles) and alters are described below.
In the typical situation, a vehicle built in two or more stages is
one in which an incomplete vehicle, such as a chassis-cab or cut-away
chassis built by one manufacturer, is completed by another manufacturer
who adds work-performing or cargo-carrying components to the vehicle.
For example, the incomplete vehicle may have a cab, but nothing built
on the frame behind the cab. As completed, it may be a dry freight van
(box truck), dump truck, tow truck, or plumber's truck. Like all
vehicles that are manufactured for sale in the United States, a multi-
stage vehicle must be certified as complying with all applicable
Federal motor
[[Page 43204]]
vehicle safety standards (FMVSS) before the vehicle is introduced into
interstate commerce.
Manufacturers involved in the production of multi-stage vehicles
can include, in addition to the incomplete vehicle manufacturer, one or
more intermediate manufacturers, who perform manufacturing operations
on the incomplete vehicle after it has left the incomplete vehicle
manufacturer's hands, and a final-stage manufacturer who completes the
vehicle so that it is capable of performing its intended function.
In some circumstances, a manufacturer at an earlier stage in the
chain of production for a multi-stage vehicle can certify that the
vehicle will comply with one or more FMVSS when completed, provided
specified conditions are met. This allows what is commonly referred to
as ``pass-through certification.'' As long as a subsequent manufacturer
meets the conditions of the prior certification, that subsequent
manufacturer may rely on this certification and pass it through when
certifying the completed vehicle.
NHTSA requests comments on how this proposal may impact multi-stage
manufacturers and alterers. The agency seeks comment on the specific
challenges that would be faced by the manufacturers in certifying to
the proposed AEB or ESC or in altering a vehicle certified to the
proposed requirements, and on whether and how NHTSA could revise this
proposal to minimize any disproportionate impact.
We believe that small-volume vehicle manufacturers are not likely
to certify compliance with the proposed AEB and ESC requirements
through their own testing but will use a combination of component
testing by brake system suppliers and engineering judgment. Already
much of the braking development work, including for ABS and ESC, for
these small-volume vehicle manufacturers is done by brake suppliers.
That is, small-volume manufacturers already must certify their vehicles
to FMVSS Nos. 136, 105, and 121. NHTSA believes that small-volume
manufacturers would certify to the proposed ESC and AEB requirements
using the means they use now to certify to those braking requirements,
which involves collaborating with their brake system suppliers, first
and second stage manufacturers, etc. This NPRM would also provide one
year after the last applicable date for manufacturer certification of
compliance, in accordance with 49 CFR 571.8(b).
NHTSA's regulations governing vehicles manufactured in two or more
stages at 49 CFR part 568 require incomplete vehicle manufacturers to
provide with each incomplete vehicle an incomplete vehicle document
(IVD). This document details, with varying degrees of specificity, the
types of future manufacturing contemplated by the incomplete vehicle
manufacturer and must provide, for each applicable safety standard, one
of the following three statements that a subsequent manufacturer can
rely on when certifying compliance of the vehicle, as finally
manufactured, to some or all of all applicable FMVSS.
First, the IVD may state, with respect to a particular safety
standard, that the vehicle, when completed, will conform to the
standard if no alterations are made in identified components of the
incomplete vehicle. This representation, which is referred to as a
``Type 1 statement,'' is most often made with respect to chassis-cabs,
since a significant portion of the occupant compartment in incomplete
vehicles of that type is already complete.
Second, the IVD may provide a statement of specific conditions of
final manufacture under which the completed vehicle will conform to a
particular standard or set of standards. This statement, which is
referred to as a ``Type 2 statement,'' is applicable in those instances
in which the incomplete vehicle manufacturer has provided all or a
portion of the equipment needed to comply with the standard, but
subsequent manufacturing might be expected to change the vehicle such
that it may not comply with the standard once finally manufactured. For
example, the incomplete vehicle could be equipped with a brake system
that would, in many instances, enable the vehicle to comply with the
applicable brake standard once the vehicle was complete, but that would
not enable it to comply if the completed vehicle's weight or center of
gravity height were altered from those specified in the IVD.
Third, the IVD may identify those standards for which no
representation of conformity is made because conformity with the
standard is not substantially affected by the design of the incomplete
vehicle. This is referred to as a ``Type 3 statement.'' A statement of
this kind could be made, for example, by a manufacturer of a stripped
chassis who may be unable to make any representations about conformity
to any crashworthiness standards if the incomplete vehicle does not
contain an occupant compartment. When it issued the original set of
regulations regarding certification of vehicles built in two or more
stages, the agency indicated that it believed final-stage manufacturers
would be able to rely on the representations made in the IVDs when
certifying the completed vehicle's compliance with all applicable
FMVSS.
Although the final-stage manufacturer normally certifies the
completed vehicle's compliance with all applicable FMVSS, this
responsibility can be assumed by any other manufacturer in the
production chain. To take on this responsibility, the other
manufacturer must ensure that it is identified as the vehicle
manufacturer on the certification label that is permanently affixed to
the vehicle. The identified manufacturer also has legal responsibility
to provide NHTSA and vehicle owners with notification of any defect
related to motor vehicle safety or noncompliance with an FMVSS that is
found to exist in the vehicle, and to remedy any such defect or
noncompliance without charge to the vehicle's owner.
An altered vehicle is one that is completed and certified in
accordance with the agency's regulations and then altered, other than
by the addition, substitution, or removal of readily attachable
components, such as mirrors or tire and rim assemblies, or by minor
finishing operations such as painting, before the first retail sale of
the vehicle, in such a manner as may affect the vehicle's compliance
with one or more FMVSS or the validity of the vehicle's stated weight
ratings or vehicle type classification. The person who performs such
operations on a completed vehicle is referred to as a vehicle
``alterer.'' An alterer must certify that the vehicle remains in
compliance with all applicable FMVSS affected by the alteration.
NHTSA seeks comment on the impacts of this NPRM on multi-stage
manufacturers and alterers and requests comments on the following
questions.
Are certain multi-stage or altered vehicles manufactured
or altered in a manner that makes it impracticable to comply with this
proposed rule? If so, please explain which vehicles and why it is
impracticable.
If an incomplete vehicle were equipped with sensors for
AEB that could become obstructed by equipment added in later
manufacturing steps, how should NHTSA apply an AEB requirement to that
vehicle?
Are there any changes needed to 49 CFR part 567 or part
568 to facilitate certification to the proposed requirements? If so,
what would those changes be? Would a final-stage manufacturer be able
to certify a vehicle based on the information provided by an
intermediate or incomplete vehicle manufacturer, or is additional
information needed in IVDs? If
[[Page 43205]]
additional information is needed, please describe the needed
information.
Are there any requirements in this proposal that ought not
to apply to multi-stage vehicles or altered vehicles? Are there
proposed requirements that should be lowered in stringency to better
enable pass-through certification? Please provide details on those
requirements and provide associated rationale.
Would intermediate manufacturers, final-stage
manufacturers, and alterers have sufficient information to identify
when an impermissible change has been made? Please explain why or why
not.
Assuming there would be cases where it may not be
practical to comply with the proposed requirements, are the existing
exemption processes detailed in 49 CFR 555, ``Temporary exemption from
motor vehicle safety and bumper standards,'' sufficient to accommodate
unique vehicles, or should NHTSA explicitly consider applicability
exclusions for certain multi-stage vehicles? If applicability
exclusions are needed, please explain what they include and why the
exclusion is needed. For example, should there be exclusions for
vehicles with permanently installed work-performing equipment installed
on the front of or extending past the front of the vehicle (e.g., auger
trucks, bucket trucks, cable reel trucks, certain car carriers, etc.)
or vehicles with a GVWR equal to or greater than 120,000 pounds (i.e.,
heavy haulers)?
VII. Proposed Performance Requirements
This NPRM proposes that all heavy vehicles, class 3-8, are subject
to the same performance requirements such that the entire heavy vehicle
fleet benefits from improvements in AEB technology. The proposed set of
requirements would compel AEB technology to operate at its highest
safety potential, while at the same time being objective and
practicable. In order to establish these requirements, the agency
considered the key aspects of the technology and how they would best be
applied to address the safety problem. For example, requiring AEB
systems to perform only at lower speeds may address a significant
portion of the rear-end crash problem, but it would not address the
rear-end crash fatalities that mostly occur at higher speeds. Thus,
NHTSA is proposing that AEB systems must be capable of activating
across a wide spectrum of speeds. Similarly, the agency is aware that
some current AEB systems may occasionally cause unwarranted braking
events, or ``false activations,'' which could lead to unwanted
consequences; we are thus proposing two test scenarios which vehicles
must pass without false activation of the AEB system.
While creating the proposed performance requirements, NHTSA
considered the capabilities and limitations of current AEB
technologies. Using information from vehicle testing, this proposal
includes test scenarios and parameters that the agency found to be
within the potential of current production vehicles. This means that at
least one vehicle model demonstrated the ability to avoid impacting a
lead vehicle, represented by a vehicle test device, or that it so
nearly avoided the impact that we expect that the additional
development time allowed by this proposal would enable the required
improvement in performance.
While certain requirements can be assessed without vehicle tests, a
large portion of this proposal has performance requirements that are
evaluated through vehicle tests. These tests, discussed in this
section, simulate real-world scenarios and are run according to
specified conditions and test parameters. NHTSA believes that these
test scenarios will realistically evaluate how AEB systems perform
while the vehicle is travelling at normal driving speeds.
Several of the vehicle test scenarios test involve multiple moving
vehicles. In these test scenarios, the heavy vehicle being evaluated
with AEB is referred to as the ``subject vehicle.'' Other vehicles
involved in the test are represented by a vehicle test device. When a
vehicle test device is used ahead of the subject vehicle in the same
lane, in the path of the moving subject vehicle, it is referred to as a
``lead vehicle.'' When moving, a lead vehicle moves in the same
direction as the subject vehicle. The speeds and relative motions of
the subject vehicle and lead vehicle are choreographed in a variety of
ways to represent the most common scenarios which lead to heavy vehicle
rear-end crashes, and the test procedures measure whether the AEB
system is able to avoid impacting the lead vehicle.
The other vehicle tests are two false activation scenarios. A false
activation refers to an unwarranted brake activation by the AEB system
when there is no object present in the path of the vehicle with which
the vehicle would collide. These two test scenarios use objects,
including VTDs and a steel trench plate, arranged in realistic ways in
or near the travel path but without obstructing the path. In these
scenarios, the subject vehicle and AEB system are required to move past
these objects without making a substantial automatic application of the
service brakes.
This proposal also includes system requirements that are not
accompanied by vehicle tests. Vehicles with AEB systems must mitigate
collision at speeds beyond the those covered by the track testing,
ensuring robustness of the system's range of performance. The AEB
system must include a forward collision warning (FCW) system that
alerts the vehicle operator of an impending collision with a lead
vehicle. Also, the system must indicate an AEB malfunction to the
vehicle operator.
A. Proposed Requirements When Approaching a Lead Vehicle
1. Automatic Emergency Brake Application Requirements
The agency is proposing that vehicles be required to have a forward
collision warning system and an automatic emergency braking system that
are able to function continuously to apply the service brakes
automatically when a collision with a vehicle or object is imminent.
The system must operate when the vehicle is traveling at any forward
speed greater than 10 km/h (6.2 mph). This is a general system
equipment requirement with no associated performance test. No specific
speed reduction or crash avoidance would be required. However, this
requirement is included to ensure that AEB systems are able to function
at all times, including at speeds above those NHTSA is proposing as
part of the performance test requirements.
This requirement complements the performance requirements in
several ways. While the track testing described below provides a
representation of real-world crash events, no amount of track testing
can fully duplicate the real world. This requirement ensures that the
AEB's perception system identifies and automatically detects a vehicle,
warns the driver, and applies braking when a collision is imminent.
This requirement also ensures that AEB systems continue to function in
environments that are not as controlled as the test track environment.
For example, unlike during track testing, other vehicles, road users,
and buildings may be present within the view of the sensors. Finally,
track test equipment limitations and safety considerations limit the
ability to test at high speeds. However, crashes still occur at higher
travel speeds. Although generally the number of rear-end crashes
decreases at higher travel speeds, these high-speed crashes are the
ones that more often result in fatalities, as shown in Figure 3. The
automatic braking requirement
[[Page 43206]]
ensures that AEB systems continue to provide safety benefits at speeds
above those for which a track-testing requirement is currently not
practicable, either because of performance capabilities or track test
limitations. Where a performance standard is not practical or does not
sufficiently meet the need for safety, NHTSA may specify an equipment
requirement as part of an FMVSS.\105\
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\105\ See 72 FR 17235, 17299 (Apr. 6, 2007) (discussing the
understeer requirement in FMVSS No. 126); Chrysler Corp. v. DOT, 515
F.2d 1053 (6th Cir. 1975) (holding that NHTSA's specification of
dimensional requirements for rectangular headlamps constitutes an
objective performance standard under the Safety Act).
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These requirements would not apply at speeds below 10 km/h. NHTSA
believes that there are real-world cases where heavy vehicles are being
maneuvered at low-speed and intentionally in proximity of other
objects, and AEB intervention could be in conflict with the vehicle
operator's intention. For example, if an operator intends to drive
towards the rear of another vehicle in a parking lot in order to park
the vehicle near the other, automatic braking during this parking
maneuver would be unwanted. Publicly available literature from at least
one AEB manufacturer shows that some or all of the AEB system functions
are not available below 15 mph (24 km/h), indicating that current
manufacturers may have similar considerations about low-speed AEB
functionality.\106\ NHTSA tentatively concludes that a minimum
operational speed of 10 km/h would allow these types of low-speed
maneuvers. This proposal would not require AEB systems to be disabled
below 10 km/h.
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\106\ SD-61-4963 Bendix Wingman Fusion Driver Assistance System
Brochure, available at https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed June 21, 2023).
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Enforcement of such a performance requirement can be based on
evidence obtained by engineering investigation that might include a
post-crash investigation and/or system design investigation. For
instance, if a crash occurs in which the vehicle under examination has
collided with a lead vehicle, NHTSA could investigate the details
surrounding the crash to determine if a warning was provided and the
automatic emergency braking system applied the service brakes
automatically. In appropriate cases in the context of an enforcement
proceeding, NHTSA could also use its information-gathering authority to
obtain information from a manufacturer on the basis for its
certification that its FCW and AEB systems meet this proposed
requirement.
2. Forward Collision Warning Requirement
NHTSA is proposing that AEB-equipped vehicles must have forward
collision warning functionality that provides a warning to the vehicle
operator if a forward collision with a lead vehicle is imminent. The
proposal defines FCW as an auditory and visual warning provided to the
vehicle operator that is designed to elicit an immediate crash
avoidance response by the vehicle operator. The system must operate
when the vehicle is traveling at any forward speed greater than 10 km/h
(6.2 mph).
While some vehicles are equipped with alerts that precede the FCW
and research has examined their use, NHTSA's proposal is not specifying
an advisory or preliminary alert that would
[[Page 43207]]
precede the FCW. Lerner, Kotwal, Lyons, and Gardner-Bonneau (1996b)
differentiated between an imminent alert, which ``requires an immediate
corrective action'' and a cautionary alert, which ``alerts the operator
to a situation which requires immediate attention and may require a
corrective action.'' \107\ A 2004 NHTSA report titled ``Safety Vehicles
using adaptive Interface Technology (Task 9): A Literature Review of
Safety Warning Countermeasures,'' examined the question of whether to
include a cautionary alert level in an FCW system. Although the two FCW
algorithms in the Automotive Collision Avoidance System Field
Operational Test algorithms included a cautionary phase, the Collision
Avoidance Metrics Partnership (1999) program recommended that only
single (imminent) stage warnings be used.
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\107\ Lerner, Kotwal, Lyons, and Gardner-Bonneau (1996).
Preliminary Human Factors Guidelines for Crash Avoidance Warning
Devices. DOT HS 808 342. National Highway Traffic Safety
Administration.
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Unlike the FCW required as part of the track testing, NHTSA is not
specifically requiring that FCW presentation occur prior to the onset
of braking in instances that are not tested on the track. This is to
provide manufacturers with the flexibility to design systems that are
most appropriate for the complexities of various crash situations, some
of which may provide very little time for a driver to take action to
avoid a crash. A requirement that FCW occur prior to automatic braking
could suppress the automatic braking function in some actual driving
scenarios, such as a lead vehicle cutting immediately in front of an
AEB-equipped vehicle, where immediate automatic braking should not wait
for a driver warning.
i. FCW Modalities
Since approximately 1994, NHTSA has completed research and
published related reports for more than 35 research efforts related to
crash avoidance warnings or forward collision warnings. These research
efforts, along with other published research and existing ISO standards
(15623 and 22839) and SAE International (SAE) documents (J3029 and
J2400) provide a basis for the proposed requirements.\108\
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\108\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures; ISO 22839--Forward
vehicle collision mitigation systems--Operation, performance, and
verification requirements (applies to light and heavy vehicles); SAE
J3029: Forward Collision Warning and Mitigation Vehicle Test
Procedure and Minimum Performance Requirements--Truck and Bus (2015-
10; WIP currently); SAE J2400 2003-08 (Information report). Human
Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements.
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NHTSA NCAP and Euro NCAP information relating to FCW was also
considered. Since model year 2011, the agency has included FCW as a
recommended technology in NCAP and identifies to consumers which light
vehicles have FCW systems that meet NCAP's performance tests. NHTSA's
March 2022 request for comments notice on proposed changes to NCAP
sought comment on which FCW modalities or modality combinations should
be necessary to receive NHTSA's NCAP recommendation.\109\ Commenters
generally supported the use of a multimodal FCW strategy. The Alliance
for Automotive Innovation and Intel both advocated allowing credit for
any effective FCW signal type. Multiple commenters supported allowing
NCAP credit for FCW having either auditory or haptic signals. BMW and
Stellantis supported use of FCW auditory or haptic signals in addition
to a visual signal. NTSB and Advocates for Highway and Auto Safety
recommended that NHTSA conduct research examining the human-machine
interface and examine the effectiveness of haptic warning signals
presented in different locations (e.g., seat belt, seat pan, brake
pulse). Dynamic Research, Inc. advocated allowing NCAP credit for
implementation of a FCW haptic brake pulse, while ZF supported use of a
haptic signal presented via the seat belt. Bosch warned that use of a
haptic signal presented via the steering wheel for lane keeping or
blind spot warning and FCW should be avoided as it may confuse the
driver. The Alliance for Automotive Innovation raised the potential
benefits of standardizing the warning characteristics to improve
effectiveness as individuals move from vehicle to vehicle.
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\109\ 87 FR 13452 (Mar. 9, 2022).
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All current U.S. vehicle models with FCW systems appear to provide
auditory and visual FCW signals, while only a few manufacturers also
provide a haptic signal (e.g., seat pan vibration or a brake pulse).
Visual FCW signals in current models consist of either a symbol or word
(e.g., ``BRAKE!''), presented on the instrument panel or head-up
display, and most are red.
For this NPRM, NHTSA proposes that the FCW be presented to the
vehicle operator via at least two sensory modalities, auditory and
visual. Use of a multimodal warning ensures that most drivers will
perceive the warning as soon as its presented, allowing the most time
for the driver to take evasive action to avoid a crash. As a vehicle
operator who is not looking toward the location of a visual warning at
the time it is presented may not see it, NHTSA's proposal views the
auditory warning signal as the primary modality and the visual signal
as a secondary, confirmatory indication that explains to the driver
what the warning was intended to communicate (i.e., a forward crash-
imminent situation). However, because hearing-impaired drivers may not
perceive an FCW auditory signal, a visual signal is important for
presenting the FCW to hearing-impaired individuals.
A multimodal FCW strategy is consistent with recommendations of
multiple U.S. and international organizations including ISO, SAE
International, and Euro NCAP. ISO recommends a multimodal approach in
both ISO 15623, ``Forward vehicle collision warning systems--
Performance requirements and test procedures'' and ISO 22839, ``Forward
vehicle collision mitigation systems--Operation, performance, and
verification requirements'' (which applies to light and heavy
vehicles). SAE addresses the topic of a multimodal FCW strategy in both
information report J2400 2003-08, ``Human Factors in Forward Collision
Warning Systems: Operating Characteristics and User Interface
Requirements,'' and J3029, ``Forward Collision Warning and Mitigation
Vehicle Test Procedure and Minimum Performance Requirements--Truck and
Bus (2015-10; Work in Progress currently).'' Most of these
recommendations specify an FCW consisting of auditory and visual
signals, while ISO 15623 specifies that an FCW include a visual
warning, as well as an auditory or haptic signal.
ii. FCW Auditory Signal Characteristics
The proposed FCW auditory signal would be the primary means used to
direct the vehicle operator's attention to the forward roadway and
should be designed to be conspicuous to quickly capture the driver's
attention, convey a high level of urgency, and be discriminable from
other auditory signals presented within the vehicle.\110\ Some
specifications from NHTSA's ``Human Factors Design Guidance For
Driver--Vehicle Interfaces'' are proposed as forward collision warning
specifications to meet these criteria.\111\
[[Page 43208]]
As the FCW auditory signal would be the primary warning mode, this
signal would not be permitted to be disabled.
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\110\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\111\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
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To be conspicuous and quickly capture the driver's attention, the
FCW auditory signal must ensure that the driver will readily detect the
warning under typical driving conditions (e.g., ambient noise). The
auditory signal must be clearly perceptible and quickly focus the
driver's attention on the forward roadway. To ensure that the FCW
auditory signal is conspicuous to the vehicle operator, any in-vehicle
system or device that produces sound that may conflict with the FCW
presentation would be required to be muted, or substantially reduced in
volume, during the presentation of the FCW.\112\ In order for the
warning to be detectable, a minimum intensity of 15-30 dB above the
masked threshold (MT) should be used.113 114 115 116 Because
sound levels inside a vehicle can vary based on any number of different
factors, such as vehicle speed and pavement condition, NHTSA is not
proposing a specific sound level at this time, but requests comments on
suitable and reasonable approaches for ensuring that the FCW auditory
signal can be detected by drivers under typical driving conditions.
---------------------------------------------------------------------------
\112\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\113\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration. ``The amplitude of auditory signals is in the range
of 10-30 dB above the masked threshold (MT), with a recommended
minimum level of 15 dB above the MT (e.g., [1, 2, 3]).
Alternatively, the signal is at least 15 dB above the ambient noise
[3].''
\114\ Campbell, J.L., Richman, J.B., Carney, C., and Lee, J.D.
(2002). In-vehicle display icons and other information elements.
Task F: Final in-vehicle symbol guidelines (FHWA-RD-03-065).
Washington, DC: Federal Highway Administration.
\115\ International Organization for Standardization. (2005).
Road vehicles--Ergonomic aspects of in-vehicle presentation for
transport information and control systems--Warning systems (ISO/TR
16532). Geneva, Switzerland: International Organization of
Standards.
\116\ MIL-STD-1472F. (1998). Human engineering. Washington, DC:
Department of Defense.
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For communicating urgency and ensuring comprehension of auditory
messages, fundamental frequency, the lowest frequency in a periodic
signal, is a key design parameter.\117\ Research has shown that
auditory warning signals with a high fundamental frequency of at least
800 Hz more effectively communicate urgency.118 119 Greater
perceived urgency of a warning is associated with faster reaction
times, which would mean a quicker crash avoidance response by the
driver.120 121 122 Therefore, NHTSA proposes that the FCW
auditory signal's fundamental frequency must be at least 800 Hz.\123\
Additional proposed FCW auditory signal requirements that support
communication of the urgency of the situation include a duty
cycle,\124\ or percentage of time sound is present, of 0.25-0.95, and
faster auditory signals with a tempo in the range of 6-12 pulses per
second to be perceived as urgent and elicit rapid driver response.\125\
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\117\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\118\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\119\ Guilluame, A., Drake, C., Rivenez, M., Pellieux, L., &
Chastres, V. (2002). Perception of urgency and alarm design.
Proceedings of the 8th International Conference on Auditory Display.
\120\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\121\ Campbell, J.L., Richman, J.B., Carney, C., & Lee, J.D.
(2004). In-vehicle display icons and other information elements,
Volume I: Guidelines (Report No. FHWA-RD-03-065). Washington, DC:
Federal Highway Administration. Available at www.fhwa.dot.gov/publications/research/safety/03065/index.cfm.
\122\ Suied, C., Susini, P., & McAdams, S. (2008). Evaluating
warning sound urgency with reaction times. Journal of Experimental
Psychology: Applied, 14(3), 201-212.
\123\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\124\ Duty cycle, or percentage of time sound is present, is
equal to the total pulse duration divided by the sum of the total
pulse duration and the sum of the inter-pulse intervals.
\125\ Gonzalez, C., Lewis, B.A., Roberts, D.M., Pratt, S.M., &
Baldwin, C.L. (2012). Perceived urgency and annoyance of auditory
alerts in a driving context. Proceedings of the Human Factors and
Ergonomics Society Annual Meeting, 56(1), 1684-1687.
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The FCW auditory signal needs to be easily discriminable from other
auditory signals in the vehicle. Therefore, vehicles equipped with more
than one crash warning type should use FCW auditory signals that are
distinguishable from other warnings.\126\ This proposed requirement is
consistent with ISO 15623 5.5.2.6.\127\ Standardization of FCW auditory
signals would likely be beneficial in ensuring driver comprehension of
the warning condition across vehicle makes and models. NHTSA invites
comments on the feasibility of specifying a common FCW auditory signal.
While this proposal contains no specific requirements ensuring that the
FCW auditory signal is distinguishable from other auditory warnings in
the vehicles, NHTSA believes that industry is likely to consider this
in their vehicle designs as part of their due diligence and safety
assurance.
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\126\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\127\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures.
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iii. FCW Visual Signal Characteristics
Current FCWs in the U.S. vehicle fleet use a mix of symbols and
words as a visual forward collision warning. Use of a common FCW symbol
across makes and models would help to improve consumer understanding of
the meaning of FCWs and encourage more appropriate driver responses in
forward crash-imminent situations.
ISO 7000, ``Graphical symbols for use on equipment--Registered
symbols'' \128\ and the SAE J2400 (2003-08) \129\ information report,
``Human Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements,'' contain recommended
FCW symbols shown in Figure 4. These symbols are similar as they both
communicate a forward impact, while the ISO symbol portrays the forward
impact as being specifically with another vehicle.
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\128\ ISO 7000--Graphical symbols for use on equipment--
Registered symbols.
\129\ SAE J2400 (info. report, not RP or standard), 2003-08.
Human Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements.
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[[Page 43209]]
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Because the symbol in SAE J2400 relates the idea of a frontal crash
without depicting a particular forward object, this symbol could
visually represent and apply to scenarios when approaching a lead
vehicle but also scenarios approaching pedestrians or other objects
which may be relevant to AEB systems. To prevent different vehicle
types from having different FCW alerts, NHTSA proposes the same FCW
characteristics and reasoning in both the light vehicle NPRM and this
NPRM. Therefore, NHTSA has taken account of considerations for
pedestrian scenarios, because the light vehicle proposed rule contains
a requirement that FCW and AEB systems function in the case of an
imminent collision with a pedestrian. NHTSA finds the SAE J2400 symbol
to be most applicable to the FCW requirements in this proposal. NHTSA
proposes that FCW visual signals using a symbol must use the SAE J2400
(2003-08) symbol.
Some other vehicle models employ a word-based visual warning, such
as ``STOP!'' or ``BRAKE!'' SAE J2400 also includes a word-based visual
warning recommendation consisting of the word, ``WARNING.'' A well-
designed warning should instruct people about what to do or what not to
do to avoid a hazard. The potential benefit of a word-based warning for
FCW is that it can communicate to the driver an instruction about what
to do to avoid or mitigate the crash, thereby expediting the driver's
initiation of an appropriate crash avoidance response. However,
Consumer Reports noted in its online ``Guide to forward collision
warning'' that for some models, visual warning word use was found to be
confusing to some drivers surveyed.\130\ Respondents reported a common
complaint that ``their vehicle would issue a visual ``BRAKE'' alert on
the dash, but it wouldn't bring the car to a stop . . .'' This
confusion as to whether the word is meant to communicate what the
driver should do or what the vehicle is doing may stem from drivers
assuming that any information presented within the instrument panel
area is communicating something relating to the vehicle's condition or
state, as symbols presented in that location generally do. Presenting a
word-based warning in a higher location away from the instrument panel,
as recommended by SAE J2400, may be interpreted more accurately by
drivers as well as increase the likelihood of FCW visual warning
perception by drivers.\131\ NHTSA requests comments on this issue and
any available objective research data that relates to the effectiveness
of word-based FCW visual signals in instrument panel versus head-up
display locations. NHTSA also requests comments regarding whether
permitting word-based warnings that are customizable in terms of
language settings is necessary to ensure warning comprehension by all
drivers.
---------------------------------------------------------------------------
\130\ ``Guide to forward collision warning: How FCW helps
drivers avoid accidents.'' Consumer Reports. https://www.consumerreports.org/car-safety/forward-collision-warning-guide/
(last accessed April 2022).
\131\ SAE J2400 2003-08 (Information report). Human Factors in
Forward Collision Warning Systems: Operating Characteristics and
User Interface Requirements.
