Federal Motor Vehicle Safety Standards; Automatic Emergency Braking Systems for Light Vehicles, 39686-39795 [2024-09054]

Agencies

• National Highway Traffic Safety Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 89, Number 91 (Thursday, May 9, 2024)]
[Rules and Regulations]
[Pages 39686-39795]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-09054]



[[Page 39685]]

Vol. 89

Thursday,

No. 91

May 9, 2024

Part II





Department of Transportation





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National Highway Traffic Safety Administration





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49 CFR Parts 571, 595, and 596





Federal Motor Vehicle Safety Standards; Automatic Emergency Braking 
Systems for Light Vehicles; Final Rule

Federal Register / Vol. 89 , No. 91 / Thursday, May 9, 2024 / Rules 
and Regulations

[[Page 39686]]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571, 595, and 596

[Docket No. NHTSA-2023-0021]
RIN 2127-AM37


Federal Motor Vehicle Safety Standards; Automatic Emergency 
Braking Systems for Light Vehicles

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation (DOT).

ACTION: Final rule.

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SUMMARY: This final rule adopts a new Federal Motor Vehicle Safety 
Standard to require automatic emergency braking (AEB), including 
pedestrian AEB (PAEB), systems on light vehicles. An AEB system uses 
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. This 
final rule specifies that an AEB system must detect and react to an 
imminent crash with both a lead vehicle or a pedestrian. This final 
rule fulfills a mandate under the Bipartisan Infrastructure Law (BIL) 
directing the Department to promulgate a rule to require that all 
passenger vehicles be equipped with an AEB system. The purpose of this 
final rule 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, and to reduce 
the consequences of such crashes.

DATES: 
    Effective Date: This rule is effective July 8, 2024.
    IBR date: The incorporation by reference of certain material listed 
in the rule is approved by the Director of the Federal Register 
beginning July 8, 2024. The incorporation by reference of certain other 
material listed in the rule was approved by the Director of the Federal 
Register as of July 8, 2022.
    Compliance Date: September 1, 2029. However, vehicles produced by 
small-volume manufacturers, final-stage manufacturers, and alterers 
must be equipped with a compliant AEB system by September 1, 2030.
    Petitions for reconsideration: Petitions for reconsideration of 
this final rule must be received not later than June 24, 2024.

ADDRESSES: Petitions for reconsideration of this final rule must refer 
to the docket number set forth above (NHTSA-2023-0021) and be submitted 
to the Administrator, National Highway Traffic Safety Administration, 
1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: For technical issues: Mr. Markus 
Price, Office of Crash Avoidance Rulemaking, Telephone: 202-366-1810, 
Facsimile: 202-366-7002. For legal issues: Ms. Sara R. Bennett, Office 
of the Chief Counsel, Telephone: 202-366-2992, Facsimile: 202-366-3820. 
The mailing address for these officials is: National Highway Traffic 
Safety Administration, 1200 New Jersey Avenue SE, Washington, DC 20590.

SUPPLEMENTARY INFORMATION: This final rule adopts a new Federal Motor 
Vehicle Safety Standard (FMVSS) No. 127 to require automatic emergency 
braking (AEB), including pedestrian AEB (PAEB), systems on light 
vehicles. FMVSS No. 127 applies to all passenger cars and to all 
multipurpose passenger vehicles (MPVs), trucks, and buses with a gross 
vehicle weight rating (GVWR) of 4,536 kilograms (kg) (10,000 pounds 
(lbs.)) or less (``light vehicles''). An AEB system uses 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.
    This final rule specifies that an AEB system must detect and react 
to an imminent crash with both a lead vehicle and a pedestrian. This 
final rule advances DOT's January 2022 National Roadway Safety 
Strategy, which identified a requirement for AEB, including PAEB 
technologies, on new passenger vehicles as a key Departmental action to 
improve vehicle and pedestrian safety. Finally, this final rule 
fulfills section 24208(a) of BIL, which directs the Secretary of 
Transportation to promulgate a rule to require that all passenger 
vehicles be equipped with an AEB system.
    NHTSA published the notice of proposed rulemaking preceding this 
final rule on June 13, 2023 (88 FR 38632).

Table of Contents

I. Executive Summary
II. Background
    A. The Safety Problem
    B. Bipartisan Infrastructure Law (BIL)
    C. High-level Summary of Comments on the NPRM
    D. Summary of the Notice of Proposed Rulemaking
    E. Additional Research Conducted in 2023
III. Final Rule and Response to Comments
    A. Summary of the Final Rule (and Modifications to the NPRM)
    B. Application
    C. Definitions
    D. FCW and AEB Equipment Requirements
    1. Minimum Activation Speed
    2. Maximum Activation Speed
    3. Environmental Conditions
    E. AEB System Requirements (Applies to Lead Vehicle and 
Pedestrian)
    1. Forward Collision Warning Requirements
    a. FCW Signal Modality
    b. FCW Auditory Signal Requirements
    c. FCW Auditory Signal Presentation with Simultaneous Muting of 
Other In-Vehicle Audio
    d. FCW Visual Symbol Requirements
    e. FCW Visual Signal Location Requirements
    2. AEB Requirement
    a. AEB Deactivation
    b. Aftermarket Modifications
    c. No-Contact Requirement for Lead Vehicle AEB
    d. No-Contact Requirement for Pedestrians
    e. Permissibility of Failure
    F. False Activation Requirement
    1. Need for Requirement
    2. Peak Additional Deceleration
    3. Process Standard Documentation as Alternative to False 
Activation Requirements
    4. Data Storage Requirement as Alternative to False Activation 
Requirements
    G. Malfunction Detection Requirement
    1. Need for Requirement
    2. Malfunction Telltale
    3. Sensor Obstructions and Testing
    H. Procedure for Testing Lead Vehicle AEB
    1. Scenarios
    2. Subject Vehicle Speed Ranges
    3. Headway
    4. Lead Vehicle Deceleration
    5. Manual Brake Application
    6. Testing Setup and Completion
    7. Miscellaneous Comments
    I. Procedures for Testing PAEB
    1. Scenarios
    2. Subject Vehicle Speed Ranges
    3. Pedestrian Test Device Speed
    4. Overlap
    5. Light Conditions
    6. Testing Setup
    J. Procedures for Testing False Activation
    K. Track Testing Conditions
    1. Environmental Test Conditions
    2. Road/Test Track Conditions
    L. Vehicle Test Device
    1. General Description
    2. Definitions
    3. Sideview Specification
    4. Field Verification Procedure
    5. Dimensional Specification
    6. Visual and Near Infrared Specification
    7. Radar Reflectivity
    8. List of Actual Vehicles
    M. Pedestrian Test Devices
    1. General Description
    2. Dimensions and Posture
    3. Visual Properties
    4. Radar Properties

[[Page 39687]]

    5. Articulation Properties
    6. Comments on Thermal Characteristics
    N. Miscellaneous Topics
    O. Effective Date and Phase-In Schedule
IV. Summary of Estimated Effectiveness, Cost, and Benefits
    A. Benefits
    B. Costs
    C. Net Impact
V. Regulatory Notices and Analyses
VI. Appendices to the Preamble
    A. Appendix A: Description of the Lead Vehicle AEB Test 
Procedures
    B. Appendix B: Description of the PAEB Test Procedures
    C. Appendix C: Description of the False Activation Test 
Procedures

I. Executive Summary

    In 2019, prior to the COVID-19 pandemic, there were nearly 2.2 
million rear-end police-reported crashes involving light vehicles, 
which led to 1,798 deaths and 574,000 injuries. In addition, there were 
6,272 pedestrian fatalities in motor vehicle crashes, representing 17 
percent of all motor vehicle fatalities.\1\ This represents the 
continuation of the recent trend of increased pedestrian deaths on our 
nation's roadways.\2\ A further 76,000 pedestrians were injured in 
motor vehicle crashes. Deaths and injuries in more recent years are 
even greater.
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    \1\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813079 Pedestrian Traffic Facts 2019 Data, May 2021.
    \2\ Id., Table 1 Pedestrian fatalities 2010--4,302, 2019--6,272.
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    NHTSA is issuing this final rule to address these significant 
safety problems through a new Federal Motor Vehicle Safety Standard 
that requires all light vehicles be equipped with forward collision 
warning (FCW),\3\ automatic emergency braking (AEB), and pedestrian 
automatic emergency braking (PAEB) technology.\4\ AEB systems reduce 
the frequency and severity of lead vehicle and pedestrian collisions. 
They employ sensor technologies and sub-systems that work together to 
sense when the vehicle is in a crash imminent situation, to 
automatically apply the vehicle brakes if the driver has not done so, 
and to apply more braking force to supplement the driver's braking. 
These systems can reduce both lead vehicle rear-end (lead vehicle AEB) 
and pedestrian (PAEB) crashes. AEB systems have reached a level of 
maturity to make a significant contribution to reducing the frequency 
and severity of crashes and are thus ready to be mandated through 
adoption of a new FMVSS on all new light vehicles.
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    \3\ A forward collision warning (FCW) system uses sensors that 
detect objects in front of vehicles and provides an alert to the 
driver. An FCW system is able to use the sensors' input to determine 
the speed of an object in front of it and the distance between the 
vehicle and the object. If the FCW system determines that the 
closing distance and velocity between the vehicle and the object is 
such that a collision may be imminent, the system is designed to 
induce an immediate forward crash avoidance response by the vehicle 
operator. FCW systems may detect impending collisions with any 
number of roadway obstacles, including vehicles and pedestrians. 
Warning systems in use today provide drivers with a visual warning 
signal, such as an illuminated telltale on or near the instrument 
panel, an auditory signal, or a haptic signal that provides tactile 
feedback to the driver to warn the driver of an impending collision 
so the driver may intervene. FCW systems alone do not brake the 
vehicle.
    \4\ Hereafter, when this final rule refers to ``AEB'' generally, 
unless the context clearly indicates otherwise, it refers to a 
system that has: (a) an FCW component to alert the driver to an 
impending collision with a forward obstacle; (b) a CIB component 
that automatically applies the vehicle's brakes if the driver does 
not respond to the FCW; and (c) a DBS component that automatically 
supplements the driver's brake application if the driver applies 
insufficient manual braking to avoid a crash. Furthermore, unless 
the context indicates otherwise, reference to AEB includes both lead 
vehicle AEB and PAEB.
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    This rule is estimated to save at least 362 lives and mitigate 
24,321 non-fatal injuries a year. It represents a crucial step forward 
in implementing DOT's January 2022 National Roadway Safety Strategy 
(NRSS) to address the rising numbers of transportation deaths and 
serious injuries occurring on this country's roadways, including those 
involving pedestrians.\5\
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    \5\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf.
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    The crash problem that the agency seeks to address with the AEB 
requirements in this final rule is substantial.\6\ For example, 60 
percent of fatal rear-end crashes and 73 percent of crashes resulting 
in injuries were on roads with posted speed limits of 60 mph or below. 
Similarly, most of these crashes occurred in clear, no adverse 
atmospheric conditions--72 percent of fatal crashes and 74 percent of 
crashes resulting in injuries. Also, about 51 percent of fatal rear-end 
crashes and 74 percent of rear-end crashes resulting in injuries, all 
involving light vehicles, occurred in daylight conditions. In addition, 
65 percent of pedestrian fatalities and 67 percent of pedestrian 
injuries were the result of a strike by the front of a light vehicle. 
Finally, 77 percent of pedestrian fatalities, and about half of the 
pedestrian injuries, occur in dark lighting conditions. Importantly, 
this final rule requires that PAEB systems be able to avoid pedestrian 
crashes in dark testing conditions.
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    \6\ The Insurance Institute for Highway Safety (IIHS) estimates 
a 50 percent reduction in front-to-rear crashes of vehicles with AEB 
(IIHS, 2020) and a 25 to 27 percent reduction in pedestrian crashes 
for PAEB (IIHS, 2022).
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    This final rule is issued under the authority of the National 
Traffic and Motor Vehicle Safety Act of 1966. Under 49 U.S.C. chapter 
301, 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. The 
responsibility for promulgation of FMVSSs is delegated to NHTSA. This 
rulemaking addresses a statutory mandate under the Bipartisan 
Infrastructure Law (BIL), codified as the Infrastructure Investment and 
Jobs Act (IIJA),\7\ which added 49 U.S.C. 30129, directing the 
Secretary of Transportation to promulgate a rule requiring that all 
passenger motor vehicles manufactured for sale in the United States be 
equipped with an FCW system and an AEB system.
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    \7\ Public Law 117-58, 24208 (Nov. 15, 2021).
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The Focus on AEB

    The decision to mandate AEB builds on decades of research and 
development, which began in the 1990s, with initial research programs 
to support development of AEB technologies and methods by which system 
performance could be assessed. NHTSA began testing AEB systems as part 
of the New Car Assessment Program (NCAP) in 2010 and reporting on the 
research and progress surrounding the technologies shortly 
thereafter.\8\ These research efforts led to NHTSA listing FCW systems 
as a ``recommended advanced technology'' in NCAP in model year 2011, 
and in November 2015, added crash imminent braking (CIB) \9\ and 
dynamic brake support (DBS) technologies to the program.\10\ Most 
recently, NHTSA proposed upgrades to the lead vehicle AEB test in its 
March 2022 request for comment on NCAP.\11\
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    \8\ 77 FR 39561 (Jul. 2, 2012).
    \9\ This final rule does not split the terminology of these CIB 
and DBS functionalities outside of certain contexts, like 
discussions of NCAP, but instead considers them both as parts of 
AEB. The final rule includes performance tests that would require an 
AEB system that has both CIB and DBS functionalities.
    \10\ 80 FR 68604 (Nov. 5, 2015).
    \11\ 87 FR 13452 (Mar. 9, 2022). See https://www.regulations.gov, docket number NHTSA-2021-0002.
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    In March 2016, NHTSA and the Insurance Institute for Highway Safety 
(IIHS) announced a commitment by 20 manufacturers representing more 
than 99 percent of the U.S. light vehicle market to include low-speed 
AEB as a standard feature on nearly all new light vehicles not later 
than September 1,

[[Page 39688]]

2022. As part of this voluntary commitment, manufacturers are including 
both FCW and a CIB system that reduces a vehicle's speed in certain 
rear-end crash-imminent test conditions.
    NHTSA also conducted research to understand the capabilities of 
PAEB systems beginning in 2011. This work began with an assessment of 
the most common pedestrian crash scenarios to determine how test 
procedures could be designed to address them. As part of this research, 
the agency looked closely at a potential pedestrian mannequin to be 
used during testing and explored several aspects of the mannequin, 
including size and articulation of the arms and legs. This work 
resulted in a November 2019 draft research test procedure providing the 
methods and specifications for collecting performance data on PAEB 
systems for light vehicles.\12\ This procedure was expanded to cover 
updated vehicle speed ranges and different ambient conditions and 
included in a March 2022 request for comments notice proposing to 
include PAEB, higher speed AEB, blind spot warning and blind spot 
intervention in NCAP.\13\
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    \12\ 84 FR 64405 (Nov. 21, 2019).
    \13\ 87 FR 13452 (Mar. 9, 2022).
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Need for Regulation

    While the above actions have increased market penetration of AEB 
systems, reduced injuries, and saved lives, NHTSA believes that 
mandating AEB systems that can address both lead vehicle and pedestrian 
crashes is appropriate and necessary to better address the safety need. 
NHTSA incorporated FCW into NCAP beginning in model year 2011 and AEB 
into NCAP beginning in model year 2018. This has achieved success, with 
approximately 65% of new vehicles meeting the lead vehicle test 
procedures included in NCAP.\14\ Similarly, the voluntary commitment 
resulted in approximately 90 percent of new light vehicles manufactured 
in 2022 having an AEB system.
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    \14\ Percentage based on the vehicle manufacturer's model year 
2022 projected sales volume reported through the New Car Assessment 
Program's annual vehicle information request.
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    That said, the test speeds and performance specifications in NCAP 
and the voluntary commitment do not ensure that the systems perform in 
a way that will prevent or mitigate crashes resulting in serious 
injuries and fatalities. The vast majority of fatalities, injuries, and 
property damage crashes occur at speeds above 40 km/h (25 mph), which 
are above those covered by the voluntary commitment.
    Voluntary measures are intended to supplement rather than 
substitute for the FMVSSs, which remain NHTSA's core method of ensuring 
that all motor vehicles can achieve an adequate level of safety 
performance. The NCAP program is designed to provide valuable safety-
related information to consumers in a simple to understand way, but the 
agency believes that gaps in market penetration will continue to exist 
for the most highly effective AEB systems. NHTSA has also observed 
that, in the case of both electronic stability control and rear 
visibility, only approximately 70 percent of vehicles had these 
technologies during the time they were part of NCAP. Thus, while NCAP 
serves a vital safety purpose, only regulation can ensure that all 
vehicles are equipped with AEB that meet minimum performance 
requirements.
    These considerations are of even greater weight when deciding 
whether to require a system that can reduce pedestrian crashes, and the 
agency has concluded that PAEB is both achievable and necessary. 
Pedestrian fatalities are increasing, and NHTSA's testing reveals that 
PAEB systems will be able to significantly reduce these deaths.\15\ 
Manufacturers' responses to adding lead vehicle AEB and other 
technologies to NCAP suggest that it will take several years after PAEB 
is introduced to NCAP before the market begins to see significant 
numbers of new vehicles that are able to meet a finalized NCAP test. 
Even so, since PAEB addresses the safety of someone other than a 
vehicle occupant, it is not clear if past experience with NCAP is 
necessarily indicative of how quickly PAEB systems will reach the 
market penetration levels of lead vehicle AEB.
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    \15\ NHTSA's accompanying Final Regulatory Impact Analysis 
(FRIA) estimates the impacts of this final rule. The FRIA can be 
found in the docket for this final rule. The docket number is listed 
in the heading of this document.
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    A final factor weighing in favor of requiring AEB is that the 
technology is significantly more mature now than it was at the time of 
the voluntary commitment and when it was introduced into NCAP. NHTSA's 
most recent testing has shown that higher performance levels than those 
in the voluntary commitment or the existing NCAP requirements are now 
practicable. Many model year 2019 and 2020 vehicles were able to 
repeatedly avoid impacting the lead vehicle in CIB tests and the 
pedestrian test mannequin in PAEB tests, even at higher test speeds 
than those prescribed currently in the agency's CIB and PAEB test 
procedures.
    These results show that AEB systems can reduce the frequency and 
severity of both lead vehicle and pedestrian crashes. Mandating AEB 
systems would address a clear and, in the case of pedestrian deaths, 
growing safety problem. To wait for market-driven adoption, even to the 
extent spurred on by NCAP, would lead to deaths and injuries that could 
be avoided if the technology were required.

Summary of the NPRM

    In view of the significant safety problem and NHTSA's recent test 
results, and consistent with the Safety Act and BIL, on June 13, 2023 
(88 FR 38632) NHTSA published an NPRM proposing a new FMVSS requiring 
AEB systems that can address both lead vehicle and pedestrian 
collisions on all new light vehicles. The proposed lead vehicle AEB 
test procedures built on the existing FCW, CIB, and DBS NCAP 
procedures, but proposed higher speed performance requirements. Crash 
avoidance was proposed at speeds up to 100 km/h (62 mph) when manual 
braking is applied and up to 80 km/h (50 mph) when no manual braking is 
applied during the test. NHTSA proposed testing under both daylight and 
darkness lighting conditions, noting the importance of darkness testing 
of PAEB because more than three-fourths of all pedestrian fatalities 
occur in conditions other than daylight.
    The proposal included four requirements for the AEB system for both 
lead vehicles and pedestrians. The AEB system would be required to: (1) 
provide an FCW at any forward speed greater than 10 km/h (6.2 mph), 
presented via auditory and visual modalities, with permissible 
additional warning modes, such as haptic; (2) apply the brakes 
automatically at any forward speed greater than 10 km/h (6.2 mph) when 
a collision with a lead vehicle or a pedestrian is imminent, including 
at speeds above those tested by NHTSA; (3) prevent the vehicle from 
colliding with the lead vehicle or pedestrian test mannequin when 
tested according to the proposed test procedures, which would include 
pedestrian tests in both daylight and darkness and two false positive 
tests; and (4) provide visual notification to the driver of any 
malfunction that causes the AEB system not to meet the minimum proposed 
performance requirements.
    To ensure test repeatability, NHTSA proposed specifications for the 
test devices that would be used in both the lead vehicle and pedestrian 
compliance tests, relying in large part on relevant International 
Organization for Standardization standards.

[[Page 39689]]

    NHTSA proposed that all vehicles manufactured four years after the 
publication date of a final rule would be required to meet all 
requirements. NHTSA also proposed that all vehicles manufactured on or 
after three years after the publication date of a final rule would be 
required to meet all requirements except that lower speed PAEB 
performance test requirements would not apply. Small-volume 
manufacturers, final-stage manufacturers, and alterers would be 
provided an additional year (added to those above) to meet the 
requirements of the final rule.
    NHTSA sought comments on all aspects of the NPRM and any 
alternative requirements that would address the safety problem. In 
response, over 1,000 comments were received from a wide variety of 
stakeholders and interested persons. These comments are available in 
the docket for the NPRM.\16\
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    \16\ https://www.regulations.gov/docket/NHTSA-2023-0021/comments.
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This Final Rule

    After careful consideration of all comments, this final rule adopts 
most of the proposed NPRM requirements, with a few of the changes 
relevant to significant matters. The differences between the NPRM and 
the final rule are noted at the end of this Executive Summary and 
discussed in the relevant sections of this preamble.
    With this final rule, NHTSA has issued a Final Regulatory Impact 
Analysis (FRIA), available in the docket for this final rule (NHTSA-
2023-0021).
    NHTSA estimates that systems can achieve the requirements of this 
final rule primarily through upgraded software, with a limited number 
of vehicles needing additional hardware. Therefore, the incremental 
cost associated with this rule reflects the cost of a software upgrade 
that will allow current systems to achieve lead vehicle AEB and PAEB 
functionality that meets the requirements specified in this rule and 
the cost to equip a second sensor (radar) on five percent of the 
estimated fleet that is not projected to have the needed hardware. 
Taking into account both software and hardware costs, the total annual 
cost associated with this final rule is approximately $354 million in 
2020 dollars.
    Table 1 below summarizes the finding of the benefit-cost analysis. 
The projected benefits of this rule greatly exceed the projected costs. 
The lifetime monetized net benefit of this rule is projected to be 
between $5.82 and $7.26 billion with a cost per equivalent life saved 
of between $550,000 and $680,000, which is far below the Department's 
recommended value of a statistical life saved, of as $11.6 million in 
2020 dollars.
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Differences Between This Final Rule and the NPRM

    NHTSA has made a number of changes to the NPRM based on information 
from the comments. The changes are discussed below. NHTSA discusses 
each of these changes in the relevant sections of this preamble.
     In the NPRM, NHTSA estimated that systems can achieve the 
proposed requirements through upgraded software alone. Commenters 
suggested that in some instances additional hardware will also be 
needed, so the incremental cost associated with this rule now includes 
the cost of a software upgrade and the cost to equip a second sensor 
(radar) on the five percent of the estimated fleet that does not now 
have the needed hardware.
     NHTSA has made changes to lead time and compliance date 
requirements. The NPRM proposed that all vehicles comply with the 
requirements within 3 years, except for some higher speed PAEB 
performance requirements in darkness (which had 1 year more to comply 
than other requirements). This final rule requires that manufacturers 
comply with all provisions of the rule at the end of a 5-year period 
starting the first September 1 following publication of this rule, 
which would be September 1, 2029.\17\ The requirements of this final 
rule compel robust AEB systems that are practicable, but the agency has 
determined that more time is needed for the technology to mature and be 
deployed into all vehicles.\18\ We expect that many vehicles will be 
equipped with AEB systems that meet the new rule earlier than September 
1, 2029, because of redesign schedules, but that manufacturers will be 
able to meet the requirement for all new vehicles by the new start 
date.
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    \17\ As proposed in the NPRM, this final rule provides small-
volume manufacturers, final stage manufacturers, and alterers an 
additional year of lead time. As a result of the changes to the 
proposed lead time and compliance date requirements, small-volume 
manufactures, final stage manufactures, and alterers would be 
required to comply with all provisions of the rule starting 
September 1, 2030.
    \18\ As part of this extension of the lead time, the agency has 
removed the graduated approach to the PAEB performance requirements. 
The NPRM proposed that most PAEB requirements be met 3 years after a 
final rule, with an additional year for the dark lighting condition 
requirement. With the 5-year lead time for all requirements, there 
is no need for the phasing-in of requirements, so the agency is not 
adopting it.
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     This final rule modifies the range of forward speeds at 
which the AEB must operate. The NPRM required FCW and AEB systems to 
operate at any forward speed greater than 10 km/h. This final rule 
places an upper bound on the requirement that an AEB system operate of 
145 km/h (90.1 mph) for FCW and lead vehicle AEB and 73 km/h (45.4 mph) 
for pedestrian AEB. This final rule also clarifies the environmental 
conditions under which the AEB system must perform to be the same 
environmental conditions specified in the track testing.
     This final rule includes an explicit prohibition against 
manufacturers installing a control designed for the sole purpose of 
deactivation of the AEB system, except where provided below as it 
relates to law enforcement. This final rule also allows for controls 
that have the ancillary effect of deactivating the AEB system. For 
instance, a manufacturer may choose to deactivate AEB if the driver has 
activated ``tow mode'' and the manufacturer has determined that AEB 
cannot perform safely while towing a trailer.
     This final rule modifies the FCW visual signal location 
requirement to increase the specified maximum visual angle from 10 
degrees to 18 degrees in the vertical direction. This change from the 
NPRM provides manufacturers with the flexibility to locate the visual 
warning signal within the typical area of the upper half of the 
instrument panel and closer to the central field of view of the driver. 
While the agency continues to believe that an FCW visual warning signal 
presented near the central forward-looking region is ideal, it does not 
consider a head-up display to be necessary for the presentation of the 
FCW visual signal that is part of a complete AEB system.
     The rule contains several additional minor changes as 
well. These include the following:

--In the obstructed pedestrian scenario in PAEB performance tests, the 
NPRM did not specify the distance between the pedestrian test dummy and 
the farthest obstructing vehicle. This final rule corrects this 
oversight.
--In the false activation tests, this final rule adjusts the regulatory 
text to clarify that testing for false activation is done with and 
without manual brake application.
--Some minor parameters and definitions were modified, and various 
definitions were added, to clarify details of the lead vehicle and PAEB 
test procedures.
--To increase practicability of running the tests, a third manual brake 
application controller option, a force only feedback controller, was 
added. The force feedback controller is substantially similar to the 
hybrid controller with the commanded brake pedal position omitted, 
leaving only the commanded brake pedal force application.
--The procedure in Annex C, section C.3 of ISO 19206-2:2018 is specific 
for pedestrian targets, but recent testing performed by the agency 
indicates that the three-position measurement specified in Annex C, 
section C.3 of ISO 19206-3:2021 provides more reduction in multi-path 
reflections and offers more accurate radar cross section values. The 
agency is incorporating by reference ISO 19206-3:2021.

II. Background

A. The Safety Problem

    There were 38,824 fatalities in motor vehicle crashes on U.S. 
roadways in 2020 and early estimates put the number of fatalities at 
42,795 for 2022.\19\ This is the highest number of fatalities since 
2005. While the upward trend in fatalities may be related to increases 
in risky driving behaviors during the COVID-19 pandemic,\20\ agency 
data show an increase of 3,356 fatalities between 2010 and 2019.\21\ 
Motor vehicle crashes have also trended upwards since 2010, which 
corresponds to an increase in fatalities, injuries, and property 
damage.
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    \19\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813428.
    \20\ These behaviors relate to increases in impaired driving, 
the non-use of seat belts, and speeding. NHTSA also cited external 
studies from telematics providers that suggested increased rates of 
cell phone manipulation during driving in the early part of the 
pandemic.
    \21\ NHTSA's Traffic Safety Facts Annual Report, Table 2, 
https://cdan.nhtsa.gov/tsftables/tsfar.htm#Accessed March 28, 2023.