---------------------------------------------------------------------------
One plausible benefit of a word-based visual warning is that some
word choices that instruct the driver to initiate a particular action,
such as ``STOP!,'' would be fully applicable to lead vehicles and other
obstacles or pedestrians, whereas a symbol containing an image of a
lead vehicle would not be directly applicable to other crash-imminent
scenarios. Although this NPRM does not propose requiring pedestrian
AEB, NHTSA believes the warning should not be directed specifically at
lead vehicle AEB. As the response desired from the driver, to apply the
brakes, the content of the visual warning need not be specific to the
type of forward obstacle, but needs simply to communicate the idea of
an impending forward crash. NHTSA requests comments and any available
research data regarding the use and effectiveness of obstacle-specific
symbols and word-based visual warnings and the relative effectiveness
of word-based visual warnings compared to symbols.
While many current vehicle models present a visual FCW signal
within the instrument panel, drawing a driver's eyes downward away from
the roadway to the instrument panel during a forward crash-imminent
situation is likely to have a negative impact on the effectiveness of
the driver's response to the FCW. Research indicates that a visual FCW
signal presented in the instrument panel can slow driver response.\132\
The research findings support the SAE J2400 recommendation advising
against the use of instrument panel based visual FCWs.\133\ SAE J2400
(2003-08) states:
---------------------------------------------------------------------------
\132\ ``Evaluation of Forward Collision Warning System Visual
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547,
https://trid.trb.org/view/1430473.
\133\ SAE J2400 2003-08 (Information report). Human Factors in
Forward Collision Warning Systems: Operating Characteristics and
User Interface Requirements.
Visual warnings shall be located within a 10-degree cone of the
driver's line of sight. Qualitatively, this generally implies a top-
of-dashboard or head-up display location. A conventional dashboard
location shall not be used for the visual warning. The rationale for
this is based on the possibility that an instrument panel-based
---------------------------------------------------------------------------
visual warning may distract the driver from the hazard ahead.
This FCW visual signal location guidance is also consistent with
ISO 15623, which states that the FCW visual signal shall be presented
in the ``main glance direction.'' Current vehicles equipped with head-
up displays have the ability to present a FCW visual signal within the
driver's forward field of view. Furthermore, some GM vehicles not
equipped with head-up displays currently have the ability to present a
FCW visual signal reflected onto the
[[Page 43210]]
windshield in the driver's forward line-of-sight. Despite the FCW
visual signal being considered secondary to the auditory signal, NHTSA
agrees that the effectiveness of a FCW visual signal would be maximized
for both hearing and hearing-impaired drivers if the signal is
presented at a location within the driver's forward field of view above
the instrument panel. To ensure maximum conspicuity of the FCW visual
signal (be it word-based or a symbol), NHTSA proposes that it be
presented within a 10-degree cone of the driver's line of sight. The
line of sight would be based on the forward-looking eye midpoint
(Mf) as described in FMVSS No. 111, ``Rear visibility,''
S14.1.5.
The FCW visual signal would be required to be red as is generally
used to communicate a dangerous condition and as recommended by ISO
15623 and SAE J2400 (2003-08). Because the FCW visual signal is
intended to be confirmatory for the majority of drivers, the symbol
would be required to be steady burning.
iv. FCW Haptic Signal Discussion
NHTSA considered also specifying a complementary haptic FCW signal
as part of the proposed FCW specifications. Currently, only a portion
of U.S. vehicles equipped with forward collision warning include a
haptic warning component. For example, General Motors vehicles equipped
with the haptic warning feature can present either a haptic seat pulse
(vibration) or auditory warning based on a driver-selectable setting.
Some other vehicle manufacturers, such as Stellantis and Audi, use a
brake pulse, or brief deceleration of the vehicle, as part of the FCW.
Some Hyundai/Kia models incorporate a haptic steering wheel vibration
into the FCW. As haptic steering wheel signals are used by many lane
keeping features of current vehicles to encourage drivers to steer the
vehicle back toward the center of the lane, providing a haptic FCW
signal via the steering wheel may result in driver confusion and be
less effective in eliciting a timely and beneficial driver response.
ISO 15623 allows a haptic signal as an alternative to an auditory
signal.\134\ It permits a haptic brake pulse warning with a duration of
less than 1 second when the driver is not already applying the brakes.
ISO 15623 also allows actuation of a seat belt pretensioner as a haptic
FCW signal.
---------------------------------------------------------------------------
\134\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures.
---------------------------------------------------------------------------
Some research has shown that haptic FCW signals can improve crash
avoidance response. NHTSA research on ``Driver-Vehicle Interfaces for
Advanced Crash Warning Systems'' found that a haptic signal delivered
via the seat belt pretensioner would be beneficial in eliciting an
effective crash avoidance response from the vehicle operator. The
research showed for FCWs issued at 2.1-s time to collision (TTC) that
seat belt pretensioner-based FCW signals elicited the most effective
crash avoidance performance.\135\ Haptic FCW signals led to faster
driver response times than did auditory tonal signals. FCW modality had
a significant effect on participant reaction times and on the speed
reductions resulting from participants' avoidance maneuvers (regardless
of whether a collision ultimately occurred). Brake pulsing or seat belt
tensioning were found to be effective for returning distracted drivers'
attention to the forward roadway and eliciting desirable vehicle
control responses; seat vibration similar to a virtual rumble strip
(vibrating the front of the seat) was not found to rapidly and reliably
return driver attention to the forward roadway within the research.
Similarly, research by Aust (2014) found that ``combining sound with
seat belt jerks or a brake pulse leads to significantly faster response
times than combining the sound with a visual warning'' and stated,
``these results suggest that future FCWs should include a haptic
modality to improve driver performance.'' \136\ Aust (2014) also found
use of a haptic seat belt FCW signal to be slightly more effective (100
ms faster driver response) than a haptic brake pulse in one of two
scenarios (response times were equal in a second scenario). Despite
these promising research results associated with use of a seat belt
based FCW haptic component, NHTSA was unable to identify any current
U.S. vehicle models equipped with a haptic seat belt FCW component.
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\135\ Lerner, N., Singer, J., Huey, R., Brown, T., Marshall, D.,
Chrysler, S., . . . & Chiang, D.P. (2015, November). Driver-vehicle
interfaces for advanced crash warning systems: Research on
evaluation methods and warning signals. (Report No. DOT HS 812 208).
Washington, DC: National Highway Traffic Safety Administration.
\136\ Aust, M. (2014) Effects of Haptic Versus Visual Modalities
When Combined With Sound in Forward Collision Warnings. Driving
Simulation Conference 2014, Paper number 36. Paris, France,
September 4-5, 2014.
---------------------------------------------------------------------------
Other studies found FCW haptic brake pulses effective at getting a
driver's attention and that drivers are more likely to detect a brake
pulse if it produces a sensation of ``jerk'' or ``self-motion.''
137 138 Kolke reported reaction times shortened by one-third
(approximately 0.3 s, non-significant) when a brake pulse was added to
an audio-visual warning.\139\ One usability drawback is that drivers
tend to report that vehicle brake pulses are too disruptive, which can
lead to unfavorable annoyance.\140\
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\137\ Lee, J.D., McGehee, D.V., Brown, T.L., & Nakamoto, J.
(2012). Driver sensitivity to brake pulse duration and magnitude.
Ergonomics, 50(6), 828-836.
\138\ Brown, S.B., Lee, S.E., Perez, M.A., Doerzaph, Z.R.,
Neale, V.L., & Dingus, T.A. (2005). Effects of haptic brake pulse
warnings on driver behavior during an intersection approach.
Proceedings of the Human Factors and Ergonomics Society 49th Annual
Meeting, 1892-1896.
\139\ Kolke, Gauss, and Silvestro (2012). Accident reduction
through emergency braking systems in passenger cars. Presentation at
the 8th ADAC/BASt-Symposium ``Driving Safely in Europe.'' October 5,
2012, Workshop B.
\140\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------
Presentation of a FCW haptic signal via the driver's seat pan has
also been investigated. NHTSA's ``Human factors design guidance for
driver-vehicle interfaces'' contains best practice information for
implementation of haptic displays, including ``Generating a Detectable
Signal in a Vibrotactile Seat.'' \141\ In a large-scale field test of
FCW and LDW systems on model year 2013 Chevrolet and Cadillac vehicles,
the University of Michigan Transportation Research Institute and GM
found that GM's Safety Alert Seat, which provides haptic seat vibration
pulses, increases driver acceptance of both FCW and LDW systems
compared to auditory signals.\142\
---------------------------------------------------------------------------
\141\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\142\ Flannagan, C., LeBlanc, D., Bogard, S., Nobukawa, K.,
Narayanaswamy, P., Leslie, A., Kiefer, R., Marchione, M., Beck, C.,
and Lobes, K. (2016, February), Large-scale field test of forward
collision alert and lane departure warning systems (Report No. DOT
HS 812 247), Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------
NHTSA's March 2022 request for comments notice on the NCAP sought
comment on which FCW modalities or modality combinations should receive
credit and asked specific questions regarding haptic signals and
whether certain types should be excluded from consideration (e.g.,
because they may be such a nuisance to drivers that they are more
likely to disable the FCW or AEB system). A preliminary review of
comments on that notice found multiple comments highlighting a need for
more
[[Page 43211]]
research relating to FCW signals. The National Transportation Safety
Board highlighted a need for additional information regarding haptic
signals presented in different locations stating ``[w]ithout examining
the efficacy of different means of providing haptic alerts and defining
appropriate, research-supported implementations, a prudent approach
would give credit only for audible unimodal alerts or for bi-modal
alerts that include audible alerts.'' Rivian stated ``[t]he agency
should award credit to systems that provide both audible and haptic
alerts and provide the option to turn either of them OFF based on
driver preference. These audible or haptic alerts should be in sync
with providing a visual alert of an impending collision. The agency
should recommend the decibel level and the haptic feedback location and
type as a baseline and based on research on reducing nuisance to the
driver.''
Given the lack of consensus within available research as to the
best location for a FCW haptic signal (seat belt, seat pan, steering
wheel, or brake pulse), and NHTSA's ongoing review of comments
submitted in response to the March 2022 request for comments, NHTSA is
not at this time proposing to require a haptic FCW component, but
invites comment on whether requiring FCW to contain a haptic component
presented via any location may increase FCW effectiveness or whether a
FCW haptic signal presented in only one specific, standardized location
should be allowed.
While the FCW auditory signal is envisioned as being the primary
means of warning the driver, providing a haptic FCW signal that would
complement or supplant the auditory warning signal would likely improve
FCW perception for hearing-impaired drivers. Some drivers also may
prefer an alternative modality to auditory warnings (e.g., due to
annoyance caused by the auditory warning). However, the degree of
additional benefit that may be accrued by requiring a haptic FCW signal
in addition to a well-designed auditory and visual FCW that meets the
specifications proposed is not known.
A haptic FCW signal, to be effective, would necessarily require the
driver to be in physical contact with the vehicle component through
which the haptic signal is presented in order to perceive the warning.
For example, if the driver is not wearing a seat belt, a haptic FCW
signal presented via the seat belt would not be effectively received. A
seat pan based haptic FCW signal would be unlikely to have such a non-
contact issue. NHTSA is interested in research data documenting the
comparison of a compliant auditory-visual FCW to that same FCW with an
added haptic component. NHTSA also welcomes any objective data
documenting the relative effectiveness of different haptic signal
presentation locations for FCW use.
3. Performance Test Requirements
This NPRM would require that, when approaching a lead vehicle
during testing, the subject vehicle must provide a forward collision
warning and subsequently apply the brakes to avoid a collision. This
performance requirement is conducted under a defined set of conditions,
parameters (e.g., relative vehicle speeds and distances), and test
procedures.
For all vehicle tests where the subject vehicle approaches a lead
vehicle, NHTSA is proposing that the minimum performance requirement is
complete avoidance of the lead vehicle. NHTSA chose the performance
criterion of collision avoidance because it maximizes the safety
benefits of the rule as compared to a metric that might permit a
reduced speed collision. NHTSA has tentatively concluded that a no-
contact criterion for the performance test requirements is practicable
to achieve, consistent with the need for safety, and may be necessary
to ensure test repeatability.
NHTSA also seeks comment on the potential consequences if vehicle
contact were allowed during testing. First, NHTSA seeks comment on how
allowing contact during testing would affect the safety benefits of AEB
systems. Second, NHTSA seeks comment on whether allowing contact during
testing would create additional testing burdens. Specifically, NHTSA is
concerned that any performance test requirement that allows for vehicle
contact not resulting in immediate test failure could result in the
non-repeatability of testing without expensive or time-consuming
interruptions to testing, and seeks comment on this concern. For
instance, if a test vehicle were to strike the lead vehicle test
device, even at a low speed, sensors on the vehicle could become
misaligned or the vehicle test device may be damaged, including in ways
that are not immediately observable. For example, damage to the test
device might affect the radar cross section that requires a long
verification procedure to discover.
4. Performance Test Scenarios
NHTSA is proposing three track test scenarios to evaluate AEB
performance. The test scenarios have the subject vehicle travelling
toward a lead vehicle which is ahead in the same lane. However, the
lead vehicle may be either stopped, moving at a constant but slower
speed, or decelerating to a stop.
These three tests were chosen because they represent the three most
common pre-crash scenarios involving a lead vehicle. A NHTSA research
study of heavy vehicles comprising the striking vehicle in rear-end
crashes in the United States determined that four pre-crash scenarios
exist in data of both fatal and non-fatal crashes.\143\ These four
scenarios include the three listed above, and also a ``cut-in'' case in
which a lead vehicle changed lanes or merged into the path of the heavy
vehicle just prior to the crash. The cut-in scenario was excluded from
the test scenarios for this proposal because the research study shows
that it was much less likely to occur than the other three
scenarios.\144\
---------------------------------------------------------------------------
\143\ Woodrooffe, J., et al. ``Performance Characterization and
Safety Effectiveness Estimates of Forward Collision Avoidance and
Mitigation Systems for Medium/Heavy Commercial Vehicles,'' Pg. 12.
Report No. UMTRI-2011-36, UMTRI (August 2012). Available at https://www.regulations.gov/document/NHTSA-2013-0067-0001 (last accessed
June 9, 2022).
\144\ The cut-in scenario represents less than 5% of the pre-
crash scenarios.
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i. Stopped Lead Vehicle
This test recreates a roadway scenario where the subject vehicle
encounters a lead vehicle which is stopped ahead in the same lane.
Figure 5 shows the basic setup for the stopped lead vehicle scenario.
The subject vehicle is driven toward the stationary lead vehicle at a
constant speed, and the accelerator is only released if a forward
collision warning is issued. The test ends when the subject vehicle
either automatically stops without impact, or proceeds to strike the
lead vehicle.
NHTSA proposes testing under two conditions for the subject
vehicle: testing without any manual brake application (to test the CIB
component) and testing with manual brake application (to ensure that
the driver's application of the brake pedal does not inhibit the
functionality of the AEB system). Testing with no brake application
simulates a driver who does not intervene in response to an FCW alert
prior to a crash. Testing with brake application simulates a driver who
applies the brakes, but the manual brake application is insufficient to
prevent a collision.
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ii. Slower-Moving Lead Vehicle
This test recreates a roadway scenario where the subject vehicle
encounters a lead vehicle that is moving at a constant but slower speed
ahead in the same lane. Figure 6 shows the basic setup for the slower-
moving lead vehicle scenario. The subject vehicle is driven toward the
lead vehicle at a constant speed, and its accelerator is then released
after the AEB system in the subject vehicle issues a forward collision
warning. The test ends when the subject vehicle either slows down to a
speed less than or equal to the lead vehicle's speed without impact or
strikes the lead vehicle. As with the stopped lead vehicle test, NHTSA
proposes testing under two conditions for the subject vehicle: without
any manual brake application and with manual brake application.
[GRAPHIC] [TIFF OMITTED] TP06JY23.006
iii. Decelerating Lead Vehicle
This test recreates a roadway scenario where the subject vehicles
encounter a lead vehicle that is slowing down ahead in the same lane.
At the start of the test, both the subject vehicle and lead vehicle
travel at the same constant speed, while maintaining a predetermined
relative distance, or headway. The lead vehicle then begins to
decelerate, reducing the headway. Once the AEB system in the subject
vehicle issues a forward collision warning, the subject vehicle's
accelerator is released. The test ends when the subject vehicle either
automatically stops without impact or strikes the lead vehicle. As with
the prior two tests, NHTSA proposes testing under two conditions for
the subject vehicle: without any manual brake application and with
manual brake application. Figure 7 shows the basic setup for the
decelerating lead vehicle scenario.
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[[Page 43213]]
5. Parameters for Vehicle Tests
The test procedures for each scenario reference a set of
parameters. These parameters are presented in Table 16, where each row
represents a potential combination of parameters to be used for a test
run. The parameters define the speeds, decelerations, headways, and
manual brake applications used for the choreography of the vehicle test
scenarios. Specifically, these include:
Subject Vehicle Speed (VSV)--speed at which the
subject vehicle travels toward the lead vehicle
Lead Vehicle Travel Speed (VLV)--speed at which the
lead vehicle travels in the same direction as the subject vehicle
Headway--the distance between the subject vehicle and the lead
vehicle
Lead Vehicle Deceleration--the rate at which the lead vehicle
reduces its speed
Manual Brake Application--specifies whether or not the service
brakes of the subject vehicle will be applied ``manually,'' or via a
brake controller
Table 16--Test Parameters When Approaching a Lead Vehicle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Speed (km/h)
Test scenarios ------------------------------------------ Headway (m) Lead vehicle decel. (g) Manual brake
VSV VLV application
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stopped Lead Vehicle.............. Any 10-80............... 0 ........................ ....................... no.
Any 70-100.............. 0 ........................ ....................... yes.
Slower-Moving Lead Vehicle........ Any 40-80............... 20 ........................ ....................... no.
Any 70-100.............. 20 ........................ ....................... yes.
Decelerating Lead Vehicle......... 50...................... 50 Any 21-40............... Any 0.3-0.4............ no.
50...................... 50 Any 21-40............... Any 0.3-0.4............ yes.
80...................... 80 Any 28-40............... Any 0.3-0.4............ no.
80...................... 80 Any 28-40............... Any 0.3-0.4............ yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Some of these parameters are proposed as ranges.\145\ The use of
ranges allows NHTSA to ensure AEB system performance remains consistent
under a variety of conditions and that no substantial degradation in
performance occurs at any point within the range. NHTSA tentatively
concludes that requiring a minimum performance only at discreet,
predetermined values within these proposed ranges may not ensure that
AEB system performance is sufficiently robust to meet the need for
safety.
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\145\ In instances where an FMVSS includes a range of values for
testing and/or performance requirements, the use of the word ``any''
is consistent with 49 CFR 571.4.
---------------------------------------------------------------------------
i. Vehicle Speed Parameters
The proposed test speed ranges were selected considering two
primary factors. The first factor is the practical ability of AEB
technology to consistently operate and avoid contact with a lead
vehicle at the widest reasonable range of speeds. A larger range of
speeds could yield more safety benefits. Also, a larger range of speeds
will more thoroughly test the capabilities of the AEB system. NHTSA,
through its understanding of vehicle braking systems described in
established standards such as FMVSS Nos. 105 and 121, knows that
testing stopping distance at 60 mph is indicative of the service brake
performance over a range of speeds, and in those cases testing at a
single speed is acceptable. However, as observed in vehicle testing for
NHTSA research, AEB performance during testing at interstate speeds
does not necessarily indicate what the same system's performance will
be at lower speeds. Thus, NHTSA tentatively concludes that testing over
a range of speeds is necessary to fully assess AEB performance.
The second factor is the practical limit of safely conducting
vehicle tests of AEB systems. NHTSA's testing must be safe and
repeatable as permitted by track conditions and testing equipment. For
example, if the AEB system does not intervene as required or if test
parameters inadvertently fall outside of the specified limits, it
should be possible to safely abort the test. In the event the subject
vehicle does collide with the lead vehicle, the test should be designed
so that it does so in a manner that will not injure the testing
personnel nor cause excessive property damage. Additionally, test
tracks may be constrained by available space and there may be
insufficient space to accelerate a heavy vehicle up to a high speed and
still have sufficient space to perform a test. Many types of heavy
vehicles are not capable of accelerating as quickly as lighter vehicles
and reaching high test speeds may require long distances that exceed
what is available at many vehicle testing facilities. At approximately
100 km/h, the agency found that constraints with available test track
length, in conjunction with the time required to accelerate the vehicle
to the desired test speed, made performing these high speed tests with
heavy vehicles logistically challenging.\146\ The agency has
tentatively concluded that at this time the maximum practicable test
speed is 100 km/h.
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\146\ During testing of a 2021 Freightliner Cascadia at speeds
approaching 100 km/h, NHTSA experienced difficulty establishing
valid test conditions due to insufficient track length.
---------------------------------------------------------------------------
The maximum speed of 100 km/h is included in the test speed range
when manual braking is present; the manual braking will guarantee a
speed reduction even if the AEB system does not activate before
reaching the lead vehicle, which would limit potential damage to the
test equipment and reduce other potential risks. When no manual braking
is allowed, the maximum test speed would be 80 km/h so that, in the
event the AEB system does not provide any braking at all, risk to
personnel and damage to test equipment are reduced. Over 82 percent of
rear-end crashes where the heavy vehicle is the striking vehicle occur
at speeds below 80 km/h.\147\ However, the majority of fatal crashes
occur at speeds above 80 km/h, and approximately 40 percent of these
occur at travel speeds between 80 and 100 km/h. The stopped lead
vehicle test scenario uses a no-manual-braking test speed range of 10
to 80 km/h and a manual-braking test speed range of 70 to 100 km/h.
Together, these test speed ranges overlap with the travel speeds at
which heavy vehicle rear-end crashes occur in the real world, while
reducing the potential risk and damage to test equipment and vehicles
and not
[[Page 43214]]
exceeding the practical physical size limits of test tracks.
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\147\ This is based on analysis of 2017-2019 crash data.
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Similarly, the slower-moving lead vehicle test scenario uses speed
ranges of 40 to 80 km/h and 70 to 100 km/h for the subject vehicle,
while the lead vehicle travels ahead at a constant speed of 20 km/h.
The lower end of the subject vehicle test speed range is 40 km/h so
that the subject vehicle is traveling faster than the lead vehicle. The
decelerating lead vehicle tests are run at either 50 or 80 km/h. This
test is performed at two discreet speeds rather than at ranges of
speeds because the main factors that test AEB performance are the
variation of headway, or the distance between the subject vehicle and
lead vehicle, and how hard the lead vehicle brakes. Additionally,
because these tests contain a larger number of variables requiring more
complex test choreography, limiting the test to two discreet test
speeds reduces the number of potential test conditions and reduces
potential test burden.
During each test run in any of the test scenarios, the vehicle test
speed will be held constant until the test procedure specifies a
change. NHTSA is proposing that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of the chosen test value. This is
important for test consistency. Vehicle speed determines the time to
collision, which is a critical variable in AEB tests. In NHTSA's
experience, both the subject vehicle and lead vehicle speeds can be
reliably controlled within the 1.6 km/h tolerance range, and speed
variation within that range yields consistent test results. A tighter
speed tolerance is burdensome and unnecessary for repeatability as it
may result in a higher test-rejection rate, without any greater
assurance of accuracy of the test track performance.
NHTSA's vehicle testing suggested that the selected speed ranges
for the various scenarios are within the capabilities of at least some
recent model year AEB-equipped production vehicles. For example, the
2021 Freightliner Cascadia avoided collision in the stopped lead
vehicle test at all speeds between 40 and 85 km/h, most speeds between
30 and 90 km/h (except 30 and 60 km/h) in the slower-moving lead
vehicle test, and in all decelerating lead vehicle tests that were run
at the proposed parameters. This vehicle's AEB system did not prevent a
collision at lower speeds between 20 and 35 km/h for the stopped lead
vehicle test. However, the 2021 Dodge Ram 550 avoided collision in all
stopped lead vehicle tests from 10 to 40 km/h. In many test cases where
current AEB systems did not prevent a collision, the AEB significantly
reduced the speed before the collision. While these current AEB systems
perform a bit differently depending on the vehicle, given that this
notice proposes a lead time for manufacturers to come into compliance
with the proposed performance requirement, the agency expects that
compliance with these requirements would be achievable.
ii. Headway
The decelerating lead vehicle test scenario includes a parameter
defining how far ahead the lead vehicle is from the subject vehicle at
the beginning of the test, which is referred to as headway. Headway and
lead vehicle deceleration are the main factors for the dynamics of the
decelerating lead vehicle test since both the lead and subject vehicles
start the test at the same constant speed. At the start of the test,
when the vehicles are both travelling at 50 km/h, the proposed headway
specification is any distance between 21 m and 40 m.\148\ When the
vehicles are both travelling at 80 km/h, the proposed headway
specification is any distance between 28 m and 40 m. Headways are
proposed as a range in order to assure AEB functionality over a wider
range of driving scenarios. A basic kinematic simulation of heavy
vehicle AEB braking under the proposed test parameters, assuming
factors such as AEB response time and foundation brake reaction time/
deceleration similar to what was observed in testing, indicated that
headways shorter than 21 and 28 m would not be realistic to achieve and
would inevitably result in a collision.
---------------------------------------------------------------------------
\148\ The bounds of the headway range are consistent with the
headways in the April 2021 European New Car Assessment Programme
(Euro NCAP), Test Protocol--AEB Car-to-Car systems, Version 3.0.3
for the same scenario.
---------------------------------------------------------------------------
The upper limit of 40 m was chosen because testing at longer
headways does not provide additional insight into AEB performance with
regard to decelerating lead vehicles. At headways greater than 40 m,
the lead vehicle decelerating may come to a full stop prior to the
subject vehicle actuating the brakes. This essentially becomes a
stopped lead vehicle test. Allowing for a range of headways during
testing also makes the choreography of the test possible by providing a
tolerance for the headway. At the start of the test, the speed of both
the subject vehicle and lead vehicle are the same and are maintained
within the tolerance specified (plus or minus 1.6 km/h). As each
vehicle's speed fluctuates a bit differently within these bounds, in
turn the headway between the vehicles accordingly fluctuates as well.
As long as the headway fluctuation is within the proposed range, the
test can still be considered valid, and no headway tolerance needs to
be established.
iii. Lead Vehicle Deceleration Parameter
The decelerating lead vehicle test scenario includes a deceleration
parameter that dictates how quickly the lead vehicle will slow down in
front of the subject vehicle. The agency has tentatively concluded that
this parameter range of 0.3g to 0.4g represents real-world, manual
application of the service brake. Previous NHTSA research had
identified 3.0 m/s\2\ (.306g) as ``reasonably comfortable for passenger
car occupants'' and that on average, drivers brake in such a manner
that the vehicle decelerates at an average of 0.48g when presented with
a unexpected obstacle.\149\ The upper limit of the lead vehicle braking
is proposed at 0.4g to avoid a test condition in which the lead vehicle
would provide greater brake inputs than those necessary to meet the
minimum stopping distance requirements. NHTSA took into consideration
the stopping distance requirements for heavy vehicles under FMVSS Nos.
105 and 121 and the resulting average decelerations that those vehicles
would be required to achieve. For example, an air-braked tractor
trailer under FMVSS No. 121 would need to brake at 0.41g to meet the
stopping distance of 310 ft from 60 mph.\150\ Given the headway
parameters and vehicle speeds in this proposal, the agency believes a
lead vehicle deceleration above 0.4g would create a requirement that
could effectively reduce the minimum stopping distance requirements for
vehicles generally.
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\149\ Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(April 2010). Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report (Report No. DOT HS 811 251) Washington,
DC: National Highway Traffic Safety Administration, pgs. 13 and 101.
\150\ This assumes an average deceleration that is achieved
after an initial brake actuation time of 0.45 seconds, as this is
the maximum actuation time allowed by FMVSS No. 121.
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6. Manual Brake Application in the Subject Vehicle
Each of the three lead vehicle test scenarios includes tests that
are conducted with manual brake application in the subject vehicle. The
process for testing with manual brake application is identical to what
is considered a test for dynamic brake support or DBS in NHTSA's NCAP
for light vehicles. While the term DBS is
[[Page 43215]]
not usually associated with heavy vehicles, NHTSA is including this
requirement in this proposal to ensure that the driver's application of
the brake pedal does not inhibit the functionality of the AEB system if
the driver's brake application is insufficient to avoid a crash. The
manual brake application procedure specifies that the subject vehicle's
service brakes are applied by using a robotic brake controller to
ensure accurate and consistent test conduct.
A NHTSA study that examined light vehicle drivers' behavior in
response to potential frontal crash situations found that they
typically exhibit multi-stage braking behavior.\151\ This means that
the drivers initially applied and held the brake moderately, and then
continued to a full application if perceived to be necessary. A
subsequent NHTSA study concluded that a significant portion of heavy
vehicle operators display the same multi-stage braking behavior.\152\
The agency believes that in real world cases where the operator may
apply insufficient brake force to avoid a rear-end collision, an AEB
system should apply the necessary supplemental braking necessary to
avoid a collision. Furthermore, by using manual brake application in
the test scenarios, NHTSA is able to test AEB performance at higher
test speeds.
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\151\ Mazzae, E., Barickman, F., Scott Baldwin, G., and
Forkenbrock G., ``Driver Crash Avoidance Behavior with ABS in an
Intersection Incursion Scenario on Dry Versus Wet Pavement,'' SAE
Technical Paper 1999-01-1288, 1999, doi:10.4271/1999-01-1288.
\152\ Every, J., Salaani, M., Barickman, F., Elsasser, D., et
al., ``Braking Behavior of Truck Drivers in Crash Imminent
Scenarios,'' SAE International Journal of Commercial Vehicles,
7(2):2014, doi:10.4271/2014-01-2380.