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[[Page 39691]]

Overall Rear-End Crash Problem
    NHTSA uses data from the Fatality Analysis Reporting System (FARS) 
and the Crash Report Sampling System (CRSS) to account for and 
understand motor vehicle 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 2020 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.\22\
---------------------------------------------------------------------------

    \22\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813251 Category II Configuration D. Rear-End.
---------------------------------------------------------------------------

    In 2019, rear-end crashes accounted for 32.5 percent of all 
crashes, making them the most prevalent type of crash.\23\ Fatal rear-
end crashes increased from 1,692 in 2010 to 2,363 in 2019 and accounted 
for 7.1 percent of all fatal crashes in 2019, up from 5.6 percent in 
2010. Because data from 2020 and 2021 may not be representative of the 
general safety problem due to the COVID-19 pandemic, and data from 2022 
are not yet available, the following discussion refers to data from 
2010 to 2020 when discussing rear-end crash safety problem trends, and 
2019 data when discussing specific characteristics of the rear-end 
crash safety problem. While injury and property-damage-only rear-end 
crashes from 2010 (476,000 and 1,267,000, respectively) and 2019 
(595,000 and 1,597,000, respectively) are not directly comparable due 
to differences in database structure and sampling, the data indicate 
that these numbers have not significantly changed from 2010-2015 (NASS-
GES sampling) and 2016-2019 (CRSS sampling).
---------------------------------------------------------------------------

    \23\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141 Traffic Safety Facts 2019, Table 29.
---------------------------------------------------------------------------

BILLING CODE 4910-59-P
[GRAPHIC] [TIFF OMITTED] TR09MY24.004

    The table below presents a breakdown of all the crashes in 2019 by 
the first harmful event where rear-end crashes represent 7.1 percent of 
the fatal crashes, 31.1 percent of injury crashes and 33.2 percent (or 
the largest percent) of property-damage-only crashes.
---------------------------------------------------------------------------

    \24\ Compiled from NHTSA's Traffic Safety Facts Annual Report, 
Table 29 from 2010 to 2020, https://cdan.nhtsa.gov/tsftables/tsfar.htm#Accessed March 28, 2023.

---------------------------------------------------------------------------

[[Page 39692]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.005

    The following paragraphs provide a breakdown of rear-end crashes by 
vehicle type, posted speed limit, light conditions and atmospheric 
conditions for the year 2019 based on NHTSA's FARS, CRSS, and the 2019 
Traffic Safety Facts sheets.
---------------------------------------------------------------------------

    \25\ NHTSA's Traffic Safety Facts Annual Report, Table 29 for 
2019, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141 Accessed March 29, 2024.
---------------------------------------------------------------------------

Rear-End Crashes by Vehicle Type
    In 2019, passenger cars and light trucks were involved in the vast 
majority of rear-end crashes. NHTSA's ``Manual on Classification of 
Motor Vehicle Traffic Accidents'' provides a standardized method for 
crash reporting. It defines passenger cars as ``motor vehicles used 
primarily for carrying passengers, including convertibles, sedans, and 
station wagons,'' and light trucks as ``trucks of 10,000 pounds gross 
vehicle weight rating or less, including pickups, vans, truck-based 
station wagons, and utility vehicles.'' \26\ The 2019 data show that 
crashes where a passenger car or light truck is a striking vehicle 
represent at least 70 percent of fatal rear-end crashes, 95 percent of 
crashes resulting in injury, and 96 percent of damage only.\27\
---------------------------------------------------------------------------

    \26\ https://www-fars.nhtsa.dot.gov/help/terms.aspx.
    \27\ NHTSA's Traffic Safety Facts Annual Report, 2019, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141.

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[[Page 39693]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.006

Rear-End Crashes by Posted Speed Limit
---------------------------------------------------------------------------

    \28\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
---------------------------------------------------------------------------

    When looking at posted speed limit and rear-end crashes, data show 
that the majority of the crashes happened in areas where the posted 
speed limit was 60 mph (97 km/h) or less. The table below shows the 
rear-end crash data by posted speed limit and vehicle type from 2019. 
About 60 percent of fatal crashes were on roads with a speed limit of 
60 mph (97 km/h) or lower. That number is 73 percent for injury crashes 
and 78 percent for property-damage-only crashes.
[GRAPHIC] [TIFF OMITTED] TR09MY24.007

Rear-End Crashes by Light Condition
---------------------------------------------------------------------------

    \29\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
    \30\ Total percentages may not equal the sum of individual 
components due to independent rounding throughout the Safety Problem 
section.
---------------------------------------------------------------------------

    Slightly more fatal rear-end crashes (51 percent) occurred during 
daylight than during dark-lighted and dark-not-lighted conditions 
combined (43 percent) in 2019. Injury and property- damage-only rear-
end crashes were reported to have happened overwhelmingly during 
daylight, at 76 percent for injury rear-end crashes and 80 percent for 
property-damage-only rear-end crashes. The table below presents a 
summary of all 2019 rear-end crashes of light vehicles by light 
conditions, where the impact location is the front of a light vehicle.

[[Page 39694]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.008

Rear-End Crashes by Atmospheric Conditions
---------------------------------------------------------------------------

    \31\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
---------------------------------------------------------------------------

    In 2019, the majority of rear-end crashes of light vehicles were 
reported to occur during clear skies with no adverse atmospheric 
conditions. These conditions were present for 72 percent of all fatal 
rear-end crashes, while 14 percent of fatal rear-end crashes were 
reported to occur during cloudy conditions. Similar trends are reported 
for injury and property-damage-only crashes. A summary of 2019 rear-end 
crashes of light vehicle with frontal impact by atmospheric conditions 
is presented in the table below.
---------------------------------------------------------------------------

    \32\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
[GRAPHIC] [TIFF OMITTED] TR09MY24.009

Pedestrian Fatalities and Injuries
    While the number of fatalities from motor vehicle traffic crashes 
is increasing, pedestrian fatalities are increasing at a greater rate 
than the general trend and becoming a larger percentage of total 
fatalities. In 2010, there were 4,302 pedestrian fatalities (13 percent 
of all fatalities), which increased to 6,272 (17 percent of all 
fatalities) in 2019. The latest agency estimation data indicate that 
there were 7,345 pedestrian fatalities in 2022.\33\ Since data from 
2020 and 2021 may not be representative of the general safety problem 
due to the COVID-19 pandemic and data for 2022 are early estimates, the 
following sections refer to data from 2010 to 2020 when discussing 
pedestrian safety problem trends, and 2019 data when discussing 
specific characteristics of the pedestrian safety problem. While the 
number of pedestrian fatalities is increasing, the number of 
pedestrians injured in crashes from 2010 to 2020 has not changed 
significantly, with exception of the 2020 pandemic year. As shown in 
the table below, the number and percentage of pedestrian fatalities and 
injuries for the 2010 to 2020 period is presented in relationship to 
the total number of fatalities and total number of people injured in 
all crashes.
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    \33\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813448.

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[[Page 39695]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.010

    The following sections present a breakdown of pedestrian fatalities 
and injuries by initial impact point, vehicle type, posted speed limit, 
lighting condition, and pedestrian age for the year 2019.
---------------------------------------------------------------------------

    \34\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813079 Pedestrian Traffic Facts 2019 Data, May 2021, 
https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813310 
Pedestrian Traffic Facts 2020, Data May 2022.
---------------------------------------------------------------------------

Pedestrian Fatalities and Injuries by Initial Point of Impact and 
Vehicle Type
    In 2019, the majority of pedestrian fatalities, 4,638 (74 percent 
of all pedestrian fatalities), and injuries, 52,886 (70 percent of all 
pedestrian injuries), were in crashes where the initial point of impact 
on the vehicle was the front. When the crashes are broken down by 
vehicle body type, the majority of pedestrian fatalities and injuries 
occur where the initial point of impact was the front of a light 
vehicle (4,069 pedestrian fatalities and 50,831 pedestrian injuries) 
(see the table below).\35\
---------------------------------------------------------------------------

    \35\ As described previously, passenger cars and light trucks 
are the representative population for vehicles with a gross vehicle 
weight rating (GVWR) of 4,536 kg (10,000 lbs.) or less.
[GRAPHIC] [TIFF OMITTED] TR09MY24.011

Pedestrian Fatalities and Injuries by Posted Speed Limit Involving 
Light Vehicles
---------------------------------------------------------------------------

    \36\ NHTSA's Traffic Safety Facts Annual Report, Table 99 for 
2019, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141 Accessed March 29, 2024.
---------------------------------------------------------------------------

    In 2019, the majority of pedestrian fatalities from crashes 
involving light vehicles with the initial point of impact as the front 
occurred on roads where the posted speed limit was 45 mph or less, 
(about 70 percent). There is a near even split between the number of 
pedestrian fatalities in 40 mph and lower speed zones and in 45 mph and 
above speed zones (50 percent and 47 percent respectively with the 
remaining unknown or not reported). As for pedestrian injuries, in 34 
percent of the sampled data, the posted speed limit is either not 
reported or unknown. In

[[Page 39696]]

2019, 57 percent of the pedestrians were injured when the posted speed 
limit was 40 mph or below, and 9 percent when the posted speed limit 
was above 40 mph with the remaining not reported, reported as unknown, 
or reported as no speed limit. The table below shows the number of 
pedestrian fatalities and injuries for each posted speed limit.
[GRAPHIC] [TIFF OMITTED] TR09MY24.012

Pedestrian Fatalities and Injuries by Lighting Condition Involving 
Light Vehicles
---------------------------------------------------------------------------

    \37\ The accompanying FRIA estimates the impacts of the rule 
based on the estimated travel speed of the striking vehicle. This 
table presents the speed limit of the roads on which pedestrian 
crashes occur.
---------------------------------------------------------------------------

    The majority of pedestrian fatalities where the front of a light 
vehicle strikes a pedestrian occurred in dark lighting conditions, 
3,131 (75 percent). There were 20,645 pedestrian injuries (40 percent) 
in dark lighting conditions and 27,603 pedestrian injuries (54 percent) 
in daylight conditions.

[[Page 39697]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.013

Pedestrian Fatalities and Injuries by Age Involving Light Vehicles
---------------------------------------------------------------------------

    \38\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
---------------------------------------------------------------------------

    In 2019, 646 fatalities and approximately 106,600 injuries involved 
children aged 9 and below. Of these, 68 fatalities and approximately 
2,700 injuries involved pedestrians aged 9 and below in crashes with 
the front of a light vehicle. As shown in the table below, the first 
two age groups (under age 5 and ages 5 to 9) each represent less than 1 
percent of the total pedestrian fatalities in crashes with the front of 
a light vehicle. These age groups also represent about 1.5 and 3.8 
percent of the total pedestrian injuries in crashes with the front of a 
light vehicle, respectively. In contrast, age groups between age 25 and 
69 each represent approximately 7 percent of the total pedestrian 
fatalities in crashes with the front of a light vehicle, with the 55 to 
59 age group having the highest percentage at 10.9 percent. Pedestrian 
injury percentages were less consistent, but distributed similarly, to 
pedestrian fatalities, with lower percentages reflected in children 
aged 9 and below and adults over age 70.

[[Page 39698]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.014

BILLING CODE 4910-59-C

B. Bipartisan Infrastructure Law (BIL)
---------------------------------------------------------------------------

    \39\ Generated from FARS and CRSS databases (https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/FARS/2019/National/, 
https://www.nhtsa.gov/file-downloads?p=nhtsa/downloads/CRSS/2019/, 
accessed October 17, 2022).
    \40\ https://www.census.gov/data/tables/2019/demo/age-and-sex/2019-age-sex-composition.html, Table 12.
---------------------------------------------------------------------------

    This final rule responds to Congress's directive that NHTSA require 
AEB on all passenger vehicles. On November 15, 2021, the President 
signed the Bipartisan Infrastructure Law, codified as the 
Infrastructure Investment and Jobs Act (Pub. L. 117-58). Section 
24208(a) of BIL added 49 U.S.C. 30129, directing the Secretary of 
Transportation to promulgate a rule to establish minimum performance 
standards with respect to crash avoidance technology and to require 
that all passenger motor vehicles manufactured for sale in the United 
States be equipped with a forward collision warning (FCW) system and an 
automatic emergency braking system. The FCW and AEB system is required 
to alert the driver if the vehicle is closing its distance too quickly 
to a vehicle ahead or to an object in the path of travel ahead and a 
collision is imminent, and to automatically apply

[[Page 39699]]

the brakes if the driver fails to do so. This final rule responds to 
this mandate and is estimated to reduce the frequency and severity of 
vehicle-to-vehicle rear-end crashes and to reduce the frequency and 
severity of vehicle crashes into pedestrians.
    BIL requires that ``all passenger motor vehicles'' manufactured for 
sale in the United States be equipped with AEB and FCW. The BIL term 
``passenger motor vehicle'' encompasses more vehicle categories than 
the term ``passenger car'' that NHTSA defines in 49 CFR 571.3. Thus, 
including multipurpose passenger vehicles, trucks, and buses aligns 
with Congress's mandate. Additionally, NHTSA considers passenger cars, 
truck, buses, and multipurpose passenger vehicles as light vehicles and 
generally uses the 10,000 GVWR cut-off for FMVSS that apply to light 
vehicles.\41\ As a result, in this final rule, NHTSA requires AEB and 
FCW on all passenger cars and multipurpose passenger vehicles, trucks, 
and buses with a gross vehicle weight rating (GVWR) of 10,000 lbs. or 
less.
---------------------------------------------------------------------------

    \41\ See, for example, 49 CFR 571.138, 571.208, and 571.111.
---------------------------------------------------------------------------

    BIL further requires that an FCW system alert the driver if there 
is a ``vehicle ahead or an object in the path of travel'' if a 
collision is imminent.
    NHTSA interprets BIL as requiring AEB capable of detecting and 
responding to vehicles and objects and authorizing NHTSA to promulgate 
specific performance requirements. NHTSA's rule requires light vehicles 
to be equipped with FCW and automatic emergency braking (AEB), and the 
proposal defines AEB as a system that detects an imminent collision 
with vehicles, objects, and road users,\42\ in or near the path of a 
vehicle and automatically controls the vehicle's service brakes to 
avoid or mitigate the collision.
---------------------------------------------------------------------------

    \42\ While AEB is defined as a system that detects imminent 
collision with vehicles, objects, and road users, the performance 
requirements focus on protecting pedestrians until NHTSA can develop 
additional research to support a proposal to expand the performance 
requirements.
---------------------------------------------------------------------------

    As discussed in the NPRM, section 24208 of BIL does not limit 
NHTSA's broad authority to issue motor vehicle safety regulations under 
the Safety Act. NHTSA interprets BIL as a mandate to act on a 
particular vehicle safety issue and as complementary to NHTSA's 
authority under the Safety Act. Thus, pursuant to its authority under 
49 U.S.C 30111, NHTSA is requiring all light passenger vehicles to be 
equipped with PAEB in addition to AEB. NHTSA is ensuring that PAEB is 
available on all light passenger vehicles to address a significant 
safety problem, and in so doing, recognizes the availability of 
technology capable of preventing needless injuries and lost lives.

C. High-level Summary of Comments on the NPRM

    NHTSA received more than a thousand comments on the proposed rule. 
The agency received comments from a wide variety of commenters 
including advocacy groups, manufacturers, trade associations, 
suppliers, and individuals. The advocacy groups submitting comments 
included AAA Inc. (AAA), AARP, Advocates for Highway and Auto Safety 
(Advocates), America Walks, American Foundation for the Blind (AFB), 
Association of Pedestrian and Bicycle Professionals (APBP), Center for 
Auto Safety (CAS), Consumer Reports, DRIVE SMART Virginia, Insurance 
Institute for Highway Safety (IIHS), International Association of Fire 
Chiefs, Intelligent Transportation Society of America (ITS America), 
League of American Bicyclists (League), McHenry County Bicycle 
Advocates, National Safety Council (NSC), Paralyzed Veterans of America 
(PVA), United Spinal Association, Utah Public Lands Alliance, and 
Vulnerable Road Users Safety Consortium (VRUSC). Trade associations 
submitting comments included Alliance for Automotive Innovation 
(Alliance), American Chemistry Council, American Motorcyclist 
Association (AMA), Automotive Safety Council (ASC), Autonomous Vehicle 
Industry Association (AVIA), the Governors Highway Safety Association 
(GHSA), Lidar Coalition, the Motor and Equipment Manufacturers 
Association (MEMA), National Automotive Dealers Association (NADA), 
National Association of City Transportation Officials (NACTO), 
Association for the Work Truck Industry (NTEA), SAE International 
(SAE), and Specialty Equipment Market Association (SEMA). We also 
received comments from individual vehicle manufacturers such as FCA US 
LLC (FCA), Ford Motor Company (Ford), General Motors LLC (GM), American 
Honda Motor, Co., Inc. (Honda), Hyundai Motor Company (Hyundai), 
Mitsubishi Motors R & D of America, Inc. (Mitsubishi), Nissan North 
America, Inc. (Nissan), Porsche Cars North America (Porsche), Rivian 
Automotive, LLC (Rivian), Toyota Motor North America, Inc. (Toyota), 
and Volkswagen Group of America (Volkswagen). Suppliers and developers 
commenting on the NPRM included Adasky North America (Adasky), Applied 
Intuition (Applied), Aptiv, Automotive Electronics Products COMPAL 
Electronics, Inc. (COMPAL), Autotalks, Forensic Rock, LLC (Forensic 
Rock), Humanetics Safety (Humanetics), Hyundai America Technical 
Center, Inc. (HATCI), Hyundai MOBIS, imagery Inc. (Imagery), LHP Inc. 
(LHP), Luminar Technologies, Inc. (Luminar), Mobileye Vision 
Technologies LTD (Mobileye), Owl Autonomous Imaging, Inc. (Owl AI), 
Radian Labs LLC (Radian), Robert Bosch LLC (Bosch), Teledyne FLIR 
(Teledyne), ZF North America (ZF), and Zoox, Inc. (Zoox). Government 
agencies that commented included the National Transportation Safety 
Board (NTSB), the City of Houston (Houston), City of Philadelphia 
(Philadelphia), Humboldt County Association of Governments, Maryland 
Department of Transportation Motor Vehicle Administration (MDOT), 
Multnomah County, and Nashville Department of Transportation and 
Multimodal Infrastructure (Nashville). Healthcare and insurance 
companies submitting comments included American Property Casualty 
Insurance Association (APCIA), National Association of Mutual Insurance 
Companies, and Richmond Ambulance Authority. The agency also received 
approximately 970 comments from individual commenters. In general, the 
commenters expressed support for the goals of this rulemaking, and many 
commenters offered recommendations on the most appropriate way to 
achieve those goals.
    Many commenters shared their general support for requiring AEB as 
standard equipment on passenger vehicles, while others opposed 
finalizing the proposed rule for various technical and policy reasons. 
In general, safety advocates supported finalizing the rule, while 
vehicle manufacturers opposed various aspects of the proposal, even if 
they expressed general support for AEB technology. The agency received 
comments on many aspects of the rule, including comments on the 
application, the performance requirements, the test procedure 
conditions and parameters, and the proposed lead time and phase-in 
schedule.
    Consumer advocacy groups primarily supported the rule, with 
concerns regarding manual deactivation and the proposed requirements 
regarding PAEB. They urged that any conditions for AEB deactivation be 
restricted and have data supporting deactivation and asserted that any 
manual deactivation would need to have multiple steps and require the 
vehicle to be stationary. Many suggested that the testing speeds be 
increased to cover a larger portion of the safety problem. Another 
concern raised

[[Page 39700]]

by advocacy groups was the lack of test procedures covering bicyclists 
and users of mobility devices and wheelchairs. They recommended that 
the agency add more PAEB testing scenarios, noting that there is a 
significant safety risk for pedestrians and all vulnerable road users. 
In general, advocacy groups supported the full collision avoidance, no-
contact requirement for all proposed AEB tests as a necessity to uphold 
the strength of the rule.
    While vehicle manufacturers supported the installation of AEB, the 
most significant concerns focused on the stringency of the 
requirements. The NPRM proposed the AEB system be operational at any 
forward speed above 10 km/h (6.2 mph). Several vehicle manufacturers 
and the Alliance opposed the open-ended upper bound, stating it was 
impracticable or that it would lead to false activations. These 
commenters stated that the lack of a defined maximum operational speed 
could create implementation ambiguity and difficulty complying with the 
rule due to significant development costs. The NPRM further proposed 
full collision avoidance with the lead vehicle during AEB testing (a 
no-contact performance requirement). The Alliance, and multiple 
manufacturers expressing support for the Alliance' comments, stated 
that a no-contact performance requirement is not practicable and 
increases the potential for unintended consequences such as inducing 
unstable vehicle dynamics, removing the driver's authority, increasing 
false activations, and creating conditions that limit bringing new 
products to market. These commenters asserted that a lack of rigorous 
testing by the agency leaves questions as to actual vehicle performance 
in the field.
    The vehicle manufacturers also commented on the feasibility of 
specific performance requirements under the proposed phase-in schedule, 
arguing that the agency was mistaken to assume in the NPRM that most 
vehicles have the necessary hardware to implement this rule. They 
commented that the proposed phase-in schedule may require redesigns to 
their systems outside of the normal product development cycle and 
contended that such a scenario would significantly increase the costs 
and burdens of compliance. The manufacturers requested that the agency 
delay the rule by as much as eight years to afford them time to 
redesign their systems in conjunction with the normal vehicle redesign 
schedule.
    Manufacturers and suppliers generally opposed the agency's proposal 
to prohibit manual deactivation of the AEB system above 10km/h. 
Commenters stated the need for deactivation during various scenarios, 
including four-wheel drive operation, towing, off-road use, car washes 
and low traction driving. There were multiple suggestions to adopt the 
deactivation criteria of the United Nations Economic Commission for 
Europe (UNECE) Regulation No. 152, in place of the NPRM proposed 
criteria, and to align with UNECE Regulation No. 152 more generally.
    Among suppliers and developers, there was not a consensus on the 
no-contact requirement. Commenters such as Adasky and Luminar expressed 
support for the no-contact requirement, stating that current technology 
is capable of this performance. ZF, Aptiv, and Hyundai MOBIS believed 
the proposed no-contact requirement was not practicable and suggested 
harmonization with UNECE Regulation No. 152. Generally, those opposed 
to the no-contact requirement supported hybrid or speed reduction 
approaches.\43\
---------------------------------------------------------------------------

    \43\ A kind of hybrid approach would maintain no-contact 
requirements for lower-mid-range speeds while permitting contact at 
higher speed if acceptable speed reductions that reduce the risk of 
serious injury can be achieved in the higher-speed scenarios.
---------------------------------------------------------------------------

    ZF, HATCI, and Aptiv supported the ability to manually deactivate 
the AEB system and recommended harmonization with UNECE Regulation No. 
152 deactivation criteria. Imagry opposed the entirety of the NPRM as 
drawing resources and development away from fully autonomous driving, 
while Autotalks supported the regulation as ``urgently needed.''
    Finally, most individual commenters expressed general support to 
the goals of this rule, citing the vulnerability of pedestrians on or 
near roadways. A significant portion of these commenters also noted 
that children, people with dark skin tones, and those using a 
wheelchair or mobility device are particularly vulnerable. Individual 
commenters opposed to this rule cited concerns about off-road operation 
and false activation.

D. Summary of the Notice of Proposed Rulemaking

    NHTSA published the NPRM for this final rule on June 2, 2023 (88 FR 
38632). Because this final rule adopts almost all of the requirements 
proposed in the NPRM, this summary is brief and mirrors the description 
of the final rule provided in the Executive Summary, supra.
    1. The NPRM proposed creating a new FMVSS to require AEB systems on 
light vehicles that can reduce the frequency and severity of both rear-
end and pedestrian crashes. The proposed AEB performance requirements 
were intended to ensure that an AEB system is able to automatically and 
completely avoid collision with the rear of another vehicle or a 
pedestrian in specific combinations of scenarios and speeds, while 
continuing to alert and apply the brakes at speeds beyond those in the 
test procedure.
    2. The NPRM proposed four requirements for the AEB systems. The 
proposed AEB system must: (a) provide the driver with a forward 
collision warning (FCW) at any forward speed greater than 10 km/h (6.2 
mph); (b) automatically apply the brakes at any forward speed greater 
than 10 km/h (6.2 mph) when a collision with a lead vehicle or a 
pedestrian is imminent; (c) prevent the vehicle from contacting the 
lead vehicle (i.e., vehicle test device) or pedestrian test device when 
tested according to the proposed test procedures; and (d) detect AEB 
system malfunctions and notify the driver of any malfunction that 
causes the AEB system not to meet the proposed minimum performance 
requirements of the safety standard.
    3. The NPRM's test procedures evaluate the lead vehicle AEB 
performance, PAEB performance, and two scenarios that evaluate 
situations where braking is not warranted (i.e., false positives). 
Under this proposed requirement, crash avoidance braking is considered 
to have occurred when the automatic portion of the brake activation 
(excluding any manual braking) exceeds 0.25g.
    4. For the lead vehicle AEB performance, the agency proposed three 
test scenarios: lead vehicle stopped, lead vehicle decelerating, and 
lead vehicle slower-moving. Each lead vehicle scenario is tested at 
specific speeds or within specified ranges of speeds to evaluate the 
AEB performance with and without applying manual braking to the subject 
vehicle.
    For the lead vehicle stopped scenario, the agency proposed that the 
subject vehicle must perform when no manual braking is used at speeds 
ranging from 10 km/h to 80 km/h, and from 70 km/h to 100 km/h when 
manual braking is used. The subject (and lead vehicle) speeds proposed 
for the decelerating lead vehicle scenario were 50 km/h and 80 km/h 
while the proposed range of lead vehicle deceleration was 0.3 g to 0.5 
g. Additionally, for the decelerating lead vehicle scenario, the agency 
proposed a headway range of 12 m to 40 m for each of the two subject 
vehicle speeds. For the slower-moving lead vehicle scenario, a subject 
vehicle must perform at speeds ranging from 40 km/h to 80 km/h when no 
manual braking

[[Page 39701]]

is used, while a subject vehicle must perform at speeds ranging from 70 
km/h to 100 km/h when manual braking is used.
    5. For the assessment of PAEB performance, the proposed test 
procedures evaluate the subject vehicle in three pre-crash scenarios 
involving pedestrians: (a) where the pedestrian crosses the road in 
front of the subject vehicle, (b) where the pedestrian walks alongside 
the road in the path of the subject vehicle, and (c) where the 
pedestrian stands in the roadway in front of the subject vehicle. The 
NPRM proposed a specified range of speeds in both daylight and darkness 
lighting conditions with lower and upper beam headlamps activated.
    6. NHTSA proposed that AEB systems continuously detect system 
malfunctions. If an AEB system detects a malfunction that prevents it 
from performing its required safety function, the vehicle would 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 considers a malfunction to include any 
condition in which the AEB system fails to meet the proposed 
performance requirements. NHTSA proposed that the driver 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.
    7. With respect to compliance dates, the NPRM proposed that 
vehicles manufactured on or after September 1, three years after the 
publication date of a final rule, but before September 1, four years 
after the publication date of a final rule, would be required to meet 
all requirements except that lower speed PAEB performance test 
requirements. Vehicles manufactured four years after the publication 
date of a final rule would be required to meet all requirements 
specified in the final rule. NHTSA proposed that small-volume 
manufacturers, final-stage manufacturers, and alterers would be 
provided an additional year of lead time for all requirements.

E. Additional Research Conducted in 2023

    While past testing conducted in support of the NPRM provided ample 
support for the proposed performance requirements, NHTSA conducted 
additional research in 2023, which included an evaluation of the newest 
vehicles available on the market.\44\ The new research confirmed that 
AEB and PAEB performance maintained good performance when compared with 
previous testing. This research used three test scenarios to evaluate 
the AEB performance of six light vehicles. The vehicles tested included 
the 2023 BMW iX, 2023 Ford F-150 Lightning, 2023 Hyundai Ioniq 5 
Limited, 2024 Mazda CX-90 Turbo S, 2023 Nissan Pathfinder SL, and the 
2023 Toyota Corolla Hybrid XLE. The lead vehicle testing evaluated the 
effects of regenerative braking settings for electric (and some hybrid) 
vehicles, adaptive cruise control settings, and ambient lighting 
conditions on the AEB performance of these vehicles.
---------------------------------------------------------------------------

    \44\ NHTSA's 2023 Light Vehicle Automatic Emergency Braking 
Research Test Summary and NHTSA's 2023 Light Vehicle Pedestrian 
Automatic Emergency Braking Research Test Summary, available in the 
docket for this final rule (NHTSA-2023-0021).
---------------------------------------------------------------------------

    The lead vehicle scenarios used in this research included the 
proposed conditions of lead vehicle stopped, moving, and decelerating. 
All conditions and parameters for this research were consistent with 
those described in the proposed rule. For nominal testing (tests not 
designed to investigate a particular condition or parameter) the Toyota 
used in this research avoided contacting the vehicle test device at all 
speeds tested from 10 km/h to 80 km/h (50 mph) in the lead vehicle 
stopped condition. The Mazda avoided contacting the lead vehicle test 
device in all lead vehicle stopped conditions up to 60 km/h (37.5 mph).
BILLING CODE 4910-59-P

[[Page 39702]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.015


[[Page 39703]]


    The Toyota, BMW, and Hyundai avoided contacting the lead vehicle 
test device in the lead vehicle moving scenarios for all speeds tested. 
The Mazda contacted the test device in a single trial at 80 km/h (50 
mph) while avoiding contact in all other tested conditions including 4 
other trials conducted at 80 km/h.
---------------------------------------------------------------------------

    \45\ SV is short for ``subject vehicle.''
    \46\ POV is short for ``principal other vehicle.''
    [GRAPHIC] [TIFF OMITTED] TR09MY24.016
    
    For the lead vehicle decelerating scenario, the BMW did not contact 
the lead vehicle test device in any tested condition while the Toyota 
contacted the test device during three of the five trials performed at 
80 km/h. Other vehicles contacted the test device as shown in the table 
below.