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In real world cases, the brake pedal can be applied by a heavy
vehicle operator in an infinite number of ways (varying force, reaction
time, duration, etc.). Since the manual brake application represents an
operator's response to an unexpected obstacle and the forward collision
warning, the agency is proposing a brake pedal application that results
in a mean deceleration of 0.3g. A heavy vehicle field study by NHTSA
indicated that when presented with an FCW triggered by a valid object
and requiring a crash avoidance maneuver, the operators braked on
average at a maximum of 0.3g.\153\ Manually applying the brake at 0.3g
also is a low enough value to improve the capability of observing an
AEB automatic braking intervention that is occurring simultaneously on
top of that. The minimum stopping distance requirements for heavy
vehicles in existing FMVSSs require braking at around 0.4g. Thus
hypothetically, if a heavy vehicle's service brakes were manually
applied at a higher deceleration of 0.4g for example, and the brakes
were only capable of a maximum of 0.4g of deceleration, AEB
intervention would be incapable of producing additional deceleration
and would not be observable.
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\153\ Grove, K., Atwood, J., Hill, P., Fitch, G., Blanco, M.,
Guo, F., . . . & Richards, T. (2016, June). Field study of heavy-
vehicle crash avoidance systems. (Final report. Report No. DOT HS
812 280). Washington, DC: National Highway Traffic Safety
Administration.
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There are two methods to perform the manual brake application--
using either displacement feedback or hybrid feedback. Both methods are
intended to be carried out by a robotic brake pedal controller in
closed loop operation, and the method that is most suitable to the
subject vehicle is chosen. Regardless of the method, it is necessary
initially to determine a pedal position which, in the absence of any
automatic braking from the AEB system, results in an average vehicle
deceleration of 0.3g. The displacement feedback method then simply
requires moving the brake pedal to the 0.3g position quickly, at a rate
of 254 mm/s,\154\ and then maintaining that position. However,
automatic braking in certain vehicles requires the pedal position to
move further toward the floor, and can cause conflict with the
displacement feedback method's control of pedal position, in turn
adversely affecting test results.\155\ The hybrid feedback pedal
control method provides a solution to this conflict. The hybrid method
initially requires the same pedal position control, but then almost
immediately begins to control the force on the pedal (and not the
position) to maintain the 0.3g deceleration. If the AEB system
thereafter requires further movement of the pedal, the brake controller
is able to ``follow'' the pedal while still applying the appropriate
force.\156\ NHTSA is proposing that the brake will be applied 1.0
second after the vehicle has provided a FCW; this is based on the
average time it takes a driver to react when presented with an
obstacle.\157\ Although these average decelerations and reaction times
are based on behavior of light vehicle drivers, we feel that it is
sufficient basis to simulate a scenario in which a heavy vehicle
operator brakes partially and insufficiently to fully avoid a rear-end
collision.
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\154\ Previous NHTSA research related to AEB examined pedal
application rates by drivers in emergency and non-emergency
situations, and determined that pedal application rate is important
in AEB testing with manual braking, and that the appropriate
application rate is 254 mm/s. NHTSA, August 2014. Automatic
Emergency Braking System (AEB) Research Report, An Update of the
June 2012 Research Report Titled, ``Forward-Looking Advanced Braking
Technologies Research Report.'' Docket NHTSA-2012-0057-0037.
\155\ NHTSA, August 2014. Automatic Emergency Braking System
(AEB) Research Report, An Update of the June 2012 Research Report
Titled, ``Forward-Looking Advanced Braking Technologies Research
Report.'' Docket No. NHTSA-2012-0057-0037.
\156\ Id.
\157\ Previous NHTSA research has shown that on average, it
takes drivers 1.04 s to begin pressing the brake when presented with
an unexpected obstacle and 0.8 s when presented with an anticipated
obstacle. Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(2010, April) ``Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report'' (Report No. DOT HS 811 251),
Washington, DC: National Highway Traffic Safety Administration, p.
101.
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B. Conditions for Vehicle Tests
The test conditions are used to control the environmental, road
surface, subject vehicle, and equipment conditions to ensure
consistency both to define potential variabilities in conditions under
which an AEB system would be expected to operate while also providing
consistent conditions to reduce test variability due to extraneous
factors. NHTSA recognizes that there are an unlimited number of non-
ideal environmental conditions present in the real world, and it would
be unreasonable to attempt to reproduce most of them within practical
constraints in the testing environment. Thus, in many cases, the
proposed test conditions were chosen to represent near-ideal conditions
with the goal of reducing variability in the test results. For example,
if testing were conducted at below-freezing temperatures with snowfall,
it would be difficult to interpret whether poor test results were due
to the AEB system or reduced road surface friction.
Many of the proposed conditions were selected based on research
data and engineering practices, and reasonable deduction. In some
cases, as appropriate, the agency considered that conditions should be
the same or similar to what is specified in other heavy vehicle brake-
related FMVSS. This usage of pre-established conditions may help reduce
testing burden, since fewer testing conditions would need to be
adjusted between different FMVSS brake-related compliance tests. It
also ensures that the minimum stopping distance requirements in the
braking standards would be achievable during an AEB test.
Each test procedure for the three scenarios specifies a point at
which thereafter the test conditions described in this section apply
and will be maintained. For the stopped lead vehicle and slower-moving
lead vehicle
[[Page 43216]]
test scenarios, this point is at a 5 second time to collision. For the
decelerating lead vehicle test scenario, this point is 1 second prior
to the onset of lead vehicle deceleration.
1. Environmental Conditions
The ambient temperature range specified in this proposal is 2 to 40
degrees Celsius; this is the same range as specified in FMVSS No. 136,
which avoided testing at 0 degrees Celsius because it could impact tire
performance and in turn the variability of test results.
The maximum wind speed is 5 m/s, which is the same as what is
specified in FMVSS No. 136. This value was chosen to reduce the
potential lateral displacement of certain heavy vehicles.
NHTSA considered that certain environmental conditions should be
near-ideal to prevent sensor performance degradation and maintain
repeatability of vehicle testing. First, ambient illumination would be
at or above 2,000 lux. This represents daytime illumination that is at
a minimum equivalent to an overcast day.\158\ A NHTSA study has shown
that darkness can cause degradation of sensor performance.\159\ NHTSA
analysis shows that 87 percent of heavy vehicle rear-end crashes occur
during daylight conditions.\160\ Therefore, NHTSA tentatively concludes
that daylight testing is necessary to ensure that AEB systems address
the rear-end crash safety problem.
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\158\ During an overcast day (no sun), when the solar altitude
is around 6 degrees, the light intensity on a horizontal surface is
around 2,000 lux. Illuminating Engineering Society of North America.
1979. ``Recommended Practice of Daylighting.''
\159\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
\160\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on initial AEB target population.
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Second, during testing, the sun would not be below 15 degrees of
elevation and within 25 degrees laterally from the center plane of the
subject vehicle. This specification reduces the likelihood of glare or
washout for camera-based sensors that could lead to degradation of
sensor and AEB system performance.\161\
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\161\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
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Visibility also would not be affected by fog, smoke, ash or other
particulate, as recommended in previous agency research findings.\162\
This improves test repeatability and also aligns with many real-world,
rear-end crash conditions. A review of NHTSA's crash data indicates
that 81 percent of those occur when the weather conditions are clear or
cloudy and with no precipitation.\163\
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\162\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
\163\ This is also supported by another study (Grove, Atwood,
Fitch and Blanco, M, 2016, ``Field Study of Heavy-Vehicle Crash
Avoidance Systems'') which concluded that over 88 percent of heavy
vehicle crashes occurred when the conditions were, clear, partly
cloudy, or overcast.
---------------------------------------------------------------------------
2. Road Surface Conditions
The road surface upon which vehicle tests will be conducted must
also be in a defined condition to help achieve repeatable testing. The
proposed conditions specify that the road surface is free of debris,
irregularities, or undulations, such as loose pavement, large cracks,
or dips. These could affect the vehicle's ability to brake properly or
maintain its heading, and ultimately reduce the repeatability of a
test. The test surface is also required to be level, with a slope
between 0 and 1 degrees, because the slope of a road surface can affect
the performance of an AEB-equipped vehicle.\164\ A surface that slopes
up and down could obstruct a sensor's view of an object ahead. It could
also influence the dynamics and layout involved in the proposed AEB
test scenarios, as travelling up or down a slope makes braking to a
stop more or less difficult. In order to have predictable tire
adherence under braking, the surface must also be dry and have a
controlled coefficient of friction. NHTSA is proposing that the test
track surface have a peak friction coefficient of 1.02 when measured in
accordance with ASTM International (ASTM) E1337 \165\ using an ASTM
F2493 standard reference test tire and without water delivery.\166\
Surface friction is a critical factor in brake system performance
testing, including AEB, since it correlates with tire grip and the
achievable stopping distance. The presence of moisture will
significantly change the measured performance of a braking system. A
dry surface is more consistent and provides for greater test
repeatability. Also, the proposed peak friction coefficient is the same
value that NHTSA uses for brake performance testing.
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\164\ Kim, H. et al., ``Autonomous Emergency Braking Considering
Road Slope and Friction Coefficient,'' International Journal of
Automotive Technology, 19, 1013-1022 (2018).
\165\ ASTM International, ASTM E1337, ``Standard Test Method for
Determining Longitudinal Peak Braking Coefficient (PBC) of Paved
Surfaces Using Standard Reference Test Tire.''
\166\ See 87 FR 34800 (June 8, 2022), Final Rule, Federal Motor
Vehicle Safety Standards, Consumer Information; Standard Reference
Test Tire.
---------------------------------------------------------------------------
This proposal specifies up to two straight lines be marked on the
test surface to simulate lane markings. In order to provide flexibility
for different road configurations at a variety of test track
facilities, lane markings may or may not be present during testing. If
present, the lines would be of any color or configuration (e.g., solid,
dashed, double-line, etc.). If two lines are used, they would be
parallel to each other and between 2.7 to 4.5 m apart, which is
representative of typical lane widths.
Lastly, the environment would not contain obstructions that could
interfere with detection of a lead vehicle or other test equipment
ahead and have an unintentional effect on the field of view of the AEB
system, in turn compromising test repeatability. Thus, the subject
vehicle during testing would not travel beneath overhead structures
such as signs, bridges, or gantries, and each compliance test would be
conducted without any vehicles, obstructions, or stationary objects
within one lane width of either side of the subject vehicle path unless
called for in the test procedure.
3. Subject Vehicle Conditions
Many of the subject vehicle conditions exist to ensure that a
vehicle chosen for testing is in a working condition that represents
the vehicle as it is sold into the market, and capable of performing as
intended by the manufacturer. Thus, the vehicle conditions specify that
no AEB malfunction telltale is active, vehicle components ahead of AEB
sensors are clean and do not obstruct the sensors, the original tires
are installed and properly inflated, and non-consumable fluids (e.g.,
brake fluid, engine coolant, etc.) are full.
Other conditions exist to ensure that vehicle performance is
comparable to that found in the real world. Prior to testing, the
vehicle's service brakes are burnished according to the burnishing
procedures already used in FMVSS No. 121 or 105 testing, as appropriate
for the vehicle prior to the beginning of testing. Burnishing helps to
gradually seat and condition new brake components, particularly the
brake pads and rotors/drums, which come into contact and provide
friction under braking. Burnishing helps achieve optimal and repeatable
brake performance. If burnishing was done previously, for example due
to the running of compliance tests for other FMVSS, it would not be
repeated.
The agency also proposes that the brake temperatures be between 66
and
[[Page 43217]]
204 degrees Celsius prior to the beginning of a test, which is the same
as specified in FMVSS No. 136. In the agency's experience, this initial
temperature range allows the brakes to perform well without being under
or over heated during testing, and the upper end of 204 degree Celsius
does not require unreasonably long cool-down time between test runs.
The agency has also considered that vehicles may have adjustable
characteristics or configurable systems that a vehicle operator may
choose to adjust, and some of these are factors that could affect the
outcome of an AEB test. Since each vehicle operator could potentially
choose different settings for these systems, the testing would ensure
that AEB systems are capable of meeting the test requirements
regardless of which choices were made. Accordingly, this proposal
specifies that these adjustable factors will be nearly in any
configurable level during testing. Consumable fluids (e.g., fuel,
diesel exhaust fluid, etc.) and propulsion battery charge will be
between 5-100 percent of their capacity. Cruise control systems would
be tested in any available setting, including adaptive cruise control
modes. In the event that adaptive cruise control is engaged and remains
engaged during the event, the FCW would not be required. This is
because an adaptive cruise control system is intended to slow the
vehicle to avoid a collision prior to a collision being imminent and
without notification to the driver.\167\
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\167\ Adaptive cruise control is a driver assistance technology
that automatically adjusts vehicle speed to maintain a certain
distance from a vehicle ahead.
---------------------------------------------------------------------------
Forward collision warnings would be tested in any configurable
setting. If the vehicle is equipped with an engine-braking system,
tests would be conducted with the system either engaged or disengaged.
The controls for the headlamps and regenerative braking would be tested
in any available position.
Regarding the weight of the subject vehicle during testing, this
proposal specifies that the vehicle is loaded to its gross vehicle
weight rating. Truck tractors will be loaded to its GVWR by connecting
a control trailer. The specifications for this control trailer, which
is an unbraked, single-axle flatbed, are equivalent to those found in
FMVSS No. 136. The agency believes it is important to test the
performance of AEB systems when the vehicle is at its heaviest
allowable condition, because heavy vehicles often travel in a fully
loaded condition and it generally presents the most challenging
scenario for braking (i.e., stopping a heavier vehicle is more
difficult). This loading condition is identical to the loaded condition
specified for FMVSS stopping distance assessment. This may improve
testing efficiency for NHTSA by having fewer loading conditions
specified among FMVSS.
Finally, because a vehicle will be tested at its GVWR, this
proposal specifies that, if a vehicle is equipped with a liftable axle,
it will be placed in the down position during testing.
C. Proposed Requirements for False Activation
1. No Automatic Braking Requirement
NHTSA proposes a requirement that the subject vehicle, when
presented with two false activation test scenarios, must not
automatically apply braking that results in a peak deceleration of more
than 0.25g when manual braking is not applied, nor a peak deceleration
of more than 0.45g when manual braking is applied. False activation
refers to cases where the AEB systems automatically activates the
service brakes although there is no object present in the path of the
vehicle with which it would collide. The associated vehicle tests are
run both with and without manual braking. During test runs without
manual braking, the AEB system must not initiate braking that results
in a peak deceleration of more than 0.25g. A 0.25g deceleration is
below the 0.3g threshold described earlier as a comfortable
deceleration which has a low probability of creating safety concerns
such as rear-end crashes (if the subject vehicle would brake too
hard).\168\ Also, 0.25g is an easily measurable deceleration when
testing.
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\168\ Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(2010, April) Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report (Report No. DOT HS 811 251) Washington,
DC: National Highway Traffic Safety Administration, p. 13.
---------------------------------------------------------------------------
During test runs when manual braking is being applied, the AEB
system must not initiate braking that results in a peak deceleration of
more than 0.45g. When testing using manual braking, the goal is to have
a manual braking deceleration of 0.3g, and so the AEB system must not
cause more than approximately 0.15g of additional deceleration. This
0.15g amount is less than the 0.25g of peak deceleration permitted in
tests without manual braking--however, allowing the same 0.25g above
manual braking would mean that up to a total peak deceleration of 0.55g
would be permitted. Because 0.55g could exceed the maximum deceleration
capacity of certain heavy vehicles, it would, in turn, render the test
impossible to fail for those vehicles. Therefore, the lower threshold
of additional deceleration is proposed for false activation tests with
manual braking.
2. Vehicle Test Scenarios
Under this proposal, the false activation requirement would be
evaluated by executing two vehicle test scenarios--a steel trench plate
test and a pass-through test. The steel trench plate test was chosen
because in previous agency testing that included eight different false
activation test scenarios, the steel trench plate scenario was the only
one that produced false activation of the AEB system.\169\ The pass-
through test is similar to the United Nations Economic Commission for
Europe (UNECE) Regulation 131 pass-through test.\170\
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\169\ Snyder, A., Martin, J., & Forkenbrock, G. (2013, July).
``Evaluation of CIB system susceptibility to non-threatening driving
scenarios on the test track.'' (Report No. DOT HS 811 795).
Washington, DC: National Highway Traffic Safety Administration.
\170\ UNECE Regulation 131, ``Uniform provisions concerning the
approval of motor vehicles with regard to the Advanced Emergency
Braking Systems (AEBS),'' see 6.8 False reaction test, U.N.
Regulation No. 131 (Feb. 27, 2020), available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R131r1e.pdf.
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The proposed false activation tests establish only a baseline for
system functionality. For practical reasons they are not comprehensive,
nor sufficient to eliminate susceptibility to false activations in the
myriad of circumstances in the real world. However, the proposed tests
are a practicable means to establish a minimum threshold of
performance. The agency expects that vehicle manufacturers will design
AEB systems to thoroughly address the potential for false
activations.\171\ Manufacturers have a strong market incentive to
mitigate false positives and have been successful even in the absence
of specific requirements.
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\171\ From NHTSA's NCAP Request for Comments notice regarding
AEB: ``Specifically, the Alliance stated that vehicle manufacturers
will optimize their systems to minimize false positive activations
for consumer acceptance purposes, and thus such tests will not be
necessary. Similarly, Honda stated that vehicle manufacturers must
already account for false positives when considering marketability
and HMI.'' 87 FR 13452 at 13460.
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i. Steel Trench Plate
This test recreates a roadway scenario where the subject vehicles
encounter a steel trench plate which is placed on the road surface
ahead in the same lane. The subject vehicle is driven at 80 km/h toward
the steel trench plate at a constant speed.
[[Page 43218]]
The tests would be conducted either with or without manual brake
application. Manual braking is included in these scenarios to ensure
that even when a vehicle's service brake is actuated, false activation
would not occur. For tests without manual braking, the accelerator is
only released if a forward collision warning is issued. For test with
manual braking, the accelerator is released at either the forward
collision warning or 1 second prior to the manual braking, whichever
occurs first. Manual braking begins when the subject vehicle is 1.1
seconds away from the steel trench plate. The test ends when the
subject vehicle either comes to a stop prior to crossing over the
leading edge of the steel trench plate, or it proceeds to drive over
the steel trench plate. Figure 8 shows the basic setup for the steel
trench plate scenario.
[GRAPHIC] [TIFF OMITTED] TP06JY23.008
Unlike the test scenarios in which the subject vehicle approaches a
lead vehicle, the agency proposes that the false activation tests be
run at a single speed rather than over a range of speeds. False
activations occurring at interstate speeds would create the most severe
unintended consequences of AEB braking. Therefore, the proposal
includes only a test at a single speed of 80 km/h.
ii. Pass-Through
This test recreates a roadway scenario where the subject vehicle
must travel between two parked cars that are adjacent to the left and
right sides of the subject vehicle's travel lane. The parked cars are
represented by two vehicle test devices. The lateral distance between
the parked cars is 4.5 m, which is sufficient to give the subject
vehicle enough space to pass between them and yet be close enough to be
in the field of view of AEB sensors. The subject vehicle is driven
along the center of the travel lane and toward the gap between the
parked cars at a speed of 80 km/h. For tests without manual braking,
the accelerator is only released if a forward collision warning is
issued. For tests with manual braking, the accelerator is released at
either the forward collision warning or 1 second prior to the manual
braking, whichever occurs first; manual braking begins when the front
plane of the subject vehicle is 1.1 seconds away from the rear plane of
the two parked cars).
[GRAPHIC] [TIFF OMITTED] TP06JY23.009
D. Conditions for False Activation Tests
The false activation requirement is conducted under a set test
conditions identical to those used for AEB tests. However, there are
equipment conditions which apply specifically to these false activation
tests.
The equipment conditions that apply to the two false positive
scenarios in this proposal relate to the steel trench plate and the
vehicles used for the pass-through test. The steel trench plate is a
piece of equipment that represents a steel plate typically used to
cover excavation holes or irregularities in the road surface during
construction work, and which is meant to be driven over by
[[Page 43219]]
vehicles. The steel trench plate specified in this proposal is made of
ASTM A36 steel, a common structural steel alloy, and has the dimensions
2.4 m x 3.7 m x 25 mm. Any metallic fasteners used to secure the steel
trench plate are flush with the top surface of the plate, to avoid
effectively increasing the profile height and radar cross-section of
the plate. The two vehicles used for the pass-through test are vehicle
test devices identical to those that would be used in the lead vehicle
testing.
E. Potential Alternatives to False Activation Tests
As alternatives to these two false activation tests, NHTSA is
considering requiring a robust documentation process, or specifying a
data storage requirement. NHTSA is considering requiring this
documentation and data in addition to or in place of the proposed false
activation tests. First, NHTSA seeks comment on the anticipated impacts
on safety and the certification burden if the agency were to finalize a
rule that did not contain one or both of the proposed false positive
tests.
The agency is considering requiring that manufacturers maintain
documentation demonstrating that process standards were followed
specific to the consideration of false application of automatic
braking. Other industries where safety-critical software-controlled
equipment failures may be life threatening (e.g., aviation,\172\
medical devices \173\) are regulated in some respects via process
controls ensuring that software development engineering best practices
are followed. This approach recognizes that system tests are limited in
their ability to evaluate complex, and constantly changing software
driven control systems.
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\172\ 14 CFR 33.201(a) The engine must be designed using a
design quality process acceptable to the Federal Aviation
Administration, that ensures the design features of the engine
minimize the occurrence of failures, malfunctions, defects, and
maintenance errors that could result in an in-flight shutdown, loss
of thrust control, or other power loss.
\173\ 21 CFR 920.30(a)(1) Each manufacturer of any class III or
class II device, and the class I devices listed in paragraph (a)(2)
of this section, shall establish and maintain procedures to control
the design of the device in order to ensure that specified design
requirements are met.
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Software development lifecycle practices that include risk
management, configuration management, and quality systems are used in
various safety-critical industries. ISO 26262 Road vehicles--Functional
safety and related standards are examples of methods for overseeing
software development practices. The agency is considering that a
process standards approach could be a viable and practical way of
regulating the risk of false positives, as false activation of braking
is a complex engineering problem with multiple factors and conditions
that must be considered in the real world. The agency seeks public
comment on all aspects of requiring that manufacturers document that
they have followed process standards in the consideration of the real-
world false activation performance of the AEB system.
Finally, the agency considered requiring targeted data recording
and storage of significant AEB activations. These data could then be
used by manufacturers to improve system performance, or by the agency
to review if a particular alleged false activation is part of a safety
defect investigation. The agency is considering requiring that an AEB
event that results in a speed reduction of greater than 20 km/h should
activate the recording and storage of the following key information:
date, time, engine hours (the time as measured in hours and minutes
during which an engine is operated), AEB activation speed, AEB exit
speed (vehicle speed at which the automatic braking is completely
released), AEB exit reason (e.g. driver override with throttle, or
brake, or system decision), location, and camera image data. This
information could be used by investigators to analyze the source of the
activation and determine if an activation was falsely applied. Such
data would need to be accessible by the agency and potentially the
vehicle operator for a full and transparent analysis. The agency seeks
comment on all aspects of this data collection approach as an
alternative to false positive testing, including whether this list of
potential elements is incomplete, overinclusive, or impractical.
F. Proposed Requirements for Malfunction Indication
NHTSA is proposing that AEB systems must continuously detect system
malfunctions. If an AEB system detects a malfunction that prevents it
from performing its required safety function, the vehicle would be
required to provide the vehicle operator with a warning. The warning
would be required to remain active as long as the malfunction exists
while the vehicle's starting system is on. NHTSA would consider a
malfunction to include any condition in which the AEB system fails to
meet the proposed performance requirements. NHTSA is proposing that the
driver must be warned in all instances of component or system failures,
sensor obstructions, environmental limitations (like heavy
precipitation), or other situations that would prevent a vehicle from
meeting the proposed AEB performance requirements. While NHTSA is not
proposing the specifics of the telltale, NHTSA anticipates that the
characteristics of the alert will be documented in the vehicle owner's
manual and provide sufficient information to the vehicle operator to
identify it as an AEB malfunction.
NHTSA considered proposing requirements pertaining to specific
failures and including an accompanying test procedure. For instance,
the agency could develop or use available tests that specify
disconnecting sensor wires, removing fuses, or covering sensors to
simulate field malfunctions. Such requirements are not included in the
proposed regulatory text, but NHTSA is interested in comments on this
issue.
NHTSA also considered proposing minimum requirements for the
malfunction telltale, to standardize ways of communicating to the
vehicle operator. NHTSA understands that some malfunctions of the AEB
system require repair (loose wires, broken sensors, etc.) while other
malfunctions are temporary and will correct themselves over time (ice
buildup on a camera). The agency considered requiring that the
malfunction telltale convey the actions that a driver should take when
a malfunction is detected. Such requirements are not included in the
proposed regulatory text, but NHTSA is interested in comments on this
issue. NHTSA seeks comment, including cost and benefit data, on the
potential advantages of specifying test procedures that would describe
how the agency would test a malfunction telltale and on the level of
detail that this regulation should require of a malfunction telltale.
Additionally, the agency considered requiring more details for the
telltale itself, such as a standardized appearance (color, size, shape,
illuminance). The agency seeks comment on the need and potential safety
benefits of requiring a standardized appearance of the malfunction
telltale and what standardized characteristics would achieve the best
safety outcomes.
G. Deactivation Switch
The proposed regulatory text does not permit vehicle manufacturers
to install a manual deactivation switch that would enable the vehicle
operator to switch off the AEB. The text is silent regarding the
permissibility of a switch but, under the framework of the FMVSS
[[Page 43220]]
and NHTSA's interpretations of the standards, a deactivation switch
would be prohibited if it would allow an AEB system to be deactivated
in any circumstance in which the standard requires an AEB system to
function. This is consistent with other FMVSS, such as FMVSS No. 108,
``Lamps, reflective devices, and associated equipment,'' which is
silent about a switch deactivating the stop lamps but where NHTSA has
interpreted the standard as prohibiting such a switch.\174\ Standards
in which a deactivation switch is permitted expressly permit the switch
in the regulatory text, for example, FMVSS No. 126, ``Electronic
stability control systems for light vehicles,'' where the standard
specifically permits and regulates the performance of a deactivation
switch,\175\ and FMVSS No. 208, ``Occupant crash protection,'' where
the standard permitted an on-off switch for the air bag for the front
passenger seat on particular vehicles.\176\
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\174\ https://isearch.nhtsa.gov/files/23833.ztv.html (last
accessed August 31, 2022).
\175\ FMVSS No. 126, ``ESC systems for light vehicles,'' S5.4:
The manufacturer may include an ``ESC Off'' control whose only
purpose is to place the ESC system in a mode or modes in which it
will no longer satisfy the performance requirements of S5.2.1,
S5.2.2, and S5.2.3.
\176\ FMVSS No. 208, ``Occupant crash protection.'' FMVSS No.
208 was written such that it permited such switches only on vehicles
configured with no back seat or a back seat too small to accommodate
a rear-facing child restraint system. This was an interim step to
allow advanced air bag technology to mature and be fully
implemented.
---------------------------------------------------------------------------
NHTSA and FMCSA realize a switch or other method that could
deactivate a vehicle's AEB system could be useful in some
circumstances. There might be some heavy vehicle design or aftermarket
equipment installations where the configuration of the vehicle could
potentially interfere with the AEB sensing system. For example, a
snowplow might be attached in a manner that obstructs an AEB sensor.
Some vehicles may have uses where an AEB system may be incompatible
with its operating environment, for example, logging operations or
other on/off road environments.
Special conditions could be addressed by drafting the standard to
allow manual deactivation under limited circumstances when the system
is compromised. However, an FMVSS in which deactivation of the system
is easily accomplished would likely reduce the safety benefit of the
proposed rule. NHTSA seeks comments on the merits of and need for
manual deactivations of AEB systems. If the standard were to permit a
deactivation mechanism of some sort, how could NHTSA allow for
deactivations while ensuring the mechanism would not be abused or
misused by users? Alternatively, NHTSA is interested in comments on the
approach of the standard's restricting the automatic deactivation of
the AEB system generally but providing for special conditions in which
the vehicle is permitted to automatically deactivate or otherwise
restrict braking authority given to the AEB system.
NHTSA seeks comment on the merits of various performance
requirements related to manual deactivation switches for AEB systems.
The agency seeks comment on the appropriate performance requirements if
the agency were to permit the installation of a manually operated
deactivation switch. Such requirements might include limitations such
that the default position of the switch be ``AEB ON'' with each cycle
of the starting system or that the deactivation functionality be
limited to specific speeds.
H. System Documentation
NHTSA seeks comment on alternate regulatory approaches that might
be appropriate for regulating complex systems that depend heavily on
software performance. FMVSS have historically included requirements
that can be inspected or tested by the agency to verify compliance. In
some cases, such as in FMVSS No. 126, the agency has required
manufacturers to maintain technical documentation available for agency
review upon request to ensure that electronic stability control systems
were designed to mitigate vehicle understeer (49 CFR 571.126 S5.6). The
agency established this requirement in the absence of suitable test
procedures for evaluating understeer.
In the case of AEB, there are similar limits to testing systems in
controlled environments. AEB systems operating on roadways will be
subject to many scenes and stimuli that are not present on a test
track--e.g., precipitation, lighting, roadway curvature and elevation
changes, signage, other road users, animals, debris, etc.--and these
scenes and stimuli could potentially influence real world effectiveness
of AEB systems. The agency seeks comment on documentation requirements
that may be effective in encouraging real world effectiveness (e.g.,
maximizing true positive rate and minimizing false positive rate) and
in ensuring that AEB systems are developed and maintained in a manner
that minimizes performance risks.