[[Page 39704]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.017

    The agency also studied lead vehicle AEB performance in darkness. 
Results from the dark ambient lighting tests are shown in the table 
below. The lead vehicle stopped scenario was used for all day/darkness 
comparative tests. The results observed during the dark ambient tests 
were largely consistent with those produced during the daylight tests. 
The dark versus day contact results observed for a given test speed 
were identical or nearly identical for the Hyundai, Mazda, Nissan, and 
Toyota. Where impacts occurred, the impact speeds were very close.

[[Page 39705]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.018

    The agency also studied the effects of regenerative braking 
settings for electric and hybrid electric vehicles on the performance 
of lead vehicle AEB. Again, the lead vehicle stopped test scenario was 
used for this comparison. The

[[Page 39706]]

regenerative braking settings did not have a negative effect on the 
performance of the tested AEB systems. As expected, performance under 
the highest regenerative braking settings was slightly better that the 
lower, or off, settings. However, the effect of regenerative brake 
setting on the vehicle's ability to avoid contact with the lead vehicle 
test device was dependent on the vehicle tested.
[GRAPHIC] [TIFF OMITTED] TR09MY24.019


[[Page 39707]]


[GRAPHIC] [TIFF OMITTED] TR09MY24.020

    The agency also conducted additional PAEB testing. The same 
vehicles used for the lead vehicle testing presented above were used to 
evaluate their PAEB performance consistent with the proposed rule. The 
results of this testing

[[Page 39708]]

are summarized in the table below. The table provides the maximum speed 
tested at which the vehicle avoided contacting the pedestrian test 
device. Of specific note, one vehicle avoided contacting the pedestrian 
test device at all speeds tested. Some vehicles contacted the test 
device at 10 km/h but under further testing, demonstrated the ability 
to avoid contacting the pedestrian test device at much higher speeds. 
Further details of this testing and additional results are available in 
the report contained in the docket provided at the beginning of this 
final rule.
[GRAPHIC] [TIFF OMITTED] TR09MY24.021

BILLING CODE 4910-59-C

III. Final Rule and Response to Comments

A. Summary of the Final Rule (and Modifications to the NPRM)

    With a few notable exceptions, this final rule adopts the 
performance requirements from the proposed rule. This rule requires 
manufacturers to install AEB systems that meet specific performance 
requirements. These performance requirements include the installation 
of an AEB system, track testing requirements for avoiding both lead 
vehicles and pedestrians, false activations test requirements, and 
malfunction indication requirements.
    This final rule includes four requirements for AEB systems for both 
lead vehicles and pedestrians. First, there is an equipment requirement 
that vehicles have an AEB system that provides the driver with an FCW 
at any forward speed greater than 10 km/h (6.2 mph) and less than 145 
km/h (90.1 mph). The FCW must be presented via auditory and visual 
modalities when a collision with a lead vehicle or a pedestrian is 
imminent. This final rule includes specifications for the auditory and 
visual warning components consistent with those of the proposed rule, 
with some modifications to keep the effectiveness of the FCW while 
reducing the potential costs associated with this rule for some vehicle 
designs. Similarly, this final rule includes an equipment requirement 
that light vehicles have an AEB system that applies the brakes 
automatically at any forward speed that is greater than 10 km/h (6.2 
mph) and less than 145 km/h (90.1 mph) when a collision with a lead 
vehicle is imminent, and at any forward speed greater than 10 km/h (6.2 
mph) and less than 73 km/h (45.4 mph) when a collision with a 
pedestrian is

[[Page 39709]]

imminent. The maximum speed of lead vehicle AEB is modified from the 
NPRM, which did not include upper limits on speeds. NHTSA also 
clarified that this requirement applies only when environmental 
conditions permit.
    Second, the AEB system is required to prevent the vehicle from 
colliding with the lead vehicle or pedestrian test devices when tested 
according to the standard's test procedures. These track test 
procedures have defined parameters, including travel speeds up to 100 
km/h (62.2 mph), that ensure that AEB systems prevent crashes in a 
controlled testing environment. The three scenarios for testing 
vehicles with a lead vehicle and four scenarios for testing vehicles 
with a pedestrian test device are finalized as proposed. The agency has 
finalized pedestrian tests in both daylight and darkness, while testing 
using the lead vehicle test device is conducted in daylight only as 
proposed.
    Third, this final rule includes the two false activation tests, 
driving over a steel trench plate and driving between two parked 
vehicles, in which the vehicle is not permitted to brake in excess of 
specified amounts proposed in the NPRM.
    Finally, a vehicle must detect AEB system malfunctions and notify 
the driver of any malfunction that causes the AEB system not to meet 
the minimum proposed performance requirements. The system must 
continuously detect system malfunctions, including performance 
degradation caused solely by sensor obstructions. If the system detects 
a malfunction, or if the system adjusts its performance such that it 
will not meet the requirements of the finalized standard, the system 
must provide the vehicle operator with a telltale notification. This 
final rule has also clarified that the purpose of the malfunction 
telltale is to provide information about the operational state of the 
vehicle. Some commenters understood the NPRM to have required that the 
malfunction telltale activate based on information about the vehicle's 
surroundings such as low friction road surfaces.
    This final rule includes several changes to the NPRM based on the 
comments received:
    First, NHTSA includes in this final rule an explicit prohibition 
against manufacturers installing a control designed for the sole 
purpose of deactivating the AEB system but allows for controls that 
have the ancillary effect of deactivating the AEB system (such as 
deactivating AEB if the driver has activated ``tow mode'' and the 
manufacturer has determined that AEB cannot perform safely while 
towing).
    NHTSA also modifies the FCW visual signal location requirement in 
this final rule to increase the specified visual angle from 10 degrees 
to 18 degrees in the vertical direction. This change from the NPRM 
provides manufacturers with the flexibility to locate the visual 
warning signal within the typical area of the upper half of the 
instrument panel and closer to the central field of view of the driver. 
While the agency continues to believe that an FCW visual warning signal 
presented near the central forward-looking region is ideal, it does not 
consider a head-up display to be necessary for the presentation of the 
FCW visual signal.
    In addition, NHTSA modifies in this final rule the range of forward 
speeds at which the AEB must operate. The NPRM required FCW and AEB 
systems to operate at any forward speed greater than 10 km/h. This 
final rule places an upper bound on the requirement that an AEB system 
operate of 145 km/h (90.1 mph) for FCW and lead vehicle AEB and 73 km/h 
(45.4 mph) for pedestrian AEB. This final rule also clarifies the 
environmental conditions under which the AEB system must perform to be 
the same environmental conditions specified in the track testing.
    NHTSA also makes a minor adjustment in this final rule to the 
measurement method used to characterize the radar cross-section for the 
pedestrian test devices. It maintains the cross-section boundaries 
contained within the proposed rule as incorporated from ISO 19206-
2:2018 but uses parts of the updated measurement method incorporated 
from ISO 10206-3:2021. This newer method was proposed for use in 
measuring the vehicle test device, while the older measurement method 
was proposed for the pedestrian test devices. The newer method provides 
for better filtration of noise by using average measurements taken at 
three radar heights as opposed to the single measurement height 
specified in the older method. This final rule modifies the measurement 
methods for the pedestrian test device to match the method used when 
characterizing the vehicle test device.
    Finally, this final rule makes a few significant changes to the 
lead-time and phase-in requirements. Instead of the deadline proposed 
under the NPRM, this final rule requires that manufacturers comply with 
all provisions of the rule at the end of the 5-year period starting the 
first September 1 after this publication. This will provide 
manufacturers with more time to meet the requirements of this final 
rule, as most vehicles do not currently meet all of the performance 
requirements set forth in this final rule and in light of manufacturer 
redesign schedules. The added lead time avoids significantly increasing 
the costs of the rule by compelling equipment redesigns outside of the 
normal production cycle.
    As part of this extension of the lead time, the agency has removed 
the phase-in approach to the PAEB performance requirements. While the 
NPRM proposed the most stringent PAEB requirements be met 4 years after 
a final rule (1 year more than all the other requirements), the agency 
is finalizing a 5-year lead time for all requirements (eliminating the 
phasing in of requirements during the lead time).

B. Application

    NHTSA proposed that the new FMVSS No. 127 apply to all passenger 
cars and to all multipurpose passenger vehicles, trucks, and buses with 
a GVWR of 4,536 kilograms (10,000 pounds) or less. The agency did not 
propose that the new FMVSS apply to vehicles with a GVWR over 4,536 
kilograms (10,000 pounds) or to include motorcycles or low-speed 
vehicles.
Vehicle Body Types
    Several commenters requested that NHTSA consider various vehicle 
types in the application of the new FMVSS. The Alliance noted that the 
agency's analysis focused only on performance for sedan, SUV and 
crossover, and pickup vehicles, and did not consider the constraints 
associated with the installation of sensors on vehicles with certain 
vehicle designs such as sports cars, which may affect system 
capabilities based on unique design characteristics and low profile. 
FCA noted that the NPRM did not include the low-speed vehicle (LSV) 
class and supported their inclusion in this rule, in part based on the 
inclusion of LSVs in the most recent modifications to FMVSS No. 111 and 
FMVSS No. 141.
    While NHTSA acknowledges the Alliance's concerns that mounting 
forward-looking sensors on certain vehicle body types, such as sports 
cars, may present some challenges, we believe that technology already 
present on some existing production vehicles can be adapted to address 
the concern. We also believe that 5 years provides adequate lead time 
for manufacturers to consider the changes necessary to their models to 
implement AEB. We further note that manufacturers are not restricted as 
to sensor placement. Existing production vehicles have sensors located 
in a variety of places. NHTSA is aware of several vehicles

[[Page 39710]]

equipped with radar and camera sensors mounted in the cabin near the 
rearview mirror. Such a sensor configuration would avoid the 
installation constraints imposed by small bumpers, avoid placement 
behind carbon fiber material, and accommodate placement further above 
the ground.
    Regarding FCA's comment, LSVs were excluded from the scope of the 
final rule for several reasons. First, there are no LSVs on the market 
that NHTSA is aware of that are currently equipped with AEB or PAEB. 
This means that NHTSA was not able to procure a vehicle for testing or 
otherwise evaluate how a LSV would perform if equipped with AEB/PAEB. 
Second, there is a lack of specific safety data to support an argument 
that LSVs should be equipped with AEB/PAEB. NHTSA does not want to 
preclude such vehicles from being equipped with these safety systems, 
but the current safety data does not provide justification for 
including them in this rule. Finally, and as discussed in the FRIA, 
LSVs were not included due to uncertainty about the feasibility and 
practicability of AEB for those vehicles. Although LSVs were included 
in the two most recent standard of significance (FMVSS 111 Backup 
Camera and FMVSS 141 Sound for Electric Vehicles) without 
practicability concerns, we note that those standards include 
requirements that provide aids to assist the driver or alerts the 
driver. In such cases, those features do not require the vehicle to 
react but instead elicit a driver reaction. As these vehicles were not 
included in the testing conducted by the agency, our analysis is unable 
to characterize the performance of AEB on these vehicles. Therefore, in 
the absence of any data to characterize how these systems may perform 
on LSVs, they were not included in the final rule.
Heavier Vehicles
    The Alliance and FCA commented about the interaction between the 
proposed standard and FMVSS Nos. 105 and 135, which regulate braking. 
The Alliance recommended a comprehensive review of the impact of the 
proposed rule with appropriate accommodations to exclude or include a 
cap on the applicability of the proposal based on vehicle weight. The 
Alliance stated that typical electronic stability control (ESC) systems 
may not provide the fluid flow rates needed to produce the braking 
performance necessary to meet the proposed rule. FCA noted that the 
proposed standard applies to vehicles between 7,716 pounds GVWR (the 
upper limit for FMVSS No. 135 application) and 10,000 pounds GVWR, 
opining that this proposed standard is not intended to force changes in 
the underlying braking performance of vehicles in that range and noting 
that testing has not been conducted on vehicles over 7,000 pounds GVWR. 
FCA suggested limiting application of proposed FMVSS No. 127 to 
vehicles under 7,716 pounds GVWR.
    NHTSA evaluated compliance test results for FMVSS No. 135 conducted 
over the last several years. There were 30 vehicles included in this 
testing, including small sedans, large pickup trucks, minivans, SUVs 
and other vehicle types to which this new FMVSS would apply. The 
results indicate that the braking performance of nearly all vehicles 
was much better than what FMVSS No. 135 requires and the average 
deceleration for the larger pickup trucks also outperformed some of the 
smaller sedans, SUVs, and minivans. These test results indicate that 
braking performance is more than sufficient to permit compliance with 
this final rule without a need for braking changes or supplements. 
While this rule is not intended to force changes in the underlying 
braking performance of vehicles, the commenters stopped short of 
asserting that braking improvements would be necessary, stating only 
that improvements may be necessary. Moreover, even if underlying 
braking performance improvements were necessary, nothing in the 
comments suggests that there are any technical barriers or any other 
impediments that would make such improvements infeasible.
Automated Driving Systems
    Several commenters suggested exempting vehicles with automated 
driving systems from the application of some or all of the proposed 
FMVSS No. 127. Volkswagen recommended exempting autonomous vehicles 
(AVs) from the parts of the regulation that involve displaying warnings 
and the parts for which manipulation of manual controls is part of the 
test procedure. Similarly, AVIA requested that the forward collision 
warning requirements not apply to AVs.
    Zoox requested that the proposed FMVSS not apply to AVs. Zoox 
viewed the proposed rule as directed toward human drivers, and that 
applying it to AVs may result in unintended consequences, such as 
establishing emergency collision avoidance standards for AVs without 
considering other avoidance tools available to AVs, thereby 
constraining their safety capabilities.
    AVIA also provided suggested changes to the proposed application 
language that would exclude vehicles equipped with ADS from the 
requirement to have an AEB system if the ADS meets the performance 
requirements of the proposed standard. The Alliance commented that ADS-
equipped vehicles without manual controls should be exempt from the 
driver warning and DBS requirements, which it viewed as relevant only 
when there is a human driver and similarly that the DBS requirements 
should be applicable only if a brake pedal is installed or required to 
be installed in the vehicle.
    NHTSA expects that ADS-equipped vehicles are capable of meeting the 
performance requirements of this rule, especially those related to 
identifying crash imminent situations with vehicles and pedestrians and 
applying the brakes to avoid contact. Volkswagen is correct that NHTSA 
is considering how to address telltales, alerts, and warnings, like 
FCW, in the context of vehicles driven by ADS.\47\ While NHTSA 
continues to engage in research to support the related rulemakings 
evaluating the application of existing FMVSS to ADS-equipped vehicles, 
NHTSA is finalizing this rule for all light vehicles and will consider 
future modifications regarding telltales, alerts, and warnings, as well 
as crash avoidance standards, generally, for ADS-equipped vehicles as 
needed under separate rulemaking efforts.\48\
---------------------------------------------------------------------------

    \47\ See https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM07.
    \48\ See https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM00.
---------------------------------------------------------------------------

C. Definitions

    The proposed rule contained key definitions to facilitate the 
understanding of the rule. While there were 15 proposed definitions 
included in section S4 of the proposed new FMVSS, this section focuses 
on those raised in comments.
AEB System
    The NPRM defined an automatic emergency braking system as 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. Several 
commenters recommended changes to the definition of AEB system:
    Bosch asked NHTSA to consider adopting the definition of ``Advanced 
Emergency Braking System (AEBS)'' used in United Nations Regulation No. 
152 (UNECE R152) to promote global harmonization and enhance clarity in

[[Page 39711]]

the terminology used across various jurisdictions.
    Porsche and Volkswagen stated that the AEB system requirements 
throughout the NPRM require performance metrics specific to mitigating 
collisions with lead vehicles and pedestrians, generally not mitigating 
collisions with objects, but the proposed definition for AEB includes 
reference to ``objects'' and ``road users.'' Specifically, Porsche 
referred to the requirements that the vehicle is required not to apply 
braking when encountering a steel trench plate. Porsche expressed 
concern that, by including ``object,'' the AEB definition could 
introduce confusion in whether braking could be applied in false 
activation tests. Volkswagen noted that the trench plate could be 
categorized as an ``object.'' Bosch commented that the broad definition 
poses challenges in requiring that there is no collision with any 
``object.''
    In reference to the term ``road users,'' Porsche and Volkswagen 
commented that the NPRM referenced pedestrians and was not more broadly 
inclusive of other road-users such as bicyclists. Both recommended 
replacing the term ``road user'' with ``pedestrian'' to align with the 
proposed requirements. Bosch did not specifically address the term 
``road users,'' but recommended that NHTSA replace ``object'' with 
``pedestrian'' in the proposal for more clarity and consistency in the 
context of the FCW and AEB system.
    An anonymous commenter stated that the AEB system definition does 
not specify what constitutes a ``crash imminent situation'' or how the 
system determines if the driver has not applied the brakes, or how much 
braking force is applied to the system. This commenter noted that these 
are important details that may affect the performance and effectiveness 
of the AEB system.
    BIL requires that an FCW system alert the driver if there is a 
``vehicle ahead or an object in the path of travel'' if a collision is 
imminent. Consistent with this definition, NHTSA defines an AEB system 
as one that detects an imminent collision with a vehicle or with an 
object. However, nothing in the definition of AEB system requires 
vehicles to detect and respond to imminent collisions with all vehicles 
or all objects in all scenarios. Such a requirement would be 
unreasonable given the wide array of harmless objects that drivers 
could encounter on the roadway that do not present safety risks.
    The agency has reviewed the various definitions used in the NPRM to 
assess whether meaningful harmonization could be achieved with UNECE 
regulations. In UNECE Regulation No. 152, ``Advanced Emergency Braking 
System (AEBS)'' means a system which can automatically detect an 
imminent forward collision and activates the vehicle braking system to 
decelerate the vehicle with the purpose of avoiding or mitigating a 
collision. The definition proposed in the NPRM is functionally very 
similar, but uses language from BIL. Unlike UNECE Regulation No. 152, 
NHTSA's definition also provides a level of clarity as to where the 
detection of vehicles, objects, and road users must occur, that is ``in 
or near the path of a vehicle.''
    The commenters' concern that this definition requires detection of 
and reaction to ``all objects'' is unfounded. NHTSA has also considered 
the use of the term ``road users'' in the AEB definition. NHTSA is 
aware of manufacturers that have designed AEB systems to detect 
pedestrians. However, the performance requirements make clear that this 
final rule requires detection and reaction to pedestrians and lead 
vehicles. The use of ``objects'' and ``road users'' merely identify 
potential hazards on a road that may require emergency braking, but are 
not intended to impose requirements beyond the requirements set forth 
in the standard.
    The agency considered comments seeking inclusion of various 
performance requirements in the definitions section. Those comments did 
not explain why such a change is necessary. As a general matter of 
regulatory structure, NHTSA limits the definition section to defining 
terms; the operative regulatory text is the appropriate location for 
performance requirements and other directives of substantive effect.
    Therefore, NHTSA adopts the proposed definition of AEB, which is 
defined as 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.
Forward Collision Warning
    The NPRM defined forward collision warning as an auditory and 
visual warning provided to the vehicle operator by the AEB system that 
is designed to induce immediate forward crash avoidance response by the 
vehicle operator.
    Consistent with its comment about alignment of the definition of 
AEB with UNECE R152, Bosch recommended that NHTSA adopt UNECE R152's 
Collision Warning definition for the FCW definition: ``a warning 
emitted by the [Advanced Emergency Brake System] AEBS to the driver 
when the AEBS has detected a potential forward collision.''
    NHTSA has finalized the definition of FCW as an auditory and visual 
warning provided to the vehicle operator by the AEB system that is 
designed to induce immediate forward crash avoidance. This definition 
provides clarity that both an auditory and visual warning are necessary 
for a complete warning that is most likely to reengage a distracted 
driver. For purposes of the test procedure established in this final 
rule, if only the visual or only the auditory component of the FCW is 
provided, then the FCW onset has not happened, and the test procedure 
steps will not take place until both the auditor and visual components 
are both in place. As such, the UNECE R152 definition suggested by the 
commenters does not provide this needed clarity.
    Zoox also recommended changes to the FCW definition to clarify 
applicability to conventional vehicles with human drivers only. As 
noted above, NHTSA is finalizing this rule for all light vehicles and 
will consider future modifications regarding telltales, alerts, and 
warnings, as well as crash avoidance standards, generally, for ADS-
equipped vehicles as needed under separate rulemaking efforts. Because 
NHTSA is not adjusting requirements to accommodate ADS, no definition 
changes are required to address this issue.
Onset
    Commenters requested clarification or addition to the definitions 
to further clarify the proposed requirements and test procedures. The 
NPRM defined ``forward collision warning onset'' as the first moment in 
time when a forward collision warning is provided. Automotive Safety 
Council sought clarification whether this would be measured in terms of 
a signal output on the Controller Area Network (CAN) bus, or measured 
by sound physically emitted from the speaker. NHTSA clarifies that FCW 
onset would be determined via measurement of the FCW auditory signal 
sound output within the vehicle cabin and the illumination of the FCW 
visual signal. CAN bus information would not be used to assess FCW 
onset.
    The NPRM did not provide a definition of braking onset. Humanetics 
stated that the term ``vehicle braking onset'' needed further 
clarification in all test protocols. Humanetics suggested a target 
value of speed change or deceleration value should be used as an 
indicator of the time of braking onset.

[[Page 39712]]

    NHTSA has decided to clarify the term ``vehicle braking onset'' in 
the regulation text as Humanetics suggested, by defining the ``subject 
vehicle braking onset'' as the point at which the subject vehicle 
achieves a deceleration of 0.15g due to the automatic control of the 
service brakes. To ensure clarity in the PAEB test procedure, NHTSA has 
used the term ``subject vehicle braking onset'' to clarify that NHTSA 
is referring to the vehicle braking onset of the subject vehicle. The 
0.15g deceleration was adopted based on the agency's experience 
conducting AEB testing as this value has proven a reliable marker for 
PAEB onset during track testing.\49\
---------------------------------------------------------------------------

    \49\ https://www.regulations.gov/document/NHTSA-2021-0002-0002.
---------------------------------------------------------------------------

Other Definitions
    NHTSA does not believe that any further additional definitions are 
necessary for manufacturers to understand the performance requirements 
of the standard or their obligations. NHTSA believes that terms 
appearing within the proposed definitions are sufficiently clear from 
the context of the regulation. For example, we believe the meaning of 
``crash imminent situation'' is discernable from close review of the 
performance requirements, including the test procedures; from these, 
the commenter can determine what the agency would consider crash 
imminent for the set of testable ranges included in this rule.
    Finally, NHTSA acknowledges Consumer Reports' and AAA's requests to 
limit the use of the terms CIB and DBS. NHTSA has already done this by 
excluding those terms from the regulatory text. While NHTSA used CIB 
and DBS throughout the preamble to the NPRM and in this final rule, it 
is doing so because these terms are frequently used by industry, and 
their use in the preamble helps readers understand what NHTSA is 
saying, particularly in the context of prior research and NCAP, which 
use those terms.

D. FCW and AEB Equipment Requirements

    NHTSA proposed that an FCW must provide the driver warning of an 
impending collision when the vehicle is traveling at a forward speed 
greater than 10 km/h (6.2 mph). Similarly, the NPRM require a vehicle 
to have an AEB system that applies the service brakes automatically 
when a collision with a lead vehicle or pedestrian is imminent at any 
forward speed greater than 10 km/h (6.2 mph). NHTSA stated in the NPRM 
that this minimum speed should not be construed to prevent a 
manufacturer from designing an AEB system that activates at speeds 
below 10 km/h (6.2 mph).
    This proposed requirement was described as an equipment requirement 
with no associated performance test. No specific speed reduction or 
crash avoidance would be required. However, this requirement was 
included to ensure that AEB systems are able to function at all times, 
including at speeds above those NHTSA proposed as part of the 
performance test requirements where on-track testing is currently not 
practicable. NHTSA received comments regarding both the minimum 
required activation speed and the lack of maximum activation speed.
1. Minimum Activation Speed
Comments
    MEMA supported not having FCW and AEB performance requirements at a 
speed below 10 km/h (6 mph), opining that AEB systems do not offer 
consistent performance at such low speeds.
    Bosch and Volkswagen suggested changing the FCW minimum activation 
speed to 30 km/h. Bosch believed that FCW may not be beneficial at 
lower speeds because the AEB system proves to be a sufficient solution. 
Bosch stated that at lower velocities no driver reaction is required 
because the AEB intervention can fully avoid the collision after the 
``last time to steer'' has already occurred. According to Bosch, as the 
vehicle speed increases, from 30 km/h upwards, the last point to steer 
gradually moves to a point after the last point to brake. In effect, a 
driver warning then becomes beneficial, and FCW can help the driver 
take appropriate action to avoid or mitigate a collision.
    Volkswagen stated that setting a requirement for FCW at low speeds 
can lead to high false positive rates. Volkswagen also noted that 
meeting the proposed performance requirements depended on the FCW being 
issued before the activation of AEB, and could lead to very sensitive 
system behavior, especially for PAEB. Volkswagen suggested increasing 
the minimum FCW activation speed to 30 km/h, but suggested it would 
still be acceptable to display the FCW symbol simultaneously with AEB 
activation at speeds below 30 km/h to make the driver aware of the 
event that just occurred.
    The Center for Auto Safety disagreed with the 10 km/h minimum speed 
threshold saying that it was not clear why it was selected. The Center 
for Auto Safety commented that PAEB should be activated as soon as the 
vehicle is shifted into gear to avoid injurious or fatal rollovers of 
children and other hazards. Consumer Reports commented that it 
understood the technical reasons for the proposed minimum speed of 10 
km/h (6.2 mph), but expressed concern that such a lower speed bound 
would fail to address the issue of what it described as ``frontover'' 
incidents.\50\ Consumer Reports said there had been an increase in 
``frontover'' incidents since 2016, and that it believed that the 
increasing market share of larger vehicles with increased blind zones 
was correlated with this increase.
---------------------------------------------------------------------------

    \50\ There is not yet a finalized definition of ``frontover'' 
that is used within NHTSA or outside of NHTSA, and NHTSA is 
currently researching how this crash type should be defined. As 
NHTSA previously indicated, until more data is gathered via the Non-
Traffic Surveillance (NTS) system, actual frontover crash counts are 
difficult to confirm due to the challenges law enforcement faces in 
distinguishing these crashes from other forward moving vehicle 
impacts with non-motorists and to the locations where these crashes 
often occur. For example, a forward moving vehicle crash involving a 
driver turning into a driveway and striking a child playing in the 
driveway would typically not be considered a frontover; but if that 
driver struck the child while pulling out of a garage (having backed 
into the garage), it would be considered a frontover. These nuances 
pose difficulties for law enforcement to accurately capture 
frontover incidents which, in turn, complicates our data collection. 
Additionally, frontover crashes frequently occur in driveways and 
parking lots that are not located on the public trafficway; thus, 
law enforcement may not report these occurrences using a crash 
report.
---------------------------------------------------------------------------

Agency Response
    NHTSA is finalizing a minimum activation speed of 10 km/h as 
proposed. The agency considered increasing this minimum to 30 km/h, as 
suggested by some commenters, to avoid unwanted and unnecessary alert 
at low speeds. However, after considering the potential impacts of such 
a modification, particularly the safety of pedestrians, the agency is 
finalizing the minimum activation speed as proposed for the forward 
collision warning. This 10 km/h minimum threshold is also harmonized 
with UNECE Regulation No. 152. Furthermore, as stated in the NPRM, 6 of 
11 manufacturers whose owner's manuals NHTSA reviewed indicated that 
their AEB system have a minimum speed below 10 km/h. NHTSA is 
encouraged that manufacturers are choosing to have lower speed 
thresholds for AEB functionality.
    As for frontover crashes, NHTSA agrees with Consumer Reports about 
the importance of understanding driver visibility and about the need to 
reduce such crashes. Additional research is needed to develop accurate 
and rigorous methods of evaluating direct visibility