The agency is considering requirements for manufacturers to
document a risk-based design approach identifying and mitigating
reasonably foreseeable risks alongside configuration management records
of all software/hardware updates performed by the manufacturer.
Manufacturers would also need to disclose certain servicing and system
limitation requirements and make AEB-related data stored in vehicles
available. Examples of requirements under consideration include:
Manufacturers must establish and maintain procedures that
provide a risk-based approach in designing, implementing, and (if
applicable) updating each system required under this standard.
Manufacturers must maintain documentation over the system lifetime
detailing the outcome of the risk-based approach taken to ensure the
safety of such systems.
Where servicing is required to maintain system
performance, each manufacturer must establish and maintain instructions
and procedures for performing and verifying that the servicing meets
the specified requirements.
Certain information must be disclosed to consumers at the
time of first sale in a single document such as an owner's manual:
[cir] If servicing requirements include periodic maintenance, the
maintenance schedule must be identified.
[cir] Manufacturers must include a statement describing the
limitations of AEB and explaining that AEB is an emergency system that
does not replace the need for normal actuation of the service brakes.
Each manufacturer must maintain documentation that
captures the full system configuration, including all hardware,
software, and firmware, for each vehicle at the time of first sale and
at the time of any update to the system configuration by the
manufacturer.
Each AEB system or a system that communicates with the AEB
system must store information logging at least the last three AEB
activation events or all AEB activation events occurring within the
past three drive cycles.
The vehicle must store the status of the AEB system
(active, inactive, disabled, warning, engaged, disengaged,
malfunctioning, etc.).
NHTSA believes that manufacturers that have installed AEB systems
in their fleet may already be meeting many of the documentation
requirements above. The agency seeks comment on the suitability of
these requirements and on any changes that manufacturers would have to
introduce in their internal processes and consumer-facing documentation
(e.g., owner's manuals). NHTSA is interested in learning
[[Page 43221]]
whether manufacturers find discrepancies between real-world performance
and data collected on test tracks with surrogate vehicles.
I. ESC Performance Test
This proposal would require nearly all heavy vehicles to have an
ESC system that meets the equipment requirements, general system
operational capability requirements, and malfunction detection
requirements of FMVSS No. 136. However, this proposal would not require
vehicles not currently required to have ESC systems to meet any test
track performance requirements for ESC systems because NHTSA is
conscious of the potential testing burden on small businesses and the
multi-stage vehicle manufacturers involved in class 3 through 6 vehicle
production. NHTSA requests comments on whether the agency should
establish performance requirements for ESC for all vehicles covered by
this proposal. If ESC performance requirements would be appropriate,
NHTSA seeks comment on which regulatory tests and requirements would be
appropriate for the class 3-8 vehicles which this notice proposes to
make applicable to FMVSS No. 136. NHTSA also seeks comment on whether
manufacturers of these vehicles should have the option to certify to
FMVSS No. 126 or FMVSS No. 136, whether a new ESC test procedure should
be developed for some or all of these vehicles, or whether NHTSA should
give the manufacturer the option to choose the ESC standard to which to
certify.
NHTSA conducted some limited ESC testing for class 3-6 vehicles, as
part of research efforts during the development of FMVSS No. 136, which
was established in 2015, and as part of its recent AEB testing.\177\
The ESC testing performed has however been sufficient to indicate that
the test procedures currently established in FMVSS Nos. 126 and 136
would require modification in order to better suit class 3 through 6
vehicles. For example, the vehicle test speeds specified in FMVSS No.
136, which are designed to induce ESC activation in class 7 and 8
trucks and buses at speeds under 48 km/h (30 mph), did not induce ESC
activation in the vehicles that were tested. This testing indicates
that the maximum test speeds and speed reduction requirements would
likely need to be modified.
---------------------------------------------------------------------------
\177\ This information is available in ``ESC Track Test Data for
Class 3-6 Vehicles,'' which has been placed in the docket identified
in the heading of this NPRM.
---------------------------------------------------------------------------
J. Severability
The issue of severability of FMVSSs is addressed in 49 CFR 571.9.
It provides that if any FMVSS or its application to any person or
circumstance is held invalid, the remainder of the part and the
application of that standard to other persons or circumstances is
unaffected. NHTSA seeks comment on the issue of severability.
VIII. Vehicle Test Device
NHTSA has proposed the same vehicle test device described below for
use in the proposed requirements for AEB for light vehicles. An
identical discussion of the vehicle test device appears in the NPRM
proposing the FMVSS for light vehicles.
A. Description and Development
To ensure repeatable and reproducible testing that reflects how a
subject vehicle would be expected to respond to an actual vehicle in
the real world, this proposal includes broad specifications for a
vehicle test device to be used as a lead vehicle or pass through
vehicle during testing. NHTSA is proposing that the vehicle test device
be based on certain specifications defined in ISO 19206-3:2021, ``Road
vehicles--Test devices for target vehicles, vulnerable road users and
other objects, for assessment of active safety functions--Part 3:
Requirements for passenger vehicle 3D targets.'' \178\ The vehicle test
device is a tool that NHTSA proposes to use to facilitate the agency's
compliance tests to measure the performance of AEB systems required by
the proposed FMVSS. This NPRM describes the vehicle test device that
NHTSA would use.
---------------------------------------------------------------------------
\178\ https://www.iso.org/standard/70133.html. May 2021.
---------------------------------------------------------------------------
The surrogate vehicle NHTSA currently uses in its research testing
is the Global Vehicle Target (GVT). The GVT is a full-sized, harmonized
surrogate vehicle developed to test crash avoidance systems while
addressing the limitations of earlier generation surrogate vehicles. To
obtain input from the public and from industry stakeholders, NHTSA
participated in a series of five public workshops and three radar
tuning meetings between August 2015 and December 2016. These workshops
and meetings provided representatives from the automotive industry with
an opportunity to inspect, measure, and assess the realism of prototype
surrogates during the various stages of development. Workshop and
meeting participants were permitted to take measurements and collect
data with their own test equipment, which they could then use to
provide specific recommendations about how the surrogate vehicle's
appearance, to any sensor, could be improved to increase realism.
After feedback from automotive vehicle manufacturers and suppliers
was incorporated into an earlier design of the GVT, a series of high-
resolution radar scans were performed by the Michigan Tech Research
Institute (MTRI) under NHTSA contract. These measurements provided an
independent assessment of how the radar characteristics of the GVT
compared to those from four real passenger cars.\179\ This study found
that the GVT has generally less radar scatter than the real vehicles to
which it was compared. However, MTRI found that ``even though the [GVT]
may more often reflect a greater amount of energy than the [real]
vehicles, it is not exceeding the maximum energy of the returns from
the vehicles. Thus, a sensor intended for the purpose of detecting
vehicles should perform well with the [GVT].'' \180\
---------------------------------------------------------------------------
\179\ The comparison passenger cars used were a 2008 Hyundai
Accent, a 2004 Toyota Camry, a 2016 Ford Fiesta hatchback, and a
2013 Subaru Impreza.
\180\ Buller, W., Hart, B., Aden, S., and Wilson, B. (2017, May)
``Comparison of RADAR Returns from Vehicles and Guided Soft Target
(GST),'' Michigan Technological University, Michigan Tech Research
Institute. Docket NHTSA-2015-0002-0007.
---------------------------------------------------------------------------
NHTSA also performed tests to determine the practicality of using
the GVT for test-track performance evaluations by examining how
difficult it was to reassemble the GVT after it was struck in a test.
Using a randomized matrix designed to minimize the effect of learning,
these tests were performed with teams of three or five members familiar
with the GVT reassembly process. NHTSA found that reassembly of the GVT
on the robotic platform takes approximately 10 minutes to complete;
however, additional time is often required to re-initialize the robotic
platform GPS afterwards.\181\
---------------------------------------------------------------------------
\181\ Snyder, Andrew C. et al., ``A Test Track Comparison of the
Global Vehicle Target (GVT) and NHTSA's Strikeable Surrogate Vehicle
(SSV),'' July 2019. https://rosap.ntl.bts.gov/view/dot/41936.
---------------------------------------------------------------------------
Finally, NHTSA conducted its own crash imminent braking tests to
compare the speed reduction achieved by three passenger cars as they
approached the GVT, compared to the Strikable Surrogate Vehicle (SSV),
the surrogate vehicle NHTSA currently uses for its NCAP AEB tests.
These tests found that any differences that might exist between the GVT
and the SSV were small enough to not appreciably influence the outcome
of vehicle testing.\182\
---------------------------------------------------------------------------
\182\ Id.
---------------------------------------------------------------------------
When used during AEB testing, the GVT is secured to the top of a
low-
[[Page 43222]]
profile robotic platform. The robotic platform is essentially flat and
is movable and programmable. The vehicle test device's movement can be
accurately and repeatably defined and choreographed with the subject
vehicle and testing lane through the use of data from the robotic
platform's on-board inertial measurement unit, GPS, and closed-loop
control facilitated by communication with the subject vehicle's
instrumentation. The shallow design of the robotic platform allows the
test vehicle to drive over it. The GVT is secured to the top of the
robotic platform using hook-and-loop fastener attachment points, which
allow the pieces of the GVT to easily and safely break away without
significant harm to the vehicle being tested if struck.
The internal frame of the GVT is constructed primarily of vinyl-
covered foam segments held together with hook-and-loop fasteners. The
GVT's exterior is comprised of multiple vinyl ``skin'' sections
designed to provide the dimensional, optical, and radar characteristics
of a real vehicle that can be recognized as such by camera and radar
sensors.\183\ If the subject vehicle impacts the GVT at low speed, the
GVT is typically pushed off and away from the robotic platform without
breaking apart. At higher impact speeds, the GVT breaks apart as the
subject vehicle essentially drives through it.
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\183\ ``A Test Track Comparison of the Global Vehicle Target
(GVT) and NHTSA's Strikeable Surrogate Vehicle,'' DOT HS 812-698.
---------------------------------------------------------------------------
B. Specifications
The most recent, widely-accepted iteration of vehicle test device
specifications is contained in ISO 19206-3:2021.\184\ Using data
collected by measuring the fixed-angle/variable-range radar cross
section for several real vehicles, ISO developed generic
``acceptability corridors,'' which are essentially boundaries that the
vehicle test device's radar cross section must fit within to be deemed
representative of a real vehicle.\185\ All vehicles that ISO tested
have radar cross section measurements that fit within the boundaries
set forth in the ISO standard.
---------------------------------------------------------------------------
\184\ Road vehicles--Test devices for target vehicles,
vulnerable road users and other objects, for assessment of active
safety functions--Part 3: Requirements for passenger vehicle 3D
targets.
\185\ The vehicles tested to develop the ISO standard are: 2016
BMW M235i, 2006 Acura RL, 2019 Tesla Model 3, 2017 Nissan Versa,
2018 Toyota Corolla, 2019 Ford Fiesta.
---------------------------------------------------------------------------
This proposal would incorporate by reference ISO 19206-3:2021 into
NHTSA's regulations and specify that the vehicle test device meets
several specifications in ISO 19206-3:2021, in addition to other
specifications identified by NHTSA. Because the GVT was considered
during the development of ISO 19206-3:2021, the GVT would meet the
standard's specifications. However, should the design of the GVT change
or a new vehicle test device be developed, reference to the more
general specifications of ISO 19206-3:2021 should ensure that NHTSA is
able to test with such other vehicle test devices and should also
ensure that such vehicle test devices have properties needed by an AEB
system to identify it as a motor vehicle.
The vehicle test device's physical dimensions are proposed to be
consistent with those of the subcompact and compact car vehicle class.
The specific range of dimensions in this proposal for individual
surfaces of the vehicle test device are incorporated from ISO 19206-
3:2021, Annex A, Table A.4. These include specifications for the test
device's width and the placement of the license plate, lights, and
reflectors relative to the rear end of the vehicle test device.
The vehicle test device is proposed to have features printed on its
surface to represent features that are identifiable on the rear of a
typical passenger vehicle, such as tail lamps, reflex reflectors,
windows, and the rear license plate. The proposed color ranges for the
various surface features, including tires, windows, and reflex
reflectors are incorporated from ISO 19206-3:2021, Annex B, Tables B.2
and B.3. Table B.2 specifies the colors of the tires, windows, and
reflectors, which reflect the colors observed the in the real world.
The color of the exterior of the vehicle is specified to be a range
representing the color white, which provides a high color contrast to
the other identifiable features. White is also a common color for motor
vehicles.\186\ The proposed reflectivity ranges for the various
features on the vehicle test device are incorporated from ISO 19206-
3:2021, Annex B, Table B.1. Table B.3 specifies the recommended
minimum, mean, and maximum color range for the white body, specifically
the outer cover.
---------------------------------------------------------------------------
\186\ Globally, white was the most popular color for light
vehicles in 2021. https://gmauthority.com/blog/2022/02/white-was-
the-most-popular-car-color-again-in-2021/
#:~:text=According%20to%20PPG%2C%2035%20percent,by%20silver%20at%2011
%20percent.
---------------------------------------------------------------------------
Because many AEB systems rely on radar sensors in some capacity to
identify the presence of other vehicles, the vehicle test device must
have a radar cross section that would be recognized as a real vehicle
by an AEB system. In particular, the vehicle test device must have a
radar cross section consistent with a real vehicle when approached from
the rear over a range of distances.
NHTSA is proposing that the radar cross section of the vehicle test
device fall within an ``acceptability corridor'' when measured using an
automotive-grade radar sensor. This acceptability corridor would be
defined by the upper and lower boundaries specified by ISO 19206-
3:2021, Annex C, Equations C.1 and C.2, using the radar cross section
boundary parameters defined in ISO 19206-3:2021, Annex C, Table C.3 for
a fixed viewing angle of 180 degrees. NHTSA is aware that, unlike some
predecessor specification documents such as Euro NCAP Technical
Bulletin 025 from May 2018, ISO 19206-3:2021 does not specify that the
radar cross section measurements be verified using a specific model of
radar. Rather, the ISO standard specifies that the radar sensor used
have certain specifications and operational characteristics. NHTSA's
proposal similarly does not specify that the vehicle test device's
initial radar cross section be measured with a specific model or brand
of radar. NHTSA only proposes that the radar sensor used to validate
the radar cross section operate within the 76-81 GHz bandwidth, have a
horizontal field of view of at least 10 degrees, a vertical field of
view of at least 5 degrees, and a range greater than 100 m.
Additionally, NHTSA's proposal does not specify that the VTD's radar
cross section during in-the-field verifications be performed to
objectively assess whether the radar cross section still falls within
the acceptability corridor. NHTSA seeks comment about whether use of
the optional field verification procedure provided in ISO 19206-3:2021,
Annex E, section E.3 should be used.
Because the test procedures proposed in this rule only involve
rear-end approaches by the subject vehicle, NHTSA is at this time only
proposing to establish specifications applicable for the rear end of
the vehicle test device. NHTSA seeks comment on whether the
specifications for the vehicle test device should include all sides of
the vehicle. If NHTSA were to include, in a final rule, specifications
for all sides of a vehicle test device, NHTSA anticipates that those
specifications would also be incorporated from ISO 19206-3:2021.
C. Alternatives Considered
One alternative test device that NHTSA considered for use in this
proposal was the agency's self-developed Strikable Surrogate Vehicle
(SSV) device, which NHTSA currently uses in its NCAP testing of AEB
performance. NHTSA adopted the use of
[[Page 43223]]
the SSV as part of its 2015 NCAP upgrade, under which the agency began
testing AEB performance.\187\ The SSV resembles the rear section of a
2011 Ford Fiesta hatchback. The SSV is constructed primarily from a
rigid carbon fiber mesh, which allows it to maintain a consistent shape
over time (unless damaged during testing). To maximize visual realism,
the SSV shell is wrapped with a vinyl material that simulates paint on
the body panels and rear bumper, and a tinted glass rear window. The
SSV is also equipped with a simulated United States specification rear
license plate. The taillights, rear bumper reflectors, and third brake
light installed on the SSV are actual original equipment from a
production vehicle. NHTSA testing shows that AEB systems will recognize
the SSV and will respond in a way that is comparable to how they would
respond to an actual vehicle.\188\
---------------------------------------------------------------------------
\187\ 80 FR 68604.
\188\ 80 FR 68607.
---------------------------------------------------------------------------
While the SSV and GVT are both recognized as real vehicles by AEB
systems from the rear approach aspect, the SSV has several
disadvantages. The foremost disadvantage of the SSV is how easily it
can be irreparably damaged when struck by a subject vehicle during
testing, particularly at high relative velocities. While NHTSA has
tried to address this issue by attaching a foam bumper to the rear of
the SSV to reduce the peak forces resulting from an impact by the
subject vehicle, the SSV can still easily be damaged to a point where
it can no longer be used if the relative impact speed is sufficiently
high (greater than 40 km/h (25 mph)); this speed is much lower than the
maximum relative impact speed of 80 km/h (50 mph) potentially
encountered during the AEB tests performed at the maximum relative
speeds proposed in this notice). Also, unlike the GVT, which has its
movement controlled by precise programming and closed loop control, the
SSV moves along a monorail secured to the test surface, which may be
visible to a camera-based AEB system.
In addition to the vehicle test device specifications, NHTSA seeks
comment on specifying a set of real vehicles to be used as vehicle test
devices in AEB testing. UN ECE Regulation No. 152 specifies that the
lead vehicle be either a regular high-volume passenger sedan or a
``soft target'' meeting the specifications of ISO 19206-1:2018.\189\ UN
ECE regulation does not require the use of real vehicles as targets,
but rather offers them as an alternative to manufacturers to homologate
their systems, at their choice. Although NHTSA has tentatively
concluded that the specification in UN ECE Regulation No. 152 of any
high-volume passenger sedan is not sufficiently specific for an FMVSS,
NHTSA seeks comment on whether it should create a list of vehicles from
which NHTSA could choose a lead vehicle for testing. Unlike the UN ECE
regulation, which provides flexibility to manufacturers, inclusion of a
list of vehicles would provide flexibility to the agency in the
assessment of the performance of AEB systems. Such a list would be in
addition to the vehicle test device proposed in this document, to
provide assurance of vehicle performance with a wider array of lead
vehicles. For example, the list could include the highest selling
vehicle models in 2020.
---------------------------------------------------------------------------
\189\ U.N. Regulation No. 152, E/ECE/TRANS/505/Rev.3/Add.151/
Amend.1 (Nov. 4, 2020), available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2020/R152am1e.pdf.
---------------------------------------------------------------------------
Using actual vehicles has various challenges, including the
potential for risk to individuals conducting the tests and damage to
the vehicles involved, and assuring a safe testing environment that
could encounter high energy collisions between real vehicles in cases
of poor AEB system performance or AEB or test equipment malfunctions.
NHTSA seeks comment on the utility and feasibility of test laboratories
safely conducting AEB tests with real vehicles, such as through
removing humans from test vehicles and automating scenario execution,
and how laboratories would adjust testing costs to factor in the risk
of damaged vehicles.
Beyond the practical safety limits and cost of testing described
above, managing a list of relevant lead vehicles would require the
standard to be updated periodically to keep pace with the vehicle fleet
and to ensure that lead vehicles are available years after a final
rule. NHTSA seeks comments on the merits and potential need for testing
using real vehicles, in addition to using a vehicle test device, as
well as challenges, limitations, and incremental costs of such.
IX. Proposed Compliance Date Schedule
NHTSA proposes a two-tiered phase-in schedule for meeting the new
standard. For heavy vehicles currently subject to FMVSS No. 136, any
vehicle manufactured on or after the first September 1 that is three
years after the date of publication of the final rule must meet the
proposed heavy vehicle AEB standard. To illustrate, if the final rule
were published on October 1, 2023, the compliance date would be
September 1, 2027. For heavy vehicles not currently subject to FMVSS
No. 136, with some exclusions, those manufactured on or after the first
September 1 that is four years after the date of publication of the
final rule must meet the amendments to FMVSS No. 136 that would require
ESC systems and the proposed AEB requirements. In the provided example
of a final rule published on October 1, 2023, that date would be
September 1, 2028. Small-volume manufacturers, final-stage
manufacturers, and alterers would be provided an additional year, added
to the dates above, to meet the requirements of this proposal.
Consistent with 49 U.S.C. 30111(d), NHTSA has tentatively concluded
that good cause exists for this proposal to take effect more than one
year after publication of a final rule because it would not be feasible
for all heavy vehicles to be equipped with AEB systems that meet the
proposed performance requirements within one year. Furthermore, NHTSA
seeks comments on whether this proposed phase-in schedule appropriately
addresses challenges to the implementation of AEB for specific
categories of heavy vehicles. The agency is particularly interested in
information about single-unit trucks with permanently installed work-
performing equipment installed on the front of or extending past the
front of the vehicle (e.g., auger trucks, bucket trucks, cable reel
trucks, certain car carriers, etc.), where AEB sensors may be located.
NHTSA seeks comments to discern the best way to implement the
applicability of AEB on class 3-6 single-unit trucks, considering all
scenarios such as vehicle configuration, vehicle service applicability,
and cargo type, which, among other factors, can affect vehicle dynamics
and drivability. The manufacture of single-unit trucks is more complex
than that of truck tractors due to wider variations in vehicle weight,
wheelbase, number of axles, center of gravity height, and cargo type.
These factors, and others, bear on the calibration and performance of
ESC. For example, ESC system design depends on vehicle dynamics
characteristics, such as the total vehicle weight and location of that
weight (center of gravity), which will differ depending on the final
vehicle configuration. Because ESC has been a prerequisite for
voluntary adoption of AEB, single-unit trucks not having had ESC
requirements suggests that AEB implementation has been slower and that
there is a need for effective date flexibility.
NHTSA is also aware that many, if not most, manufacturers of
single-unit trucks are final-stage manufacturers, which are typically
small businesses. To
[[Page 43224]]
provide more flexibility to small businesses to meet the proposed rule,
this NPRM proposes to permit small-volume manufacturers, final-stage
manufacturers, and alterers an additional year to meet the requirements
of the final rule. The additional time would provide flexibility to the
manufacturers to install ESC and collaborate with AEB suppliers to meet
the proposed requirements.
FMCSA proposes that vehicles currently subject to FMVSS No. 136
(i.e., those manufactured on or after August 1, 2019, the initial
compliance date for FMVSS No. 136) would be required to comply with
FMCSA's proposed ESC regulation on the final rule's effective date.
Vehicles with a GVWR greater than 4,536 kilograms (10,000 pounds) not
currently subject to FMVSS No. 136 would be required to meet the
proposed ESC regulation on or after the first September 1 that is five
years after the date of publication of the final rule.
FMCSA proposes that, for vehicles currently subject to FMVSS No.
136, any vehicle manufactured on or after the first September 1 that is
three years after the date of publication of the final rule would be
required to meet the proposed heavy vehicle AEB standard. FMCSA
proposes that vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136
and vehicles supplied to motor carriers by small-volume manufacturers,
final-stage manufacturers, and alterers would be required to meet the
proposed heavy vehicle AEB standard on or after the first September 1
that is five years after the date of publication of the final rule.
This proposed implementation timeframe simplifies FMCSR training
and enforcement because the Agency expects a large number of final
stage manufacturers supplying vehicles to motor carriers in the
category of vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds).
FMCSA will require the ESC and AEB systems to be inspected and
maintained in accordance with Sec. 396.3.
X. Retrofitting
The Secretary has the statutory authority to promulgate safety
standards for commercial motor vehicles and equipment subsequent to
initial manufacture. The Secretary has delegated authority to NHTSA, in
coordination with FMCSA, to promulgate safety standards for commercial
motor vehicles and equipment subsequent to initial manufacture when the
standards are based upon and similar to an FMVSS.\190\
---------------------------------------------------------------------------
\190\ Sec. 101(f) of Motor Carrier Safety Improvement Act of
1999 (Pub. L. 106-159; Dec. 9, 1999). 49 CFR 1.95(c).
---------------------------------------------------------------------------
NHTSA considered, but decided against, proposing to require
retrofitting of in-service vehicles with GVWR greater than 4,536 kg
(10,000 lbs.) with AEB systems. NHTSA believes that retrofitting in-
service vehicles with AEB systems could be very complex and costly
because of the integration between an AEB system and the vehicles'
chassis, engine, and braking systems. There may be changes that would
have to be made to an originally manufactured vehicle's systems that
interface with an AEB system, such as plumbing for new air brake valves
and lines and a new electronic control unit for a revised antilock
braking system and a new electronic stability control system. NHTSA
might also have to develop and establish additional requirements to
ensure that AEB control components on in-service (used) vehicles are at
an acceptable level of performance for a compliance test of AEB. This
would be likely given the uniqueness of each vehicle's maintenance
condition, particularly for items such as tires and brake components,
which are foundational for AEB performance (and which are subject to
high demands of wear-and-tear).
Nonetheless, although this NPRM does not propose requiring heavy
vehicles to be equipped with AEB subsequent to initial manufacture,
NHTSA requests comment on the following issues related to retrofitting
to learn more about the technical and economic feasibility of a
retrofit requirement going forward.
The complexity, cost, and burdens of a requirement to
retrofit in-service vehicles with AEB.
The changes that would be needed to an originally
manufactured vehicle's systems that interface with an AEB system, such
as plumbing for new air brake valves and lines and a new electronic
control unit for a revised ABS and a new ESC system.
Approaches NHTSA could take to identify portions of the
on-road fleet to which a retrofit requirement could apply. For a
retrofitting requirement, should the requirement distinguish among in-
service vehicles based on the vehicles' date of manufacture? Is it
reasonable to assume that older in-service vehicles would have greater
challenges to meet a retrofit requirement? What should, for example,
the original manufacture date be of vehicles that should be subject to
a retrofit requirement?
Should there be provisions to ensure that the various
components related to AEB performance (e.g., brakes and tires) are at
an acceptable level of performance for a compliance test, given the
uniqueness of the maintenance condition for vehicles in service,
especially for items particularly subject to wear-and-tear (e.g., brake
components and tires)?
Relatedly, would it be warranted to vary the performance
requirements for retrofitted vehicles, so that the requirements would
be less stringent for used vehicles? If yes, what would be appropriate
level of stringency? If not, how can the requirements be adjusted for
in-service vehicles?
NHTSA requests comment on other options the agency could
take to identify portions of the on-road fleet to which a retrofit
requirement should apply. Are there other voluntary improvements that
heavy vehicle operators would consider in attaining the benefits
provided by AEB for their in-service vehicles?
XI. Summary of Estimated Effectiveness, Cost, Benefits, and Comparison
of Regulatory Alternatives
A. Crash Problem
NHTSA's assessment of available safety data indicates that between
2017 and 2019, an average of approximately 60,000 crashes occurred
annually in which a heavy vehicle rear-ended another vehicle. These
crashes resulted in an annual average of 388 fatalities, approximately
30,000 non-fatal injuries, and 84,000 property-damage-only vehicles.
Additionally, class 3-6 heavy vehicles were involved in approximately
17,000 rollover and loss of control crashes annually. These crashes
resulted in 178 fatalities, approximately 4,000 non-fatal injuries, and
13,000 property-damage-only vehicles annually. In total, these rear-
end, rollover, and loss of control crashes add up to 77,000 annually,
which represent 1.2 percent of all police-reported crashes and over 14
percent of all crashes involving heavy vehicles. In total, these
crashes resulted in 566 fatalities and 34,000 non-fatal injuries. These
crashes also damaged 97,000 vehicles in property-damage-only crashes.
B. AEB System Effectiveness
NHTSA evaluated the effectiveness of AEB indicates based on the
efficacy of the system in avoiding a rear-end crash. This relates to
the proposed requirement that a vehicle avoid an imminent rear-
[[Page 43225]]
end collision under a set of test scenarios. One method of estimating
effectiveness would be to perform a statistical analysis of real-world
crash data and observe the differences in statistics between heavy
vehicles equipped with AEB and those not equipped with AEB. However,
this approach is not feasible currently due to the low penetration rate
of AEB in the on-road vehicle fleet. Consequently, NHTSA estimated the
effectiveness of AEB systems using performance data from the agency's
vehicle testing. Effectiveness was assessed against all crash severity
levels collectively, rather than for specific crash severity levels
(i.e., minor injury versus fatal).
The AEB effectiveness estimates were derived from performance data
from four vehicles tested by NHTSA, and the agency is continuing its
effort to test a larger variety of vehicles to further evaluate AEB
system performance. These vehicles were subject to the same test
scenarios (stopped lead vehicle, slower-moving lead vehicle, and
decelerating lead vehicle) that are proposed in this notice, and
effectiveness estimates are based on each vehicle's capacity to avoid a
collision during a test scenario. For example, if a vehicle avoided
colliding with a stopped lead vehicle in four out of five test runs,
its effectiveness in that scenario would be 80 percent. The test
results for each vehicle were combined into an aggregate effectiveness
value by vehicle class range and crash scenario, as displayed in Table
17.
Table 17--AEB Effectiveness (%) by Vehicle Class Range and Crash Scenario
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving Decelerating lead
Vehicle class range vehicle lead vehicle vehicle
----------------------------------------------------------------------------------------------------------------
7-8.................................................... 38.5 49.2 49.2
3-6.................................................... 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------
As shown in Table 17, after aggregating class 7 and class 8
together, AEB would avoid 38.5 percent of rear-end crashes for the
stopped lead vehicle scenario, and 49.2 percent of slower-moving and
decelerating lead vehicle target crashes. For class 3-6, AEB is 43.0
percent effective against stopped lead vehicle crashes and 47.8 percent
against slower-moving and decelerating lead vehicle target crashes.
These effectiveness values are the values used for assessing the
benefits of this proposed rule. Further detail on the derivation of AEB
effectiveness can be found in the PRIA accompanying this proposal.
C. ESC System Effectiveness
ESC effectiveness rates were adopted from those estimated in the
final regulatory impact analysis for the final rule implementing heavy
vehicle ESC requirements in FMVSS No. 136.\191\ In that final rule, a
range of ESC crash avoidance effectiveness was established for the
first-event rollover crashes but only a single-point estimate was
established for loss of control crashes. ESC was estimated to be 40 to
56 percent effective at preventing rollover crashes and 14 percent
effective at preventing loss-of-control crashes. For simplicity, and to
correspond with the single-point estimate for loss of control crashes,
the PRIA used the mid-point between the lower and upper bounds of the
estimated range as the effectiveness for rollovers.
---------------------------------------------------------------------------
\191\ Final Regulatory Impact Analysis, FMVSS No. 136 Electronic
Stability Control on Heavy Vehicles, June 2014, Docket No. NHTSA-
2015-0056.
---------------------------------------------------------------------------
The propensity for vehicles to experience rollover and loss-of-
control crashes is influenced by their body type and center of gravity,
and the implementation of ESC varies. ESC was estimated to be less
effective on class 7 and 8 vehicles than it was on light vehicles,
especially for rollover crashes.\192\ Vehicle characteristics for class
3 through 6 vehicles range between that of light trucks and vans and
class 7 and 8 vehicles, it would be plausible to assume that ESC
effectiveness would be between the effectiveness estimated in the FMVSS
No. 126 and FMVSS No. 136 final rules. Nevertheless, this NPRM uses the
effectiveness estimates from the FMVSS No. 136 final rule.
---------------------------------------------------------------------------
\192\ Dang, J. (July 2007) Statistical Analyzing of the
Effectiveness of Electronic Stability Control (ESC) Systems--Final
Report, DOT HS 810 794, Washington, DC, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/810794.
Table 18--ESC Effectiveness (%) by Crash Scenario
------------------------------------------------------------------------
Loss of
Vehicle class range Rollover control
------------------------------------------------------------------------
3-6............................................. 48.0 14.0
------------------------------------------------------------------------
D. Avoided Crashes and Related Benefits
Considering the annual heavy vehicle rear-end, rollover, and loss
of control crashes, as well as the effectiveness of AEB and ESC at
avoiding these crashes, the proposed rule would prevent an estimated
19,118 crashes, 155 fatalities, and 8,814 non-fatal injuries annually.
In addition, the proposed rule would eliminate an estimated 24,828
PDOVs annually. The benefit estimates include assumptions that likely
result in the underestimation of the benefits of this proposal because
it only reflects the benefits from crash avoidance. That is, the
benefits only reflect those resulting from crashes that are avoided as
a result of the AEB and ESC performance proposed. It is likely that AEB
will also reduce the severity of crashes that are not prevented. Some
of these crashes may include fatalities and significant injuries that
will be prevented or mitigated by AEB.
Table 19 tabulates these benefits in two ways, one by vehicle class
and one by technology. These benefits are measured for the portion of
the vehicle fleet that has not voluntarily adopted AEB prior to the
NPRM. These benefits also assume reduced performance under dark or
hazardous weather conditions. The estimated annual benefits would be
the undiscounted lifetime benefits once the proposal is fully
implemented (four years after publication of a final rule). The
undiscounted lifetime benefits for each new model year of vehicles
would equal the annual benefits of the on-road fleet when that fleet
has been fully equipped with this technology. The actual annual
benefits will increase each year as the on-road vehicle fleet is
replaced with vehicles that would be subject to the proposed
requirements.
[[Page 43226]]
Table 19--Undiscounted Estimated Annual Benefits of the Proposed Rule
----------------------------------------------------------------------------------------------------------------
Non-fatal
Crashes Fatalities injuries PDOVs
----------------------------------------------------------------------------------------------------------------
By Vehicle Class:
Class 7-8................................... 5,691 40 2,822 7,958
Class 3-6................................... 13,427 115 5,992 16,870
---------------------------------------------------------------
Total................................... 19,118 155 8,814 24,828
By Technology:
AEB......................................... 16,224 106 8,058 22,713
ESC......................................... 2,894 49 756 2,115
---------------------------------------------------------------
Total................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------
E. Technology Costs
The AEB system is estimated to cost $396 per vehicle. The unit cost
includes all the components, labor cost for training customers, tuning
the system to ensure the performance of AEB, and the AEB malfunction
telltale. The component unit costs were based on the agency's 2018
weight and teardown study, which accounted for scale efficiencies in
production and labor.\193\ The cost for an ESC system would range from
$320 to $687, which was calculated by adjusting the assumed unit cost
for ESC in the FMVSS No. 136 final rule for inflation.\194\ Therefore,
for vehicles that need both AEB and ESC, the total unit cost would
range from $716 to $1,083 per affected vehicle.\195\ The total number
of affected vehicles including trucks and buses are estimated to be
569,792 units annually: 164,405 units for class 7-8 and 405,387 units
for class 3-6 vehicles. The total cost corresponding to the estimated
annual benefits is estimated to be $353 million ($288 million for class
7-8 and $65 million for class 3-6). The affected vehicle units were
based on the 10 year average of units sold between 2011 and 2020.\196\
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\193\ ``Cost and Weight Analysis of Heavy Vehicle Forward
Collision Warning (FCW) and Automatic Emergency Braking (AEB)
Systems for Heavy Trucks,'' September 27, 2018, Contract number:
DTNH2216D00037, Task Order: DTNH2217F00147.
\194\ Final Regulatory Impact Analysis, FMVSS No. 136 Electronic
Stability Control on Heavy Vehicles, June 2014, Docket No. NHTSA-
2015-0056.
\195\ AEB and ESC unit cost estimates are the additional
component costs for the vehicles without the systems. Specifically,
AEB cost is the additional hardware to those vehicles that already
had ESC.
\196\ Due to data constraints, the average is only available for
trucks and school buses. The annual sales volume for motorcoaches
and transit buses was based on the agency's estimate for earlier
final rules and other sources. Please consult Appendix B of the PRIA
for details.
---------------------------------------------------------------------------
F. Monetized Benefits
Table 20 summarizes the primary benefit cost estimates, which
include the annual total cost, total monetized savings, cost per
equivalent life saved, and net benefits of the proposed rule under
three and seven percent discount rates. Monetized savings are measured
by comprehensive costs, which include the tangible costs of reducing
fatalities and injuries such as savings from medical care, emergency
services, insurance administration, workplace costs, legal costs,
congestion and property damage, lost productivity as well as
nontangible cost of quality life lost. The nontangible cost components
were based on the value of statistical life of $11.8 million.\197\
---------------------------------------------------------------------------
\197\ Departmental Guidance on Valuation of a Statistical Life
in Economic Analysis, Effective Date: Friday, March 4, 2022, https://www.transportation.gov/office-policy/transportation-policy/revised-departmental-guidance-on-valuation-of-a-statistical-life-in-economic-analysis.
---------------------------------------------------------------------------
The proposed rule would generate a net benefit of $1.81 billion to
$2.58 billion, annually under 3 and 7 percent discount rates. The
proposed rule would be cost-effective given that the highest estimated
net cost per fatal equivalent would be $0.50 million, a value less than
$12.2 million (the comprehensive cost of a fatality). The negative net
cost per fatal equivalent for the 3 percent discount rate indicates
that the savings from reducing traffic congestion and property damage
is greater than the total cost of the proposed rule. Net benefits are
likely to be even higher given that the estimates only include benefits
from crashes prevented by AEB, but do not include benefits from crashes
for which AEB mitigates the severity of, but does not prevent.
Table 20--Estimated Annual Cost, Monetized Benefits, Cost-Effectiveness, and Net Benefits of the Proposed Rule
[2021 dollars in millions]
----------------------------------------------------------------------------------------------------------------
Net cost per
Discount rates Annual cost * Monetized savings fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent........................... $353.3 $2,937.0 **-$0.12 $2,583.7
7 Percent........................... 353.3 2,160.4 0.50 1,807.1
----------------------------------------------------------------------------------------------------------------
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the
cost, resulting in negative net cost per equivalent life. The negative value indicates cost-effectiveness.
G. Alternatives
NHTSA has identified and assessed alternatives to the preferred
alternative set forth in the proposed regulatory text. The agency
considered two primary alternatives to the proposed rule.
The first alternative would not require AEB or ESC on vehicles not
currently subject to FMVSS No. 136. Eliminating the requirement would
reduce the burden on heavy vehicle manufacturers associated with
installing AEB and ESC on vehicles with different body types, but would
result in significantly fewer
[[Page 43227]]
safety benefits and lives saved. A summary of the costs, benefits, and
cost-effectiveness associated with Alternative 1 is in Table 21.
Table 21--Discounted Benefits of Alternative 1
[Millions of 2021$]
----------------------------------------------------------------------------------------------------------------
Net cost per
Annual cost * Monetized savings fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent Discount.................. $65.10 $874.59 **-$1.00 $809.50
7 Percent Discount.................. 65.10 662.23 -0.66 597.10
----------------------------------------------------------------------------------------------------------------
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the
cost, resulting in negative net cost per equivalent life. The negative value indicates cost-effectiveness.
The second alternative would require all class 3-6 heavy vehicles
to have AEB and ESC within four years, as with the primary agency
proposal. However, this alternative would include a one-year phase-in
period beginning three years after publication of the final rule in
which 50 percent of class 3-6 vehicles would be required to install AEB
and ESC. This alternative was considered because it has the potential
to save more lives sooner. This alternative would have the same annual
cost, savings, net cost per fatal equivalent, and net benefits as the
primary proposal. However, this alternative would result in added
benefits from vehicles manufactured in the phase-in period. The
estimated total additional benefits associated with alternative 2 above
the primary estimate are summarized in Table 22.
Table 22--Discounted Additional Benefits of Alternative 2 Above the
Primary Proposal
[Millions of 2021$]
------------------------------------------------------------------------
Percent discount 3 7
------------------------------------------------------------------------
Net Additional Benefit.......................... $830.5 $566.4
------------------------------------------------------------------------
Detailed benefit-cost calculations of these alternatives are
discussed in the PRIA. The agency seeks comment on the feasibility of
the second alternative.
Because of the significant safety benefits that accrue by including
Class 3-6 vehicles, and to allow time for the Class 3-6 vehicle
manufactures to optimize implementations of both ESC and AEB into their
vehicles, the agency decided not to select either alternative.
XII. Regulatory Notices and Analyses
Executive Orders 12866, 13563, and 14094 and DOT Regulatory Policies
and Procedures
NHTSA and FMCSA have considered the impact of this rulemaking
action under Executive Order 12866, as amended by Executive Order
14094, Executive Order 13563, and the Department of Transportation's
regulatory procedures. This rulemaking is considered significant under
section 3(f)(1) of Executive Order 12866, as amended, and was reviewed
by the Office of Management and Budget under that Executive Order.
NHTSA and FMCSA have prepared a preliminary regulatory impact analysis
(PRIA) that assesses the cost and benefits of this proposed rule. The
benefits, costs and other impacts of this NPRM are discussed in the
prior section.
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act of 1980, Public Law 96-
354, 94 Stat. 1164 (5 U.S.C. 601 et seq., as amended), whenever an
agency is required to publish an NPRM or a final rule, it must prepare
and make available for public comment a regulatory flexibility analysis
that describes the effect of the rule on small entities (i.e., small
businesses, small not-for-profit organizations, and small governmental
jurisdictions). I certify that this NPRM would not have a significant
economic impact on a substantial number of small entities.
NHTSA's proposal would directly affect manufacturers of class 3-
through 8 trucks, buses, and multipurpose passenger vehicles. Of the
more than 20 companies who are sole manufacturers or first-stage
manufacturers of class 3 through 8 vehicles in the United States, NHTSA
found two companies (Proterra and Workhorse Group, Inc.) that qualify
as a small entities.\198\ Table 23. Below show the list of heavy duty
truck manufacturers.
---------------------------------------------------------------------------
\198\ NHTSA researched MD and HD vehicle manufacturing companies
and found their estimated number of employees and annual revenue (as
of Dec 2022) from the following sources: zoominfo.com,
macrotrends.net, zippia.com, statista.com, and linkedin.com.
Table 23--Heavy Duty Truck Manufacturers
----------------------------------------------------------------------------------------------------------------
Annual revenue
Type Company # Employees (millions) Notes
----------------------------------------------------------------------------------------------------------------
Trucks.......................... Autocar company.... 487 $126 Parent Company: GVW
Group.
Brightdrop......... 252 138 Parent Company: GM.
Ford............... 186,000 158,060 ...................
GM................. 167,000 156,700 ...................
International...... 2,760 721 Parent Company:
Navistar.
Freightliner....... 15,000 450 Parent Company:
Daimler.
Hendrickson 6,000 1,600 ...................
International.
Mack............... 2,000 671 Parent Company:
Volvo.
Navistar........... 14,500 3,900 ...................
Oshkosh Corp....... 15,000 8,300 ...................
PACCAR............. 31,100 28,800 Subsidiaries:
Kenworth,
Peterbilt.
Ram................ 200,000 180,000 Parent Company:
Stellantis.
[[Page 43228]]
Shyft Group........ 4,200 1,000 ...................
Western Star....... 3,221 680 Parent Company:
Daimler.
Workhorse.......... 331 5 Small Business.
Buses........................... Bluebird........... 1,702 726 ...................
Forest River....... 11,000 3,300 Parent Company:
Berkshire
Hathaway.
Gillig............. 900 267 Parent Company:
Henry Crown & Co.
IC Bus............. 219 44 Parent Company:
Navistar.
Nikola............. 1,500 51 ...................
Proterra........... 938 247 Small Business.
REV group.......... 6,800 2,300 Subsidiary: El
Dorado.
Thomas Built Buses. 1,276 288 Parent Company:
Daimler.
----------------------------------------------------------------------------------------------------------------
Workhorse Group, Inc. currently has about 330 employees. Its
vehicles are already equipped with ESC and AEB and are unlikely to be
affected by this proposal. Proterra is a manufacturer of large electric
transit buses and falls into the small business threshold with about
9,400 employees. Although its vehicles are not currently equipped with
AEB, its vehicles sell for approximately $750,000. With such a high
sale price, NHTSA considers the effect of this rule on the price of the
vehicle to be de minimis. Accordingly, NHTSA has concluded that this
proposal would not have a significant economic impact upon these small
entities. However, NHTSA seeks comment on this conclusion.
Final stage manufacturers are also affected by this proposal, and
final stage manufacturers would be considered small entities. According
to the U.S. Census, there are 570 small businesses in body
manufacturing for light, medium, and heavy-duty classes.\199\ This
proposal likely would affect a substantial number of final stage
manufacturers that are small businesses. It is NHTSA's understanding
that these small entities rarely make modifications to a vehicle's
braking system and instead rely upon the pass-through certification
provided by the first-stage manufacturer, which is not typically a
small business.. More information about multi-stage vehicle
manufacturing can be found in section VI.E of this proposal.
Additionally, this proposal would further accommodate final-stage
manufacturers by providing them an additional year before compliance is
required. Therefore, NHTSA does not believe at this time that the
impacts of this proposal on small entities would be significant.
---------------------------------------------------------------------------
\199\ 2020 SUSB Annual Data Tables by Establishment Industry,
``U.S. and states, NAICS, detailed employment sizes.'' https://www.census.gov/data/tables/2020/econ/susb/2020-susb-annual.html.
---------------------------------------------------------------------------
This rule may also affect purchasers of class 3 through 8 vehicles.
It is assumed that the incremental costs of this proposal would be
passed on to these purchasers. Class 7 through 8 vehicles are primarily
purchased by motor carriers, an industry composed of approximately
757,652 interstate, intrastate, and hazardous materials motor carriers,
in which over ninety percent of its companies (687,139) are considered
small.\200\ Class 3-6 vehicles consisting of work pickup trucks, small
buses, and moving/cargo vans are purchased and utilized in industries
where small businesses are not uncommon as well. It is not known
precisely how frequently small businesses purchase new vehicles
(instead of used vehicles) affected by the proposed rule, however,
small entities usually have the option to finance or lease these
vehicles to mitigate financial burden by spreading out cost over time.
Table 24 below shows a list of industries, where small businesses may
be affected by the proposed rule.
---------------------------------------------------------------------------
\200\ Assume a motor carrier of 10 or less power units is
considered a small entity, which is very conservative given an SBA
size standard of $30 million in annual revenue. 2022 Pocket Guide to
Large Truck and Bus Statistics (December 2022), Federal Motor
Carrier Safety Administration, p.13.
Table 24--SBA Size Standards of Indirectly Affected Industries
----------------------------------------------------------------------------------------------------------------
Size standards in
NAICS Code NAICS Industry description millions of
dollars
----------------------------------------------------------------------------------------------------------------
484110....................................... General Freight Trucking, Local............... 30
484122....................................... General Freight Trucking, Long-Distance, 30
Truckload.
484122....................................... General Freight Trucking, Long-Distance, Less 38
Than Truckload.
484210....................................... Used Household and Office Goods Moving........ 30
484220....................................... Specialized Freight (except Used Goods) 30
Trucking, Local.
484230....................................... Specialized Freight (except Used Goods) 30
Trucking, Long-Distance.
485113....................................... Bus and Other Motor Vehicle Transit Systems... 28.5
485210....................................... Interurban and Rural Bus Transportation....... 28
485410....................................... School & Employee Bus Transportation.......... 26.5
485510....................................... Charter Bus Industry.......................... 17
485991....................................... Special Needs Transportation.................. 16.5
488410....................................... Motor Vehicle Towing.......................... 8
----------------------------------------------------------------------------------------------------------------
[[Page 43229]]
FMCSA's proposed requirement would ensure that the benefits
resulting from CMVs equipped with AEBs are sustained through proper
maintenance and operation. The cost of maintaining AEB systems is
minimal and may be covered by regular annual maintenance. Therefore,
FMCSA does not expect this requirement to have a significant economic
impact on a substantial number of small entities.
Additional information concerning the potential impacts of this
proposal on small businesses is presented in the PRIA accompanying this
proposal. The agencies seek comment on the effects this NPRM would have
on small businesses.
National Environmental Policy Act
The National Environmental Policy Act of 1969 (NEPA) \201\ requires
Federal agencies to analyze the environmental impacts of proposed major
Federal actions significantly affecting the quality of the human
environment, as well as the impacts of alternatives to the proposed
action.\202\ The Council on Environmental Quality (CEQ)'s NEPA
implementing regulations direct federal agencies to determine the
appropriate level of NEPA review for a proposed action; an agency can
determine that a proposed action normally does not have significant
effects and is categorically excluded,\203\ or can prepare an
environmental assessment for a proposed action ``that is not likely to
have significant effects or when the significance of the effects is
unknown.'' \204\ When a Federal agency prepares an environmental
assessment, CEQ's NEPA implementing regulations require it to (1)
``[b]riefly provide sufficient evidence and analysis for determining
whether to prepare an environmental impact statement or a finding of no
significant impact;'' and (2) ``[b]riefly discuss the purpose and need
for the proposed action, alternatives . . . , and the environmental
impacts of the proposed action and alternatives, and include a listing
of agencies and persons consulted.'' \205\
---------------------------------------------------------------------------
\201\ 42 U.S.C. 4321-4347.
\202\ 42 U.S.C. 4332(2)(C).
\203\ 40 CFR 1501.4.
\204\ 40 CFR 1501.5(a).
\205\ 40 CFR 1501.5(c).
---------------------------------------------------------------------------
As discussed further below, FMCSA has determined that its proposed
action is categorically excluded from further analysis and
documentation in accordance with FMCSA Order 5610.1.\206\ NHTSA
determined that there is no similarly applicable categorical exclusion
for its proposed action and has therefore determined that it is
appropriate to prepare a Draft Environmental Assessment (EA). The
preamble provides additional information about the distinction between
NHTSA and FMCSA's proposed requirements based on each agency's
statutory authority.
---------------------------------------------------------------------------
\206\ 69 FR 9680 (Mar. 1, 2004).
---------------------------------------------------------------------------
This section serves as NHTSA's Draft EA. In this Draft EA, NHTSA
outlines the purpose and need for the proposed rulemaking, a reasonable
range of alternative actions the agency could adopt through rulemaking,
and the projected environmental impacts of these alternatives.
Purpose and Need
This NPRM preamble and the accompanying PRIA set forth the purpose
of and need for this action. The preamble and PRIA outline the safety
need for this proposal, in particular to address safety problems
associated with heavy vehicles, i.e., vehicles with a GVWR greater than
4,536 kilograms (10,000 pounds). These heavy vehicles, also referred to
as Class 3-8 vehicles,\207\ include single unit straight trucks,
combination trucks, truck tractors, motorcoaches, transit buses, school
buses, and certain pickup trucks. An annualized average of 2017 to 2019
data from NHTSA's FARS and CRSS shows heavy vehicles were involved in
around 60,000 rear-end crashes in which the heavy vehicle was the
striking vehicle annually, which represents 11 percent of all crashes
involving heavy vehicles.\208\ These rear-end crashes resulted in 388
fatalities annually, which comprises 7.4 percent of all fatalities in
heavy vehicle crashes. These crashes resulted in approximately 30,000
injuries annually, or 14.4 percent of all injuries in heavy vehicle
crashes, and 84,000 damaged vehicles with no injuries or fatalities.
Considering vehicle size, approximately half of the rear-end crashes,
injuries, and fatalities resulting from rear-end crashes where the
heavy vehicle was the striking vehicle involved vehicles with a GVWR
above 4,536 kilograms (10,000 pounds) up to 11,793 kilograms (26,000
pounds). Similarly, half of all rear-end crashes and the fatalities and
injuries resulting from those crashes where the heavy vehicle was the
striking vehicle involved vehicles with a GVWR of greater than 11.793
kilograms (26,000 pounds).
---------------------------------------------------------------------------
\207\ Class is a vehicle classification system used by the
Federal Highway Administration of Department of Transportation to
categorize vehicles into 8 Classes based on vehicle size, weight,
and number of wheels. The following lists the GVWR for Class 3-8
heavy vehicles. A complete vehicle class categorization table is
included in 49 CFR part 565.
Class GVWR
Class 3: 4,536-6,350 kg (10,001-14,000 pounds)
Class 4: 6,351-7,257 kg (14,001-16,000 pounds)
Class 5: 7,258-8,845 kg (16,001-19,500 pounds)
Class 6: 8,846-11,793 kg (19,501-26,000 pounds)
Class 7: 11,794-14,969 kg (26,001-33,000 pounds)
Class 8: 14,969 kg (33,001 pounds) and above
\208\ These rear-end crashes are cases where the heavy vehicle
was the striking vehicle.
---------------------------------------------------------------------------
To address this safety need, NHTSA proposes to adopt a new FMVSS to
require AEB systems on certain heavy vehicles.\209\ Current AEB systems
use radar and camera-based sensors or combinations thereof and build
upon older FCW-only systems. An FCW-only system provides an alert to a
driver of an impending rear-end collision with a lead vehicle to induce
the driver to take action to avoid the crash but does not automatically
apply the brakes. This proposal would require both FCW and AEB systems.
For simplicity, when referring to AEB systems in general, this proposal
is referring to both FCW and AEB unless the context suggests otherwise.
NHTSA also proposes to amend FMVSS No. 136 to require nearly all heavy
vehicles to have an ESC system that meets the equipment requirements,
general system operational capability requirements, and malfunction
detection requirements of FMVSS No. 136. In addition to requiring
certain heavy vehicles be equipped with AEB/ESC, the proposed rule
requires the heavy vehicles to be able to avoid a collision in various
rear-end crash scenarios at different speeds.
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\209\ Some heavy vehicles are excluded from the proposed rule.
These include those vehicles that are excluded from FMVSS No. 121
and FMVSS No. 136.
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As explained earlier in this preamble, the AEB system improves
safety by using various sensor technologies and sub-systems that work
together to detect when the vehicle is in a crash imminent situation,
to automatically apply the vehicle brakes if the driver has not done
so, or to apply more braking force to supplement the driver's braking,
thereby detecting and reacting to an imminent crash. This proposed rule
is anticipated to address the safety need by mitigating the amount of
fatalities, non-fatal injuries, and property damage that would result
from crashes that could potentially be prevented or mitigated because
of AEB and ESC. This proposed rule is expected to substantially
decrease risks associated with rear-end, rollover, and loss of control
crashes.
This NPRM follows NHTSA's 2015 grant of a petition for rulemaking
from the Truck Safety Coalition, the Center for Auto Safety, Advocates
for Highway
[[Page 43230]]
and Auto Safety and Road Safe America, requesting that NHTSA establish
a safety standard to require AEB on certain heavy vehicles. This NPRM
also responds to a mandate under the Bipartisan Infrastructure Law,
enacted as the Infrastructure Investment and Jobs Act, directing the
Department to prescribe an FMVSS that requires heavy commercial
vehicles with FMVSS-required ESC systems to be equipped with an AEB
system, and also promotes DOT's January 2022 National Roadway Safety
Strategy to initiate a rulemaking to require AEB on heavy trucks. This
NPRM also proposes Federal Motor Carrier Safety Regulations requiring
the ESC and AEB systems to be on during vehicle operation.
Alternatives
NHTSA has considered three regulatory alternatives for the proposed
action and a ``no action alternative.'' Under the no action
alternative, NHTSA would not issue a final rule requiring that vehicles
be equipped (installation standards) with systems that meet minimum
specified performance standards, and manufacturers would continue to
add these systems voluntarily. However, since the BIL directs NHTSA to
promulgate a rule that would require heavy vehicles subject to FMVSS
No. 136 to be equipped with an AEB system, the no action alternative is
not a permissible option. The proposed standard (the preferred
alternative) requires specific AEB/ESC installation and performance
standards for certain Class 3-8 heavy vehicles with a two-tiered phase-
in schedule based on whether the heavy vehicle is currently subject to
FMVSS No. 136. Alternative 1, which is considered less stringent than
the preferred alternative, would set AEB/ESC installation and
performance standards only for vehicles currently subject to FMVSS No.
136. Alternative 2, which is considered more stringent than the
preferred alternative, would require a more aggressive phase-in
schedule for the AEB/ESC installation requirements for Class 3-6 heavy
vehicles.
Although these regulatory alternatives differ in phase-in schedule
and heavy vehicle Class applicability, the functional AEB/ESC
installation and performance requirements would be the same. Please see
the preamble and PRIA Chapter 11, Regulatory Alternatives, for more
information about the preferred alternative and other regulatory
alternatives, and the proposed standards' requirements.
Environmental Impacts of the Proposed Action and Alternatives
Based on the purpose and need for the proposed action and the
regulatory alternatives described above, the primary environmental
impacts that could potentially result from this rulemaking are
associated with greenhouse gas (GHG) emissions and air quality,
socioeconomics, public health and safety, solid waste/property damage/
congestion, and hazardous materials.\210\ Consistent with CEQ
regulations and guidance, this EA discusses impacts in proportion to
their potential significance. The effects of the proposed rulemaking
that were analyzed further are summarized below.
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\210\ NHTSA anticipates that the proposed action and
alternatives would have negligible or no impact on the following
resources and impact categories, and therefore has not analyzed them
further: topography, geology, soils, water resources (including
wetlands and floodplains), biological resources, resources protected
under the Endangered Species Act, historical and archeological
resources, farmland resources, environmental justice, and Section
4(f) properties.
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Greenhouse Gas Emissions and Air Quality
NHTSA has previously recognized that additional weight required by
FMVSS could potentially negatively impact the amount of fuel consumed
by a vehicle, and accordingly result in GHG emissions or air quality
impacts from criteria pollutant emissions.\211\ Atmospheric GHGs affect
Earth's surface temperature by absorbing solar radiation that would
otherwise be reflected back into space. Carbon dioxide (CO2)
is the most significant GHG resulting from human activity. Motor
vehicles emit CO2 as well as other GHGs, including methane
and nitrous oxides, in addition to criteria pollutant emissions that
negatively affect public health and welfare.
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\211\ Criteria pollutants is a term used to describe the six
common air pollutants for which the Clean Air Act (CAA) requires the
Environmental Protection Agency (EPA) to set National Ambient Air
Quality Standards (NAAQS). EPA calls these pollutants criteria air
pollutants because it regulates them by developing human health-
based or environmentally based criteria (i.e., science-based
guidelines) for setting permissible levels.
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Additional weight added to a vehicle, like added hardware from
safety systems, can potentially cause an increase in vehicle fuel
consumption and emissions. NHTSA analyzed in PRIA Chapter 9.1,
Technology Unit Costs and Added Weights, the cost associated with
meeting the performance requirements in the proposed rule, including
the potential weight added to the vehicle. An AEB system for heavy
vehicles requires the following hardware: sensors (radar mounted at
front bumper and, in some cases, camera located at top, inside portion
of windshield), control units (electronic control unit), display (in
some cases integrated with existing dash cluster, in other cases, a
separate display), associated wiring harnesses, mounting hardware
specific to FCW/AEB system, and other materials and scrap (for
electronic parts, this category includes labels, soldering materials,
flux, and fasteners).\212\ Although AEB and ESC have some shared system
components, NHTSA also estimated that a limited amount of additional
hardware would be required for ESC systems depending on the vehicle
class, including accelerometers, yaw rate sensors, and steer angle
sensors.\213\ Based on a study conducted for NHTSA on the cost and
weight of heavy vehicle FCW and AEB systems,\214\ NHTSA concluded that
the added weight for the installation of AEB is estimated to be up to
3.10 kg (~ 7 lbs) and AEB and ESC combined is up to 6.70 kg (~ 15 lbs).