[[Page 39713]]

from the driver's seat. Research is also needed to better understand 
the safety problem and the scenarios associated with forward blind 
zones and frontover crashes. Beginning in January 2023, two new non-
traffic crash data elements related to backovers \51\ and frontovers 
were added to the agency's Non-Traffic Surveillance System, which will 
enhance evaluation of the scope and factors associated with frontover 
crashes.
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    \51\ NHTSA has previously defined backover crashes as crashes 
where non-occupants of vehicles (such as pedestrians or cyclists) 
are struck by vehicles moving in reverse. See https://www.federalregister.gov/documents/2014/04/07/2014-07469/federal-motor-vehicle-safety-standards-rear-visibility.
---------------------------------------------------------------------------

2. Maximum Activation Speed
Comments
    The National Transportation Safety Board (NTSB) supported the 
proposed requirements for FCW, specifically pertaining to the necessity 
of the warning at all speeds above 10 km/h, but the NTSB stated that 
FCW activation must never delay AEB engagement. NTSB stated that its 
support was rooted in several NTSB investigations of vehicles operating 
in partial automation mode at the time of the crash.
    In contrast, many commenters raised substantial concerns about the 
proposed NPRM requirement that FCW and AEB function, at least at some 
level, at all speeds and under all environmental conditions. Among 
these concerns was that the requirement would not meet various aspects 
of the Safety Act.
    The Alliance disagreed with the agency setting undefined 
performance requirements that are not stated in objective terms 
consistent with 49 U.S.C. 30111 and urged NHTSA to provide 
clarification when issuing a final rule that compliance verification 
will be measured only by defined test procedures that meet established 
criteria for rulemaking. It objected to what it viewed as undefined 
performance requirements without a clearly demonstrated safety need 
that create significant challenges from a product development 
perspective, making it unclear whether or how NHTSA might seek to 
verify compliance. Without defined and objective criteria, the Alliance 
thought that policy uncertainty would create ambiguity about potential 
enforcement actions as there would be no clear parameters to reliably 
measure performance.
    The Alliance suggested that a defined upper bound or maximum 
operational speed for the AEB/PAEB system was needed due to the 
possible unstable vehicle dynamics that could result from hard braking 
at very high speeds. Furthermore, the Alliance opposed open-ended 
performance requirements through regulation without objective test 
procedures, noting that it becomes increasingly more challenging to 
provide significant levels of speed reductions at higher speeds, and it 
viewed the expectation that manufacturers are capable of providing 
undefined levels of avoidance at all speeds as neither practicable nor 
reasonable. According to the Alliance, requirements that exceed the 
current speed ranges must be supported by relevant data to support 
practicability and must include defined and objective test procedures. 
The Alliance noted that the complexity of designing systems capable of 
going beyond what the agency proposes to test would likely result in 
significant development costs that are not accounted for in the 
agency's cost-benefit analysis and that would add unnecessary costs for 
consumers, while diverting research and development efforts from other 
priority areas that may yield greater improvements in vehicle safety.
    Multiple automakers expressed similar concerns, some recommending 
that NHTSA limit AEB activation to maximum speeds and several 
specifying suggested upper bounds. For example, Honda suggested that 
NHTSA limit AEB activation to when the vehicle is traveling at maximum 
135 km/h (84 mph) when approaching a lead vehicle traveling at maximum 
75 km/h (47 mph) and limit pedestrian AEB activation to when the 
vehicle is traveling at maximum 88 km/h (55 mph). Porsche suggested 
that for the lead vehicle, DBS apply to speeds above 100 km/h (62 mph) 
and for pedestrians to speeds above 65 km/h (40 mph), and that crash 
imminent braking (CIB) be required to operate between 10 km/h (6 mph) 
and 100 km/h (62 mph) for lead vehicle and between 10 km/h (6 mph) and 
65 km/h (40 mph) for pedestrian. Porsche also provided suggested 
regulatory text.\52\
---------------------------------------------------------------------------

    \52\ https://www.regulations.gov/comment/NHTSA-2023-0021-0868.
---------------------------------------------------------------------------

    NTSB expressed similar concerns about the need for testing, stating 
that without a dedicated test protocol or an explicit statement about 
the extent of operational functionality, broader capabilities (above 
the testing requirements) remain only presumed and not necessarily 
expected. NTSB encouraged NHTSA to clarify its intent and expectations 
for system performance in scenarios and conditions outside the proposed 
test-track compliance testing by considering additional testing or 
other compliance tools to examine the performance of AEB systems under 
other real-world conditions, and particularly whether the operational 
functionality would extend to non-tested hazards such as traffic safety 
hardware, bicyclists and motorcyclists, and vehicles with untested 
profiles or at varying angles and offsets.
    Commenters raised potential technical challenges to effective 
implementation of the proposed requirement. For example, Honda was 
concerned about AEB and radar sensor limitations when operating at high 
speeds--mainly the complex interdependency between speed and the 
distance and accuracy at which objects must be detected to be avoided 
(or even to mitigate a crash). Honda noted that higher speeds mean that 
objects will need to be detected at greater distances, and at greater 
distances there is less image resolution, greater positional error, and 
greater impact from things like roadway geometry. Honda and Porsche 
stated that requiring braking to occur at unrestricted high speeds 
leads to misidentification of objects and increases false positive 
activations.
    Honda further asserted that camera resolution is limited by the 
pixel count on the image capture chip and that at longer distances, the 
number of pixels for an object will be reduced, resulting in blur that 
makes it difficult to detect objects (the blur can be further 
exacerbated by the designed focal length of the lens). Further, Honda 
stated that a higher resolution can be achieved only through new sensor 
hardware that would require further developmental work as well as more 
processing power, including a change of imaging processing electronic 
control unit (ECU). Honda stated that for camera-radar fusion systems, 
small errors in the fusion algorithm are amplified at higher speeds 
(due to the longer distances) and could compromise the system's 
performance. Additionally, according to Honda, these reductions in 
sensor accuracy significantly increase the risk of misidentification of 
potential objects and may lead to excessive false positive activations, 
potentially creating negative safety consequences. This could include 
situations where the system mistakenly recognizes the same lane as the 
adjacent lane or roadway objects as other vehicles.
    Other commenters also raised concerns about the potential for false 
activations caused by the need for AEB to operate at very high speeds. 
For example, Volkswagen commented that false activation becomes more of 
a risk as speeds increase, and that these risks

[[Page 39714]]

are not controllable, as defined in ISO 26262.
    Commenters raised concerns about whether braking was the most 
appropriate avoidance maneuver in high-speed scenarios. Honda was 
concerned that AEB activation might interfere with other technologies 
such as the Automatic Emergency Steering. Mitsubishi, and Toyota echoed 
the Alliance's concern that in some situations AEB activation while 
traveling at high speed may induce unstable vehicle dynamics. 
Mitsubishi stated that these situations may occur due to unfavorable 
interactions with road surface conditions, road curvature, or for other 
unpredictable reasons. Mitsubishi thought that such activation could 
also lead to unexpected outcomes for a vehicle following the subject 
vehicle.
    Rivian stated that if post-crash review is used to assess 
compliance, it may introduce a number of uncontrollable or subjective 
variables into the compliance evaluation. Rivian opined that post-crash 
review would necessarily involve evaluation of a motor vehicle that is 
no longer a new motor vehicle and that may have been modified or 
altered in a manner to affect the AEB performance. It further noted 
that varying environment or roadway conditions could also impact the 
AEB performance and, without a proper comparison using reference test 
equipment, it would be difficult to identify discrepancies between the 
expected AEB results and the actual results, limiting the technical 
effectiveness of a post-crash review.
    Commenters suggested a number of different solutions to resolve 
their concerns. Most requested that the all-speeds requirement be 
removed. Alternatively, Honda and others (as noted earlier) asked that 
NHTSA establish a maximum speed at which AEB detection performance is 
assessed according to an established test procedure. Volkswagen asked 
that NHTSA exclude activation against vulnerable road users at high 
speeds, believing it would decrease false positive rates significantly. 
Volkswagen thought this could be justified as pedestrians would not be 
expected on the roads with these higher speeds.
Agency Response
Authority Under the Safety Act
    Various commenters asserted that performance requirements without 
objective test criteria were inconsistent with the Safety Act's 
requirements for objectivity and practicability. NHTSA believes that 
these assertions reflect a misunderstanding of the proposal. 
Essentially, NHTSA proposed specific performance requirements for AEB 
within a defined range of speeds (accompanied by specific testing 
procedures) and, separately, an equipment requirement--i.e., a 
requirement for a functioning vehicle AEB system. The proposed 
requirement for a functioning AEB system at all speeds was an equipment 
requirement, not a performance requirement. Case law supports that 
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.\53\ Testing at high speeds is not practical due to 
the dynamics of such testing and testing equipment limitations. As 
detailed in the NPRM, the testing requirement upper speeds are based on 
the capability to safely and repeatably conduct testing. The testing 
devices can only be driven, and can only tolerate impacts, up to 
certain speeds. These edge speeds are the main limiting factor for the 
upper bound of the testing speeds, as testing above those speeds would 
be impractical. NHTSA has previously specified an equipment requirement 
without an accompanying test procedure. For example, under FMVSS No. 
126, NHTSA issued an equipment requirement for understeer and explained 
why a performance test for understeer was too cumbersome for the agency 
and the regulated community.\54\ In the final rule for FMVSS No. 126, 
NHTSA stated that historically, ``the agency has striven to set motor 
vehicle safety standards that are as performance-based as possible, but 
we have interpreted our mandate as permitting the adoption of more 
specific regulatory requirements when such action is in the interest of 
safety.'' \55\
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    \53\ Chrysler Corp. v. Dep't of Transp., OT, 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).
    \54\ 72 FR 17236 (Apr. 6, 2007).
    \55\ Id. at 17299.
---------------------------------------------------------------------------

    There are other FMVSS that contain equipment requirements, 
sometimes in addition to performance requirements. FMVSS No. 111 has 
several requirements that are equipment requirements. S5.1 of FMVSS No. 
111 requires that each passenger car be equipped with an inside 
rearview mirror of unit magnification, which is the equipment 
requirement without an associated test procedure. S5.3 requires that 
any vehicle that has an inside rearview mirror that does not meet the 
performance requirements for field of view included in S5.1.1 must also 
have an outside rearview mirror meeting certain performance 
requirements. FMVSS No. 135 requires that the service brakes shall be 
activated by means of foot control. This is an equipment requirement in 
an FMVSS that also has performance requirements. S5.1 of FMVSS No. 224, 
``Rear impact protection,'' requires trailers and semitrailers with a 
GVWR of 4,536 kg or more to be equipped with a rear impact guard 
certified as meeting FMVSS No. 223, ``Rear impact guards.''
Technical Concerns
    Various commenters raised concerns about technical limitations that 
might create challenges for AEB systems at high speeds, such as sensor 
limitations, false activations, and whether hard braking was an 
appropriate response at higher speeds.
    NHTSA is aware, from a review of owner's manuals, that many 
manufacturers have equipped their vehicles with AEB systems that 
activate at speeds higher than the testable ranges NHTSA proposed. As 
an example, the 2022 Toyota Prius Prime owner's manual informs vehicle 
owners that the maximum AEB activation speed for its system is 180 km/h 
(112 mph). Other examples include: the 2023 Hyundai Palisade lists the 
maximum AEB activation speed as 200 km/h (124.27 mph), the 2018 Tesla 
Model 3 Dual Motor lists the maximum AEB activation speed as 150 km/h 
(93.2 mph), the 2021 Volvo S60 lists the maximum AEB activation speeds 
as 115 km/h (71.4 mph), the 2021 Ford Bronco lists the maximum AEB 
activation speed as 120 km/h (74.5 mph), and the 2022 Lexus NX 250 
lists a maximum AEB activation speed of 180 km/h (111.8 mph). This 
demonstrates that it is common practice for AEB systems to function 
above the testable range of speeds.
    The agency considered comments asserting that higher travel speeds 
require longer sensing ranges. However, the equipment requirement does 
not specify a particular speed reduction or level of avoidance. The 
agency considered the kinematics for an AEB system installed on a 
vehicle that meets the track test requirements at 80 km/h without 
manual braking. For a vehicle with automatic initiated deceleration 
capabilities of 0.7g, in a lead vehicle stopped situation, the brakes 
must be applied at a distance of approximately 37 m (equates to a time-
to-collision of 1.66 s). In such a situation, the vehicle's sensor 
range would need to demonstrate capabilities at a distance of at least 
37 m. In a similar rear end collision situation with the vehicle 
traveling at 145 km/h and an identical detection

[[Page 39715]]

range of 37 m, the time-to-collision would be only 0.91 s. If the 
vehicle applied the same 0.7g deceleration at the same 37 m distance, a 
collision would not be avoided. A theoretical collision would occur 
with the vehicle impacting the stopped vehicle at 119 km/h (74 mph). 
However, the vehicle would have an AEB system that applied the brakes 
when a crash is imminent, as the proposal would require.
    Requiring that the AEB system function at higher speeds has 
significant safety benefits. According to the injury risk curve used in 
the FRIA available in this docket, the probability of a fatality 
occurring in a rear-end collision where the striking vehicle is 
impacting at 90 mph is almost 20 percent. That probability is reduced 
to 6.8 percent for a travel speed of 74 mph. That reduction in fatality 
risk is afforded with little to no additional sensing system 
capabilities beyond what is required to satisfy the track tested 
requirements. In other words, if the AEB system activates at 90 mph and 
slows the vehicle down by just 16 mph, the risk of a fatality declines 
significantly. If the system were deactivated at speeds above the test 
procedure limit of 62 mph, many more fatalities would occur than if the 
system is activated and functioning with the capabilities required to 
satisfy the track tested requirements. Beyond 145 km/h (90.1 mph), 
however, the expected safety benefits are greatly diminished, primarily 
because very high travel speeds are relatively uncommon and currently 
above legal operating speeds in the U.S.
    NHTSA does recognize that pedestrian crash interactions are much 
less straightforward kinematically than a lead vehicle rear-end crash 
interaction. This is because the pedestrian may be moving in any number 
of directions in front of the vehicle, including suddenly darting in 
front of a vehicle, making detection and mitigation more challenging as 
speed increases. In such situations, the agency agrees with commenters 
that it is not practical to require an alert and braking at speeds 
greatly above those for which the track test applies. For this reason, 
this final rule reduces the speed range for pedestrian detection 
functionality to any speed greater than 10 km/h (6.2 mph) and less than 
73 km/h (45.4 mph). Similarly, for pedestrian AEB functionality, this 
final rule reduces the upper end speed for which alerts and braking are 
required to 73 km/h (45.4 mph). This speed range balances 
practicability and safety.
Post-Crash Review
    As for Rivian's comment on post-crash review, NHTSA can determine 
compliance with this equipment requirement through visual observation 
and other information, if requested from the manufacturer. Post-crash 
review is an important tool to the agency. NHTSA acknowledges Rivian's 
discomfort with post-crash review being considered as a primary tool 
for compliance purposes, but NHTSA does not believe post-crash review 
will be necessary to enforce this requirement. Instead, NHTSA believes 
it can rely on visual observation, manufacturer test results used as a 
basis for certification, and other information to determine whether a 
vehicle meets this equipment requirement.
Conclusion
    After careful consideration and in response to commenters stating 
that there was not a safety need justifying the lack of a maximum speed 
cap on this equipment requirement, NHTSA has decided to modify the 
proposed requirement. The agency recognizes that while vehicles are 
capable of very high speeds, the current maximum speed limit in the 
United States is 85 mph. With this in mind and in response to comments 
urging a speed cap for AEB operation, NHTSA decided to require that AEB 
systems operate (i.e., warn the driver and apply the brakes) at speeds 
up to 145 km/h (90.1 mph) for lead vehicle detection and 73 km/h (45.4 
mph--based on the overall complexity of detecting and differentiating 
between an imminent pedestrian crash and a pedestrian encounter that is 
unlikely to result in a crash, such as when a pedestrian is located on 
the sidewalk) for pedestrian detection. NHTSA also believes that 
adopting this speed cap is consistent with the agency's analysis of the 
safety problem and with NHTSA's goals of resolving as much of the 
safety problems as possible.
    NHTSA believes this requirement is feasible, particularly in light 
of the absence of any performance requirements (for example, that a 
vehicle brake automatically to avoid contact) other than at the speeds 
tested in the performance requirements specified in this standard. This 
final rule simply requires that an AEB system function to warn and 
apply the brakes at speeds up to 145 km/h (90.1 mph) for FCW and lead 
vehicle AEB. The agency is not preventing manufacturers from having FCW 
activate at speeds above 145 km/h (90.1 mph). NHTSA is aware from 
recent research into owner's manuals that many AEB systems operate at 
speeds above the testable range, and NHTSA wants to ensure that 
manufacturers have the flexibility to provide FCW (and AEB) at speeds 
above those included in this final rule. This maximum required 
activation speed addresses the concerns raised by commenters about a 
requirement without an upper bound.
3. Environmental Conditions
    In the NPRM, NHTSA explained that this equipment requirement was 
intended to complement the performance requirements by, among other 
things, ensuring that AEB systems continue to function in all 
environments, not just the test track environment. Unlike track 
testing, real world traffic scenarios may involve additional vehicles, 
pedestrians, bicyclists, buildings, and other objects within the view 
of the sensors and should not negatively affect their operation.
    NHTSA received several comments expressing concern about the 
unspecified environmental conditions included in the NPRM.
    NHTSA is committed to establishing performance requirements that 
are as reflective of the real world as possible, and that encourage 
manufacturers to develop robust AEB systems with sufficient resiliency 
to handle the widely variable scenarios they are intended to handle. In 
general, NHTSA is concerned that high system brittleness will not 
provide the maximum safety benefits and could be confusing to the 
public because of expectations about how AEB systems should work. The 
language of the NPRM sought to provide safety under environmental 
conditions outside of those specified in a track testing environment.
    That said, NHTSA agrees with commenters that the expectation that 
the AEB system work in unspecified environments should be clarified for 
manufacturers to certify that their vehicles will meet the equipment 
requirement established by this final rule. There are environmental 
conditions that may preclude the safe application of automatic braking, 
and to a lesser extent warnings. However, the complexity of conditions 
and combination of conditional factors make it difficult to clearly 
enumerate those conditions. Therefore, this final rule now clearly 
specifies the conditions in which the systems are expected to perform 
to meet the equipment requirement are those conditions specified for 
testing the performance requirements. Notwithstanding this specificity, 
NHTSA encourages manufacturers to continue working

[[Page 39716]]

toward delivering AEB systems that are robust and that function in as 
many real-world environments as possible.
    The Utah Public Lands Alliance commented that the proposed rule did 
not take into account the complexities of off-road environments, such 
as obstacles, mud, rocks, and varying slopes, which may render the AEB 
less effective or even cause false alarms, disrupting the driving 
experience. NHTSA notes that the final rule does not include off-road 
environments as a required aspect of AEB performance because the 
agency's authority under the Safety Act focuses on the on-road 
environment.

E. AEB System Requirements (Applies to Lead Vehicle and Pedestrian)

1. Forward Collision Warning Requirements
    Because the window of time that FCW affords a driver in a crash-
imminent situation is small, the proposed warning characteristics were 
intended to facilitate quick direction of the driver's attention to the 
roadway in front of them and to compel the driver to apply the brakes 
assertively. The FCW criteria proposed were based on many years of 
warning research and vehicle crash avoidance research conducted by 
NHTSA and others as described in the NPRM. The criteria seek to achieve 
an effective warning strategy that is consistent across vehicle models 
and proven by research to promote the highest likelihood of drivers 
quickly understanding the situation and responding efficiently to avoid 
a crash.
Comments
    Commenters generally supported a requirement for an FCW to be 
presented for lead vehicle and pedestrian scenarios. However, a 
majority of commenters preferred more flexibility of FCW implementation 
than is afforded by the requirements, as summarized below.
    Multiple commenters were opposed to the degree of specificity 
included in the proposed FCW requirements. These commenters thought 
that the state of varied implementation of FCW that exists currently 
was sufficient. For example, Volkswagen opined that the regulation 
``should specify the warning modes (visual, auditory, optionally 
haptic), but leave the implementation up to the manufacturer if the 
warning is easily perceivable and visually distinguishable from other 
warnings.'' Volkswagen thought that variation in FCW strategy across 
manufacturers would not be a problem since manufacturers ``explain 
their warning strategy in their owner's manuals.'' Similarly, the 
Alliance contended that U.S. customers may be ``already familiar with 
the ISO symbol and flashing alert'' and that it ``would be beneficial 
to safety'' for NHTSA to allow flexibility for manufacturers to select 
the visual warnings deemed to be most effective in the context of the 
overall vehicle HMI.
    IIHS cited its own research as a basis for contending that the 
proposed FCW ``design requirements are unnecessarily overly 
prescriptive'' given that ``existing industry practices for FCW are not 
only effective for preventing crashes but are also acceptable and 
understandable to drivers.'' IIHS highlighted its crash data analyses 
for FCW-equipped vehicles stating, ``Our analyses of police-reported 
crashes and insurance loss data indicate that most FCW systems are 
effective for preventing rear-end crashes despite disparate designs. 
Cicchino (2017) examined rear-end crash involvement rates for vehicles 
with FCW from five automakers relative to vehicles without the system. 
The presence of FCW was associated with statistically significant 
reductions in rear-end crash involvement rates for three of the five 
automakers.''
    Some commenters suggested that the FCW requirements should more 
closely follow other related standards. Ford recommended establishing 
FCW requirements similar to existing AEB regulations from Europe (UNECE 
R152 \56\), Australia (ADR98 \57\), and Korea (KMVSS \58\) instead of 
restricting the individual components of the warning. Hyundai opposed 
``overly specifying details for FCW and oppose[d] the use of SAE J2400 
standards (particularly 10-degree vision cone provision).'' Porsche's 
comments sought additional flexibility and alignment with UNECE 
Regulation No. 152.
---------------------------------------------------------------------------

    \56\ UN Regulation No 152--Uniform provisions concerning the 
approval of motor vehicles with regard to the Advanced Emergency 
Braking System (AEBS) for M1 and N1 vehicles [2020/1597] (OJ L 360 
30.10.2020, p. 66, ELI: https://data.europa.eu/eli/reg/2020/1597/oj).
    \57\ Australian Design Rule, Vehicle Standard (Australian Design 
Rule 98/01--Advanced Emergency Braking for Passenger Vehicles and 
Light Goods Vehicles) 2021.
    \58\ Korean Motor Vehicle Safety Standard (KMVSS) Article 15-3, 
``Advanced Emergency Braking Systems (AEBS).''
---------------------------------------------------------------------------

    Lastly, multiple commenters voiced support for standardization of 
FCW characteristics. The GHSA indicated support for FCW 
standardization, stating that ``increased consistency will bolster the 
safety impact of these features as drivers become more accustomed to 
what to expect and how to react when these systems are engaged.'' AAA 
also expressed support for standardization, stating that ``consumers 
would find it beneficial to standardize visual alert characteristics. . 
. such as the location of the warning.'' AAA cited its previous testing 
experience that found ``characteristics among vehicles significantly 
vary with some warnings hardly noticeable relative to visual warnings 
presented in other vehicles.'' As a result, AAA urged NHTSA to 
``consider standardization requirements for visual alerts to promote 
consistency and understanding for all drivers, particularly hearing-
impaired drivers who may not perceive an auditory signal.''
Agency Response
    NHTSA notes the general support from commenters for requiring some 
kind of FCW to be presented prior to AEB activation. The point of FCW 
is to elicit a timely and productive crash avoidance response from the 
driver, thereby mitigating or, if possible, avoiding the need for AEB 
to intervene in a crash-imminent situation. The proposed FCW 
characteristics outlined in the NPRM are based on more than 35 NHTSA 
research efforts related to crash avoidance warnings or forward 
collision warnings conducted over the past nearly 30 years. Other 
research, existing standards (ISO Standards 15623 and 22839), and SAE 
documents (J3029 and J2400) also were considered as input for the 
proposed requirements. While multiple commenters sought flexibility for 
automakers to use an FCW of their own preference in lieu of one 
conforming to the proposed specification, no safety data were provided 
concerning consumers' degree of understanding of the wide variety of 
existing FCW implementations--just generalized statements about 
consumer familiarity. NHTSA does not view these arguments as sufficient 
to overcome the value of standardization as a means of ensuring 
consumer familiarity.
    Data from NHTSA's 2023 AEB testing showed that each of six test 
vehicle models from different manufacturers used a different FCW visual 
signal or symbol. Only one model used the ISO FCW symbol. FCW visual 
symbols that differ by manufacturer and, in some cases across models 
from the same manufacturer, are likely to lead to confusion among 
consumers. The observed substantial variety in existing FCW 
implementations highlights the need for improved consistency of FCW 
visual symbols to increase efficient comprehension of crash-imminent 
warnings by vehicle operators and aid them in understanding the reason 
for

[[Page 39717]]

their vehicle's (or, indeed, an unfamiliar rental vehicle's) active 
crash avoidance intervention. Allowing for individual design choices--
even those with positive safety records--does not address this 
important safety consideration.
    Such confusion has also been documented by past research. Research 
by industry published in a 2004 SAE paper focused on comprehension 
testing of active safety symbols and assessed the ISO FCW symbol and 
the SAE J2400 FCW symbol to assess their ability to communicate the 
idea, ``Warning: You may be about to crash into a car in front of 
you.'' Results of that research showed the ISO FCW symbol to have 45 
percent ``high comprehension'' and the SAE J2400 symbol to have 23 
percent high comprehension. However, while high comprehension was noted 
for the lead vehicle crash scenario, NHTSA is not aware of any data 
supporting effectiveness of the ISO FCW symbol for communicating the 
idea of an impending forward pedestrian crash.'' \59\
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    \59\ Campbell, John & Hoffmeister, David & Kiefer, Raymond & 
Selke, Daniel & Green, Paul & Richman, Joel. (2004). Comprehension 
Testing of Active Safety Symbols. 10.4271/2004-01-0450.
---------------------------------------------------------------------------

    NHTSA acknowledges the research by IIHS showing crash reduction 
benefits from some existing FCW designs. IIHS research results found 
that some automakers' FCW designs were associated with higher crash 
reductions than others. However, this research did not evaluate FCW 
characteristics by automaker or by model for vehicle models it studied 
and whether such characteristics may have contributed to FCW 
effectiveness differences, so care should be taken when drawing 
conclusions. Regardless, while the IIHS studies have shown some 
existing FCW in light vehicles are effective for preventing rear-end 
crashes, research does not support an argument against taking other 
measures to increase FCW effectiveness, as this action seeks to do. It 
is likely that increasing the consistency of FCW characteristics and 
standardization of the primary warning signals across vehicles and 
models will lead to benefits beyond those documented to date due to 
increased driver understanding of the meaning of FCW signals.
    The agency disagrees with Volkswagen's comment that explanations in 
the owner's manual adequately inform consumers about manufacturer-
specific FCW signals. A British study found that only 29% of motorists 
surveyed had read their car handbook in full.\60\ That same study 
examined owner's manual word counts and estimated that the time 
required to read some of the longest would take up to 12 hours. An 
April 2022 Forbes article states that ``the average new-vehicle's 
owners' manuals, which, concurrent with the complexity of contemporary 
cars, have become imposingly thick and mind-numbing tomes of what 
should be essential information... remain unread in their respective 
models' gloveboxes.'' \61\ With these concerns in mind, NHTSA does not 
believe that owner's manual information is an acceptable substitute for 
standardization of this important safety functionality across all 
vehicles.
---------------------------------------------------------------------------

    \60\ ``Car Handbooks Are Longer Than Many Famous Novels--Have 
You Read Yours?'' https://www.bristolstreet.co.uk/news/car-handbooks-are-longer-than-many-famous-novels--have-you-read-yours/.
    \61\ ``Here's Why Nobody Reads Their Car's Owner's Manual'' 
https://www.forbes.com/sites/jimgorzelany/2022/04/07/heres-why-nobody-reads-their-cars-owners-manual/?sh=2a76d5d4462d.
---------------------------------------------------------------------------