These weights are considered negligible compared to the 4,536 kg
(10,000 lbs) or greater curb weight of Class 3-8 vehicles. NHTSA
tentatively concluded in the PRIA that the proposed rule is not
expected to impact the fuel consumption of Class 3-8 vehicles, and
therefore none of the regulatory alternatives would be presumed to
result in GHG or criteria pollutant impacts.
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\212\ PRIA, at 141.
\213\ Final Regulatory Impact Analysis, FMVSS No. 136,
Electronic Stability Control Systems on Heavy Vehicles; Docket No.
NHTSA-2015-0056-0002, at VI-5.
\214\ Department of Transportation National Highway Traffic
Safety Administration Office of Acquisition Management (NPO-320)
West Building 51-117 1200 New Jersey Avenue SE Washington, DC 20590
Contract Number: DTNH2216D00037 Task Order: DTNH2217F00147 Cost and
Weight Analysis of Heavy Vehicle Forward Collision Warning (FCW) and
Automatic Emergency Braking (AEB) Systems for Heavy Trucks Ricardo
Inc. Detroit Technical Center Van Buren Twp., MI 48111 USA September
27, 2018.
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NHTSA also analyzed this action for purposes of the Clean Air Act
(CAA)'s General Conformity Rule.\215\ The
[[Page 43231]]
General Conformity Rule does not require a conformity determination for
Federal actions that are ``rulemaking and policy development and
issuance,'' such as this action.\216\ Therefore, NHTSA has determined
it is not required to perform a conformity analysis for this action.
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\215\ Section 176(c) of the CAA, codified at 42 U.S.C. 7506(c);
To implement CAA Section 176(c), EPA issued the General Conformity
Rule (40 CFR part 51, subpart W and part 93, subpart B). Pursuant to
the CAA, the U.S. Environmental Protection Agency (EPA) has
established a set of National Ambient Air Quality Standards (NAAQS)
for the following criteria pollutants: carbon monoxide (CO),
nitrogen dioxide (NO2), ozone, particulate matter (PM)
less than 10 micrometers in diameter (PM10), PM less than
2.5 micrometers in diameter (PM2.5), sulfur dioxide
(SO2), and lead (Pb). EPA requires a ``conformity
determination'' when a Federal action would result in total direct
and indirect emissions of a criteria pollutant or precursor
originating in nonattainment or maintenance areas equaling or
exceeding the emissions thresholds specified in 40 CFR 93.153(b)(1)
and (2).
\216\ 40 CFR 93.153(c)(2)(iii).
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Socioeconomics
The socioeconomic impacts of the proposed rule would be primarily
felt by heavy vehicle and equipment manufacturers, heavy vehicle
drivers, and other road users that would otherwise be killed or injured
as a result of heavy vehicle crashes. NHTSA conducted a detailed
assessment of the economic costs and benefits of establishing the new
rule in its PRIA. The main economic benefits come primarily from the
reduction in fatalities and non-fatal injuries (safety benefits).
Reductions in the severity of heavy vehicle crashes would be
anticipated to have corresponding reductions in costs for medical care,
emergency services, insurance administrative costs, workplace costs,
and legal costs due to the fatalities and injuries avoided. Other
socioeconomic factors discussed in the PRIA that would affect these
parties include quantified property damage savings, and additional
quantified and unquantified impacts like less disruptions to commodity
flow and improved traffic conditions. Most of these socioeconomic
benefits are related to public health and safety and are discussed in
more detail below.
Table 25--Comparison of Regulatory Alternatives
[2021 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Net cost per equivalent live saved Net benefits
Regulatory option Relative to the proposed rule ---------------------------------------------------------------------------
3% 7% 3% 7%
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Rule............................... .............................. -$118,922 $496,746 $2,583,652,432 $1,807,064,498
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alternative 1: AEB Requirements only for Less Stringent................ -1,003,884 -662,217 809,485,467 597,125,719
Class 7-8.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alternative 2: More Aggressive Phase in More Stringent................ -118,922 496,746 2,583,652,432 1,807,064,498
Schedule for Class 3-6.
--------------------------------------------------------------------------------------------------------------------------------------------------------
The total annual cost, considering the implementation of both AEB
and ESC technologies proposed in this rule, is estimated to be $353
million. The proposed rule would generate a net benefit of $2.58 to
$1.81 billion, annually under 3 and 7 percent discount rates. The
proposed rule would be cost-effective given that the highest estimated
net cost per fatal equivalent would be $0.50 million. Maintenance costs
are considered de minimis and therefore not included in the cost
estimate. Please see PRIA for additional information about the annual
cost, monetized benefits, cost-effectiveness, and net benefits of this
proposal.
Public Health and Safety
The affected environment for public health and safety includes
roads, highways and other driving locations used by heavy vehicle
drivers, drivers and passengers in light vehicles and other motor
vehicles, and pedestrians or other individuals who could be injured or
killed in crashes involving the vehicles regulated by the proposed
action. In the PRIA, the agency determined the impacts on public health
and safety by estimating the reduction in fatalities and injuries
resulting from the decreased crash severity due to the use of AEB
systems under the regulatory alternatives. Under the proposed standard
(the preferred alternative), it is expected that the addition of a
requirement for specific AEB/ESC installation and performance standards
for certain Class 3-8 heavy vehicles with a two-tiered phase-in
schedule, would result each year in 151 to 206 equivalent lives saved.
Under Alternative 1, it is expected that the addition of a less
stringent requirement that would set AEB/ESC installation and
performance standards only for Class 7-8 heavy vehicles, with the same
phase-in schedule as the preferred alternative, would result each year
in 45 to 60 equivalent lives saved. Under Alternative 2, it is expected
that the addition of a more stringent requirement that would require a
more aggressive phase-in schedule for the AEB/ESC installation
requirements for Class 3-6 heavy vehicles, would result in 94 to 128
equivalent lives saved in 2024 and 151 to 206 equivalent lives saved in
2025 onwards. The PRIA discusses this information in further detail.
Solid Waste/Property Damage/Congestion
Vehicle crashes can generate solid wastes and release hazardous
materials into the environment. The chassis and engines, as well as
associated fluids and components of automobiles and the contents of the
vehicles, can all be deemed waste and/or hazardous materials. Solid
waste can also include damage to the roadway infrastructure, including
road surface, barriers, bridges, and signage. Hazardous materials are
substances that may pose a threat to public safety or the environment
because of their physical, chemical, or radioactive properties when
they are released into the environment, in this case as a result of a
crash. Vehicle crashes also generate socioeconomic and environmental
effects from congestion as engines idle while drivers are caught in
traffic jams and slowdowns, in particular from wasted fuel and the
resulting increased greenhouse gas emissions.\217\
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\217\ Blincoe, L.J., Miller, T.R., Zaloshnja, E., & Lawrence,
B.A. (2015, May). The economic and societal impact of motor vehicle
crashes, 2010. (Revised) (Report No. DOT HS 812 013). Washington,
DC: National Highway Traffic Safety Administration.
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The proposal is projected to reduce the amount and severity of
heavy vehicle crashes, and therefore is expected to reduce the quantity
of solid waste, hazardous materials, and other property damage
generated by vehicle crashes in the United States, in addition to
reducing the traffic congestion that occurs as a consequence of a
crash. Less solid waste translates into cost and environmental savings
from reductions in the following areas: (1) transport of waste
material, (2) energy required for recycling efforts, and (3) landfill
or
[[Page 43232]]
incinerator fees. Less waste will result in beneficial environmental
effects through less GHG emissions used in the transport of it to a
landfill, less energy used to recycle the waste, less emissions through
the incineration of waste, and less point source pollution at the scene
of the crash that would result in increased emissions levels or
increased toxins leaking from the crashed vehicles into the surrounding
environment. Similarly, as mentioned above, less congestion translates
into economic and environmental benefits from fuel savings and reduced
GHG emissions, in addition to benefits from the time that drivers are
not caught in additional traffic congestion.
As discussed in the PRIA, NHTSA's monetized benefits are calculated
by multiplying the number of non-fatal injuries and fatalities
mitigated by their corresponding ``comprehensive costs.'' The
comprehensive costs include economic costs that are external to the
value of a statistical life (VSL) costs, such as emergency management
services or legal costs, and congestion costs. NHTSA calculated the
monetized benefits attributable to reduced traffic congestion and
property damage in the PRIA accompanying this proposed rule for the
proposed action and the regulatory alternatives. As shown in Table 26,
the monetized benefits from reduced traffic congestion and property
damage increase as the regulatory alternatives increase the heavy
vehicle classes covered by the proposal and the proposal's phase-in
year. Please see PRIA for additional information about the
comprehensive cost values used in this proposal.
Table 26--Congestion and Property Damage Savings
----------------------------------------------------------------------------------------------------------------
Alternative 1 Preferred alternative Alternative 2
----------------------------------------------------------------------------------------------------------------
3% Discount 7% Discount 3% Discount 7% Discount 3% Discount 7% Discount
----------------------------------------------------------------------------------------------------------------
$125,337,423......... $94,904,159 $377,815,690 $278,309,156 2024: 2024:
$243,518,740. $180,753,307.
2025 Onwards: 2025 Onwards:
$377,815,690. $278,309,156.
----------------------------------------------------------------------------------------------------------------
While NHTSA did not quantify impacts aside from the monetized
benefits from congestion and property damage savings, like the specific
quantity of solid waste avoided from reduced crashes, NHTSA believes
the benefits would increase relative to the crashes avoided and would
be relative across the different alternatives. This is based in part on
NHTSA and FMCSA's previously conducted Draft EA on heavy vehicle speed
limiting devices.\218\ While that Draft EA analyzed the effects of
reduced crash severity, there would be similar, if not increasing
benefits to avoided crashes as a result of the addition of AEB to heavy
vehicles.\219\ The PRIA discusses information related to quantified
costs and benefits of crashes, and in particular property damage due to
crashes, for each regulatory alternative in further detail.
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\218\ Speed Limiting Devices Draft Environmental Assessment, DOT
HS 812 324 (August 2016).
\219\ Id. at 33 (``Using this procedure, the results in this
section are expected to be more conservative than if presented in
terms of crash avoidance.''
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Cumulative Impacts
In addition to direct and indirect effects, CEQ regulations require
agencies to consider cumulative impacts of major Federal actions. CEQ
regulations define cumulative impacts as the impact ``on the
environment that result from the incremental [impact] of the action
when added to . . . other past, present, and reasonably foreseeable
future actions regardless of what agency (Federal or non-Federal) or
person undertakes such other actions.'' \220\ NHTSA notes that the
public health and safety, solid waste/property damage/congestion, air
quality and GHG emissions, socioeconomic, and hazardous material
benefits identified in this EA were based on calculations described in
the PRIA, in addition to other NHTSA actions and studies on motor
vehicle safety. That methodology required the agency to adjust
historical figures to reflect vehicle safety rulemakings that have
recently become effective. As a result, many of the calculations in
this EA already reflect the incremental impact of this action when
added to other past actions.
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\220\ 40 CFR 1508.1(g)(3).
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NHTSA's and other parties' past actions that improve the safety of
heavy vehicles, as well as future actions taken by the agency or other
parties that improve the safety of heavy vehicles, could further reduce
the severity or number of crashes involving these vehicles. Any such
cumulative improvement in the safety of heavy vehicles would have an
additional effect in reducing injuries and fatalities and could reduce
the quantity of solid and hazardous materials generated by crashes.
Additional federal actions like NHTSA's fuel efficiency standards for
heavy vehicles, and EPA's GHG and criteria pollutant emissions
standards for heavy vehicles, could also result in additional decreased
fuel use and emissions reductions in the future.
Agencies and Persons Consulted
This preamble describes the various materials, persons, and
agencies consulted in the development of the proposal.
Finding of No Significant Impact
Although this rule is anticipated to result in increased FMVSS
requirements for heavy vehicle manufacturers, NHTSA's analysis
indicates that it would likely result in environmental and other
socioeconomic benefits. The addition of regulatory requirements to
standardize heavy vehicle AEB is anticipated to result in no additional
fuel consumption (and accordingly, no additional GHG or criteria
pollutant emissions impacts), increasing socioeconomic and public
safety benefits depending on the regulatory alternative phase-in year
and vehicle class applicability requirements from the no-action
alternative, and an increase in benefits from the reduction in solid
waste, property damage, and congestion (including associated traffic-
level impacts like a reduction in energy consumption and tailpipe
pollutant emissions from congestion) from fewer crashes.
Based on the information in this Draft EA and assuming no
additional information or changed circumstances, NHTSA expects to issue
a Finding of No Significant Impact (FONSI).\221\ NHTSA has tentatively
concluded that none of the impacts anticipated to result from the
proposed action and alternatives under consideration will have a
significant effect on the human environment. Such a finding will be
made only after careful review of all public comments received. A Final
EA and a FONSI, if appropriate, will be issued as part of the final
rule.
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\221\ 40 CFR 1501.6(a).
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[[Page 43233]]
FMCSA
FMCSA analyzed this rule pursuant to the National Environmental
Policy Act and determined this action is categorically excluded from
further analysis and documentation in an environmental assessment or
environmental impact statement under FMCSA Order 5610.1 (69 FR 9680,
Mar. 1, 2004), Appendix 2, paragraph 6(aa). The Categorical Exclusion
in paragraph 6(aa) covers regulations requiring motor carriers, their
officers, drivers, agents, representatives, and employees directly in
control of CMVs to inspect, repair, and provide maintenance for every
CMV used on a public road. In addition, this rule does not have any
effect on the quality of environment.
Executive Order 13132 (Federalism)
NHTSA has examined this NPRM pursuant to Executive Order 13132 (64
FR 43255, August 10, 1999) and concludes that no additional
consultation with States, local governments or their representatives is
mandated beyond the rulemaking process. The agency has concluded that
the rulemaking would not have sufficient federalism implications to
warrant consultation with State and local officials or the preparation
of a federalism summary impact statement. The NPRM would not have
``substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government.''
NHTSA rules can preempt in two ways. First, the National Traffic
and Motor Vehicle Safety Act contains an express preemption provision:
When a motor vehicle safety standard is in effect under this chapter, a
State or a political subdivision of a State may prescribe or continue
in effect a standard applicable to the same aspect of performance of a
motor vehicle or motor vehicle equipment only if the standard is
identical to the standard prescribed under this chapter. 49 U.S.C.
30103(b)(1). It is this statutory command by Congress that preempts any
non-identical State legislative and administrative law addressing the
same aspect of performance.
The express preemption provision described above is subject to a
savings clause under which ``[c]ompliance with a motor vehicle safety
standard prescribed under this chapter does not exempt a person from
liability at common law.'' 49 U.S.C. 30103(e). Pursuant to this
provision, State common law tort causes of action against motor vehicle
manufacturers that might otherwise be preempted by the express
preemption provision are generally preserved.
However, the Supreme Court has recognized the possibility, in some
instances, of implied preemption of such State common law tort causes
of action by virtue of NHTSA's rules, even if not expressly preempted.
This second way that NHTSA rules can preempt is dependent upon there
being an actual conflict between an FMVSS and the higher standard that
would effectively be imposed on motor vehicle manufacturers if someone
obtained a State common law tort judgment against the manufacturer,
notwithstanding the manufacturer's compliance with the NHTSA standard.
Because most NHTSA standards established by an FMVSS are minimum
standards, a State common law tort cause of action that seeks to impose
a higher standard on motor vehicle manufacturers will generally not be
preempted. However, if and when such a conflict does exist--for
example, when the standard at issue is both a minimum and a maximum
standard--the State common law tort cause of action is impliedly
preempted. See Geier v. American Honda Motor Co., 529 U.S. 861 (2000).
Pursuant to Executive Order 13132 and 12988, NHTSA has considered
whether this proposed rule could or should preempt State common law
causes of action. The agency's ability to announce its conclusion
regarding the preemptive effect of one of its rules reduces the
likelihood that preemption will be an issue in any subsequent tort
litigation. To this end, the agency has examined the nature (e.g., the
language and structure of the regulatory text) and objectives of this
final rule and finds that this rule, like many NHTSA rules, would
prescribe only a minimum safety standard. As such, NHTSA does not
intend this NPRM to preempt State tort law that would effectively
impose a higher standard on motor vehicle manufacturers than that
established by a final rule. Establishment of a higher standard by
means of State tort law will not conflict with the minimum standard
adopted here. Without any conflict, there could not be any implied
preemption of a State common law tort cause of action.
FMCSA has determined that this proposed rule would not have
substantial direct costs on or for States concerning the adoption and
enforcement of compatible motor carrier safety rules for intrastate
motor carriers, nor would it limit the policymaking discretion of
States. Nothing in this document would preempt any State motor carrier
safety law or regulation. Therefore, this proposed rule would not have
sufficient federalism implications to warrant the preparation of a
Federalism Impact Statement related to the delivery of FMCSA's
programs.
Civil Justice Reform
With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729, February 7, 1996) requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses other important issues affecting
clarity and general draftsmanship under any guidelines issued by the
Attorney General. This document is consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows. The preemptive
effect of this rulemaking is discussed above. NHTSA notes further that
there is no requirement that individuals submit a petition for
reconsideration or pursue other administrative proceeding before they
may file suit in court.
Paperwork Reduction Act (PRA)
Under the PRA of 1995, a person is not required to respond to a
collection of information by a Federal agency unless the collection
displays a valid OMB control number. There are no ``collections of
information'' (as defined at 5 CFR 1320.3(c)) in this proposed rule.
National Technology Transfer and Advancement Act
Under the National Technology Transfer and Advancement Act of 1995
(NTTAA) (Public Law 104-113), all Federal agencies and departments
shall use technical standards that are developed or adopted by
voluntary consensus standards bodies, using such technical standards as
a means to carry out policy objectives or activities determined by the
agencies and departments. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies, such as the International
Organization for Standardization (ISO) and SAE International. The NTTAA
[[Page 43234]]
directs Federal agencies to provide Congress, through OMB, explanations
when a Federal agency decides not to use available and applicable
voluntary consensus standards.
NHTSA is proposing to incorporate by reference ISO and ASTM
standards into this proposed rule. NHTSA considered several ISO
standards and has proposed to use ISO 19206-3:2021 to specify the
vehicle test device. NHTSA is incorporating by reference ASTM E1337-19,
which is already incorporated by reference into many FMVSSs, to measure
the peak braking coefficient of the testing surface.
NHTSA considered SAE J3029, Forward Collision Warning and
Mitigation Vehicle Test Procedure--Truck and Bus, which defines the
conditions for testing AEB and FCW systems. This document outlines a
basic test procedure to be performed under specified operating and
environmental conditions. It does not define tests for all possible
operating and environmental conditions. The procedures in this SAE
recommended practice are substantially similar to this proposal.
Minimum performance requirements are not addressed in SAE J3029.
In Appendix B of this preamble, NHTSA describes several
international test procedures and regulations the agency considered for
use in this NPRM. This proposed rule also has substantial technical
overlap with the UNECE No. 131 described in the appendix. First, this
proposed rule and UNECE No. 131 specify a warning and automatic
emergency braking in lead vehicle crash situations. Several lead
vehicle scenarios are nearly identical, including the stopped lead
vehicle and lead vehicle moving scenarios. Finally, NHTSA has based its
test target for the lead vehicle test device on the ``soft target
option'' condition contained in UNECE No. 152. As discussed in the
appendix, this proposed rule differs from the UNECE standards in the
areas of maximum test speed and the basic performance criteria. This
proposed rule uses higher test speeds to better match the safety
problem in the United States. This proposed rule includes a requirement
that the test vehicle avoid contact. This approach would increase the
repeatability of the test and maximize the realized safety benefits of
the rule.
Incorporation by Reference
Under regulations issued by the Office of the Federal Register (1
CFR 51.5(a)), an agency, as part of a proposed rule that includes
material incorporated by reference, must summarize material that is
proposed to be incorporated by reference and discuss the ways the
material is reasonably available to interested parties or how the
agency worked to make materials available to interested parties.
In this NPRM, NHTSA proposes to incorporate by reference three
documents into the Code of Federal Regulations, one of which is already
incorporated by reference. The document already incorporated by
reference into 49 CFR part 571 is ASTM E1337, ``Standard Test Method
for Determining Longitudinal Peak Braking Coefficient (PBC) of Paved
Surfaces Using Standard Reference Test Tire.'' ASTM E1337 is a standard
test method for evaluating peak braking coefficient of a test surface
using a standard reference test tire using a trailer towed by a
vehicle. NHTSA uses this method in all of its braking and electronic
stability control standards to evaluate the test surfaces for
conducting compliance test procedures.
NHTSA is also proposing to incorporate by reference into part 571
SAE J2400, ``Human Factors in Forward Collision Warning System:
Operating Characteristics and User Interface Requirements.'' SAE J2400
is an information report that is intended as a starting point of
reference for designers of forward collision warning systems. NHTSA
would incorporate this document by reference solely to specify the
location specification and symbol for a visual forward collision
warning.
NHTSA is proposing to incorporate by reference ISO 19206-3:2021(E),
``Test devices for target vehicles, vulnerable road users and other
objects, for assessment of active safety functions --Part 3:
Requirements for passenger vehicle 3D targets.'' This document provides
specification of three-dimensional test devices that resemble real
vehicles. It is designed to ensure the safety of the test operators and
to prevent damage to subject vehicles in the event of a collision
during testing. NHTSA is referencing many, but not all, of the
specifications of ISO 19206-3:2021(E), as discussed in section VIII.B
of this NPRM.
All standards proposed to be incorporated by reference in this NPRM
are available for review at NHTSA's headquarters in Washington, DC, and
for purchase from the organizations promulgating the standards. The
ASTM standard presently incorporated by reference into other NHTSA
regulations is also available for review at ASTM's online reading
room.\222\
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\222\ https://www.astm/org/READINGLIBRARY/.
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Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires
agencies to prepare a written assessment of the costs, benefits, and
other effects of proposed or final rules that include a Federal mandate
likely to result in the expenditures by States, local or tribal
governments, in the aggregate, or by the private sector, $100 million
or more (adjusted annually for inflation with base year of 1995) in any
one year. Adjusting this amount by the Consumer Price Index for All-
Urban Consumers (CPI-U) for the year 2021 and 1995 results in an
estimated current value of $178 million (= 2021 index value of 270.970/
1995 index value of 152.400). This proposed rule is not likely to
result in expenditures by State, local, or tribal governments of more
than $178 million in any one year. However, it is estimated to result
in the expenditures by motor vehicle manufacturers of more than $178
million. The prior section of this NPRM contains a summary of the costs
and benefits of this proposed rule, and the PRIA discusses the costs
and benefits of this proposed rule in detail.
Executive Order 13609 (Promoting International Regulatory Cooperation)
The policy statement in section 1 of E.O. 13609 states, in part,
that the regulatory approaches taken by foreign governments may differ
from those taken by U.S. regulatory agencies to address similar issues
and that, in some cases, the differences between the regulatory
approaches of U.S. agencies and those of their foreign counterparts
might not be necessary and might impair the ability of American
businesses to export and compete internationally. The E.O. states that,
in meeting shared challenges involving health, safety, labor, security,
environmental, and other issues, international regulatory cooperation
can identify approaches that are at least as protective as those that
are or would be adopted in the absence of such cooperation and that
international regulatory cooperation can also reduce, eliminate, or
prevent unnecessary differences in regulatory requirements. NHTSA
requests public comment on the ``regulatory approaches taken by foreign
governments'' concerning the subject matter of this rulemaking.
Regulation Identifier Number
The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified
[[Page 43235]]
Agenda in April and October of each year. You may use the RINs
contained in the heading at the beginning of this document to find this
action in the Unified Agenda.
Plain Language
Executive Order 12866 requires each agency to write all rules in
plain language. Application of the principles of plain language
includes consideration of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please write to us
with your views.
XV. Public Participation
How long do I have to submit comments?
Please see the DATES section at the beginning of this document.
How do I prepare and submit comments?
Your comments must be written in English.
To ensure that your comments are correctly filed in the
Docket, please include the Docket Number shown at the beginning of this
document in your comments.
Your comments must not be more than 15 pages long. (49 CFR
553.21). NHTSA established this limit to encourage you to write your
primary comments in a concise fashion. However, you may attach
necessary additional documents to your comments. There is no limit on
the length of the attachments. FMCSA does not impose a page limit on
docket comments, but like NHTSA, it appreciates a concise statement of
the issues addressed by commenters.
If you are submitting comments electronically as a PDF
(Adobe) File, NHTSA asks that the documents be submitted using the
Optical Character Recognition (OCR) process, thus allowing NHTSA to
search and copy certain portions of your submissions. Comments may be
submitted to the docket electronically by logging onto the Docket
Management System website at https://www.regulations.gov. Follow the
online instructions for submitting comments.
You may also submit two copies of your comments, including
the attachments, to Docket Management at the address given above under
ADDRESSES.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at https://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT's
guidelines may be accessed at https://www.bts.gov/programs/statistical_policy_and_research/data_quality_guidelines.
How can I be sure that my comments were received?
If you wish Docket Management to notify you upon its receipt of
your comments, enclose a self-addressed, stamped postcard in the
envelope containing your comments. Upon receiving your comments, Docket
Management will return the postcard by mail.
How do I submit confidential business information?
NHTSA
If you wish to submit any information under a claim of
confidentiality, you should submit three copies of your complete
submission, including the information you claim to be confidential
business information (CBI), to the Chief Counsel, NHTSA, at the address
given above under FOR FURTHER INFORMATION CONTACT. In addition, you
should submit two copies, from which you have deleted the claimed
confidential business information, to Docket Management at the address
given above under ADDRESSES. When you send a comment containing
information claimed to be confidential business information, you should
include a cover letter setting forth the information specified in our
confidential business information regulation. (49 CFR part 512). To
facilitate social distancing during COVID-19, NHTSA is temporarily
accepting confidential business information electronically. Please see
https://www.nhtsa.gov/coronavirus/submission-confidential-business-information for details.
FMCSA
CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (5 U.S.C. 552), CBI is exempt from public disclosure.
If your comments responsive to the NPRM contain commercial or financial
information that is customarily treated as private, that you actually
treat as private, and that is relevant or responsive to the NPRM, it is
important that you clearly designate the submitted comments as CBI.
Please mark each page of your submission that constitutes CBI as
``PROPIN'' to indicate it contains proprietary information. FMCSA will
treat such marked submissions as confidential under the Freedom of
Information Act, and they will not be placed in the public docket of
the NPRM. Submissions containing CBI should be sent to Mr. Brian
Dahlin, Chief, Regulatory Evaluation Division, Office of Policy, FMCSA,
1200 New Jersey Avenue SE, Washington, DC 20590-0001. Any comments
FMCSA receives not specifically designated as CBI will be placed in the
public docket for this rulemaking.
Will the agency consider late comments?
NHTSA will consider all comments that Docket Management receives
before the close of business on the comment closing date indicated
above under DATES. To the extent possible, we will also consider
comments that Docket Management receives after that date. If Docket
Management receives a comment too late for us to consider in developing
the final rule, we will consider that comment as an informal suggestion
for future rulemaking action. FMCSA will consider all comments and
material received during the comment period and through the closing
date up to 11:59:59 p.m. ET.
How can I read the comments submitted by other people?
You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location. You may also see the comments on
the internet. To read the comments on the internet, go to https://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that, even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments.
[[Page 43236]]
Accordingly, we recommend that you periodically check the Docket for
new material.
XIV. Appendices to the Preamble
Appendix A: Description of Technologies
For the convenience of readers, this section describes various
technologies of an AEB system. An AEB system employs multiple sensor
technologies and sub-systems that work together to sense a crash
imminent scenario and, where applicable, automatically apply the
vehicle brakes to avoid or mitigate a crash. Current systems utilize
radar- and camera-based sensors. AEB has been implemented in
vehicles having electronic stability control technology, which
itself leverages antilock braking system technologies. It also
builds upon older forward collision warning-only systems.
Radar-Based Sensors
At its simplest form, radar is a time-of-flight sensor that
measures the time between when a radio wave is transmitted and its
reflection is recorded. This time-of-flight is then used to
calculate the distance to the object that caused the reflection.
More information about the reflecting object, such as speed, can be
determined by comparing the output signal to the input signal.
Typical automotive applications use a type of radar called Frequency
Modulated Continuous Wave radar. This radar system sends out a radio
pulse where the pulse frequency rises through the duration of the
pulse. This pulse is reflected off the object and the radar sensor
compares the reflected signal to the original pulse to determine the
range and relative speed.
Radar sensors are widely used in AEB application, for many
reasons. These sensors can have a wide range of applicability, with
automotive grade radars sensing ranges on the order of 1 meter (3
ft) up to over 200 meters (656 ft). Radar sensors are also
relatively unaffected by time of day, precipitation, fog, and many
other adverse weather conditions. Automotive radar systems typically
operate on millimeter wave lengths, easily reflecting off even the
smallest metallic surfaces found on vehicles. Radio waves tend to
penetrate soft materials, such as rubber and plastic, allowing these
sensors to be mounted in the front ends of vehicles behind
protective, and visually appealing, grilles and bumper fascia.