    After careful review of these comments, NHTSA has decided to adopt 
a majority of the proposed FCW requirements unchanged as described in 
the following sections.
a. FCW Signal Modality
    NHTSA proposed that FCW modalities and related characteristics of 
auditory and visual components be the same for lead vehicle AEB and 
PAEB performance, and that the FCW be presented to the vehicle operator 
via at least two sensory modalities--auditory and visual. The FCW 
auditory signal was proposed to be the primary means used to direct the 
vehicle operator's attention to the forward roadway. NHTSA did not 
propose to require a haptic FCW signal component but invited comment on 
whether requiring FCW to contain a haptic component presented via any 
location may increase FCW effectiveness or whether an FCW haptic signal 
presented in only one standardized location should be allowed.
Comments
    Of those commenting on FCW signal modality, all supported a 
multimodal FCW signal strategy. Multiple commenters including NTSB, 
Consumer Reports, Ford, GHSA, Honda, MEMA, and Porsche expressed 
support for the combination of auditory and visual warning modalities 
that was proposed by NHTSA. For example, NTSB expressed support for 
visual and auditory warning, and noted several NTSB investigations in 
which visual warnings were found to be ineffective in capturing 
drivers' attention. GHSA expressed support for requiring standardized 
auditory and visual warnings when a collision is imminent, believing 
that increased consistency would bolster the safety impact of these 
features. Ford supported an auditory and visual alert based on their 
experience implementing an FCW system. Honda stated that a multimodal 
auditory and visual warning provided sufficient redundancy. Consumer 
Reports also highlighted the importance of providing a visual warning 
for those who are hearing impaired, who are listening to music, or are 
otherwise distracted.
    The remaining supporters of the multimodal approach preferred the 
flexibility to use any combination of possible modalities (auditory, 
visual and haptic). These included the Alliance, ASC, Bosch, GM, HATCI, 
and Rivian. For example, the Alliance agreed with the agency's 
conclusion that the auditory signal should be the primary means of 
communicating with the driver, but expressed support for allowing 
warnings to be provided using any combination of two of the three alert 
modalities, with a third allowable, but not required. ASC recommended 
that the warnings be aligned with UNECE Regulation No. 152. ASC and ZF 
also cited research showing FCW with auditory and haptic components 
prompt a quicker driver reaction time than FCW with auditory and visual 
components.
    Ford and MEMA agreed that OEMs should be permitted to supplement 
the primary auditory and visual FCW signal modalities with a haptic 
warning component. Bosch encouraged NHTSA to include haptic as one of 
the warning modes, citing the potential for advantages in loud 
environments or with hearing impaired individuals. Volkswagen agreed 
with NHTSA's proposal to not require an FCW haptic component, but 
clarified that if haptic was required, then only two out of the three 
warning types should be required. HATCI requested that NHTSA permit 
haptic signals to be used as the primary or secondary warning, stating 
that haptic warnings draw the driver's attention to the hazard without 
requiring them to identify a warning symbol with their eyes.
    Consumer Reports suggested that a haptic signal may cause driver 
confusion because haptic steering signals are also used by many lane 
departure warning systems, which activate more frequently. Along the 
same line, Porsche noted its desire ``to avoid causing driver confusion 
related to other safety systems where haptic signals may be more 
appropriate (e.g.,

[[Page 39718]]

steering wheel vibration used for lane keeping).''
Agency Response
    After consideration of the comments, NHTSA is moving forward with 
the originally proposed requirements for a primary FCW auditory signal 
and a secondary visual signal, while neither requiring nor prohibiting 
a supplementary FCW haptic signal. While a few commenters expressed the 
desire to require a haptic FCW signal, no supporting data were 
provided. Therefore, NHTSA declines to make a haptic warning signal a 
requirement. However, NHTSA cautions those interested in implementing 
supplementary FCW haptic signals to take steps to ensure that the 
haptic signal used will not be confused with those currently used in 
association with systems not designed to elicit a forward crash 
avoidance response, for example, lane-keeping driver assistance 
features.
b. FCW Auditory Signal Requirements
    NHTSA proposed that the FCW auditory signal would be the primary 
warning modality and asserted criteria to ensure that the FCW would be 
successful in quickly capturing the driver's attention, directing the 
driver's attention to the forward roadway, and compelling the driver to 
quickly apply the brakes. NHTSA proposed that the FCW auditory signal's 
fundamental frequency be at least 800 Hz and that it include a duty 
cycle, or percentage of time the sound is present, of 0.25-0.95, and a 
tempo in the range of 6-12 pulses per second. This final rule also 
includes FCW requirements that were discussed in the NPRM. 
Specifically, the FCW auditory signal is required to have a minimum 
intensity of 15-30 dB above the masked threshold.
Comments
    GHSA, Honda, and Rivian supported the proposed standardized FCW 
auditory signal requirements. Honda stated that the proposed tone, 
tempo, and frequency would contribute to making this a distinct and 
recognizable warning, especially if standardized across the fleet. 
Rivian agreed that a common FCW auditory signal is necessary so that 
drivers can easily recognize warning conditions across different 
vehicle makers and models.
    Multiple commenters, including the Alliance, Ford, Nissan, Porsche, 
Toyota, and Volkswagen indicated a preference for more flexibility in 
the allowed FCW auditory signal characteristics. More specifically, the 
Alliance and Nissan stated that not defining the required sound level 
and characteristics is consistent with UNECE Regulation No. 152. Ford 
recommended that the manufacturer be provided with flexibility to 
design FCW auditory warning signals. Ford stated that the parameters 
for an audible alert are often tuned for different vehicle applications 
or customizable by drivers. Both Porsche and Volkswagen contended that 
consumers may be used to existing FCW auditory signals used in current 
vehicles. Volkswagen further stated that allowing flexibility in FCW 
auditory signal characteristics enables manufacturers to update or 
adjust the warnings as technologies evolve.
    Regarding FCW auditory signal distinguishability, IIHS recommended 
that NHTSA consider IIHS's method for assessing auditory seat belt 
reminders to ensure auditory FCWs are easily discerned by drivers 
beyond ambient levels of sound inside the vehicle.
    On the issue of FCW auditory signal deactivation, Hyundai MOBIS 
encouraged NHTSA to consider permitting the audible warning to be 
suppressed as long as the FCW visual warning remains illuminated.
Agency Response
    The FCW auditory signal minimum intensity requirement was 
inadvertently left out of the proposed regulatory text, although it was 
discussed in the preamble of the NPRM. Multiple commenters addressed 
the topic of FCW auditory signal intensity in their comments. While 
multiple commenters disagreed with NHTSA's proposed FCW auditory signal 
criteria, NHTSA's data from 2023 AEB testing also showed that some 
existing systems already meet some of the FCW proposed requirements. 
One vehicle, a 2024 Mazda CX-90, met all proposed FCW auditory 
requirements. Two vehicles met all proposed auditory requirements 
except the minimum intensity requirement of 15-30 dB above the masked 
threshold. Two other vehicles met 3 of the 5 FCW auditory signal 
requirements while the last vehicle met only 2 of the 5 requirements. 
All six vehicles' FCW auditory signals met the proposed duty cycle 
requirement and four of the six met the fundamental frequency 
requirement. Some variety in AEB test vehicles' FCW auditory signals 
was also seen. FCW auditory signal intensities above the masked 
threshold spanned a range of 28.8 dBA and five of the six tested 
vehicles did not meet the proposed intensity requirement. FCW auditory 
signals fundamental frequencies ranged from 600 to 2000 Hz.
    NHTSA believes that auditory signal intensities are especially 
important for FCW because of the urgency of the crash-imminent 
situation, the goal of compelling a driver to apply the brakes, and the 
speed with which action is necessary. Additionally, the minimum sound 
intensity is supported by research that provides a strong foundation 
for this requirement. Commenters who did not support the proposed FCW 
auditory signal requirements provided no data to document the 
effectiveness of existing FCW auditory signals, nor the purported 
benefits of permitting vehicle manufacturers to choose their own unique 
FCW designs. While providing flexibility for design choices that have 
been proven to increase safety is valuable, providing flexibility that 
allows for differences related to branding or that just serves to make 
a model unique does not add safety value.
    Regarding Ford's comment expressing interest in the ability to 
decrease FCW auditory signal intensity when the driver's alertness 
level is confirmed to be high, NHTSA notes that the proposed 
requirements provide leeway for manufacturers to implement a less 
invasive advisory or preliminary alert that would precede the required 
FCW. It also would not prevent multiple intensities that all meet the 
minimum requirement in this final rule.
    NHTSA disagrees with the suggestion by Hyundai MOBIS to permit the 
auditory warning to be suppressed as long as the FCW visual warning 
remains illuminated. As the FCW auditory signal is considered the 
primary means of warning a potentially inattentive driver, allowing the 
auditory FCW signal to be suppressed would undercut its important 
safety function.
    After considering the comments, NHTSA has decided to finalize the 
proposed FCW auditory signal intensity discussed in the preamble of the 
NPRM in this final rule.
c. FCW Auditory Signal Presentation With Simultaneous Muting of Other 
In-Vehicle Audio
    In the preamble to the NPRM, NHTSA explained its intent to require 
muting or substantial reduction in volume of other in-vehicle audio 
(i.e., entertainment and other non-critical audio information) during 
the presentation of the FCW. This requirement would serve to ensure 
that the FCW auditory signal is conspicuous to the vehicle operator and 
detectable at the critical moment at which a crash avoidance response 
by the driver is needed. However, this intended requirement was 
inadvertently left out of the proposed regulatory text.
Comments
    ASC, MEMA, and ZF supported the muting or reducing other in-vehicle

[[Page 39719]]

audio during an audio FCW alert because the FCW alert is the highest 
priority in the vehicle and should override all other sounds. ASC and 
MEMA suggested that FCW alert volume should rise with speed to overcome 
external sounds like wind noise or road noise.
    Honda, Porsche and Volkswagen opposed muting of other in-vehicle 
audio during FCW presentation. Honda stated that, because environmental 
sound levels can vary drastically, it is unnecessary to require audio 
muting. Honda cited the lack of a sound level requirement for the FMVSS 
No. 208 seatbelt warning as rationale for not needing such a 
requirement for FCW. Porsche and Volkswagen suggested that it is the 
driver's responsibility to ensure that in-vehicle audio does not 
interfere with the driving task. Volkswagen cited the requirement of a 
both a visual and audio warning as justification for not requiring 
muting of in-vehicle audio. Volkswagen also questioned how to 
accommodate other mandatory audio signals if these occur simultaneous 
with the collision warning.
Agency Response
    Regarding Honda's comparison to the FMVSS No. 208 auditory warning 
signal requirement for fastening seatbelts, NHTSA does not believe the 
two requirements are comparable. The immediate consequences associated 
with an impending forward crash are not comparable to those associated 
with vehicle occupants fastening seat belts at the start of a drive.
    In response to concerns expressed by Volkswagen and Porsche about 
addressing multiple simultaneous auditory signals, NHTSA will clarify 
that the audio required to be muted would be any audio for other than 
crash avoidance or safety purposes, such as music or other 
entertainment related audio.
    Regarding the assertions by both Porsche and Volkswagen that 
drivers are responsible for ensuring that in-vehicle audio system use 
does not interfere with the driver's full attention to the driving 
task, the situations in which FCW is expected to emit sound are urgent 
enough that the most attentive driver would need to be able to hear the 
auditory signal. NHTSA does not believe that attention or inattention 
is the crux of the issue, though inattention could complicate a 
driver's response. It is important to ensure that the FCW auditory 
signal is audible even when sound levels from in-vehicle sources are 
high.
    Although the requirement to mute other in-vehicle audio during the 
presentation of the FCW was inadvertently left out of the proposed 
regulatory text, NHTSA is including such a requirement in this final 
rule. Similar to the issue of auditory intensity, multiple commenters 
addressed the topic of muting. The requirement will be finalized to 
require that in-vehicle audio not related to a safety purpose or safety 
system (i.e., entertainment and other audio content not related to or 
essential for safe performance of the driving task) must be muted, or 
reduced in volume to within 5 dB of the masked threshold, during 
presentation of the FCW auditory signal. This specification will serve 
to ensure that the amplitude of the FCW auditory signal is at least 10 
dB above the masked threshold (MT) to preserve the saliency of the 
auditory warning.\62\
---------------------------------------------------------------------------

    \62\ 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].''
---------------------------------------------------------------------------

d. FCW Visual Symbol Requirements
    NHTSA proposed that FCW visual signals must use the SAE J2400 
(2003-08) symbol.\63\ The SAE J2400 symbol relates the idea of an 
impending frontal crash without depicting a particular forward object 
and, as such, is readily applicable to both lead vehicle and pedestrian 
scenarios. 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 and because 
NHTSA-sponsored research \64\ has shown that instrument-panel-based 
crash warnings can draw drivers' eyes downward away from the roadway at 
a critical time when crash avoidance action may be needed \65\ the 
symbol would be required to be steady burning.
---------------------------------------------------------------------------

    \63\ SAE J2400 2003-08 (Information report). Human Factors in 
Forward Collision Warning Systems: Operating Characteristics and 
User Interface Requirements.
    \64\ DOT HS 812 191 September 2015, Evaluation of Heavy-Vehicle 
Crash Warning Interfaces. https://www.nhtsa.gov/sites/nhtsa.gov/files/812191_evalheavyvehiclecrashwarninterface.pdf.
    \65\ ``Evaluation of Forward Collision Warning System Visual 
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547, 
https://trid.trb.org/view/1430473.
---------------------------------------------------------------------------

Comments
    Multiple commenters voiced support for standardization of FCW 
characteristics. For example, the Governors Highway Safety Association 
(GHSA) indicated support for FCW standardization, stating that 
increased consistency will bolster the safety impact of these features. 
AAA cited its previous testing experience that some warnings were 
hardly noticeable relative to visual warnings presented in other 
vehicles.
    Multiple commenters were opposed to specificity included in the 
proposed FCW requirements. These commenters thought that the state of 
varied implementation of FCW that exists currently was sufficient. For 
example, Volkswagen described the proposed warning strategy for AEB as 
too prescriptive. Volkswagen thought the regulation should specify the 
warning modes, but leave the implementation up to the manufacturer if 
the warning is easily perceivable and visually distinguishable from 
other warnings. Volkswagen thought that variation in FCW strategy 
across manufacturers would not be a problem because manufacturers 
explain their warning strategy in their owner's manuals. NADA, Nissan, 
Mitsubishi, and Porsche also suggested manufacturers have more 
flexibility to choose the form of visual warning.
    The Alliance opined that NHTSA should allow flexibility for 
manufacturers to select the visual warnings deemed to be most effective 
in the context of the overall vehicle human-machine interface, which 
could include ISO or SAE symbols, word-based warnings, or other 
flashing or steady burning illumination as appropriate. The Alliance 
stated that NHTSA has not presented data to indicate that any one 
visual alert type or symbol is any more or less effective than another. 
Consumer Reports supported standardization but recommended that a word 
be used rather than a symbol.
    Some commenters suggested that the FCW requirements should more 
closely follow other related standards. Ford recommended establishing 
FCW requirements similar to existing AEB regulations from Europe,\66\ 
Australia,\67\

[[Page 39720]]

and Korea \68\ instead of restricting the individual components of the 
warning. Hyundai opposed the use of SAE J2400 standards, including the 
symbol. Hyundai believed it was more appropriate to adopt ISO 15623. 
Porsche's comments seek additional flexibility and alignment with UNECE 
Regulation No. 152.
---------------------------------------------------------------------------

    \66\ UN Regulation No 152--Uniform provisions concerning the 
approval of motor vehicles with regard to the Advanced Emergency 
Braking System (AEBS) for M1 and N1 vehicles [2020/1597] (OJ L 360 
30.10.2020, p. 66, ELI: https://data.europa.eu/eli/reg/2020/1597/oj).
    \67\ Australian Design Rule, Vehicle Standard (Australian Design 
Rule 98/01--Advanced Emergency Braking for Passenger Vehicles and 
Light Goods Vehicles) 2021.
    \68\ Korean Motor Vehicle Safety Standard (KMVSS) Article 15-3, 
``Advanced Emergency Braking Systems (AEBS).''
---------------------------------------------------------------------------

    Hyundai MOBIS, Toyota, the Alliance, Ford, and Honda, disagreed 
with the steady burning requirement for the FCW visual signal, 
expressing support for allowing it to flash. Honda recommended aligning 
with the specifications of ISO 15008.
    Honda supported both visual symbol and word-based FCW options. 
Honda recommended that NHTSA allow flexibility to continue using 
already well understood text-based warnings like ``BRAKE!,'' which 
Honda currently employs, reasoning that a well-designed warning would 
instruct drivers what to do to avoid a hazard. Rivian also supported 
allowing the use of the word, ``BRAKE,'' in lieu of an FCW visual 
symbol.
Agency Response
    After careful review of these comments, NHTSA has decided to adopt 
the proposed standardized FCW visual warning requirements unchanged. 
While multiple commenters sought flexibility for automakers to use an 
FCW visual signal of their own choice rather than a standardized 
signal, no safety data were provided concerning consumers' degree of 
understanding of the wide variety of existing FCW implementations nor 
any safety advantages or benefits of not standardizing the visual 
symbol. The proposed FCW characteristics outlined in the NPRM are based 
on more than 35 NHTSA research efforts related to crash avoidance 
warnings or forward collision warnings conducted over the past nearly 
30 years. Other research, existing standards (ISO Standards 15623 and 
22839), and SAE documents (J3029 and J2400) also were considered as 
input for the proposed requirements. NHTSA does not view the provided 
arguments as sufficient to overcome the value of standardization as a 
means of ensuring consumer familiarity and ensuring the applicability 
of the chosen symbol to both lead vehicle and pedestrian scenarios.
    Data from NHTSA's 2023 AEB testing showed that each of six test 
vehicle models from different manufacturers used a different FCW visual 
signal or symbol. Only one model used the ISO FCW symbol. FCW visual 
symbols that differ by manufacturer and, in some cases across models 
from the same manufacturer, are likely to lead to confusion among 
consumers. The observed substantial variety in existing FCW 
implementations highlights the need for improved consistency of FCW 
visual symbols to increase efficient comprehension of crash-imminent 
warnings by vehicle operators and aid them in understanding the reason 
for their vehicle's (or an unfamiliar rental vehicle's) active crash 
avoidance intervention. Allowing for individual design choices does not 
address this important safety consideration.
    Such confusion relating to automotive symbol comprehension has also 
been documented by NHTSA research. Past research conducted by NHTSA to 
assess comprehension of vehicle symbols including the ISO tire 
pressure, ISO tire failure, and ISO engine symbols showed that while 95 
percent of subjects correctly identified the engine symbol, recognition 
percentages for the ISO tire pressure and tire failure icons were the 
lowest of the 16 icons tested, 37.5 percent and 25 percent, 
respectively.'' \69\ Research by industry published in a 2004 SAE paper 
focused on comprehension testing of active safety symbols and assessed 
the ISO FCW symbol and the SAE J2400 FCW symbol to assess their ability 
to communicate the idea, ``Warning: You may be about to crash into a 
car in front of you.'' Results of that research showed the ISO FCW 
symbol to have 45 percent ``high comprehension'' and the SAE J2400 
symbol to have 23 percent high comprehension. However, while high 
comprehension was noted for the lead vehicle crash scenario, NHTSA is 
not aware of any data supporting effectiveness of the ISO FCW symbol 
for communicating the idea of an impending forward pedestrian crash.'' 
\70\
---------------------------------------------------------------------------

    \69\ Mazzae, E.N. and Ranney, T.A. (2001). ``Development of an 
Automotive Icon for Indication of Significant Tire Underinflation.'' 
Article in Proceedings of the Human Factors and Ergonomics Society 
Annual Meeting [middot] October 2001. DOI: 10.1177/
154193120104502317.
    \70\ Campbell, John & Hoffmeister, David & Kiefer, Raymond & 
Selke, Daniel & Green, Paul & Richman, Joel. (2004). Comprehension 
Testing of Active Safety Symbols. 10.4271/2004-01-0450.
---------------------------------------------------------------------------

    Consumer Reports ``Guide to ADAS'' states that ``CR's most recent 
survey data shows that industry-wide, only 48% of owners of vehicles 
equipped with FCW say they understand how it works.'' \71\ NHTSA 
believes that improved consistency of FCW visual symbols is important 
to increase efficient comprehension of crash-imminent warnings.
---------------------------------------------------------------------------

    \71\ Consumer Reports' Guide to ADAS Usability: Consumer 
insights on understanding, use, and satisfaction of ADAS December 
2022. https://data.consumerreports.org/wp-content/uploads/2021/09/consumer-reports-active-driving-assistance-systems-ux-guide-revised-december-09-2022.pdf.
---------------------------------------------------------------------------

    NHTSA acknowledges the research by IIHS showing crash reduction 
benefits from some existing FCW designs. IIHS research results found 
that some automakers' FCW designs were associated with higher crash 
reductions than others. However, this research did not evaluate FCW 
characteristics by automaker or by model for vehicle models it studied 
and whether such characteristics may have contributed to FCW 
effectiveness differences, so care should be taken when drawing 
conclusions. Regardless, the IIHS studies have shown some existing FCW 
in light vehicles FCW systems are effective for preventing rear-end 
crashes, research does not support an argument against taking other 
measures to increase FCW effectiveness. It is likely that increasing 
the consistency of FCW characteristics and standardization of the 
primary warning signals across vehicles and models will lead to 
benefits beyond those documented to date due to increased driver 
understanding of the meaning of FCW signals.
    The agency disagrees with Volkswagen's comment that explanations in 
the owner's manual adequately inform consumers about manufacturer-
specific FCW signals. As noted previously, a British study found that 
only 29% of motorists surveyed had read their car handbook in full.\72\ 
That same study examined owner's manual word counts and estimated that 
the time required to read some of the longest would take up to 12 
hours. An April 2022 Forbes article states that ``the average new-
vehicle's owners' manuals, which, concurrent with the complexity of 
contemporary cars, have become imposingly thick and mind-numbing tomes 
of what should be essential information . . . remain unread in their 
respective models' gloveboxes.'' \73\ With these concerns in mind, 
NHTSA does not believe that owner's manual information is an acceptable 
substitute for standardization of this important safety functionality 
across all vehicles.
---------------------------------------------------------------------------

    \72\ ``Car Handbooks Are Longer Than Many Famous Novels--Have 
You Read Yours?'' https://www.bristolstreet.co.uk/news/car-handbooks-are-longer-than-many-famous-novels--have-you-read-yours/.
    \73\ ``Here's Why Nobody Reads Their Car's Owner's Manual'' 
https://www.forbes.com/sites/jimgorzelany/2022/04/07/heres-why-nobody-reads-their-cars-owners-manual/?sh=2a76d5d4462d.

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[[Page 39721]]

    Finally, as for the use of words instead of a symbol, as noted in 
the NPRM, word-based FCW visual warnings are used by some U.S. vehicle 
models including, ``BRAKE!,'' ``BRAKE,'' and ``STOP!''. SAE J2400 also 
includes a word-based visual warning recommendation consisting of the 
word, ``WARNING.'' With regard to this existing use of word-based FCW 
visual warnings in some models, research by Consumer Reports noted in 
its online ``Guide to forward collision warning'' found that for some 
models, visual warning word use was found to be confusing to some 
drivers surveyed. Specifically, survey 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.'' \74\ While NHTSA 
does find merit in the rationale for using an effective word-based 
visual warning for FCW purposes, we have decided in favor of the value 
of consistency across U.S. vehicles to promote consumer recognition of 
a dedicated FCW symbol. This symbol-based strategy for the FCW visual 
signal follows is consistent with the strategies of ISO 15623 and SAE 
J2400 (2003-08).
---------------------------------------------------------------------------

    \74\ ``Guide to forward collision warning: How FCW helps drivers 
avoid accidents.'' Consumer Reports. https://www.consumerreports.org/carsafety/forward-collision-warning-guide/. 
Accessed April 2022.
---------------------------------------------------------------------------

    NHTSA notes, however, that this requirement does not preclude the 
use of a word-based warning that supplements the required FCW symbol 
presentation. In that event, NHTSA agrees with Honda and Consumer 
Reports that the word, ``BRAKE!'', including the exclamation point, is 
likely the best choice for effective communication to the driver the 
need for them to apply the brakes. NHTSA believes, as has been 
suggested by Consumer Reports, that there is a tendency for drivers to 
interpret some words used as warnings as describing an action being 
performed by the vehicle, rather than a command to the driver. To avoid 
such confusion by the driver, NHTSA recommends that manufacturers 
wishing to complement the FCW symbol with a word-based warning use, 
``BRAKE!'' to aid in drivers interpreting the word as an instruction.
    Finally, with respect to the steady-burning requirement, NHTSA does 
not agree with commenters recommending that the FCW visual warning be 
allowed to flash. As the FCW visual signal is intended to be secondary 
to the FCW auditory signal, allowing the symbol to flash in an attempt 
to draw the drivers' attention could actually draw the drivers' gaze 
downward to the instrument panel rather than to the forward roadway at 
a critical time for the driver to initiate a crash avoidance response.
    After evaluation of the comments, the agency has determined to 
retain the proposal requirement for the visual symbol from SAE J2400 
(2003-08), ``Human Factors in Forward Collision Warning Systems: 
Operating Characteristics and User Interface Requirements'' 
(Information report), to communicate the idea of an impending frontal 
crash without depicting a particular forward object. With no comments 
opposed to requiring the FCW visual signal to be presented using the 
color red, NHTSA is also finalizing that requirement as proposed and 
clarifying that it will apply to the required FCW symbol and any 
manufacturer-chosen words to accompany the required symbol.
e. FCW Visual Signal Location Requirements
    The agency proposed that the FCW visual signal be presented within 
a 10-degree cone of the driver's forward line of sight.\75\ This 
requirement is based on SAE J2400, ``Human Factors in Forward Collision 
Warning Systems: Operating Characteristics and User Interface 
Requirements,'' paragraph 4.1.14. 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.'' 
Multiple research studies provide support for a visual warning location 
close to the driver's forward line of sight. NHTSA-sponsored research 
also supports this requirement, showing that instrument-panel-based 
crash warnings can draw drivers' eyes downward away from the roadway at 
a critical time when crash avoidance action may be needed.\76\ 
Industry-sponsored research published in 2009 also indicates that an 
FCW visual signal presented in the instrument panel can slow driver 
response.\77\ The 10-degree requirement would also increase the 
likelihood of FCW visual signal detection by hearing-impaired drivers.
---------------------------------------------------------------------------

    \75\ Line of sight based on the forward-looking eye midpoint 
(Mf) as described in FMVSS No. 111, ``Rear visibility,'' S14.1.5.
    \76\ DOT HS 812 191 September 2015, Evaluation of Heavy-Vehicle 
Crash Warning Interfaces. https://www.nhtsa.gov/sites/nhtsa.gov/files/812191_evalheavyvehiclecrashwarninterface.pdf.
    \77\ ``Evaluation of Forward Collision Warning System Visual 
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547, 
https://trid.trb.org/view/1430473.
---------------------------------------------------------------------------

Comments
    Consumer Reports and AAA supported the proposed requirement that 
the FCW visual signal be presented in a location within a 10-degree 
cone of the driver's forward line of sight. In contrast, multiple 
commenters opposed the 10-degree cone requirement, some believing that 
the requirement could only be met using a head-up display. A majority 
of commenters who addressed this point requested that NHTSA consider 
expanding the 10-degree cone of the driver's line of sight requirement 
for FCW visual signal location.
    FCA, Hyundai, Nissan, NADA, Rivian, and Volkswagen opposed the 10-
degree cone requirement. The Alliance disagrees that the SAE J2400 
information report provides adequate justification for the 10-degree 
requirement.
    FCA thought the proposed requirement was impracticable. Rivian 
recommended that the FCW visual signal be presented on the top location 
of the driver instrument panel, in the instrument panel, or in a head-
up display unless NHTSA can demonstrate that the data indicates that 
one location is clearly superior for driver perception. Toyota 
requested that the cone size be expanded to allow for suitable 
placement of the visual alert in areas such as the meter cluster or 
multi-information display, which would still be clearly visible in 
front of the driver.
    Porsche recommended that NHTSA consider replacing the 10-degree 
with an allowance of up to 30 degrees, arguing that this would 
facilitate the use of long-established visual warning locations which 
it viewed as sufficient to provide the necessary cues. Multiple 
commenters, including Mitsubishi, the Alliance, and Honda, recommended 
use of a 60-degree cone requirement. Mitsubishi explained that the 60-
degree value is based on a book chapter titled, Visual Fields, by R.H. 
Spector, et al., which states the vertical viewing angle of humans to 
be 60 degrees.
Agency Response
    While many current vehicle models present an FCW visual signal 
within the instrument panel, drawing a driver's eyes downward away from 
the roadway in front of them 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. NHTSA's research 
indicates that a visual FCW signal presented in the instrument panel 
can draw drivers' eye gaze downward away from the forward roadway and 
slow driver response to a forward crash-

[[Page 39722]]

imminent event.\78\ Further, Industry-sponsored research published in 
2009 also indicates that an FCW visual signal presented in the 
instrument panel can slow driver response.\79\
---------------------------------------------------------------------------

    \78\ DOT HS 812 191 September 2015, Evaluation of Heavy-Vehicle 
Crash Warning Interfaces. https://www.nhtsa.gov/sites/nhtsa.gov/files/812191_evalheavyvehiclecrashwarninterface.pdf.
    \79\ ``Evaluation of Forward Collision Warning System Visual 
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547, 
https://trid.trb.org/view/1430473.
---------------------------------------------------------------------------

    Mitsubishi highlighted content from ``Visual Fields,'' by R.H. 
Spector, et.al that states the vertical viewing angle of humans to be 
60 degrees.\80\ Specter's chapter specifically states that ``a normal 
visual field is an island of vision measuring 90 degrees temporally to 
central fixation, 50 degrees superiorly and nasally, and 60 degrees 
inferiorly.'' Mitsubishi contended that if the FCW visual warning is 
displayed within this range, the driver will be able to recognize it. 
However, the referenced Spector visual field information relates to 
average humans' ability see objects presented before them and not 
specifically to drivers' ability to detect and quickly respond to an 
FCW visual signal within the potentially cluttered visual scene of a 
driver's-view perspective. Research sponsored by NHTSA and industry, 
respectively, has shown that instrument panel based visual crash 
warnings can draw drivers' eyes downward away from the roadway at a 
critical time when crash avoidance action may be needed and that an FCW 
visual signal presented in the instrument panel can slow driver 
response.81 82 Comparison to other warnings is not apt 
because other most other warnings do not require as immediate of a 
response as FCW.
---------------------------------------------------------------------------

    \80\ Spector RH. Visual Fields. In: Walker HK, Hall WD, Hurst 
JW, editors. Clinical Methods: The History, Physical, and Laboratory 
Examinations. 3rd ed. Boston: Butterworths; 1990. Chapter 116. PMID: 
21250064.
    \81\ DOT HS 812 191 September 2015, Evaluation of Heavy-Vehicle 
Crash Warning Interfaces. https://www.nhtsa.gov/sites/nhtsa.gov/files/812191_evalheavyvehiclecrashwarninterface.pdf.
    \82\ ``Evaluation of Forward Collision Warning System Visual 
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547, 
https://trid.trb.org/view/1430473.
---------------------------------------------------------------------------

    As the text of SAE J2400 states, locating the FCW visual signal 
within a 10-degree cone could be accomplished in a top-of-dashboard 
location, NHTSA did not intend to require presentation of the FCW 
visual signal only via head-up display. To evaluate the potential 
difficulties associated with attempting to meet this FCW visual symbol 
location requirement, NHTSA gathered additional information regarding 
what visual angle about the driver's forward line of sight could be 
used to locate the FCW visual signal near the driver's forward line of 
sight, such as within the upper center portion of the instrument panel, 
without requiring substantial redesign of vehicles' instrument panels 
or dashboards, or require a head-up display.
    NHTSA gathered information regarding the driver's visual angle when 
looking at the instrument panel for a set of 10 light vehicles. Eight 
of the vehicles were model year 2022, one was from the 2021 model year, 
and one was from model year 2023. Vehicle makes examined spanned a wide 
range of manufacturers including Chevrolet, Ford, Honda, Hyundai, Jeep, 
Nissan, RAM Subaru, Toyota, and Volkswagen. The vehicles examined also 
spanned a range of vehicle sizes including two large pickup trucks.
    NHTSA used a coordinate measuring machine to record within a single 
coordinate system the locations of the upper and lower extents of the 
active display area of each vehicle's instrument panel, as well as the 
left and right extents of the instrument panel. These points were used 
to locate the geometric center of the instrument panel. The eye 
midpoint location for a properly seated 50th percentile male driver was 
also located using an H-point machine and recorded. The 50th percentile 
male driver size was used to represent the midpoint of the range of 
possible driver eye midpoint locations across all driver sizes. This 
full set of coordinate data was used to calculate visual angles between 
the eye midpoint and each of the center and upper and lower extents of 
the vehicles' instrument panels at their horizontal center. The plot 
below depicts visual angle calculation results for the instrument panel 
central upper edge, center point, and central lower edge for a 50th 
male driver's point of view.

[[Page 39723]]

[GRAPHIC] [TIFF OMITTED] TR09MY24.022

    Visual angle values for the instrument panel center point for these 
vehicles were found to range from 15.7 to 18.5 degrees. Nine of the ten 
vehicles were found to have instrument panel center locations that 
reside within 18 degrees downward of the driver's forward horizontal 
line of sight. Based on these data, NHTSA believes that revising the 
FCW visual symbol location 10-degree requirement to an 18-degree 
vertical angle would permit the large majority of current vehicle 
designs to display a telltale-sized or larger FCW visual symbol in the 
upper half of the instrument panel without any structural redesign or 
necessity of using a head-up display. Therefore, NHTSA has decided to 
expand the vertical angle to 18 degrees while retaining the 10-degree 
horizontal angle. The 10-degree value is being retained for the 
horizontal angle to preserve the FCW symbol's presentation at the 
center of the driver's forward field of view to maximize its 
perceptibility.
2. AEB Requirement
a. AEB Deactivation
    NHTSA discussed the issue of AEB deactivation in various 
circumstances, and the various ways it might become deactivated (i.e., 
manually or automatically). NHTSA used both ``disablement'' and 
``deactivation'' in the proposal, intending that those terms mean the 
same thing. The NPRM proposed prohibiting manual AEB system 
deactivation at any speed above the proposed 10 km/h minimum speed 
threshold for AEB system operation. NHTSA sought comment on this and 
whether the agency should permit manual deactivation similar to that 
permitted for ESC systems in FMVSS No. 126. NHTSA also sought comment 
on the appropriate performance requirements if the standard permitted 
installation of a manually operated deactivation switch.
    Regarding automatic deactivation, NHTSA stated that it anticipated 
driving situations in which AEB activation may not increase safety and 
in some rare cases may increase risk. For instance, an AEB system where 
sensors have been compromised because of misalignment, frayed wiring, 
or other partial failure, could provide the perception system with 
incomplete information that is misinterpreted and causes a dangerous 
vehicle maneuver. In instances where a light vehicle is towing a 
trailer with no independent brakes, or with brakes that do not include 
stability control functions, emergency braking may cause jack-knifing, 
or other dangerous outcomes. In the proposal, NHTSA stated that it was 
considering restricting the automatic deactivation of the AEB system 
generally and sought comment on providing a list of situations in which 
the vehicle is permitted to automatically deactivate the AEB or 
otherwise restrict braking authority granted to the AEB system.
    In addition to these situations, NHTSA requested comment on 
allowing the AEB system to be placed in a nonfunctioning mode whenever 
the vehicle is in 4-wheel drive low or the ESC is turned off, and 
whenever equipment is attached to the vehicle that might interfere with 
the AEB system's sensors or perception system, such as a snowplow. 
NHTSA requested comment on the permissibility of automatic deactivation 
of the AEB system and under which situations the regulation should 
explicitly permit automatic deactivation of the AEB system.
Comments
    Several commenters discussed AEB deactivation. The City of 
Philadelphia, the Richmond Ambulance Authority, DRIVE SMART Virginia, 
the National Association of City Transportation Officials (NACTO), 
Advocates for Highway and Auto Safety (Advocates), the Nashville 
Department of Transportation and Multimodal Infrastructure, and the 
City of Houston supported the proposed requirement to prevent AEB 
deactivation. In general, they stated that allowing system deactivation 
would diminish safety benefits.
    In contrast, many commenters stated that AEB deactivation should be 
allowed. For example, ASC, ZF, MEMA, NADA, Mitsubishi, Porsche, Aptiv 
and Volkswagen suggested that the agency should follow the specific 
deactivation criteria under UNECE Regulation No. 152. That regulation 
requires at least

[[Page 39724]]

two deliberate actions to deactivate the AEB system, and the system 
must default back to ``on'' after each ignition cycle.\83\ Toyota, 
Porsche, and Hyundai stated that manual deactivation for AEB systems 
should be similar to what is allowed for ESC systems in FMVSS No. 126. 
Rivian stated that manual deactivation should be allowed via either a 
software or hardware switch.
---------------------------------------------------------------------------

    \83\ UN Regulation No 152--Uniform provisions concerning the 
approval of motor vehicles with regard to the Advanced Emergency 
Braking System (AEBS) for M1 and N1 vehicles [2020/1597] (OJ L 360 
30.10.2020, p. 66, ELI: https://data.europa.eu/eli/reg/2020/1597/oj).
---------------------------------------------------------------------------

    Advocates opposed allowing deactivation of AEB systems, but they 
provided some suggestions for NHTSA if deactivation were allowed in 
narrowly tailored instances for specific applications with strong 
justification and supporting data. Advocates stated that any conditions 
allowed for automatic deactivation must not enable a means to 
intentionally deactivate the AEB system and suggest that any 
deactivation should trigger the malfunction telltale and be recorded as 
part of a data recording requirement. If NHTSA were to allow manual AEB 
deactivation, Advocates thought the process should require multiple 
steps while the vehicle is not moving and require drivers to engage in 
a deliberate and significant effort (i.e. a driver should not be able 
to disable AEB by pressing a single button). Advocates aligned with 
other commenters in suggesting that if any AEB deactivation occur, the 
system should default back to ``on'' at any new ignition cycle.
    The Alliance, Honda, NADA, Porsche, and Volkswagen suggested that 
the agency should allow manual deactivation to mitigate consumer 
dissatisfaction. Honda and NADA also stated that not allowing 
deactivation may lead to substantially higher false positive rates, 
while AAA stated that allowing for automatic or manual deactivation 
could increase consumer acceptance and minimize the perception that the 
systems are overbearing. NADA also stated that AEB false positives are 
a significant source of consumer complaints about AEB systems and that 
only 59 percent of respondents to a Consumer Reports survey indicated 
that they were satisfied with their AEB systems. The Alliance stated 
that in many cases, the circumstances warranting AEB deactivation are 
already described in vehicle owner's manuals or other information 
sources, and that it supports the continuation of describing such 
circumstances to the user.
    ASC stated that for ADAS-equipped vehicles where the primary 
operating responsibility belongs to the driver, AEB is an assist 
function and the driver should be able to deactivate the AEB system if 
required. ASC also stated that under extreme operating or environmental 
conditions, the AEB system may be outside its operating design domain 
and should automatically deactivate (temporarily) and that in some 
situations such as testing, or service, the AEB system should be able 
to be deactivated.
    SEMA, Ford, The Alliance, Rivian, Volkswagen, and HATCI suggested 
that there are likely several circumstances where deactivation of the 
system may be needed to ensure a safe vehicle operation, including 
track use, off-road use, and car washes. Some specific examples 
suggested by commenters include the use of chains on tires for 
traction, towing, four-wheel drive, low traction driving scenarios, and 
off-roading. SEMA and Mitsubishi stated that on a vehicle towing a 
trailer without an independent brake system, AEB activation may cause 
jack-knifing or other dangerous conditions. MEMA stated that drivers of 
many existing vehicles can currently disable their AEB system in cases 
where the AEB system is predictably, but incorrectly, triggered by 
objects or structures.
    NTEA stated that there is a need to be able to deactivate AEB when 
certain vocational equipment is attached in frontal areas where it 
intrudes into the field-of-view of an AEB system. NTEA stated that 
final stage manufacturers and alterers are not currently (nor 
foreseeably in the future) able to move/reinstall/recalibrate these 
systems to accommodate vocational upfits that can be in direct conflict 
with how these systems need to function. NTEA uses snowplows as an 
example of a vehicle equipment for which sensor relocation cannot 
accommodate AEB. NTEA stated, as an example of how provisions for 
deactivation could be included in the requirement, that one vehicle 
manufacturer has previously created a method to detect the presence of 
a plow blade in their electrical architecture, so that when the blade 
is attached, AEB is deactivated. AEB functionality resumes when the 
blade hardware is removed. NTEA provided examples of other front-
mounted equipment such as winches, sirens and push bumpers on emergency 
vehicles that could cause unintended consequences with the system 
reaction of AEB. Further, NTEA identified operational aspects of 
emergency and first responder vehicles that merit more consideration 
for AEB deactivation.
    The Alliance and Porsche stated that NHTSA should provide 
manufacturers with the ability to define automatic deactivation 
criteria. While Volkswagen stated that NHTSA should provide a list of 
situations where automatic deactivation is allowed it stated that this 
list should not be mandatory and joined the Alliance and Porsche in 
stating that OEM's should establish the situations where the AEB system 
is permitted to automatically deactivate, or otherwise restrict braking 
authority granted to the AEB system. HATCI did not specifically comment 
on the list of situations, but stated that allowing manual deactivation 
would provide affordances for unforeseen scenarios that industry and 
NHTSA have not yet contemplated which would help futureproof against 
situations that may not exist today. The Alliance stated that this 
approach introduces additional complexity in terms of demonstrating 
compliance with the standard. Porsche stated that providing a not 
``overly intrusive'' deactivation warning message would be appropriate 
and that the range of situations in which the systems would be 
automatically deactivated be infrequent and of limited duration.
    Finally, the Alliance also addressed whether the deactivation of 
ESC may cause deactivation of AEB. While not encouraged, a driver 
seeking to disable AEB may be left with no option but to turn both AEB 
and ESC systems off under NHTSA's proposal, reducing potential safety 
benefits from having the ESC system remain active.
Agency Response
    In this final rule, NHTSA does not allow for vehicles to be 
equipped with a manual control whose sole functionality is the 
deactivation of the AEB system. NHTSA agrees with the commenters who 
noted concerns about diminishing the safety benefits of this rule. 
Harmonization alone is an insufficient justification for allowing a 
control to deactivate the AEB system. Commenters have not explained why 
there is a safety need of a dedicated deactivation control or why a 
dedicated deactivation control would not diminish the safety benefits 
of AEB. The agency also disagrees with ASC's assertion that AEB is an 
``assist function,'' and even if true, that such a description would 
serve as a justification for allowing a manual deactivation control.
    NHTSA does not agree that any theoretical consumer dissatisfaction 
is one of the circumstances that justify allowing manual deactivation. 
AEB systems have been available on vehicles for many years. It is not 
reasonable to assume that there will be consumer acceptance issues due 
to the requirements of this final rule.

[[Page 39725]]

    NHTSA is not persuaded by comments that suggest that not permitting 
deactivation would lead to substantially higher false positive rates. 
NHTSA recognizes that AEB false positives are a source of consumer 
complaints, but NHTSA does not believe AEB deactivation is the solution 
to the engineering challenges manufacturers with lower performing 
systems might face in meeting this rule's requirements.
    That said, NHTSA recognizes that there are certain circumstances 
where deactivation may be appropriate, and the commenters raise several 
situations where NHTSA believes automatic deactivation would be the 
best approach. Examples of such a scenario include when a trailer is 
being towed, or when a snowplow is attached to a pickup truck. AEB 
activation while towing a trailer may be unsafe if the trailer does not 
have brakes. A snowplow may interfere with the sensing capabilities of 
the AEB system. In such cases, NHTSA expects that the manufacturer 
would automatically disable AEB functionality when interference with 
the sensing capabilities occurs. Using the example of towing, NHTSA 
expects that the manufacturer would design AEB to scan for towing 
connections and automatically disable AEB if it registers any.
    NHTSA agrees that it is important for the AEB system to default 
back to ``on'' after each ignition cycle, except in one circumstance--
in a low-range four-wheel drive configuration selected by the driver on 
the previous ignition cycle that is designed for low-speed, off-road 
driving. In that situation, NHTSA believes that reverting to the 
manufacturer's original default AEB setting would not be necessary. 
There is a similar exception for the ESC Off control.
    NHTSA also agrees with the Advocates that any deactivation should 
trigger the malfunction telltale because consistent illumination is 
important to remind drivers that safety equipment (i.e., AEB) is not 
functioning as the driver expects. Should the OEM design its systems in 
a way where the AEB system would automatically deactivate when the 
system detects that it cannot function properly (i.e., change 
performance in a way that takes the AEB system out of compliance with 
the requirements of the standard), then the driver must be alerted of 
this performance issue through a telltale. This applies to partial or 
full disablement of the system.
    NHTSA does not agree with the Alliance that restricting the 
installation of an ``AEB off'' control leaves a driver seeking to 
disable AEB with no option but to turn both AEB and ESC systems off. 
First, it is up to the manufacturer to decide if AEB is automatically 
turned off when ESC is turned off. Second, while it is not restricted 
by the FMVSS, it is the manufacturer's choice to install an ESC off 
switch. Finally, the agency asserts that if a driver does use the ESC 
off control for the purpose of turning off AEB, the restrictions 
included in this final rule limit the potential safety impacts 
particularly once the vehicle's ignition is turned off because AEB is 
required to turn back on with each ignition cycle, except when using a 
low-range four-wheel drive configuration.
    While NHTSA understands commenters' concerns about emergency 
vehicles, the Agency notes that flexibilities already exist for these 
vehicles, and we anticipate those flexibilities would be appropriate 
and sufficient to address these concerns. There are a number of ways 
that owners, and purchasers of emergency vehicles for official 
purposes, could modify their vehicles to fit the unique needs of 
emergency responders. Currently, manufacturers have the ability to sell 
upfit packages that provide the means, and instructions (upfit guides), 
for an emergency responder to interact with various vehicle features, 
including mandated safety features. A common example of these 
modifications involves the modification of lighting equipment and the 
activation of patterns which are not compliant with FMVSS No.108. While 
a vehicle manufacturer cannot manufacture a vehicle for sale with such 
lighting and activation patterns that fail to comply with FMVSS No. 
108, Lamps, reflective devices, and associated equipment, an emergency 
responder, as the owner of a vehicle, is not prohibited from making 
modifications to the vehicle.\84\ In addition, this final rule allows 
for the deactivation of AEB when ancillary systems that may affect AEB 
performance are activated.
---------------------------------------------------------------------------

    \84\ In the absence of an AEB mandate, some OEMs currently 
facilitate deactivation for emergency responders; for example 
``Available PreCollision Assist With Pedestrian Detection-- . . . 
For unique law-enforcement demands, a switch allows the feature to 
be temporarily disabled.'' https://www.ford.com/police-vehicles/hybrid-utility/, Accessed March 7th, 2024 at 10:20 a.m.
---------------------------------------------------------------------------

    In summary, NHTSA agrees with those commenters expressing 
opposition to broad inclusion of an on-off switch. The agency believes, 
as do those commenters, that the lifesaving benefits would be 
significantly compromised. However, some commenters noted that certain 
vehicles are used in unusual environments or for unique purposes, and 
their operation might be hampered by an AEB system that cannot be 
deactivated. The agency has not included on-off AEB functionality for 
emergency vehicles, as a broad group, as these purpose-built vehicles 
already have flexibilities. However, the agency believes that one other 
situation is appropriate for inclusion of on-off functionality--
vehicles used by law enforcement.
    Law enforcement has unique needs that often necessitate some 
differences in the configuration or functionality of their motor 
vehicles. The motor vehicles they purchase may be purpose-built police 
vehicles or unaltered vehicles available to the general public. In 
either case, law enforcement has a critical need to deactivate AEB when 
such vehicles are used in intervention maneuvers to disable a suspect's 
vehicle or in security escorts and processions driving in tight 
formation. For this reason, this final rule provides a limited 
exception that allows the manufacture, or the modification after sale, 
of vehicles that include the ability to activate and deactivate AEB for 
vehicles owned by law enforcement agencies.\85\ Manufacturers should 
work to directly provide an on-off capability for verified law-
enforcement-owned vehicles or make it as easy as possible for a third 
party to do so on behalf of law enforcement, with appropriate security 
safeguards, and NHTSA is committed to actively facilitating this 
process. Should manufacturers fail to address this important need, 
NHTSA may consider taking additional regulatory action. NHTSA 
anticipates that law enforcement vehicles resold to other than law 
enforcement entities will be restored to their original condition 
(i.e., by disabling the on-off capability).
---------------------------------------------------------------------------

    \85\ The agency does not have a precise estimate of the number 
of vehicles that may be affected by this flexibility, but notes 
that, when considered as part of the entire fleet, this effect is 
likely to be de minimis.
---------------------------------------------------------------------------

    NTEA's comment requests that NHTSA consider adding regulatory 
compliance pathways for upfitters. NHTSA understands NTEA's concern 
regarding glass replacement and the impact that has on FCW/AEB sensors. 
As AEB is not a new system, this is not a new issue for glass 
replacement upfitters. The agency is aware of glass replacement 
upfitters that already work with manufacturers to ensure proper sensor 
calibration. It is not expected that the requirements of this final 
rulemaking will affect their ability to continue to collaborate as they 
have been. NHTSA also expects that manufacturers might provide for 
automatic deactivation for vocationally

[[Page 39726]]

specific equipment when it is in use, such as the snowplow example NTEA 
provides in its comment.
    As for the equipment installed for vocational vehicles, NHTSA 
expects upfitters to avoid installing equipment that would result in 
AEB no longer working (or malfunctioning). NHTSA expects that in rare 
cases where no engineering solution may exist such as with snowplows, 
that upfitters would leave final installation of this equipment to the 
vehicle owners to avoid making inoperative required safety equipment. 
In such situations, NHTSA expects that the malfunction indicator would 
illuminate as a constant reminder to the driver that AEB is not 
working. As discussed in other sections, NHTSA believes that this 
consistent illumination is important to remind drivers that important 
safety equipment (i.e., AEB) is not functioning as the driver expects.
b. Aftermarket Modifications
    SEMA stated that while the proposed rule applies to motor vehicle 
manufacturers and alterers of new passenger cars and light trucks, it 
does not specify how aftermarket vehicle modifications and alterations 
may impact AEB systems. SEMA stated that they seek guidance from NHTSA 
on implementing FMVSS for AEB and PAEB and the legal obligations of 
SEMA members who produce, install, or sell aftermarket parts, as well 
manufacturers, installers, retailers, distributors, and independent 
repair shops regarding the ``tampering/make inoperative'' provision (49 
U.S.C. 30122).
    NHTSA notes that SEMA's comment invokes two separate provisions of 
the Safety Act because the situations of alterers and repair businesses 
are different. NHTSA has issued several interpretations of the 
obligations of both alterers and repair businesses, and the agency 
summarizes those key points here.\86\
---------------------------------------------------------------------------

    \86\ Letter to Antonio Salvetti (Dec. 29, 1994) https://
www.nhtsa.gov/interpretations/
10425#:~:text=An%20%22alterer%22%20is%20one%20who,such%20as%20paintin
g%2C%20or%20by; Letter to Alan Nappier, Earl Stewart Toyota (Apr 17, 
2015). https://www.nhtsa.gov/interpretations/30122-make-inoperative-alan-nappier-april-14.
---------------------------------------------------------------------------

    An ``alterer'' is defined as a person who alters by addition, 
substitution, or removal of components (other than readily attachable 
components) a certified vehicle before the first purchase of the 
vehicle other than for resale.\87\ The Safety Act and NHTSA's 
regulations require vehicle manufacturers certify that their vehicles 
comply with all applicable FMVSSs (49 U.S.C. 30112; 49 CFR part 567). 
NHTSA's regulations at 49 CFR 567.7 require the alterer to ensure that 
the vehicle, as altered, conforms to the FMVSSs affected by the 
alteration(s) and to certify to that effect in accordance with the same 
section. Alterers make this certification by affixing a permanent label 
to the altered vehicle identifying the alterer and the date of 
alteration.
---------------------------------------------------------------------------

    \87\ 49 CFR 567.3.
---------------------------------------------------------------------------

    In contrast, a vehicle repair business is defined as a person 
holding itself out to the public to repair for compensation a motor 
vehicle or motor vehicle equipment. Repair businesses usually work on 
vehicles after the time of first sale, which means that instead of 
complying with the certification requirements like a manufacturer or 
alterer, a repair business must ensure that it does not violate the 
Safety Act's make inoperative prohibition. The Safety Act states that a 
vehicle manufacturer, distributor, dealer, rental company or repair 
business is prohibited from knowingly making inoperative any part of a 
device or element of design installed in or on a motor vehicle that 
complies with an applicable FMVSS.\88\ An entity does not need to have 
actual knowledge that a device or element of design would be made 
inoperative by the entity's modification in order for that modification 
to violate section 30122.\89\
---------------------------------------------------------------------------

    \88\ 49 U.S.C. 30122.
    \89\ Letter to Alan Nappier, Earl Stewart Toyota (Apr. 17, 
2015), https://www.nhtsa.gov/interpretations/30122-make-inoperative-alan-nappier-april-14.
---------------------------------------------------------------------------

    Additionally, section 30122 does not require repair shops to 
restore safety systems damaged in a collision to a new or pre-crash 
condition.\90\ Instead, under section 30122, when any repair to a 
vehicle is completed, the vehicle must be returned to the customer with 
the safety systems capable of functioning at least as well as they were 
able to when the vehicle was received by the repair shop.\91\
---------------------------------------------------------------------------

    \90\ See, e.g., https://isearch.nhtsa.gov/aiam/aiam4681.html, 
letter to Linda L. Conrad, January 19, 1990.
    \91\ Nonetheless, NHTSA strongly encourages repair shops to 
restore functionality to safety systems to ensure that the vehicles 
will continue to provide crash protection for occupants during the 
life of the vehicle.
---------------------------------------------------------------------------

    Given the information above, NHTSA concludes the two types of 
entities about which SEMA is concerned both have an obligation to 
prevent a noncompliance with the FMVSS created by this final rule. 
Since NHTSA is establishing a new FMVSS with this final rule, the same 
rules of certification and make inoperative will apply, except for 
narrow circumstances for law enforcement-owned vehicles.
    NHTSA is aware that many law enforcement vehicles are modified 
after purchase to meet the unique needs of law enforcement. Sometimes 
this work is completed by in-house entities, and other times, this work 
may be contracted out to third parties. If those third parties are the 
entities listed in 49 U.S.C. 30122, they are prohibited from making 
inoperative any system or element of design that is in compliance with 
a FMVSS, including this new FMVSS. To ensure that law enforcement are 
able to modify their vehicles to fit their unique needs, and to ensure 
that third-party repair businesses are capable of assisting them, NHTSA 
has added a make inoperative exemption in 49 CFR part 595 that permits 
manufacturers, dealers,and motor vehicle repair businesses to modify a 
vehicle owners by a law enforcement agency to provide a means to 
temporarily deactivate an AEB system. This addition is complementary to 
the additional text added in S5.4.2.1 and discussed in the proceeding 
section.
c. No-Contact Requirement for Lead Vehicle AEB
    The proposed performance criterion for all AEB tests involving a 
lead vehicle is full collision avoidance, meaning the subject vehicle 
must not contact the lead vehicle.
    NHTSA requested comment on two alternatives to a no-contact 
requirement for the lead vehicle performance test requirements. The 
first alternative would be to permit low speed contact in NHTSA's on-
track testing. The agency requested comment on the appropriateness of 
such a requirement, any factors to consider surrounding such a 
performance level, and what the appropriate reduction in speed or 
maximum impact speed should be. The other alternative discussed in the 
proposed rule was a requirement that permits the vehicle to use 
multiple runs to achieve the performance test requirements. This 
alternative is discussed in the ``Permissibility of Failure'' section.
Comments
    In response to the NPRM, the IIHS, the Advocates, NTSB, AAA, 
Adasky, and Luminar, expressed support for the full collision avoidance 
(i.e., no-contact) requirement in all proposed AEB tests. IIHS stated 
that their evaluations of existing AEB systems indicated that some 
current systems are completely avoiding collisions at the highest 
speeds IIHS has tested, which is 70 km/h. Advocates stated that the 
vehicles are