Radar-based sensors have limitations that impact their
effectiveness. Radar is a line-of-sight sensor, in that they only
operate in the direction the receiving antenna is pointed and
therefore have a limited angular view. Also, while radar is
excellent at identifying radar-reflective objects, the nature of the
radar reflection makes classification of that object difficult. In
addition, objects that do not reflect radio waves easily, such as
rubber, plastic, humans, and other soft objects, are difficult for
radar-based sensors to detect. Lastly, because forward facing radar
sensors are usually mounted inside the front end of equipped
vehicles, damage caused from front-end collisions can lead to
alignment issues and reduced effectiveness.
Camera Sensors
Cameras are passive sensors in which optical data are recorded
by digital imaging chips, which are then processed to allow for
object detection and classification. They are an important part of
most automotive AEB systems and one or more cameras are typically
mounted behind the front windshield, often high up near the rearview
mirror. This provides a good view of the road, plus the windshield
wipers provide protection from debris and grease, dirt and the like
that can cover the sensor.
Camera-based imaging systems are one of the few sensor types
that can determine both color and contrast information. This makes
them able to recognize and classify objects such as road signs,
other vehicles, and pedestrians, much in the same way the human eye
does. In addition, systems that utilize two or more cameras can see
stereoscopically, allowing the processing system to determine range
information along with detection and classification.
Like all sensor systems, camera-based sensors have their
benefits and limitations. Monocular camera systems lack depth
perception and are poor at determining range, and even stereoscopic
camera systems are not ideal for determining speed. Because cameras
rely on the visible spectrum of light, conditions that make it
difficult to see such as rain, snow, sleet, fog, and even dark unlit
areas, decrease the effectiveness of perception checks of these
systems. It is also possible for the imaging sensor to saturate when
exposed to excessive light, such as driving towards the sun. For
these reasons, camera sensors are often used in conjunction with
other sensors like radar.
Electronically Modulated Braking Systems
Automatic actuation of the vehicle brakes requires more than
just systems to sense when a collision is imminent. Regardless of
how good a sensing system is, hardware is needed to physically apply
the brakes without relying on the driver to modulate the brake
pedal. The automatic braking system leverages two foundational
braking technologies, antilock braking systems and electronic safety
control.
Antilock brakes are a foundational technology that automatically
controls the degree of wheel slip during braking to prevent wheel
lock and minimize skidding, by sensing the rate of angular rotation
of the wheels and modulating the braking force at the wheels to keep
the wheels from slipping. Modern ABS systems have wheel speed
sensors and independent brake modulation at each wheel and can
increase and decrease braking pressures as needed.
ESC builds upon the antilock brakes and increases their
capability with the addition of at least two sensors, a steering
wheel angle sensor and an inertial measurement unit. These sensors
allow the ESC controller to determine intended steering direction
(from the steering wheel angle sensor), compare it to the actual
vehicle direction, and then apply appropriate braking forces at each
wheel to induce a counter yaw when the vehicle starts to lose
lateral stability. AEB uses the hardware needed for ESC and
automatically applies the brakes to avoid certain scenarios where a
crash with a vehicle is imminent.
Forward Collision Warning
Using the sensors described above, coupled with an alert
mechanism and perception calculations, a FCW system is able to
monitor a vehicle's speed, the speed of the vehicle in front of it,
and the distance between the two vehicles. If the FCW system
determines that the distance from the driver's vehicle to the
vehicle in front of it is too short, and the closing velocity
between the two vehicles is too high, the system warns the driver of
an impending rear-end collision.
Typically, FCW systems are comprised of two components: a
sensing system, which can detect a vehicle in front of the driver's
vehicle, and a warning system, which alerts the driver to a
potential crash threat. The sensing portion of the system may
consist of forward-looking radar, camera systems, lidar or a
combination of these. Warning systems in use today provide drivers
with a visual display, such as an illuminated telltale on the
instrument panel, an auditory signal (e.g., beeping tone or chime),
and/or a haptic signal that provides tactile feedback to the driver
(e.g., rapid vibrations of the seat pan or steering wheel or a
momentary brake pulse) to alert the driver of an impending crash so
that they may manually intervene (e.g., apply the vehicle's brakes
or make an evasive steering maneuver) to avoid or mitigate the
crash.
FCW systems alone are designed to warn the driver, but do not
provide automatic braking of the vehicle (some FCW systems use
haptic brake pulses to alert the driver of a crash-imminent driving
situation, but they are not intended to effectively slow the
vehicle). Since the first introduction of FCW systems, the
technology has advanced such that it is now possible to couple those
sensors, software, and alerts with the vehicles service brake system
to provide additional functionality covering a broader portion of
the safety problem.
From a functional perspective, research suggests that active
braking systems, such as AEB, provide greater safety benefits than
warning systems, such as FCW systems. However, NHTSA has found that
current AEB systems often integrate the functionalities of FCW and
AEB into one frontal crash prevention system to deliver improved
real-world safety performance and high consumer acceptance. FCW can
now be considered a component of AEB. As such, this NPRM integrates
FCW directly into the performance requirements for AEB. This
integration would also enable the agency to assess vehicles'
compliance with the proposed FCW and AEB requirements at the same
time in a single test.
Automatic Emergency Braking
Unlike systems that only alert, AEB systems (systems that
automatically apply the brakes), are designed to actively help
drivers avoid or mitigate the severity of rear-end crashes. AEB has
been previously broken into two primary functions, crash imminent
braking and dynamic brake support. CIB systems provide automatic
braking when forward-looking sensors indicate that a crash is
imminent and the driver has not applied
[[Page 43237]]
the brakes, whereas DBS systems use the same forward-looking
sensors, but provides supplemental braking after the driver applies
the brakes when sensors determine that driver-applied braking is
insufficient to avoid an imminent rear-end crash. This NPRM does not
split the terminology of these functionalities and instead discusses
them together as ``AEB.'' In some crash situations, AEB functions
independently of the driver's use of the brake pedal (CIB), while in
other situations, the vehicle uses the driver's pedal input to
better evaluate the situation and avoid the crash (in the light
vehicle context, this is called DBS). This proposal considers each
function necessary to address the safety need and presents a
performance-based regulatory approach that can permit the detailed
application of each function to be based on the specific vehicle
application and the manufacturer's approach to meeting the standard.
In response to an FCW alert or a driver noticing an imminent
crash scenario, a driver may initiate braking to avoid a rear-end
crash. In situations where the driver's braking is insufficient to
prevent a collision, the AEB system can automatically supplement the
driver's braking action to prevent or mitigate the crash. Similar to
FCW systems, AEB systems employ forward-looking sensors such as
radar and vision-based sensors to detect vehicles in the path
directly ahead and monitor a vehicle's operating conditions such as
speed or brake application. However, AEB systems can also actively
supplement braking to assist the driver whereas FCW systems serve
only to warn the driver of a potential crash threat.
If a driver does not take any action to brake when a rear-end
crash is imminent, AEB systems utilize the same types of forward-
looking sensors to apply the vehicle's brakes automatically to slow
or stop the vehicle. The amount of braking applied varies by
manufacturer, and several systems are designed to achieve maximum
vehicle deceleration just prior to impact. This NPRM would not
directly require a particular deceleration capability but specifies
situations in which crash avoidance must be achieved. Avoidance may
be produced by a combination of warnings, vehicle deceleration, and
AEB application timing.
Appendix B: International Regulatory Requirements and Other Standards
European Union (EU)
UNECE 131: Uniform provisions concerning the approval of motor
vehicles regarding the Advanced Emergency Braking Systems (AEBS).
Europe mandated AEBS for nearly all heavy vehicles starting in
November 2013. The mandate requires warning and automatic braking on
Lead Vehicle Moving (LVM) and Stopped lead vehicle (LVS), but it
does not require Dynamic Braking Support (DBS). It also requires
Forward Collision Warning (FCW) in 2 of 3 modes (audio, visual,
haptic). This mandate was implemented into two phases. Phase 1,
which is for new types (i.e., an all-new vehicle configuration) was
mandated in November 2013, and new vehicles in November 2015. Phase
2 which covers more stringent implementations, was put in place for
the new types in November 2016 and all new heavy vehicles in
November 2018. The requirements apply to buses and trucks over 3,500
kg (7,716 lbs.). EU regulations include an electronic stability
control (ESC) requirement for all heavy-duty vehicle segments.
The United Nations Economic Commission for Europe (UNECE) is the
main entity that regulates vehicle safety in the European Union.
UNECE has developed regulations for the implementation of AEBS
(using a type approval process) in motor vehicles, as described
below (UNECE Regulation 131). Regarding AEBS test procedures, the
lead-vehicle-moving scenario in UNECE regulations has a subject
vehicle speed of 80 km/h (50 mph). For the lead-vehicle-stopped
scenario, the subject vehicle speed is also 80 km/h (50 mph).
In addition, it also has false positive test requirements for
vehicle speeds of 50 km/h (31 mph). However, these false positive
test requirements are different from the ones in NHTSA's proposal,
because NHTSA uses a steel trench plate and pass-through vehicles,
as opposed to UNECE, which only uses pass-through vehicles.
There are similarities between the performance requirements of
the UNECE regulation and proposed FMVSS No. 128 as the speeds of the
subject vehicle in the scenarios of stopped lead vehicle as well as
slow moving lead vehicle are the same. However, the UNECE regulation
does not have performance requirements for decelerating lead vehicle
scenarios, which NHTSA does have. Because NHTSA has tentatively
determined it is important to have a decelerating lead vehicle test
scenario, NHTSA decided not to completely base its requirements on
the UNECE regulation parameters.
We note that UNECE 131 is considering the implementation of
Automatic Emergency Braking-Pedestrian (PAEB) into its existing
regulation. NHTSA is not proposing PAEB for heavy vehicles in this
NPRM. NHTSA believes there are unknowns at this time about the
performance of PAEB on heavy vehicles in the U.S., as well as cost
and other technical and practicability considerations to support a
proposed implementation of PAEB for heavy vehicles. Rather than
delay this NPRM to obtain this information, we have decided to
proceed with the rulemaking as set forth in this NPRM.
Japan
In January 2017, the Japanese government, under the Ministry of
Land, Infrastructure, Transport and Tourism (MLIT) presented a
proposal for UN Regulation on AEBS for M1/N1 vehicles.\223\ As part
of the harmonization efforts under consideration by the UNECE
working group (WP.29), MLIT proposed a new United Nations regulation
on AEBS in September 2008, initially including M2, N2, M3 and N3
vehicles, and having as a future target M1 and N1 vehicles. NHTSA's
consideration of UNECE Regulation 131 is discussed above.
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\223\ https://unece.org/DAM/trans/doc/2017/wp29grrf/GRRF-83-17e.pdf.
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South Korea
The Republic of Korea (ROK), under the Ministry of Land,
Infrastructure and Transport (MOLIT), in January 2019 required all
passenger vehicles to have AEBS and lane departure warning systems.
Those requirements were applied to trucks and other vehicles in July
2021. Article 90-3 (Advanced Emergency Braking System (AEBS)) from
the Korean standard applies to buses and trucks/special purpose
vehicle with a gross vehicle weight more than 3.5 tons (over 3,500
kg) (7,716 lbs.).\224\ The majority of the performance requirements
from the Korean standard is derived from UNECE Regulation 131.
NHTSA's consideration of ECE Regulation 131 is discussed above.
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\224\ Regulations for Performance sand Safety Standards of Motor
Vehicle and Vehicle Parts: Article 90-3 and Table 7-8.
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SAE International (SAE)
SAE J3029: Forward Collision Warning and Mitigation Vehicle Test
Procedure--Truck and Bus.
This SAE Recommended Practice (RP) establishes uniform powered
vehicle level test procedures for Forward Collision Avoidance and
Mitigation (FCAM) systems (also identified as AEB systems) used in
highway commercial vehicles and coaches greater than 4,535 kg
(10,000 lbs.) GVWR. This document outlines a basic test procedure to
be performed under specified operating and environmental conditions.
It does not define tests for all possible operating and
environmental conditions. Minimum performance requirements are not
addressed in this document.
When comparing the SAE test procedure with proposed FMVSS No.
128, the SAE procedure specifies lower test conditions than NHTSA's
proposal. The SAE subject vehicle speed for the stopped lead vehicle
scenario is 40.2 km/h (25 mph), compared to 80 km/h (50 mph) in this
NPRM. For the case of false activation test parameters, SAE uses
50.7 km/h (32 mph), compared to 80 km/h (50 mph) used in the NHTSA
proposed performance requirements. NHTSA is not proposing to use the
performance requirements from the SAE tests because the agency
believes they are not stringent enough to provide the level of
safety benefit the agency seeks for this NPRM.
International Organization for Standardization (ISO)
ISO 19377: Heavy commercial vehicles and buses--Emergency
braking on a defined path--Test method for trajectory measurement.
This standard describes test methods for determining the
deviation of the path travelled by a vehicle during a braking
maneuver induced by an emergency braking system from a pre-defined
desired path. The standard evaluates the vehicle path during and
following the system intervention. The corrective steering actions
for keeping the vehicle on the desired path can be applied either by
the driver or by a steering machine or by a driver assistance
system.
This document applies to heavy vehicles equipped with an
advanced emergency
[[Page 43238]]
braking system, including commercial vehicles, commercial vehicle
combinations, buses and articulated buses as defined in ISO 3833
\225\ (trucks and trailers with maximum weight above 3,5 tonnes
(3,500 kg or 7,716 lbs.) and buses and articulated buses with
maximum weight above 5 tonnes (5,000 kg or 11,023 lbs.), according
to ECE and European Commission on vehicle classification, categories
M3, N2, N3, O3 and O4).
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\225\ ISO 3833, ``Road vehicles--Types--Terms and Definitions,''
ISO 3833 defines terms relating to some types of road vehicles
designated according to certain design and technical
characteristics. ISO 3833--European Standards (en-standard.eu).
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NHTSA considered the ISO test procedure but decided it is
limited because the ISO standard tests braking on a defined path on
a straight line as well as braking in a constant radius curve, which
NHTSA does not. Therefore, NHTSA is not proposing performance
requirements based on the ISO standard.
Proposed Regulatory Text
List of Subjects
49 CFR Part 393
Highways and roads, Motor carriers, Motor vehicle equipment, Motor
vehicle safety.
49 CFR Part 396
Highway safety, Motor carriers, Motor vehicle safety, Reporting and
recordkeeping requirements.
49 CFR Part 571
Imports, Incorporation by reference, Motor vehicle safety,
Reporting and recordkeeping requirements, Tires.
49 CFR Part 596
Motor vehicle safety, Automatic emergency braking, Incorporation by
reference, Motor vehicle safety, Test devices.
In consideration of the foregoing, FMCSA proposes to amend 49 CFR
parts 393 and 396, and NHTSA proposes to amend part 571 and add part
596 as follows:
PART 393--PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION
0
1. The authority citation for 49 CFR part 393 is amended to read as
follows:
Authority: 49 U.S.C. 31136, 31151, and 31502; sec. 1041(b) of
Pub. L. 102-240, 105 Stat. 1914, 1993 (1991); sec. 5301 and 5524 of
Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; sec. 23010, Pub. L. 117-
58, 135 Stat. 429, 766-767, and 49 CFR 1.87.
0
2. Amend Sec. 393.5 by adding, in alphabetical order, the definition
for ``Automatic emergency braking (AEB) system'' and ``Electronic
stability control system or ESC system'' to read as follows:
Sec. 393.5 Definitions.
* * * * *
Automatic emergency braking (AEB) system is a system that detects
an imminent collision with vehicles, objects, and road users in or near
the path of a vehicle and automatically controls the vehicle's service
brakes to avoid or mitigate the collision.
Electronic stability control system or ESC system means a system
that has all of the following attributes:
(1) It augments vehicle directional stability by having the means
to apply and adjust the vehicle brake torques individually at each
wheel position on at least one front and at least one rear axle of the
vehicle to induce correcting yaw moment to limit vehicle oversteer and
to limit vehicle understeer;
(2) It enhances rollover stability by having the means to apply and
adjust the vehicle brake torques individually at each wheel position on
at least one front and at least one rear axle of the vehicle to reduce
lateral acceleration of a vehicle;
(3) It is computer-controlled with the computer using a closed-loop
algorithm to induce correcting yaw moment and enhance rollover
stability;
(4) It has a means to determine the vehicle's lateral acceleration;
(5) It has a means to determine the vehicle's yaw rate and to
estimate its side slip or side slip derivative with respect to time;
(6) It has a means to estimate vehicle mass or, if applicable,
combination vehicle mass;
(7) It has a means to monitor driver steering inputs;
(8) It has a means to modify engine torque, as necessary, to assist
the driver in maintaining control of the vehicle and/or combination
vehicle; and
(9) When installed on a truck tractor, it has the means to provide
brake pressure to automatically apply and modulate the brake torques of
a towed trailer.
* * * * *
0
3. Add Sec. 393.56 to read as follows:
Sec. 393.56 Electronic Stability Control Systems.
(a) Truck tractors manufactured between August 1, 2019 and [the
first September 1 that is 5 years after the date of publication of a
final rule]. Each truck tractor (except as provided by 49 CFR 571.136,
paragraph S3.1 or truck tractors engaged in driveaway-towaway
operations) with a gross vehicle weight rating of greater than 11,793
kilograms (26,000 pounds) manufactured on or after August 1, 2019, but
before [the first September 1 that is 5 years after the date of
publication of a final rule], must be equipped with an electronic
stability control (ESC) system that meets the requirements of Federal
Motor Vehicle Safety Standard No. 136 (49 CFR 571.136).
(b) Buses manufactured between August 1, 2019 and [the first
September 1 that is 5 years after the date of publication of a final
rule]. Each bus (except as provided by 49 CFR 571.136, paragraph S3.1
or buses engaged in driveaway-towaway operations) with a gross vehicle
weight rating of greater than 11,793 kilograms (26,000 pounds)
manufactured on or after August 1, 2019, but before [the first
September 1 that is 5 years after the date of publication of a final
rule], must be equipped with an ESC system that meets the requirements
of FMVSS No. 136.
(c) Commercial motor vehicles manufactured on and after [the first
September 1 that is 5 years after the date of publication of a final
rule]. Trucks and buses, with a GVWR greater than 4,536 kilograms
(10,000 pounds) and truck tractors manufactured on or after [the first
September 1 that is 5 years after the date of publication of a final
rule] (except trucks, buses, and truck tractors engaged in driveaway-
towaway operations), must be equipped with an electronic stability
control (ESC) system that meets the requirements of Federal Motor
Vehicle Safety Standard No. 136 (49 CFR 571.136).
(d) ESC Malfunction Detection. Each truck, truck tractor and bus
must be equipped with an indicator lamp, mounted in front of and in
clear view of the driver, which is activated whenever there is a
malfunction that affects the generation or transmission of control or
response signals in the vehicle's electronic stability control system.
0
4. Add Sec. 393.57 to read as follows:
Sec. 393.57 Automatic Emergency Braking Systems.
(a) Truck tractors manufactured on or after [the first September 1
that is 3 years after the date of publication of a final rule]. Each
truck tractor (except as provided by 49 CFR 571.136, paragraph S3.1 or
truck tractors engaged in driveaway-towaway operations) with a gross
vehicle weight rating of greater than 11,793 kilograms (26,000 pounds)
manufactured on or after the first September 1 that is 3 years after
the date of publication of a final rule], must be equipped with an
automatic emergency brake (AEB) system that meets the requirements of
Federal Motor Vehicle Safety Standard No. 128 (49 CFR 571.128).
[[Page 43239]]
(b) Buses manufactured on or after [the first September 1 that is 3
years after the date of publication of a final rule]. Each bus (except
as provided by 49 CFR 571.136, paragraph S3.1 or buses engaged in
driveaway-towaway operations) with a gross vehicle weight rating of
greater than 11,793 kilograms (26,000 pounds) manufactured on or after
the first September 1 that is 3 years after the date of publication of
a final rule], must be equipped with an AEB system that meets the
requirements of FMVSS No. 128.
(c) Commercial motor vehicles manufactured on and after [the first
September 1 that is 5 years after the date of publication of a final
rule]. Trucks and buses, with a GVWR greater than 4,536 kilograms
(10,000 pounds) and truck tractors manufactured on or after [the first
September 1 that is 5 years after the date of publication of a final
rule] (except trucks, buses, and truck tractors engaged in driveaway-
towaway), must be equipped with an AEB system that meets the
requirements of Federal Motor Vehicle Safety Standard No. 128 (49 CFR
571.128).
(d) AEB Malfunction Detection. Each commercial motor vehicle
subject to FMVSS No. 128 must be equipped with a telltale that meets
the requirements of S5.3 of FMVSS No. 128 (49 CFR 571.128), mounted in
front of and in clear view of the driver, which is activated whenever
there is a malfunction that affects the generation or transmission of
control or response signals in the vehicle's AEB system.
PART 396--INSPECTION, REPAIR, AND MAINTENANCE
0
5. The authority citation for 49 CFR part 396 is amended to read as
follows:
Authority: 49 U.S.C. 504, 31133, 31136, 31151, 31502; sec.
32934, Pub. L. 112-141, 126 Stat. 405, 830; sec. 5524, Pub. L. 114-
94, 129 Stat. 1312, 1560; sec. 23010, Pub. L. 117-58, 135 Stat. 429,
766-767 and 49 CFR 1.87.
0
6. Amend Appendix A to Part 396 by adding paragraphs 1.n. and o to read
as follows:
Appendix A to Part 396--Minimum Periodic Inspection Standards
* * * * *
1. Brake System
n. Electronic Stability Control (ESC) System.
(1) Missing ESC malfunction detection components.
(2) The ESC malfunction telltale must be identified by the
symbol shown for ``Electronic Stability Control System Malfunction''
or the specified words or abbreviations listed in Table 1 of
Standard No. 101 (Sec. 571.101).
(3) The ESC malfunction telltale must be activated as a check-
of-lamp function either when the ignition locking system is turned
to the ``On'' (``Run'') position when the engine is not running, or
when the ignition locking system is in a position between the ``On''
(``Run'') and ``Start'' that is designated by the manufacturer as a
check-light position.
(4) Other missing or inoperative ESC system components.
o. Automatic Emergency Braking (AEB).
(1) Missing AEB malfunction telltale components (e.g., bulb/LED,
wiring, etc.).
(2) AEB malfunction telltale that does not illuminate while
power is continuously applied during initial powerup.
(3) AEB malfunction telltale that stays illuminated while power
is continuously applied during normal vehicle operation.
(4) Other missing or inoperative AEB components.
* * * * *
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS
0
7. The authority citation for part 571 continues to read as follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.
0
7. Amend Sec. 571.5 by:
0
a. Revising paragraph (d)(34);
0
b. Redesignating paragraphs (l)(49) and (50) as paragraphs (l)(50) and
(51), respectively; and
0
c. Adding new paragraph (l)(49).
The revision and addition read as follows:
Sec. 571.5 Matter incorporated by reference
* * * * *
(d) * * *
(34) ASTM E1337-19, ``Standard Test Method for Determining
Longitudinal Peak Braking Coefficient (PBC) of Paved Surfaces Using
Standard Reference Test Tire,'' approved December 1, 2019, into
Sec. Sec. 571.105; 571.121; 571.122; 571.126; 571.128; 571.135;
571.136; 571.500.
* * * * *
(l) * * *
(49) SAE J2400, ``Human Factors in Forward Collision Warning
System: Operating Characteristics and User Interface Requirements,''
August 2003 into Sec. 571.128.
* * * * *
0
9. Add Sec. 571.128 to read as follows:
Sec. 571.128 Standard No. 128; Automatic emergency braking systems
for heavy vehicles.
S1. Scope. This standard establishes performance requirements for
automatic emergency braking (AEB) systems for heavy vehicles.
S2. Purpose. The purpose of this standard is to reduce the number
of deaths and injuries that result from crashes in which drivers do not
apply the brakes or fail to apply sufficient braking power to avoid or
mitigate a crash.
S3. Application. This standard applies to multipurpose passenger
vehicles, trucks, and buses with a gross vehicle weight rating greater
than 4,536 kilograms (10,000 pounds) that are subject to Sec. Sec.
571.105 or 571.121 of this part.
S4. Definitions.
Adaptive cruise control system is an automatic speed control system
that allows the equipped vehicle to follow a lead vehicle at a pre-
selected gap by controlling the engine, power train, and service
brakes.
Ambient illumination is the illumination as measured at the test
surface, not including any illumination provided by the subject
vehicle.
Automatic emergency braking (AEB) system is a system that detects
an imminent collision with vehicles, objects, and road users in or near
the path of a vehicle and automatically controls the vehicle's service
brakes to avoid or mitigate the collision.
Brake pedal application onset is when the brake controller begins
to displace the brake pedal.
Forward collision warning is an auditory and visual warning
provided to the vehicle operator by the AEB system that is designed to
induce an immediate forward crash avoidance response by the vehicle
operator.
Forward collision warning onset is the first moment in time when a
forward collision warning is provided.
Headway is the distance between the lead vehicle's rearmost plane
normal to its centerline and the subject vehicle's frontmost plane
normal to its centerline.
Lead vehicle is a vehicle test device facing the same direction and
preceding a subject vehicle within the same travel lane.
Lead vehicle braking onset is the point at which the lead vehicle
achieves a deceleration of 0.05g due to brake application.
Over-the-road bus means a bus characterized by an elevated
passenger deck located over a baggage compartment, except a school bus.
Perimeter-seating bus means a bus with 7 or fewer designated
seating positions rearward of the driver's seating position that are
forward-facing or can convert to forward-facing without the use of
tools and is not an over-the-road bus.
Small-volume manufacturer means an original vehicle manufacturer
that produces or assembles fewer than 5,000 vehicles annually for sales
in the United States.
[[Page 43240]]
Steel trench plate is a rectangular steel plate often used in road
construction to temporarily cover sections of pavement unsafe to drive
over directly.
Subject vehicle is the vehicle under examination for compliance
with this standard.
Transit bus means a bus that is equipped with a stop-request system
sold for public transportation provided by, or on behalf of, a State or
local government and that is not an over-the-road bus.
Travel path is the path projected onto the road surface of a point
located at the intersection of the subject vehicle's frontmost vertical
plane and longitudinal vertical center plane, as the subject vehicle
travels forward.
Vehicle test device is a device meeting the specifications set
forth in subpart C of 49 CFR part 596.
S5. Requirements.
(a) Truck tractors and buses with a GVWR greater than 11,793
kilograms (26,000 pounds), other than school buses, perimeter-seating
buses, and transit buses and which are manufactured on or after [the
first September 1 that is three years after the date of publication of
a final rule] must meet the requirements of this standard.
(b) Vehicles with a GVWR greater than 4,536 kilograms (10,000
pounds) which are manufactured on or after [the first September 1 that
is four years after the date of publication of a final rule] must meet
the requirements of this standard.
(c) The requirements of paragraphs (a) and (b) of this section S5
do not apply to small-volume manufacturers, final-stage manufacturers
and alterers until one year after the dates specified in those
paragraphs.
S5.1. Requirements when approaching a lead vehicle.
S5.1.1. Forward Collision Warning. A vehicle is required to have a
forward collision warning system, as defined in S4 of this section,
that provides an auditory and visual signal to the driver of an
impending collision with a lead vehicle when traveling at any forward
speed greater than 10 km/h (6.2 mph). The auditory signal must have a
high fundamental frequency of at least 800 Hz, a duty cycle of 0.25--
0.95, and tempo in the range of 6-12 pulses per second. The visual
signal must be located according to SAE J2400 (incorporated by
reference, see Sec. 571.5), paragraph 4.1.14, and must include the
symbol in the bottom right of paragraph 4.1.16. Line of sight is based
on the forward-looking eye midpoint (Mf) as described in
S14.1.5 of Sec. 571.111. The symbol must be red in color and steady-
burning.
S5.1.2. Automatic Emergency Braking. A vehicle is required to have
an automatic emergency braking system, as defined in S4 of this
section, that applies the service brakes automatically when a collision
with a lead vehicle is imminent. The system must operate when the
vehicle is traveling at any forward speed greater than 10 km/h (6.2
mph).
S5.1.3. Performance Test Requirements. The vehicle must provide a
forward collision warning and subsequently apply the service brakes
automatically when a collision with a lead vehicle is imminent such
that the subject vehicle does not collide with the lead vehicle when
tested using the procedures in S7. The forward collision warning is not
required if adaptive cruise control is engaged.
S5.2. False Activation. The vehicle must not automatically apply
braking that results in peak deceleration of 0.25g or greater when
manual braking is not applied, nor a peak deceleration of 0.45g or
greater when manual braking is applied, when tested using the
procedures in S8.
S5.3. Malfunction Detection. The system must continuously detect
system malfunctions, including malfunctions caused solely by sensor
obstructions. If the system detects a malfunction that prevents the
system from meeting the requirements specified in S5.1 or S5.2, the
system must provide the vehicle operator with a telltale that the
malfunction exists.
S6. Test Conditions.
S6.1. Environmental conditions.
S6.1.1. Temperature. The ambient temperature is any temperature
between 2 [deg]C and 40 [deg]C.
S6.1.2. Wind. The maximum wind speed is no greater than 5 m/s (11
mph) during tests approaching a lead vehicle.
S6.1.3. Ambient Lighting.
(a) The ambient illumination on the test surface is any level at or
above 2,000 lux.
(b) Testing is not performed while driving toward or away from the
sun such that the horizontal angle between the sun and a vertical plane
containing the centerline of the subject vehicle is less than 25
degrees and the solar elevation angle is less than 15 degrees.
S6.1.4. Precipitation. Testing is not conducted during periods of
precipitation or when visibility is affected by fog, smoke, ash, or
other particulate.
S6.2. Road conditions.