[[Page 39727]]

tested under nearly ideal conditions and, by requiring a no-contact 
condition for success, the benefits of the system will be stronger 
under less-than-ideal conditions in the real world. NTSB and AAA stated 
that the no-contact requirement is consistent with the need for safety, 
and potentially necessary to ensure test repeatability. Luminar stated 
that they were concerned that regulating some degree of contact in 
these scenarios presents significant concerns for test efficiency, 
integrity and cost related to compliance. Luminar stated that the no-
contact performance is within the capability of existing technology.
    Several commenters, including the Alliance, Honda, FCA, Nissan, 
Volkswagen, SEMA, and MEMA stated that the proposed no-contact 
requirement in lead vehicle AEB tests is not practicable at the 
proposed test speeds. Many of these commenters suggested a hybrid 
approach of collision avoidance at lower speeds and speed reduction at 
higher speeds. Multiple commenters stated that the proposed test speeds 
will require earlier intervention by AEB systems to meet the ``no-
contact'' requirement, which they state will cause various unintended 
consequences, such as false positives due to test speeds or AEB 
intervention at a time where evasive steering may still be possible.
    Many commenters stated that the expectation of no contact in the 
real world is not practical. The Alliance stated that while the 
research indicated that certain vehicles performed better under certain 
test conditions, the number of tests run, particularly at higher 
speeds, is insufficient to make any reliable determination as to the 
repeatability and reproducibility of testing and that the agency ran 
only one test per vehicle at each of the different speed ranges in each 
scenario. Many commenters also observed that no vehicle was found to 
have met all the proposed requirements.
    Further, the Alliance described two aspects of brake performance 
that they suggested should be considered. First, they stated that peak 
deceleration capability of the vehicle is generally limited by the tire 
adhesion and is therefore not likely to be impacted by brake hardware 
changes, and performance today typically exceeds the mandated 
performance from FMVSS No. 135 or FMVSS No. 105. The second aspect of 
brake performance which the Alliance stated must be considered is the 
time factor to reach the target deceleration.
    Honda, Nissan, and other commenters stated that the proposed test 
requirements do not consider the trade-off between collision avoidance 
through evasive steering and emergency braking, leading to increased 
concerns for false activations. Further, Honda stated that to meet the 
proposed higher speed no-contact requirements, current systems would be 
forced to provide braking intervention with significantly reduced 
recognition reliability and that current AEB systems would need to be 
completely redesigned.
    Bosch stated that its testing shows that when the speed reaches 
approximately 75 km/h, there are reproducibility challenges with multi-
sensor fusion of the object in time to initiate AEB and avoid the 
obstruction, and considerations should be made on how these 
requirements align with current functional safety requirements.
    Volkswagen stated that they conducted an analysis using the Crash 
Investigation Sampling System (CISS) where data from rear-end crashes 
were collected from Event Data Recorder (EDR) data. The results were 
that there were no injuries above the Vehicle Abbreviated Injury Scale 
(VAIS) of 3+ in this small sample, noting that this was a non-
statistically significant sample of 56 rear end crashes below a 
relative collision speed of 50 km/h.
    MEMA stated that they agreed with the NHTSA alternate proposal for 
contact which, consistent with European regulations, allows low speed 
contact during testing. MEMA suggested a no-contact test requirement at 
speeds up to 25 mph (roughly 40 km/h), and a realistic speed reduction 
requirement above this speed (i.e., collision mitigation). Hyundai 
stated that a target deceleration rather than no contact should be used 
as the appropriate criterion for assessing AEB performance.
    HATCI stated that the requirements for damageability from 49 CFR 
part 581 address the need to reduce severity of any impact following 
activation of AEB, such that reductions in fatalities and injuries are 
achieved without stipulating no contact. Further, HATCI stated that the 
part 581 bumper standard speeds do not cause damage to the vehicle or 
Global Vehicle Target (GVT) and are highly unlikely to cause injuries 
to the vehicle occupants.
    Mitsubishi stated the agency should allow for maximum contact speed 
instead of no contact, especially for higher test speeds, as the NPRM's 
proposed requirement would require OEMs to fully redesign their AEB 
systems, including new hardware. Further, Mitsubishi stated that the 
benefit for systems which allow a low speed, such as a 10 km/h, impact 
to the rear-end of another vehicle can be considered comparable to no 
contact in terms of fatal or severe injury likelihood. Mitsubishi also 
stated that they opposed a regulatory requirement whose purpose appears 
to be reduction of the test burden by seeking to avoid rebuilding the 
strikable target when impacted. Therefore, Mitsubishi stated that they 
suggest 1) allowing low speed contact, 2) eliminating the higher 
approaching-speed test, and 3) securing reasonable headway distance, 
particularly with higher speed of the decelerating lead-vehicle 
scenarios.
    FCA raised issues with whether the no-contact requirement was 
appropriate for vehicles with greater mass. FCA provided a graph 
developed from their research that suggests that as test weight went 
up, the overall pass (contact) rate went down.\92\ FCA stated that this 
means one of two things: heavier vehicles installed less capable AEB 
systems or otherwise if all AEB systems were comparable, then the test 
weight of vehicle hardware could be a dominant factor in the compliant 
``no-contact'' outcomes.
---------------------------------------------------------------------------

    \92\ https://www.regulations.gov/comment/NHTSA-2023-0021-0999, 
see page 9.
---------------------------------------------------------------------------

    Furthermore, FCA stated that the proposed requirements that the 
subject vehicle under test ``does not collide'' is subjective. The soft 
coverings over both devices will have dimensional variation as they 
exhibit wrinkles and folds or fluttering. FCA stated that they do not 
understand what ``not collide'' means in this context. FCA suggested 
NHTSA investigate this concept and make a new proposal as to what 
``collide'' means as an objective, regulatory concept.
Agency Response
    This final rule adopts the full collision avoidance (i.e., no-
contact) requirement proposed in the NPRM, which requires that the 
subject vehicle must not contact the lead vehicle in all AEB 
performance tests listed in the regulation. After considering all 
comments and for the reasons discussed below, the agency believes that 
the proposed no-contact requirement continues to be the most 
appropriate. NHTSA does not believe that further investigation is 
necessary to determine what collide means, in the context of this rule.
No Contact Provides Maximum Safety Benefits and Is Consistent With the 
Safety Act
    As noted in the NPRM, one of the primary reasons for choosing the 
no-contact requirement in lead vehicle AEB tests is to maximize the 
safety benefits of the rule. Many commentors agreed

[[Page 39728]]

with the agency's decision to obtain maximum benefits to the public. 
Advocates stated that allowing contact during AEB testing will lessen 
the strength/benefit of the rule. Similarly, NTSB stated that the no-
contact requirement is consistent with the need for safety and should 
be mandated to obtain the best possible safety outcome. Further, AAA 
and NSC stated that the no-contact requirement could eliminate millions 
of injuries and thousands of fatalities over a five-year period. 
Alliance acknowledged that the alternative approaches proposed by the 
organization could provide meaningful safety gains (not the best 
benefit). As for additional benefits of the requirement, we agree with 
Luminar that the no-contact requirement also provides economic benefit 
by reducing the total cost of vehicle ownership with insurance savings.
    NHTSA agrees with the commenters who stated that obtaining safety 
benefits is crucial for this final rule. NHTSA agrees with IIHS that 
some current systems are already completely avoiding collisions under 
the proposed lead vehicle AEB testing more than five years before this 
rule will take effect. One vehicle discussed in the additional research 
section performed very well and passed all lead vehicle AEB 
requirements except for only the most stringent condition under the 
lead vehicle decelerating scenario--satisfying the requirements in two 
out of five tests. Thus, the outcome of that additional confirmatory 
testing is encouraging and demonstrates that these requirements are 
practicable. The testing results provided by IIHS in their comment 
provide NHTSA with additional evidence that the requirements are within 
reach for manufacturers because the technology exists and the final 
rule provides sufficient lead time.
The No-Contact Requirement Is Practicable
    The commenters who opposed the no-contact requirement and asserted 
that it is not practicable rely heavily on the 2020 testing and that no 
single vehicle achieved compliance in any single run. This assertion 
rests on misunderstandings of the applicable law and a failure to 
consider the trajectory of the technology and its performance.
    First, no single vehicle must meet every requirement for an FMVSS 
to be considered practicable under the Safety Act. The Sixth Circuit in 
Chrysler Corp. v. Dep't of Transp. provided detailed analysis of the 
technology-forcing authority possessed by NHTSA and the legislative 
history that reinforces the court's conclusion.\93\ The Sixth Circuit 
stated:
---------------------------------------------------------------------------

    \93\ 472 F.2d 659 (6th Cir. 1972).
---------------------------------------------------------------------------

    ``[the] explicit purpose of the Act, as amplified in its 
legislative history, is to enable the Federal government to impel 
automobile manufacturers to develop and apply new technology to the 
task of improving the safety design of automobiles as readily as 
possible.'' \94\ The Senate Report also states that Congress rejected 
the Automobile Manufacturers Association's attempt to bind the rate of 
innovation imposed by safety standards to the pace of innovation of the 
manufacturers.\95\ Similarly, the House Report states that NHTSA should 
consider all relevant factors when considering whether a safety 
standard is practicable, ``including technological ability to achieve 
the goal of a particular standard.'' \96\ The Sixth Circuit rightly 
points out that there would be no need for NHTSA to consider 
technological ability to achieve a particular safety goal if NHTSA was 
limited to issuing standards that reflected the current state of 
technology.\97\ The court ultimately ruled that NHTSA is empowered by 
the Safety Act to issue FMVSS that require improvements in existing 
technology or that might even require development of new 
technology.\98\
---------------------------------------------------------------------------

    \94\ Id. at 671, citing S.Rep. 1301, 89th Cong., 2d Sess., 2 
U.S.Code, Cong. and Admin.News, 2709 (1966).
    \95\ S.Rep. 1301, 89th Cong., 2d Sess., 2 U.S.Code, Cong. and 
Admin.News, 2709 (1966), which states ``In fact, specific efforts by 
the Automobile Manufacturers Association to tie the rate of 
innovation imposed by safety standards to the pace of innovation of 
the manufacturers were rejected by the House Committee on Interstate 
and Foreign Commerce, and the reported bill proposed that safety 
standards be ``practicable, meet the need for motor vehicle safety, 
and be stated in objective terms.''
    \96\ H.R. Rep. 1776, p. 16.
    \97\ 472 F.2d at 672.
    \98\ Id. at 673.
---------------------------------------------------------------------------

    Second, NHTSA has evidence that AEB performance improved 
dramatically between 2020 and 2023 model years. Considering the marked 
improvement in AEB system performance demonstrated in NHTSA's 
additional testing, NHTSA finds that manufacturers are already coming 
close to meeting the requirements of this final rule.
    The agency disagrees with commenters that the no-contact 
requirement is not practicable because no vehicle in the agency's 2020 
research met all lead vehicle AEB tests as presented in the NPRM. We 
believe that the vehicles used in the 2020 research were designed with 
the intention to meet the demands from the 2016 voluntary commitment 
and the existing U.S. NCAP. As presented in the NPRM, these programs 
demand a much lower level of AEB performance than those of this final 
rule. For example, the highest test speeds of the 2016 voluntary 
commitment and the NCAP are both 40 km/h (25 mph) in a lead vehicle 
stopped test scenario. On the other hand, the highest subject vehicle 
test speed of this rule for the same scenario is 80 km/h (50 mph)--much 
higher than that of the programs. Even though the AEB systems were 
designed with substantially low target performance goals, three out of 
eleven vehicles in the 2020 research were able to meet the no-contact 
requirement at the speed up to 72.4 kph (45 mph) in the lead vehicle 
stopped test scenario.
    NHTSA conducted additional AEB research with six model year 2023 
vehicles (from six different manufacturers) using the performance 
requirements and test procedures of this final rule.\99\ The results of 
this additional research demonstrated that one vehicle was able to meet 
the no-contact requirement at least once in all required lead vehicle 
AEB test conditions. Thus, the technologies needed to make the AEB 
systems which can meet the no-contact requirement and other performance 
requirements of this final rule are currently available. IIHS also 
observed similar results, which they assert indicate that some existing 
AEB systems are able to completely avoid collisions in the required 
lead vehicle AEB testing conditions.
---------------------------------------------------------------------------

    \99\ NHTSA's 2023 Light Vehicle Automatic Emergency Braking 
Research Test Summary, available in the docket for this final rule 
(NHTSA-2023-0021).
---------------------------------------------------------------------------

    Furthermore, in analyzing whether an FMVSS is objective, 
practicable and meets the need for motor vehicle safety, NHTSA must 
balance benefits and costs and consider safety as the preeminent factor 
in its considerations.\100\ NHTSA believes that lowering the 
performance requirement to one that allows for contact would fail to 
treat safety as the preeminent factor for this final rule and otherwise 
be inconsistent with the goals of the Safety Act.
---------------------------------------------------------------------------

    \100\ See, e.g., Motor Vehicle Mfrs. Assn. of United States, 
Inc. v. State Farm Mut. Automobile Ins. Co., 463 U.S. 29, 55 (1983) 
(``The agency is correct to look at the costs as well as the 
benefits of Standard 208 . . . When the agency reexamines its 
findings as to the likely increase in seat belt usage, it must also 
reconsider its judgment of the reasonableness of the monetary and 
other costs associated with the standard. In reaching its judgment, 
NHTSA should bear in mind that Congress intended safety to be the 
preeminent factor under the Motor Vehicle Safety Act.'').

---------------------------------------------------------------------------

[[Page 39729]]

Increasing Unintended Consequences
    In the comments, vehicle manufacturers and equipment suppliers 
expressed concern that the no-contact requirement may cause some 
unintended consequences, such as increasing false positive activations 
and taking away driver's authority at a high speed.
    As for the false positives, the concern is based on a hypothetical 
situation that the no-contact requirement might cause a vehicle to 
prematurely activate the AEB system from a far distance where there is 
not a true risk of an imminent crash. The rationale is that the vehicle 
would be forced to initiate an early braking to achieve a full 
collision avoidance. These comments represent a combination of 
concerns--concerns with the no-contact requirement and concerns with 
the maximum speed in the testable range. This section addresses only 
the issue of no contact. Other related issues are addressed in the 
appropriate sections.
    NHTSA does not expect that false activation would occur for well-
designed systems. NHTSA recognizes that false activation could occur 
when an AEB system has low accuracy and reliability. As mentioned 
previously, we agree with Luminar and other commentors that no-contact 
performance is within the capability of existing technology. For 
example, Honda asserted that an AEB system will likely intervene 
improperly when the road in front of a subject vehicle is curved to the 
left and there is a vehicle parked on the right side of the road that 
causes no risk of collision. If the subject vehicle is equipped with 
sufficient technology to detect the shape of the road ahead, the AEB 
system would not improperly activate based on the mere fact that a 
parked vehicle appeared in the middle of AEB's field of view. There are 
manners in which an algorithm can assess the shape of the road. The 
system will also be continuously receiving more data as the vehicle 
gets closer.
    Another technical option is having redundant systems as suggested 
in the Alliance's comment. Regardless of whatever technical solution 
manufacturers choose, NHTSA does not believe that it should lower 
performance to match that of poor performers. Rather, manufacturers 
with poorly performing vehicles should strive to resolve their systems' 
deficiencies so that they can perform as well as the market's better or 
best performing vehicles.
    Additionally, while this rule imposes performance requirements for 
AEB systems, it does not specify how manufacturers must meet the 
requirements. The agency is providing maximum flexibility to 
manufacturers in designing AEB system for their vehicles. NHTSA 
recognizes that different manufacturers have different economic and 
practical realities that face their businesses. NHTSA principal concern 
is with the safety outcome and not the path that a manufacturer chooses 
to take to get to the required outcome. Given the various technical 
options, selecting technology for their AEB systems and setting the 
level of accuracy and reliability are at the manufacturers' discretion. 
At the same time, the manufacturers should be responsible for any 
safety-related defects in their vehicle products, in this case 
potential false positive activations. Therefore, we expect that vehicle 
and equipment manufacturers will mitigate and resolve any product 
defect issues including potential false activation in their AEB 
systems. NHTSA will continue to monitor complaints on AEB systems from 
the public, including those involving false activations, and will 
evaluate the risks they present.
    NHTSA does not agree with the Alliance and other commenters that an 
AEB activation at a high speed may remove a safer crash avoidance 
option from drivers. The AEB system presumably only starts braking when 
the system detects an imminent crash, which is the first thing NHTSA 
expects a driver would do. While last-minute steering by the driver 
intended to avoid a crash is another possibility, NHTSA is not 
persuaded this is the safest option or that it is incompatible with AEB 
activation. A steering maneuver to avoid a crash might succeed under 
very limited circumstances. First, there must be another lane adjacent 
to the primary lane where a subject vehicle and a target vehicle are 
located. Second, a sufficient space must also be available in the 
adjacent lane. Finally, the driver must have the ability to safely 
maneuver a vehicle at such a high speed. Regardless, nothing in this 
rule specifies what an AEB system must do when a driver executes a 
steering maneuver to avoid a crash.
Global Harmonization Is Not Possible for No Contact Because it 
Unreasonably Lowers the Safety Benefits Received by the Public
    NHTSA received comments that requested NHTSA to reject the no-
contact requirement and adopt UNECE Regulation No. 152 requirements 
that permit low speed contact. Consistent with NHTSA's longstanding 
commitment to international harmonization \101\ and section 24211 of 
BIL, NHTSA cooperates to the maximum extent practicable with respect to 
global harmonization of vehicle regulations as a means for improving 
motor vehicle safety.
---------------------------------------------------------------------------

    \101\ https://www.federalregister.gov/documents/1994/03/08/94-5181/revision-of-the-1958-united-nations-economic-commission-for-europe-agreement-regarding-the.
---------------------------------------------------------------------------

    NHTSA has been a leader in various international forums that impact 
vehicle safety for decades. The primary forum in which NHTSA engages in 
these activities is UNECE World Forum for Harmonization of Vehicle 
Regulations (WP.29). This international work is crucial to NHTSA's 
safety mission because it allows the agency to share its knowledge and 
expertise with foreign counterparts around the world, and for NHTSA to 
learn from its foreign counterparts. It also allows for NHTSA to 
advocate for standards that meet NHTSA's robust requirements and 
improve safety is measurable ways. Analysis of safety benefits provide 
NHTSA with a good understanding of the expected impact of its 
regulations. Such analysis is not necessarily required or conducted at 
WP.29.
    NHTSA does not interpret section 24211 of BIL as requiring that 
NHTSA adopt harmonized regulations for the primary purpose of 
harmonization. To adopt this interpretation would be inconsistent with 
the text of section 24211 and the Safety Act. NHTSA interprets section 
24211 as requiring NHTSA to promote safety in global forums. NHTSA 
believes that ``as a means for improving motor vehicle safety'' is 
intended to convey that the requirement to harmonize has the goal of 
improving motor vehicle safety. In situations where adopting an 
international or regional regulation would result in reducing motor 
vehicle safety, NHTSA does not believe the agency carries any 
obligation under the abovementioned section to adopt regulations that 
result in lower performance.
    UNECE Regulation No. 152 was drafted by entities under an agreement 
to which NHTSA is not a party, and it was drafted years before NHTSA's 
NPRM. The testing NHTSA has conducted in support of this rule indicate 
that the industry has made substantial progress between 2020 and 2023 
model years. NHTSA's adoption of more stringent requirements than 
existing UN Regulations indicates NHTSA's commitment to maximizing 
safety.

[[Page 39730]]

Variability and Compliance Margins
    FCA's comment indicates that it is concerned both about variability 
and about the compliance margins it thinks may be necessary for it to 
ensure compliance with this rule. First, FCA commented that the no-
contact requirement would force early decisions and that the NPRM did 
not discuss why, in multiple runs, vehicles can pass some but not all 
tests without contacts. From NHTSA's perspective, the variability seen 
in NHTSA testing is expected because the systems tested were not 
designed to be compliant with the proposed requirements. As NHTSA has 
seen through its NCAP testing, manufacturers design systems to meet 
whatever thresholds are set, and when they do that, their vehicles are 
designed to pass those tests. This suggests to NHTSA that the 
variability in the NHTSA testing is due to the fact that no 
manufacturer has designed their systems to meet all of these 
requirements. While NHTSA understands that industry is concerned about 
the stringency of the no-contact requirement, variability does not seem 
to be at the heart of that issue.
    FCA also raised concerns about the compliance margins it believes 
may be necessary for its products to comply with the no-contact 
requirement. Compliance margins are usually manufacturer dependent due 
to a variety of reasons that include the fact that each manufacturer 
establishes a different level of organizational risk acceptance and 
each manufacturers' products are usually unique to that manufacturer. 
As stated in the FRIA accompanying this rule, different manufacturers 
may have differing compliance margins with which their companies are 
most comfortable. Differing compliance margins and overall 
organizational risk management practices can impact the product and 
costs to make that product. Manufacturers are free to choose what 
compliance margins make sense for their organization and their 
products, and NHTSA does not dictate that. NHTSA establishes a minimum 
level of performance and manufacturers are required to ensure that 
their products meet that minimum level.
NHTSA's Testing Is Sufficient To Support This Rule
    The testing conducted by the agency included the most common rear-
end crash scenarios across several speeds and included a range of 
vehicle types and both camera and radar and camera fusion systems. In 
the case that the vehicle met the requirements (no contact) for a 
specific crash scenario and speed, testing continued at higher speeds. 
For the Lead Vehicle AEB testing, each vehicle was tested five to seven 
times for each scenario and speed combination. For the PAEB testing, 
each vehicle was typically tested five times for each combination of 
scenario, speed, and lighting condition.
    In the absence of unlimited time and resources, it is not possible 
to test every vehicle across each combination of scenario, speed, and 
condition. Further, contact with a target object has the potential to 
compromise future test runs. Even relatively low speed impacts can 
result in a misalignment of forward-looking sensors, particularly those 
mounted behind lower trim and/or the grill. As a result, subsequent 
(i.e., post impact) tests may not be representative of the vehicle 
condition at time of first sale.
    The vehicles included in the testing conducted by the agency 
include a variety of body styles including heavier vehicles such as 
SUVs and pick-up trucks. The heavier vehicles included in testing NHTSA 
used to support the NPRM were Ford F-150 SuperCrew, Mercedes-Benz GLC 
300, Hyundai Palisade, Audi Q5, and Range Rover Sport. The vehicles 
that NHTSA tested also included a mix of camera only and radar and 
camera fused systems utilized by model year 2020/19 vehicles.
    Furthermore, NHTSA performed additional confirmatory testing that 
included 2023 model years. This testing showed that the models tested 
performed even better than those in 2020, which supports NHTSA's 
position that this rule is not only achievable but very close to being 
within reach for many manufacturers. NHTSA believes that the research 
from 2020 and 2023 is sufficient to support this final rule.
d. No-Contact Requirement for Pedestrians
    Similar to the lead vehicle AEB performance test requirements, 
NHTSA proposed that PAEB-equipped vehicles must completely avoid a 
collision with a pedestrian test mannequin during specific test track 
scenarios. NHTSA requested comment on the same two alternatives to a 
no-contact requirement for pedestrian performance test requirements.
    NHTSA notes that the positions taken by commenters for both lead 
vehicle AEB and PAEB are substantially similar, and therefore, much of 
what was said in the previous section also applies. This section 
primarily addresses issues specific to pedestrians.
Comments
    IIHS stated that their evaluations of existing PAEB systems 
indicated that some current systems are completely avoiding collisions 
in the required PAEB testing conditions. IIHS stated that they began 
evaluating PAEB performance in new vehicles during the day in 2019 and 
at night in 2022. Furthermore, they stated that IIHS's PAEB ratings are 
based on a mixture of the data submitted by manufacturers for 
verification and the results from their internal testing. As of June 
2023, IIHS stated that they rated 194 model year 2023 PAEB systems 
tested during the day. Of those, 33 (17 percent) fully avoided the 
pedestrian mannequin in every test condition. IIHS further stated that 
of the 114 model year 2023 PAEB systems tested at night, 12 (11 
percent) fully avoided the pedestrian mannequin in every test 
condition.
    MEMA commented that full avoidance is not reproduceable at higher 
velocities in low light conditions and in obstructed scenes. Due to 
external influences, MEMA contended that it is impossible to ensure 
that every test run is performed under the exact same conditions in 
this test, which is why it cannot be guaranteed that AEB will always 
achieve its maximum performance.
    The Alliance stated that they suggest that the agency set the 
requirements of the regulation with the goal of minimizing the risk of 
serious injury in cases where vehicle to pedestrian contact occur, 
while providing for more certainty in making a determination to apply 
the brakes for crash avoidance and mitigation. Based on available 
research, the Alliance stated that establishing a no-contact 
requirement up to 30 km/h and a residual relative speed contact 
threshold not to exceed 25km/h would ensure the risks of sustaining a 
MAIS 3+ injury is well below 10%. Further, The Alliance stated that 
this exceeds the acceptable injury thresholds established in NCAP (for 
achieving a five-star rating) as well as the recommendations of 
Academic Expert Group for the 3rd Global Ministerial Conference on Road 
Safety. The Alliance stated that the suggested hybrid approach which 
would maintain the no-contact requirements at vehicles speeds up to 30 
km/h but permit some level of contact if an acceptable speed reduction 
were achieved would reduce the potential for false positives under real 
world conditions.
    Bosch stated that they wanted to address the ``no-contact'' 
requirement in performance testing and its implications for safety 
systems, particularly in the

[[Page 39731]]

context of pedestrian dummy detection and reaction. Further, Bosch 
stated that considering the challenge of detecting and reacting to the 
pedestrian dummy, there are still reservations concerning the no-
contact requirement. Further, Bosch stated that they suggest that the 
criteria for collision mitigation systems be based on a certain amount 
of minimum speed reduction while considering injury-related 
assessments, such as the Head Injury Criteria (HIC) or similar measures 
(e.g., acceleration exerted on the body during crash).
Agency Response
    After considering the comments, the agency has concluded that the 
full collision avoidance requirement in PAEB tests, as proposed in the 
NPRM, is most appropriate for this final rule.
    First, we agree with commenters that pedestrians could suffer 
severe injury at any speed in the testable range. Pedestrians are 
particularly vulnerable when coming in contact with a vehicle of any 
size. This is especially true when pedestrians are stuck by larger 
vehicles such as SUVs and pickup trucks. NHTSA believes that the 
increased vulnerability of pedestrians makes it even less desirable to 
permit any vehicle-to-pedestrian contact within the testable range.
    Second, the impracticability argument raised by Alliance, MEMA and 
other manufacturers is not persuasive. That argument is primarily based 
on the agency's 2020 PAEB research presented in the NPRM, in which no 
vehicle met all required PAEB performance tests. The commenters assert 
that this reflects that the existing AEB related technologies are not 
ready for the level of PAEB performance required by this rule. However, 
we disagree with the commentors and believe that the results of the 
2020 research are not indicative of shortcomings in the overall 
capability of the current PAEB technology. Rather, they are systems 
designed to meet a lower level of performance.
    The agency conducted PAEB research with six model year 2023 
vehicles (from six different manufacturers) using the proposed 
performance requirements and test procedures.\102\ The results 
demonstrated that at least one vehicle was able to meet all performance 
requirements of this final rule. To the extent others do not, NHTSA has 
authority to issue technology-forcing standards when it is shown, as it 
is here, that meeting the standard is practicable.
---------------------------------------------------------------------------

    \102\ NHTSA's 2023 Light Vehicle Pedestrian Automatic Emergency 
Braking Research Test Summary, available in the docket for this 
final rule (NHTSA-2023-0021).
---------------------------------------------------------------------------

    While the Alliance asserts that reducing impact speeds with 
pedestrians below 25 km/h could reduce the risk of serious injury, 
NHTSA believes that striking a person with a vehicle is not acceptable 
at any speed under any conditions. NHTSA included pedestrians in this 
rule because of their vulnerability and the trend of increasing 
pedestrian fatalities. Accordingly, we believe that retaining the no-
contact requirement for the PAEB performance tests in the final rule is 
the most appropriate to ensure the maximum safety of the pedestrians.
e. Permissibility of Failure
    As an alternative to the no-contact requirement with a single run 
that NHTSA proposed for lead vehicle AEB and PAEB, NHTSA sought comment 
on permitting the subject vehicle to use multiple test runs to achieve 
the performance test requirements. NHTSA provided background about how 
NHTSA's crash imminent braking and dynamic brake support testing within 
the New Car Assessment Program tests performance criteria, at the time 
of NPRM publication, specify that the speed reduction requirements for 
each test scenario must be met in at least 5 out of 7 tests runs. NHTSA 
stated this approach would provide a vehicle more opportunities to 
achieve the required performance and the agency more statistical power 
in characterizing the performance of the vehicle.
    The agency also requested comment on the number of repeated tests 
for a given test condition and on potential procedures for repeated 
tests. The agency further requested comment on the merits of permitting 
a vehicle that fails to activate its AEB system in a test to be 
permitted additional repeat tests, including a repeat test process 
similar to that in the recent revisions to UNECE Regulation No. 152. 
Finally, the agency requested comment on whether there should be 
additional tests performed in the event no failure occurs on an initial 
test for each series.
    The Advocates, Forensic Rock and AAA oppose allowing repeated test 
trials in all test situations. Forensic Rock stated test failures 
should not be allowed when performing testing under ideal conditions. 
AAA stated that repeated tests would lead to ambiguity around whether a 
vehicle that has previously passed the test should be retested.
    The ASC, ZF, Humanetics, MEMA, Bosch, Mitsubishi, the Alliance, 
Porsche, Hyundai, Aptiv, Rivian, and Volkswagen all support allowing 
repeated test trials. ASC, ZF, Humanetics, MEMA, Bosch, and the 
Alliance specifically acknowledge that testing with a 5 out of 7 
passing threshold for the speed reduction tests would be appropriate. 
Rivian recommends running between 3 and 5 tests and averaging the speed 
reduction achieved with a passing grade being given to vehicles that 
average greater than a 50 percent speed reduction. The Alliance and 
Porsche also recommend that a vehicle could pass after three 
consecutive successful tests. ASC and ZF recommend that repeated trial 
testing be used at speeds of 25 mph and higher. ZF recommends that the 
speed reduction targets should be data driven based on speeds where 
there is a severely limited risk of injury to pedestrians or vehicle 
occupants. ZF, Porsche, Aptiv, Volkswagen and ASC also suggest the test 
requirements be aligned with UNECE Regulation No. 152 speed reduction 
requirements for daytime scenarios.
    NHTSA is not including multiple test trials in this final rule. 
NHTSA agrees with commenters that allowing for repeated test trials, 
which would essentially permit a certain threshold of failures, under 
ideal test conditions is not acceptable. NHTSA believes that a single 
test run, and the expectation that a manufacturer pass all test runs if 
NHTSA chooses to run the same test several times, provides the 
performance consistency that consumers expect and safety demands. This 
is particularly true given that NHTSA will be conducting testing in 
idealized, controlled conditions when compared to real-world 
situations. For many years, NCAP testing and other testing around the 
world has permitted repeated test trials, and NHTSA believes that is 
appropriate for a technology that is new or being developed. However, 
for more mature systems with a long record of real-world use, NHTSA 
believes that a single test run is necessary to provide the agency the 
confidence that the performance it is regulating will perform as 
consistently as possible.
    NHTSA believes it is even more important that PAEB perform in a 
single run with no contact due to the vulnerability of pedestrians in a 
vehicle-to-pedestrian crash. First, the speed ranges in which PAEB is 
expected to not contact a pedestrian mannequin during testing are lower 
than they are for lead vehicle AEB. Second, as with the no-contact 
provision, allowing for multiple runs is even more unacceptable for 
vehicle-to-pedestrian crashes because pedestrians are more vulnerable 
when being struck by a vehicle.