S6.2.1. Test Track Surface and Construction. The tests are
conducted on a dry, uniform, solid-paved surface. Surfaces with debris,
irregularities, or undulations, such as loose pavement, large cracks,
or dips are not used.
S6.2.2. Surface Friction. The road test surface produces a peak
friction coefficient (PFC) of 1.02 when measured using an ASTM
International (ASTM) F2493 standard reference test tire, in accordance
with ASTM E1337-19 (incorporated by reference, see Sec. 571.5), at a
speed of 64 km/h (40 mph), without water delivery.
S6.2.3. Slope. The test surface has any consistent slope between 0
percent and 1 percent.
S6.2.4. Markings. The road surface within 2.3 m of the intended
travel path is marked with zero, one, or two lines of any configuration
or color. If one line is used, it is straight. If two lines are used,
they are straight, parallel to each other, and at any distance from 2.7
m to 4.5 m apart.
S6.2.5. Obstructions. Testing is conducted such that the vehicle
does not travel beneath any overhead structures, including but not
limited to overhead signs, bridges, or gantries. No vehicles,
obstructions, or stationary objects are within 7.4 m of either side of
the intended travel path except as specified.
S6.3. Subject vehicle conditions.
S6.3.1. Malfunction notification. Testing is not conducted while
the AEB malfunction telltale specified in S5.3 is illuminated.
S6.3.2. Sensor obstruction. All sensors used by the system and any
part of the vehicle immediately ahead of the sensors, such as plastic
trim, the windshield, etc., are free of debris or obstructions.
S6.3.3. Tires. The vehicle is equipped with the original tires
present at the time of initial sale. The tires are inflated to the
vehicle manufacturer's recommended cold tire inflation pressure(s)
specified on the vehicle's placard or the tire inflation pressure
label.
S6.3.4. Brake burnish.
(a) Vehicles subject to Sec. 571.105 are burnished in accordance
with S7.4 of that section.
(b) Vehicles subject to Sec. 571.121 are burnished in accordance
with S6.1.8 of that section.
S6.3.5. Brake temperature. The average temperature of the service
brakes on the hottest axle of the vehicle during testing, measured
according to S6.1.16 of Sec. 571.121, is between 66[deg]C and
204[deg]C prior to braking.
S6.3.6. Fluids. All non-consumable fluids for the vehicle are at
100 percent capacity. All consumable fluids are at any level from 5 to
100 percent capacity.
[[Page 43241]]
S6.3.7. Propulsion battery charge. The propulsion batteries are
charged at any level from 5 to 100 percent capacity.
S6.3.8. Cruise control. Cruise control, including adaptive cruise
control, is configured under any available setting.
S6.3.9. Adjustable forward collision warning. Forward collision
warning is configured in any operator-configurable setting.
S6.3.10. Engine braking. A vehicle equipped with an engine braking
system that is engaged and disengaged by the operator is tested with
the system in any selectable configuration.
S6.3.11. Regenerative braking. Regenerative braking is configured
under any available setting.
S6.3.12. Liftable Axles. A vehicle with one or more liftable axles
is tested with the liftable axles down.
S6.3.13. Headlamps. Testing is conducted with the headlamp control
in any selectable position.
S6.3.14. Subject vehicle loading.
(a) Except as provided in S6.3.14(b), the vehicle is loaded to its
GVWR so that the load on each axle, measured at the tire-ground
interface, is most nearly proportional to the axles' respective GAWRs,
without exceeding the GAWR of any axle.
(b) Truck tractors.
(1) A truck tractor is loaded to its GVWR with the operator and
test instrumentation, and by coupling it to a control trailer as
provided in S6.3.14(b)(2) of this section and placing ballast (weight)
on the control trailer which loads the tractor's non-steer axles. The
control trailer is loaded with ballast without exceeding the GAWR of
the trailer axle. The location of the center of gravity of the ballast
on the control trailer is directly above the kingpin. The height of the
center of gravity of the ballast on the control trailer is less than
610 mm (24 inches) above the top of the tractor's fifth-wheel hitch
(the area where the truck tractor attaches to the trailer). If the
tractor's fifth-wheel hitch position is adjustable, the fifth-wheel
hitch is adjusted to proportionally distribute the load on each of the
tractor's axle(s), according to each axle's GAWR, without exceeding the
GAWR of any axle(s). If the fifth-wheel hitch position cannot be
adjusted to prevent the load from exceeding the GAWR of the tractor's
axle(s), the ballast is reduced until the axle load is equal to or less
than the GAWR of the tractor's rear axle(s), maintaining load
proportioning as close as possible to specified proportioning.
(2) The control trailer is an unbraked, flatbed semi-trailer that
has a single axle with a GAWR of 8,165 kilograms (18,000 pounds). The
control trailer has a length of at least 6,400 mm (252 inches), but no
more than 7,010 mm (276 inches), when measured from the transverse
centerline of the axle to the centerline of the kingpin (the point
where the trailer attaches to the truck tractor). At the manufacturer's
option, truck tractors with four or more axles may use a control
trailer with a length of more than 7,010 mm (276 inches), but no more
than 13,208 mm (520 inches) when measured from the transverse
centerline of the axle to the centerline of the kingpin.
S6.3.15. AEB system initialization. The vehicle is driven at a
speed of 10 km/h or higher for at least one minute prior to testing,
and subsequently the starting system is not cycled off prior to
testing.
S6.4. Equipment and test Devices.
S6.4.1. The vehicle test device is specified in 49 CFR part 596
subpart C. Local fluttering of the lead vehicle's external surfaces
does not exceed 10 mm perpendicularly from the reference surface, and
distortion of the lead vehicle's overall shape does not exceed 25 mm in
any direction.
S6.4.2. The steel trench plate used for the false activation test
has the dimensions 2.4 m x 3.7 m x 25 mm and is made of ASTM A36 steel.
Any metallic fasteners used to secure the steel trench plate are flush
with the top surface of the steel trench plate.
S7. Testing when approaching a lead vehicle.
S7.1. Setup.
(a) The testing area is set up in accordance with Figure 1 to this
section.
(b) Testing is conducted during daylight.
(c) For reference, Table 1 to S7.1 specifies the subject vehicle
speed (VSV), lead vehicle speed (VLV), headway,
and lead vehicle deceleration for each test that may be conducted.
(d) The intended travel path of the vehicle is a straight line
toward the lead vehicle from the location corresponding to a headway of
L0.
(e) If the road surface is marked with a single or double lane
line, the intended travel path is parallel to and 1.8 m from the inside
of the closest line. If the road surface is marked with two lane lines
bordering the lane, the intended travel path is centered between the
two lines.
(f) For each test run conducted, the subject vehicle speed
(VSV), lead vehicle speed (VLV), headway, and
lead vehicle deceleration will be selected from the ranges specified.
Table 1 to S7.1--Test Parameters When Approaching a Lead Vehicle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Speed (km/h)
Test scenarios ----------------------------------------- Headway (m) Lead vehicle decel (g) Manual brake
VSV VLV application
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stopped Lead Vehicle................ Any 10-80.............. 0 ....................... ....................... no.
Any 70-100............. 0 ....................... ....................... yes.
Slower-Moving Lead Vehicle.......... Any 40-80.............. 20 ....................... ....................... no.
Any 70-100............. 20 ....................... ....................... yes.
Decelerating Lead Vehicle........... 50..................... 50 Any 21-40.............. Any 0.3-0.4............ no.
50..................... 50 Any 21-40.............. Any 0.3-0.4............ yes.
80..................... 80 Any 28-40.............. Any 0.3-0.4............ no.
80..................... 80 Any 28-40.............. Any 0.3-0.4............ yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------
S7.2. Headway calculation. For each test run conducted under S7.3
and S7.4, the headway (L0), in meters, providing 5 seconds time to
collision (TTC) is calculated. L0 is determined with the following
equation where VSV is the speed of the subject vehicle in m/s and VLV
is the speed of the lead vehicle in m/s:
L0 = TTC0 x (VSV-VLV)
TTC0 = 5
S7.3. Stopped lead vehicle.
S7.3.1. Test parameters.
(a) For testing with no subject vehicle manual brake application,
the subject vehicle test speed is any speed between 10 km/h and 80 km/
h, and the lead vehicle speed is 0 km/h.
(b) For testing with manual brake application of the subject
vehicle, the
[[Page 43242]]
subject vehicle test speed is any speed between 70 km/h and 100 km/h,
and the lead vehicle speed is 0 km/h.
S7.3.2. Test conduct prior to forward collision warning onset.
(a) The lead vehicle is placed stationary with its longitudinal
centerline coincident to the intended travel path.
(b) Before the headway corresponds to L0, the subject
vehicle is driven at any speed, in any direction, on any road surface,
for any amount of time.
(c) The subject vehicle approaches the rear of the lead vehicle.
(d) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h of the test speed
with minimal and smooth accelerator pedal inputs.
(e) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path and the subject vehicle's yaw rate does not
exceed 1.0 deg/s.
S7.3.3. Test conduct after forward collision warning onset.
(a) The accelerator pedal is released at any rate such that it is
fully released within 500 ms. This action is omitted for vehicles
tested with cruise control active.
(b) For testing conducted with manual brake application, the
service brakes are applied as specified in S9. The onset of brake pedal
application occurs 1.0 0.1 second after forward collision
warning onset.
(c) For testing conducted without manual brake application, no
manual brake application is made until the test completion criteria of
S7.3.4 are satisfied.
S7.3.4. Test completion criteria. The test run is complete when the
subject vehicle comes to a complete stop without making contact with
the lead vehicle or when the subject vehicle makes contact with the
lead vehicle.
S7.4. Slower-moving lead vehicle.
S7.4.1. Test parameters.
(a) For testing with no subject vehicle manual brake application,
the subject vehicle test speed is any speed between 40 km/h and 80 km/
h, and the lead vehicle speed is 20 km/h.
(b) For testing with manual brake application of the subject
vehicle, the subject vehicle test speed is any speed between 70 km/h
and 100 km/h, and the lead vehicle speed is 20 km/h.
S7.4.2. Test conduct prior to forward collision warning onset.
(a) The lead vehicle is propelled forward in a manner such that the
longitudinal center plane of the lead vehicle does not deviate
laterally more than 0.3m from the intended travel path.
(b) The subject vehicle approaches the lead vehicle.
(c) Beginning when the headway corresponds to L0, the
subject vehicle and lead vehicle speed is maintained within 1.6 km/h of
the test speed with minimal and smooth accelerator pedal inputs.
(d) Beginning when the headway corresponds to L0, the
subject vehicle and lead vehicle headings are maintained with minimal
steering input such that the subject vehicle's travel path does not
deviate more than 0.3 m laterally from the centerline of the lead
vehicle, and the yaw rate of the subject vehicle does not exceed 1.0 deg/s prior to forward collision warning onset.
S7.4.3. Test conduct after forward collision warning onset.
(a) The subject vehicle's accelerator pedal is released at any rate
such that it is fully released within 500 ms. This action is omitted
for vehicles tested with cruise control active.
(b) For testing conducted with manual braking application, the
service brakes are applied as specified in S9. The onset of brake pedal
application is 1.0 0.1 second after the forward collision
warning onset.
(c) For testing conducted without manual braking application, no
manual brake application is made until the test completion criteria of
S7.4.4 are satisfied.
S7.4.4. Test completion criteria. The test run is complete when the
subject vehicle speed is less than or equal to the lead vehicle speed
without making contact with the lead vehicle or when the subject
vehicle makes contact with the lead vehicle.
S7.5. Decelerating lead vehicle.
S7.5.1. Test parameters.
(a) The subject vehicle test speed is 50 km/h or 80 km/h, and the
lead vehicle speed is identical to the subject vehicle test speed.
(b) [Reserved]
S7.5.2. Test conduct prior to lead vehicle braking onset.
(a) Before the 1 second prior to lead vehicle braking onset, the
subject vehicle is driven at any speed, in any direction, on any road
surface, for any amount of time.
(b) Between 1 second prior to lead vehicle braking onset and lead
vehicle braking onset:
(1) The lead vehicle is propelled forward in a manner such that the
longitudinal center plane of the vehicle does not deviate laterally
more than 0.3 m from the intended travel path.
(2) The subject vehicle follows the lead vehicle at a headway of
any distance between 21 m and 40 m if the subject vehicle test speed is
50 km/h, or any distance between 28 m and 40 m if the subject vehicle
test speed is 80 km/h.
(3) The subject vehicle's speed is maintained within 1.6 km/h of
the test speed with minimal and smooth accelerator pedal inputs prior
to forward collision warning onset.
(4) The lead vehicle's speed is maintained within 1.6 km/h.
(5) The subject vehicle and lead vehicle headings are maintained
with minimal steering input such that their travel paths do not deviate
more than 0.3 m laterally from the centerline of the lead vehicle, and
the yaw rate of the subject vehicle does not exceed 1.0
deg/s until forward collision warning onset.
S7.5.3. Test conduct following lead vehicle braking onset.
(a) The lead vehicle is decelerated to a stop with a targeted
average deceleration of any value between 0.3g and 0.4g. The targeted
deceleration magnitude is achieved within 1.5 seconds of lead vehicle
braking onset and is maintained until 250 ms prior to coming to a stop.
(b) After forward collision warning onset, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms. This action is omitted for vehicles with cruise
control active.
(c) For testing conducted with manual braking application, the
service brakes are applied as specified in S9. The brake pedal
application onset occurs 1.0 0.1 second after the forward
collision warning onset.
(d) For testing conducted without manual braking application, no
manual brake application is made until the test completion criteria of
S7.5.4 are satisfied.
S7.5.4. Test completion criteria. The test run is complete when the
subject vehicle comes to a complete stop without making contact with
the lead vehicle or when the subject vehicle makes contact with the
lead vehicle.
S8. False AEB activation.
S8.1. Headway calculation. For each test run to be conducted under
S8.2 and S8.3, the headway (L0, L2.1, L1.1), in meters, between the
front plane of the subject vehicle and either the steel trench plate's
leading edge or the rearmost plane normal to the centerline of the
vehicle test devices providing 5.0 seconds, 2.1 seconds, and 1.1
seconds time to collision (TTC) is calculated. L0, L2.1, and L1.1 are
determined with the following equation where VSV is the speed of the
subject vehicle in m/s:
Lx = TTCx x (VSV)
[[Page 43243]]
TTC0 = 5.0
TTC2.1 = 2.1
TTC1.1 = 1.1
S8.2. Steel trench plate.
S8.2.1. Test parameters and setup.
(a) The testing area is set up in accordance with Figure 2 to this
section.
(b) The steel trench plate is secured flat on the test surface so
that its longest side is parallel to the subject vehicle's intended
travel path and horizontally centered on the subject vehicle's intended
travel path.
(c) The subject vehicle test speed is 80 km/h.
S8.2.2. Test conduct.
(a) The subject vehicle approaches the steel trench plate.
(b) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h of the test speed
with minimal and smooth accelerator pedal inputs.
(c) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path, and the yaw rate of the subject vehicle does
not exceed 1.0 deg/s.
(d) If forward collision warning occurs, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms. This action is omitted for vehicles with cruise
control active.
(e) For tests where no manual brake application occurs, manual
braking is not applied until the test completion criteria of S8.2.3 are
satisfied.
(f) For tests where manual brake application occurs, the subject
vehicle's accelerator pedal, if not already released, is released when
the headway corresponds to L2.1 at any rate such that it is
fully released within 500 ms.
(g) For tests where manual brake application occurs, the service
brakes are applied as specified in S9. The brake application pedal
onset occurs at headway L1.1.
S8.2.3. Test completion criteria. The test run is complete when the
subject vehicle comes to a stop prior to crossing over the leading edge
of the steel trench plate or when the subject vehicle crosses over the
leading edge of the steel trench plate.
S8.3. Pass-through.
S8.3.1. Test parameters and setup.
(a) The testing area is set up in accordance with Figure 3 to this
section.
(b) Two vehicle test devices are secured in a stationary position
parallel to one another with a lateral distance of 4.5 m 0.1 m between the vehicles' closest front wheels. The centerline
between the two vehicles is parallel to the intended travel path.
(c) The subject vehicle test speed is 80 km/h.
(d) Testing may be conducted with manual subject vehicle pedal
application.
S8.3.2. Test conduct.
(a) The subject vehicle approaches the gap between the two vehicle
test devices.
(b) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h with minimal and
smooth accelerator pedal inputs.
(c) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path, and the yaw rate of the subject vehicle does
not exceed 1.0 deg/s.
(d) If forward collision warning occurs, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms.
(e) For tests where no manual brake application occurs, manual
braking is not applied until the test completion criteria of S8.3.3 are
satisfied.
(f) For tests where manual brake application occurs, the subject
vehicle's accelerator pedal, if not already released, is released when
the headway corresponds to L2.1 at any rate such that it is
fully released within 500 ms.
(g) For tests where manual brake application occurs, the service
brakes are applied as specified in S9. The brake application onset
occurs when the headway corresponds to L1.1.
S8.3.3. Test completion criteria. The test run is complete when the
subject vehicle comes to a stop prior to its rearmost point passing the
vertical plane connecting the forwardmost point of the vehicle test
devices or when the rearmost point of the subject vehicle passes the
vertical plane connecting the forwardmost point of the vehicle test
devices.
S9. Subject Vehicle Brake Application Procedure.
S9.1. The procedure begins with the subject vehicle brake pedal in
its natural resting position with no preload or position offset.
S9.2. At the option of the manufacturer, either displacement
feedback or hybrid feedback control is used.
S9.3. Displacement feedback procedure. For displacement feedback,
the commanded brake pedal position is the brake pedal position that
results in a mean deceleration of 0.3g in the absence of AEB system
activation.
(a) The mean deceleration is the deceleration over the time from
the pedal achieving the commanded position to 250 ms before the vehicle
comes to a stop.
(b) The pedal displacement controller depresses the pedal at a rate
of 254 mm/s 25.4 mm/s to the commanded brake pedal
position.
(c) The pedal displacement controller may overshoot the commanded
position by any amount up to 20 percent. If such an overshoot occurs,
it is corrected within 100 ms.
(d) The achieved brake pedal position is any position within 10
percent of the commanded position from 100 ms after pedal displacement
occurs and any overshoot is corrected.
S9.4. Hybrid brake pedal feedback procedure. For hybrid brake pedal
feedback, the commanded brake pedal application is the brake pedal
position and a subsequent commanded brake pedal force that results in a
mean deceleration of 0.3g in the absence of AEB system activation.
(a) The mean deceleration is the deceleration over the time from
the pedal achieving the commanded position to 250 ms before the vehicle
comes to a stop.
(b) The hybrid controller displaces the pedal at a rate of 254 mm/s
25.4 mm/s to the commanded pedal position.
(c) The hybrid controller may overshoot the commanded position by
any amount up to 20 percent. If such an overshoot occurs, it is
corrected within 100 ms.
(d) The hybrid controller begins to control the force applied to
the pedal and stops controlling pedal displacement 100 ms after pedal
displacement occurs and any overshoot is corrected.
(e) The hybrid controller applies a pedal force of at least 11.1 N.
(f) The applied pedal force is maintained within 10 percent of the
commanded brake pedal force from 350 ms after commended pedal
displacement occurs and any overshoot is corrected until test
completion.
[[Page 43244]]
Figure 1 to Sec. 571.128--Setup for Tests Approaching a Lead Vehicle
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[GRAPHIC] [TIFF OMITTED] TP06JY23.010
Figure 2 to Sec. 571.128--Setup for Steel Trench Plate False
Activation Tests
[GRAPHIC] [TIFF OMITTED] TP06JY23.011
Figure 3 to Sec. 571.128--Setup for Pass-Through False Activation
Tests
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0
9. Amend Sec. 571.136 by revising paragraphs S3, S3.1, S3.2, and
paragraphs (1) and (2) of the definition of ``Electronic stability
control system or ESC system'' in S4, and adding S8.3 to read as
follows:
Sec. 571.136 Standard No. 136; Electronic stability control systems
for heavy vehicles.
* * * * *
S3 Application.
S3.1 This standard applies to passenger cars, multipurpose
passenger vehicles, trucks, and buses, with a GVWR greater than 4,536
kilograms (10,000 pounds) except:
(a) Any vehicle equipped with an axle that has a gross axle weight
rating of 13,154 kilograms (29,000 pounds) or more;
(b) Any truck or bus that has a speed attainable in 3.2 kilometers
(2 miles) of not more than 53 km/h (33 mph); and
(c) Any truck that has a speed attainable in 3.2 kilometers (2
miles) of not more than 72 km/h (45 mph), an unloaded vehicle weight
that is not less than 95 percent of its gross vehicle weight rating,
and no capacity to carry occupants other than the driver and operating
crew.
S3.2 The following vehicles are subject only to the requirements in
S5.1, S5.2, and S5.4 of this standard:
(a) Vehicles with a gross vehicle weight rating of 11,793 kilograms
(26,000 pounds) or less;
(b) Trucks other than truck tractors;
(c) School buses;
(d) Perimeter-seating buses;
(e) Transit buses;
(f) Passenger cars; and
(g) Multipurpose passenger vehicles.
* * * * *
S4 Definitions
* * * * *
Electronic stability control system or ESC system means a system
that has all of the following attributes:
(1) It augments vehicle directional stability by having the means
to apply and adjust the vehicle brake torques individually at each
wheel position on at least one front and at least one rear axle of the
vehicle to induce correcting yaw moment to limit vehicle oversteer and
to limit vehicle understeer;
(2) It enhances rollover stability by having the means to apply and
adjust the vehicle brake torques individually at each wheel position on
at least one front and at least one rear axle of the vehicle to reduce
lateral acceleration of a vehicle;
* * * * *
S8.3 Vehicles with a gross vehicle weight rating of 11,793
kilograms (26,000 pounds) or less, trucks other than truck tractors,
school buses, perimeter-seating buses, transit buses, passenger cars,
and multipurpose passenger vehicles are not required to comply this
standard before [the first September 1 that is four years after the
date of publication of a final rule].
* * * * *
0
11. Add part 596 to read as follows.
PART 596--AUTOMATIC EMERGENCY BRAKING TEST DEVICES
Subpart A--General
Sec.
596.1 Scope.
596.2 Purpose.
596.3 Application
596.4 Definitions.
596.5 Matter incorporated by reference.
Subpart B--[Reserved]
Subpart C--Vehicle Test Device
596.9 General Description
596.10 Specifications for the Vehicle Test Device
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.
Subpart A--General
Sec. 596.1 Scope.
This part describes the test devices that are to be used for
compliance testing of motor vehicles with motor vehicle safety
standards for automatic emergency braking.
Sec. 596.2 Purpose.
The design and performance criteria specified in this part are
intended to describe devices with sufficient precision such that
testing performed with these test devices will produce repetitive and
correlative results under similar test conditions to reflect adequately
the automatic emergency braking performance of a motor vehicle.
Sec. 596.3 Application.
This part does not in itself impose duties or liabilities on any
person. It is a description of tools that are used in compliance tests
to measure the performance of automatic emergency braking systems
required by the safety standards that refer to these tools. This part
is designed to be referenced by, and become part of, the test
procedures specified in motor vehicle safety standards.
Sec. 596.4 Definitions.
All terms defined in section 30102 of the National Traffic and
Motor Vehicle Safety Act (49 U.S.C. chapter 301, et seq.) are used in
their statutory meaning.
Vehicle Test Device means a test device that simulates a passenger
vehicle for the purpose of testing automatic emergency brake system
performance.
Vehicle Test Device Carrier means a movable platform on which a
Lead Vehicle Test Device may be attached during compliance testing.
[[Page 43246]]
Sec. 596.5 Matter incorporated by reference.
(a) Certain material is incorporated by reference into this part
with the approval of the Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, the National Highway Traffic Safety
Administration (NHTSA) must publish notice of change in the Federal
Register and the material must be available to the public. All approved
material is available for inspection at NHTSA at the National Archives
and Records Administration (NARA). Contact NHTSA at: NHTSA Office of
Technical Information Services, 1200 New Jersey Avenue SE, Washington,
DC 20590; (202) 366-2588. For information on the availability of this
material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations.html or email [email protected]. The material may be
obtained from the source(s) in the following paragraph of this section.
(b) International Organization for Standardization (ISO), 1, ch. de
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland; phone: + 41 22
749 01 11; fax: + 41 22 733 34 30; website: www.iso.org/.
(1) [Reserved].
(2) [Reserved].
(3) ISO 19206-3:2021(E), ``Test devices for target vehicles,
vulnerable road users and other objects, for assessment of active
safety functions--Part 3: Requirements for passenger vehicle 3D
targets,'' First edition, 2021-05; into Sec. 596.10.
(4) [Reserved]
Subpart B--[Reserved]
Subpart C--Vehicle Test Device
Sec. 596.9 General Description.
(a) The Vehicle Test Device provides a sensor representation of a
passenger motor vehicle.
(b) The rear view of the Vehicle Test Device contains
representations of the vehicle silhouette, a rear window, a high-
mounted stop lamp, two taillamps, a rear license plate, two rear reflex
reflectors, and two tires.
Sec. 596.10 Specifications for the Vehicle Test Device.
(a) Word Usage--Recommendations. The words ``recommended,''
``should,'' ``can be,'' or ``should be'' appearing in sections of ISO
19206-3:2021(E) (incorporated by reference, see Sec. 596.5),
referenced in this section, are read as setting forth specifications
that are used.
(b) Word Usage--Options. The words ``may be,'' or ``either,'' used
in connection with a set of items appearing in sections of ISO 19206-
3:2021(E) (incorporated by reference, see Sec. 596.5), referenced in
this section, are read as setting forth the totality of items, any one
of which may be selected by NHTSA for testing.
(c) Dimensional specifications. (1) The rear silhouette and the
rear window are symmetrical about a shared vertical centerline.
(2) Representations of the taillamps, rear reflex reflectors, and
tires are symmetrical about the surrogate's centerline.
(3) The license plate representation has a width of 300 15 mm and a height of 150 15 mm and mounted with a
license plate holder angle within the range described in 49 CFR 571.108
S6.6.3.1.
(4) The Vehicle Test Device representations are located within the
minimum and maximum measurement values specified in columns 3 and 4 of
Tables A.4 of ISO 19206-3:2021(E) Annex A (incorporated by reference,
see Sec. 596.5). The tire representations are located within the
minimum and maximum measurement values specified in columns 3 and 4 of
Tables A.3 of ISO 19206-3:2021(E) Annex A (incorporated by reference,
see Sec. 596.5). The terms ``rear light'' means ``taillamp,''
``retroreflector'' means ``reflex reflector,'' and ``high centre
taillight'' means ``high-mounted stop lamp.''
(d) Visual and near infrared specification. (1) The Vehicle Test
Device rear representation colors are within the ranges specified in
Tables B.2 and B.3 of ISO 19206-3:2021(E) Annex B (incorporated by
reference, see Sec. 596.5).
(2) The rear representation infrared properties of the Vehicle Test
Device are within the ranges specified in Table B.1 of ISO 19206-
3:2021(E) Annex B (incorporated by reference, see Sec. 596.5) for
wavelengths of 850 to 950 nm when measured according to the calibration
and measurement setup specified in paragraph B.3 of ISO 19206-3:2021(E)
Annex B (incorporated by reference, see Sec. 596.5).
(3) The Vehicle Test Device rear reflex reflectors, and at least 50
cm\2\ of the taillamp representations are grade DOT-C2 reflective
sheeting as specified in 49 CFR 571.108 S8.2.
(e) Radar reflectivity specifications. (1) The radar cross section
of the Vehicle Test Device is measured with it attached to the carrier
(robotic platform). The radar reflectivity of the carrier platform is
less than 0 dBm\2\ for a viewing angle of 180 degrees and over a range
of 5 to 100 m when measured according to the radar measurement
procedure specified in C.3 of ISO 19206-3:2021(E) Annex C (incorporated
by reference, see Sec. 596.5) for fixed-angle scans.
(2) The rear bumper area as shown in Table C.1 of ISO 19206-
3:2021(E) Annex C (incorporated by reference, see Sec. 596.5)
contributes to the target radar cross section.
(3) The radar cross section is assessed using radar sensor that
operates at 76 to 81 GHz and has a range of at least 5 to 100 m, a
range gate length smaller than 0.6m, a horizontal field of view of 10
degrees or more (-3dB amplitude limit), and an elevation field of view
of 5 degrees or more (-3dB amplitude).
(4) At least 92 percent of the filtered data points of the
surrogate radar cross section for the fixed vehicle angle, variable
range measurements are within the RCS boundaries defined in Sections
C.2.2.4 of ISO 19206-3:2021(E) Annex C (incorporated by reference, see
Sec. 596.5) for a viewing angle of 180 degrees when measured according
to the radar measurement procedure specified in C.3 of ISO 19206-
3:2021(E) Annex C (incorporated by reference, see Sec. 596.5) for
fixed-angle scans.
(5) Between 86 to 95 percent of the Vehicle Test Device spatial
radar cross section reflective power is with the primary reflection
region defined in Section C.2.2.5 of ISO 19206-3:2021(E) Annex C
(incorporated by reference, see Sec. 596.5) when measured according to
the radar measurement procedure specified in C.3 of ISO 19206-3:2021(E)
Annex C (incorporated by reference, see Sec. 596.5) using the angle-
penetration method.
Issued under the authority delegated in 49 CFR 1.87.
Robin Hutcheson,
Administrator.
Issued under authority delegated in 49 CFR part 1.95 and 49 CFR
501.8.
Raymond R. Posten,
Associate Administrator for Rulemaking.
[FR Doc. 2023-13622 Filed 7-5-23; 8:45 am]
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