[[Page 39732]]

F. False Activation Requirement

    NHTSA proposed to include two scenarios in which braking is not 
warranted. The agency proposed that AEB systems need to be able to 
differentiate between a real threat and a non-threat to avoid false 
activations. The two proposed false activation scenarios were the steel 
trench plate and the vehicle pass-through test scenarios.
1. Need for Requirement
    NHTSA remains concerned that false activation events may introduce 
hard braking situations when such actions are not warranted, 
potentially causing rear-end crashes. The false activation tests 
establish only a baseline for system functionality. They are by no 
means comprehensive, nor sufficient to eliminate susceptibility to 
false activations. Rather, the tests are a means to establish minimum 
performance. NHTSA expects that vehicle manufacturers will design AEB 
systems to thoroughly address the potential for false activations. 
Vehicles that have excessive false positive activations may pose an 
unreasonable risk to safety and may be considered to have a safety-
related defect. Previous implementations of other technologies have 
shown that manufacturers have a strong incentive to mitigate false 
positives and are successful even in the absence of specific 
requirements.
    The two proposed false activation scenarios are the steel trench 
plate and the vehicle pass-through test scenarios. Both of these tests 
include acceleration pedal release and testing both with and without 
manual braking, similar to testing with a stopped lead vehicle. NHTSA 
proposed that, during each test trial, the subject vehicle accelerator 
pedal will be released either when a forward collision warning is given 
or at a headway that corresponds to a time-to-collision of 2.1 seconds, 
whichever occurs earlier. For tests where manual braking occurs, the 
brake is applied at a headway that corresponds to a time-to-collision 
of 1.1 seconds.
    In the steel trench plate false activation scenario, a subject 
vehicle traveling at 80 km/h (50 mph) encounters a secured 2.4 m (7.9 
ft) wide by 3.7 m (12.1 ft) long steel by 25 mm (1 in) thick ASTM A36 
steel plate placed flat in the subject vehicle's lane of travel, and 
centered in the travel path, with its short side toward the vehicle 
(long side transverse to the path of the vehicle).
    The pass-through test, as the name suggests, simulates the subject 
vehicle encountering two vehicles outside of the subject vehicle's path 
that do not present a threat to the subject vehicle. The test is 
similar to the UNECE Regulation No. 131 and UNECE Regulation No. 152 
false reaction tests.\103\ In the pass-through scenario, two vehicle 
test devices (VTDs) are positioned in the adjacent lanes to the left 
and right of the subject vehicle's travel path, while the lane in which 
the subject vehicle is traveling is free of obstacles.
---------------------------------------------------------------------------

    \103\ UNECE Regulation No. 131 (Feb. 27, 2020), available at 
https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R131r1e.pdf; UNECE 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.
---------------------------------------------------------------------------

    The two stopped VTDs are positioned parallel to each other and 4.5 
m (14.8 ft) apart in the two adjacent lanes to that of the subject 
vehicle (one to the left and one to the right with a 4.5 m (14.8 ft) 
gap between them). The 4.5 m (14.8 ft) gap represents a typical travel 
lane of about 3.6 m (11.8 ft) plus a reasonable distance at which a 
vehicle would be stationary within the adjacent travel lanes.
Comments
    ASC, MEMA, Hyundai, Volkswagen, Mitsubishi, and the Alliance for 
Automotive Innovation submitted comments opposing the proposed false 
activation tests. ASC stated that EuroNCAP does not include a false 
activation test because the vehicle could be programmed to pass any 
specific false activation test. ASC further stated that the current 
sensors used in vehicles do not have the same susceptibility to false 
activations that the proposed tests were designed to identify. 
Volkswagen and Hyundai questioned whether the test scenarios were 
comparable to real world scenarios. MEMA and the Alliance stated that 
testing for two specific scenarios does not entirely represent what is 
required to design AEB systems that accurately discriminate between 
actual crash-imminent situations and false triggers. As a consequence, 
the commenters asserted that meeting the proposed performance 
requirements only increases testing burdens while not providing a good 
indicator of the likelihood of a system producing false activations in 
real world driving conditions.
    Advocates, Humanetics, and Consumer Reports support the proposed 
false activation requirements, stating that to maximize safety and 
consumer acceptance, false activations must be limited as much as 
possible through test procedures included in the final rule. In 
addition, these performance-based tests are a more robust solution than 
a document-based approach. Adasky also supported including false 
positive testing.
    Luminar Technologies stated that it is neutral on the matter of 
requiring the false positive testing as proposed or demonstration of 
false positive measures by the manufacturer in another way. Luminar 
believes that false positive testing is absolutely necessary for safety 
and to create public trust, but understands that in some situations, 
especially for future autonomous vehicles, that the proposed false 
positive scenario may not necessarily occur in the real world.
    Porsche recommends NHTSA consider aligning false activation test 
requirements with those that are found on the UNECE Regulation No. 152.
Agency Response
    The agency has retained the two false activation requirements 
including the steel trench plate and the vehicle pass-through 
scenarios. Like many NHTSA tests, the false activation tests do not 
cover all the situations in the real world where false activations can 
occur. However, NHTSA believes that these tests add value to the rule. 
The steel trench place test provides protection against a known 
engineering challenge for some sensing technologies. Road construction 
sites often include steel trench plates for which vehicles will 
encounter in the real world. Likewise, a vehicle driven particularly in 
urban areas often drives between parked cars on both sides of the road.
    Manufacturers must be responsible for false activations regardless 
of FMVSS test requirements and must engage in the precision engineering 
to prevent false activation and unintended consequences. The industry 
responsibility does not mean that NHTSA should not include aspects of 
performance that products must continue to meet. NHTSA believes that 
issuing an FMVSS with false activation prevent testing underscores the 
industry responsibility and works to ensure better performing systems.
    The comments from MEMA and Alliance suggests a potential need for 
more robust false activation testing. However, it is impossible for 
NHTSA to test all circumstances in which false activations may occur. 
That is not a logical basis for having no false activation tests. The 
commenters did not suggest additional tests for NHTSA to consider in 
this final rule.
    NHTSA agrees with Advocates, Humanetics, and Consumer Reports that 
maximizing safety and consumer acceptance are essential elements to

[[Page 39733]]

help ensure the public receives the benefits of this technology. NHTSA 
agrees with Mitsubishi that ultimately protecting against the 
activation of AEB in situations where there is no imminent crash is the 
responsibility of the manufacturer. However, it is also appropriate for 
the FMVSS to set a minimum standard below which no vehicles should 
perform. While current systems may be less prone to false activations 
in the scenarios proposed, the scenarios represent known 
vulnerabilities in previous technologies. The tests ensure that 
performance of new technologies continue to provide the resistance to 
these false activation situations.
    Considering Porsche's suggestion that NHTSA use the same false 
activation tests as the UNECE, NHTSA agrees that the curved road and 
turning scenarios that are part of UNECE Regulation No. 152 are 
relevant real-world conditions. Not all situations, however, can be 
tested through regulation. NHTSA is finalizing the two false activation 
tests it proposed because of the expected positive impacts they will 
have on system performance by preventing reemergence of prior 
performance issues and preventing other types of false activations.
2. Peak Additional Deceleration
    NHTSA proposed that the AEB system must not engage the brakes to 
create a peak deceleration of more than 0.25g additional deceleration 
than any manual brake application generates (if used) in the steel 
trench plate false activation scenario. Similarly, NHTSA proposed that 
the AEB must not engage the brakes to create a peak deceleration of 
more than 0.25g beyond any manual braking in the pass-through test.
Comments
    Consumer Reports suggested the threshold for maximum deceleration 
should be zero, especially under manual brake application. Consumer 
Reports opined that a 0.25g braking event is noticeable by passengers 
and could confuse or distract the driver. Consumer Reports asked that 
NHTSA remove any tolerance for false braking in these scenarios, or at 
the very least lower the threshold.
Agency Response
    NHTSA is finalizing the braking criteria limit of 0.25g beyond 
manual braking as proposed. The agency balanced two factors in 
determining that a 0.25g criterion is more appropriate than using a 
0.0g criterion. First, the ability to measure negative acceleration 
that results from the automatic application of the service brakes is 
difficult at low levels. As the total magnitude of deceleration 
increases, it is easier to establish that the service brakes are 
contributing as opposed to wind, tire friction, or engine drag. Second, 
it is unlikely that small levels of additional deceleration (less than 
0.25g) could present a safety risk that could potentially lead to a 
crash.
3. Process Standard Documentation as Alternative to False Activation 
Requirements
    As an alternative to the false activation requirements that were 
proposed, NHTSA requested comment on requiring manufacturers to 
maintain documentation demonstrating that robust process standards were 
followed specific to the consideration and suppression of false 
application of AEB in the real world. ISO 26262, ``Road vehicles--
Functional safety,'' ISO 21448, ``Safety of the Intended Functionality 
(SOTIF),'' and related standards, are examples of this approach. The 
agency requested public comment on all aspects of requiring 
manufacturers to maintain documentation that they have followed 
industry process standards in the consideration of the real-world false 
activation performance of the AEB system.
Comments
    Advocates, Mitsubishi, the Alliance for Automotive Innovation, 
Honda, and FCA opposed the agency's alternative to require that 
manufacturers maintain technical documentation that they have followed 
industry process standards. Advocates and Consumer Reports stated that 
documentation should not be used as a replacement for testing, but as a 
supplement to testing. MEMA, ZF and Volkswagen supported the technical 
documentation option presented in the NPRM.
    Mitsubishi explained as part of its opposition to technical 
documentation that it is impossible to predict all false-positive 
scenarios and be able to generate technical documentation for it. The 
Alliance stated such a requirement will increase the administrative 
burden on manufacturers with no added safety benefit. FCA and 
Mitsubishi stated that the suggested processes standard, like ISO 26262 
or SOTIF, should not be an element of any FMVSS. FCA also stated that 
any FMVSS should be purely about a vehicle presented to a test site and 
with performance assessed according to objective criteria. FCA further 
stated that it is not necessary for the agency to understand how a 
product was developed to meet a minimum performance requirement, just 
that it does. Finally, FCA noted that NHTSA has other information 
gathering powers over industry (e.g., the current ADAS Standing General 
Order) and development practices or engineering methods should fall 
under that authority, not as part of an FMVSS.
    In its support for a technical documentation requirement, ZF stated 
that, although they do not recommend a false activation test, they 
agree that efforts should be made in system design to mitigate against 
that risk. ZF supported some documentation to demonstrate efforts had 
been made in system design to prevent false activation. Volkswagen 
stated the most effective way to combat false positives is during the 
development process. Volkswagen and ZF both considered the suggested 
documentation requirements on measures taken against false positives to 
be a suitable approach.
Agency Response
    After considering comments, NHTSA has opted not to include a 
requirement in the FMVSS that manufacturers maintain documentation of 
the application of process standards during AEB system development. 
Instead, the agency chooses to keep the false activation tests proposed 
and incorporate them into this final rule. NHTSA believes that 
performance testing of final products remains an important compliance 
tool for the agency.
    Even though the agency is not finalizing the documentation 
proposal, NHTSA disagrees with commenters who asserted that this sort 
of documentation is not of use to the agency. The agency believes that 
the application of process standards in good faith is likely to 
increase the chances that manufacturers have created products that 
minimize unreasonable safety risks. NHTSA agrees that the agency has 
other pathways through which it could seek this sort of information, 
including during an inquiry into the reasonableness of a manufacturer's 
certification and through a defect investigation. Therefore, it is not 
necessary to include such a requirement in the FMVSS.
4. Data Storage Requirement as Alternative to False Activation 
Requirements
    As another alternative to the two proposed false activation tests, 
NHTSA requested comment on requiring targeted data recording and 
storage of significant AEB activations. As an example, NHTSA considered 
requiring that an AEB event that results in a speed

[[Page 39734]]

reduction of greater than 20 km/h (12 mph) activate the recording and 
storage of key information.
Comments
    ASC, IIHS, MEMA, APCI, NTSB, and Forensic Rock supported data 
storage requirements. Advocates and Consumer Reports stated data 
storage requirements should not be used as a replacement for testing, 
but as a supplement to testing. ZF recommended that AEB system data be 
retained in some capacity by EDR systems. They stated that 
classification of the target that triggered the AEB activation may be 
useful for accident or false activation reconstruction. AAA and Rivian 
recommended the agency weigh how the data recording requirement would 
be implemented in the context of consumer privacy concerns. ASC stated 
its support of Event Data Recording (EDR) to assist in crash 
reconstruction and identification of false activation trigger factors. 
NTSB stated that without the data, it will be extremely challenging to 
determine whether and to what extent these systems were engaged during 
a crash. Forensic Rock stated that ensuring investigators have access 
to post-collision data that can objectively evaluate the performance of 
the AEB system in both lead vehicle and pedestrian collision scenarios 
is paramount and should be included in the FMVSS.
    Honda, Bosch, Hyundai, Mitsubishi, the Alliance for Automotive 
Innovation and Volkswagen opposed requirements that would include AEB 
data storage. Honda stated that it was unclear as to the problem such a 
requirement would be meant to address. Bosch stated data recorders have 
limitations and are not able to determine whether a safety system's 
decision was reasonable, considering the provided sensor data. Hyundai 
stated it would entail significant burdens and unwarranted delays to 
this rulemaking and would provide no direct safety benefit. Mitsubishi 
stated a lack of objective and clear definitions of false activation 
indefinitely increases the data elements to record, which would require 
hardware reengineering. In addition, Mitsubishi stated that data is 
more likely to include privacy-sensitive information. The Alliance 
stated the agency has not provided any analysis on the technical 
feasibility of the proposal under consideration, nor has sufficient 
justification been made as to the practical utility of any data 
obtained as part of an information collection effort or the overall 
safety benefit to consumers. Volkswagen stated that to determine 
whether an activation was justified, camera data would be required in 
most cases and that storing camera data is not technically feasible for 
most current vehicle platforms due to processing and storage 
limitations of the existing architectures.
Agency Response
    After considering comments, NHTSA is not including data storage as 
part of this FMVSS, and intends to keep the false activation tests that 
it proposed. NHTSA believes that the false activation tests will 
provide the minimum level of assurance that AEB systems will not 
provide unwarranted engagement. In the future, NHTSA can consider 
amending the EDR requirements established in 49 CFR part 563 and more 
broadly consider updates to vehicle data collection, event triggers for 
crash reconstruction, and potential gaps in performance of AEB and 
other safety systems. By looking at vehicle data holistically and 
considering the updates necessary to modernize 49 CFR part 563 and 
capture the information necessary for various driver assistance 
systems, the agency can further consider the data needs and associated 
burden to update the regulation to reflect the vehicle safety needs of 
today, current vehicle systems, and current manufacturer practices, 
while balancing privacy concerns.\104\ Finally, regarding data 
manufacturers are already collecting, NHTSA has broad authority to 
request information from manufacturers during the course of 
investigations. Therefore, even absent a data recording requirement in 
an FMVSS or regulation, NHTSA expects that it can require manufacturers 
to provide the information that they are currently collecting on AEB 
systems.
---------------------------------------------------------------------------

    \104\ With regard to consumer privacy, those concerns should be 
alleviated, at least partially, by the existence and application of 
the Driver Privacy Act of 2015, part of the Fixing America's Surface 
Transportation Act of 2015. The Driver Privacy Act assigned 
ownership of EDR data, as defined in 49 CFR 563.5, as the property 
of the owner or lessee of a vehicle. Importantly, it limits the 
access of EDR data to specific parties for specific purposes.
---------------------------------------------------------------------------

G. Malfunction Detection Requirement

    In the NPRM, NHTSA proposed 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 illuminate a telltale that identifies (or indicates) the 
malfunction condition. The telltale 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 no longer functions as required by this rule. 
NHTSA proposed that the driver must be informed of the malfunction 
condition in all instances of component or system failures, sensor 
obstructions, or other situations that would prevent a vehicle from 
meeting the proposed AEB performance requirements. While NHTSA did not 
propose a specific telltale, NHTSA anticipates that the characteristics 
of the alert will provide sufficient information to the vehicle 
operator to identify it as an AEB malfunction.
1. Need for Requirement
    The rationale behind the requirement that AEB systems continuously 
detect system malfunctions is that drivers would need to know when AEB 
is not functioning because AEB is an important safety system. NHTSA 
stated in the NPRM that it was considering minimum requirements for the 
malfunction indication to standardize the means by which the 
malfunction is communicated to the vehicle operator. Malfunctions of an 
AEB system are somewhat different than other malfunctions NHTSA has 
considered in the past. While some malfunctions may be similar to other 
malfunctions NHTSA has considered in FMVSSs because they require repair 
(loose wires, broken sensors, etc.), others are likely to resolve 
without any intervention, such as low visibility due to environmental 
conditions or blockages due to build-up of snow, ice, or loose debris.
Comments
    Advocates, NAMIC, IIHS, MEMA and NTSB supported the proposed 
requirements for malfunction. NAMIC commented that it is important to 
include in a final rule a requirement that manufacturers notify the 
driver when AEB or other advanced driver assistance systems are 
malfunctioning or not performing as designed, and to include detailed 
directions for resolving the issue such as cleaning the sensor or going 
to a service center.
    The Alliance stated that wording of the proposed malfunction 
requirements would likely result in excessive notifications to 
consumers and notifications that do not accurately communicate the 
status of the system. and may be misleading as to the actions required 
on the part of the driver to remedy the situation. The Alliance and 
Aptiv stated that it is not reasonable or practicable to require a 
manufacturer to detect changes in the roadway environment (e.g., road 
surface condition) or the extent to which these changes may affect the 
performance of a vehicle in meeting the requirements of the rule. The 
Alliance, Consumer Reports, and ITS America commented

[[Page 39735]]

that malfunction failure indication should be limited to specific 
failures related to the hardware or software components that comprise 
an AEB system, not diminished performance due to environmental 
conditions such as heavy fog or snow.
    The Alliance, NADA, and AAA recommended that NHTSA create separate 
definitions for ``malfunction warning'' and ``system availability 
warning'' to characterize these two conditions more accurately. Aptiv, 
Volkswagen, and Porsche suggested a warning based on UNECE Regulation 
No. 152 for non-electrical failures (for example, obstructions due to 
weather). Bosch suggested further specification in the warning of ``an 
appreciable time interval between each AEB system self-check.''
    NTEA recommended that a compromised system function should not only 
warn the driver, but consider the possible prohibition of AEB 
activation. NTEA also provided cases where they feel sensors need self-
monitoring abilities and temporary deactivation, such as a when going 
through a car wash or when overhead cargo is present that obstructs a 
portion of the forward camera's field of view.
Agency Response
    The agency agrees with commenters who state that it is necessary 
that AEB systems monitor system health and notify the driver when a 
malfunction is present. Where the agency diverges from commenters is 
with regard to the need to require manufacturers to provide detailed 
information regarding the nature of the malfunction. The primary 
information necessary for a driver to determine if it is safe to 
operate the vehicle is simply whether the AEB system is working 
relative to the performance requirements of this new final rule.
    The agency agrees with the commenters who stated that external 
conditions that limit system performance (such as minute changes in the 
road surface construction, the presence of sand or gravel on the road 
surface, etc.) are not malfunctions of the system, and in some cases, 
it is not possible to determine the AEB system's ability to perform. 
These conditions are often not readily measurable by vehicle sensors 
and are often temporary in nature.
    NHTSA is clarifying that it did not intend to mandate that AEB 
perform in all environmental conditions. Rather, NHTSA requires that 
AEB systems function as required within the set of conditions provided 
in S6 of the regulatory text. The same is true for malfunction 
detection. NHTSA understands that there are differences between the 
driving environment hindering ideal AEB performance and true 
malfunctions of the system that likely require intervention to resolve. 
To give an example, snow might cause degraded performance for a variety 
of reasons, but a malfunction notification would not be necessary 
unless that snow results in deactivation of the AEB system, such as a 
situation when the snow obstructs the AEB sensors, causing the system 
to not meet the performance requirements. Alerting the driver to this 
type of malfunction is vital to the safe operation of the vehicle. Any 
notification of degraded system performance arising from any source 
(temporary or permanent) should end when the conditions that lead to 
the degradation end.
    Therefore, this final rule clarifies that if the system detects a 
malfunction, or if the system adjusts its performance such that it will 
not meet the performance requirements, the system must provide the 
vehicle operator with a telltale notification. This requirement makes 
clear that if the system reduces its performance capabilities 
(regardless of if the reason is because of environmental conditions or 
for other reasons), the driver must be informed. Also, if the system is 
broken or a sensor is obstructed, the driver must be informed. However, 
if there are environmental conditions that decrease the system's 
ability to function (for instance decreased stopping distance) but the 
system has made no internal adjustments, a telltale is not required.
    As for the issue of separate telltales to inform the driver of 
permanent and temporary malfunctions, the requirement proposed and 
adopted here was intended to give manufacturers flexibility in the 
style and nature of the driver malfunction notification. The 
requirements allow for different notification types for different types 
of degraded performance (e.g., internal malfunctions or external 
conditions) that degrade performance, should the manufacturer choose to 
do so. The manufacturer may also, at the manufacturer's discretion, 
choose to use the same telltale or other notification for the different 
types of degraded performance. NHTSA has observed that some 
manufacturers currently do this and nothing in the NPRM was intended to 
prohibit this. This is consistent with the malfunction warning 
requirements in UNECE Regulation No. 152.
    The agency appreciates Bosch suggesting a more specific definition, 
but NHTSA is not adopting the proposed definition for malfunction 
detection provided at this time because it is not workable for an 
FMVSS. For example, ``appreciable time interval'' is not an objective 
measure of timing, nor does it give manufacturers notice as to what 
NHTSA expects of them. Furthermore, NHTSA does not have a basis for why 
it would treat electrical failure conditions differently than any other 
type of system malfunction, as suggested by Bosch.
    Regarding NTEA's suggestion that NHTSA prohibit AEB activation in 
the instances where a malfunction may be present, NHTSA does not 
believe that mandating the prohibition of AEB activation is necessary 
since there is no evidence that a manufacturer would permit its systems 
to function in a state so degraded as to present an unreasonable risk 
to safety.
2. Malfunction Telltale
    NHTSA did not propose the specifics of the telltale but anticipated 
that the characteristics of the alert would provide sufficient 
information to the vehicle operator to identify it as an AEB 
malfunction, and would also be documented in the vehicle owner's 
manual. NHTSA requested comment on the potential advantages of 
specifying test procedures that would describe how the agency would 
test a malfunction telltale and on the related level of detail that 
this regulation should require. The agency also requested comment on 
the need and potential safety benefits of requiring a standardized 
appearance for the malfunction telltale and what standardized 
characteristics would achieve the best safety outcomes. The agency 
further requested comment on the use of an amber FCW warning symbol as 
the malfunction notification.
Comments
    The Alliance and Nissan commented that specifics of a telltale for 
malfunction (and related system status) should be defined by the 
manufacturer. Nissan observed that UNECE Regulation No. 152 does not 
define the specific form of the malfunction telltale.
    ASC suggested that the agency require an AEB malfunction telltale 
to be located on the vehicle's instrument panel. ASC stated that on 
start-up, the AEB system could run diagnostics and trigger the 
malfunction telltale if a failure or obstruction is detected.
    However, several other commenters suggested standardization of a 
common malfunction telltale. ZF and MEMA suggest a telltale modeled 
after the ESC telltale, in an effort to better alert the driver to an 
AEB malfunction.
    Toyota stated that an amber telltale may be appropriate, as it 
aligns with

[[Page 39736]]

similar malfunction requirements, such as those in FMVSS No. 135.
    IIHS commented that NHTSA should require manufacturers to notify 
the driver when AEB or other ADAS are malfunctioning or not performing 
as designed. They noted that, ideally, the notification should provide 
directions for resolving the issue, such as cleaning the sensor or 
going to a service center, noting that drivers should not be expected 
to troubleshoot misbehavior or malfunctions from their ADAS, especially 
when the malfunction introduces new risks. They provided two examples 
of a vehicle with a misaligned radar following a crash and a skewed 
camera following a windshield replacement, which did not provide an 
indication of malfunction or reduction of performance.
    AVIA commented that for AVs, NHTSA should consider adding language 
that allows a malfunction detection notification to be directly 
communicated to the ADS itself or communicated to a remote assistant or 
to service personnel in the case of an AV without manually operated 
driving controls. They added that for an ADS-equipped vehicle with 
manually operated driving controls, the notification can be directly 
communicated to the ADS when it is engaged as well as through a 
telltale notification to the human operator. Zoox commented that the 
malfunction telltale requirement should specify that it be visible from 
the driver seating position and that, for vehicles without a driver 
seating position, the mechanism is specified by the manufacturer and 
provided upon request, and suggested that testing not be conducted 
while an equivalent notification to the telltale is active for vehicles 
without a driver seating position.
Agency Response
    NHTSA agrees that the specifics of a telltale for malfunction 
should be defined in detail by the manufacturer. The agency has 
concerns, however, about drivers confusing a malfunction indicator that 
is co-located with the FCW symbol. As such, Toyota's suggestion to 
align the malfunction telltale with the FCW symbol may be problematic. 
The agency is concerned about confusing drivers, because using the same 
telltale could be interpreted as asking the driver to brake or as a 
malfunction.
    NHTSA understands the positions of commenters who requested a 
standardized malfunction telltale. Nothing prohibits the industry from 
working together, such as through a standards organization, to 
implement a common telltale. However, NHTSA does not believe 
standardization is necessary at this time. Commenters did not provide 
sufficient evidence to demonstrate a need for a standardized 
malfunction indicator. Thus, NHTSA is not adding additional constraints 
on the telltale, in this final rule. If warranted, NHTSA would consider 
standardization if in the future it is determined that drivers do not 
adequately comprehend when an AEB malfunction has occurred.
    NHTSA does not agree with ASC's suggestion of a standardized 
location for a telltale. FMVSS No. 101 does not provide specification 
for the location of any telltale except that it be visible to the 
driver when a driver is restrained by a seat belt. There is no evidence 
of a safety need for any more specific location requirement for an AEB 
system malfunction telltale.
    As discussed in other sections, NHTSA agrees with IIHS that the 
driver should be notified when AEB is malfunctioning, which is the 
entire goal of a malfunction telltale requirement. NHTSA does not 
believe that it is necessary to notify drivers of the directions for 
resolving the issue, but that such information could be provided to 
drivers in the owner's manual. A driver who is driving on the street 
doesn't need to be told while the vehicle is moving that she needs to 
clean the sensor. Rather, this is diagnostic information that could be 
communicated through other means, like through the use of diagnostic 
tools accessing information in the OBD-II port.
    As for the comments related to AVs, NHTSA believes it is most 
appropriate to address specific concerns related to AVs through other 
mechanisms, rather than shaping this particular FMVSS around the needs 
of a very specific set of vehicles that may still have to apply for an 
exemption from other FMVSS. NHTSA is considering crash avoidance test 
procedures to facilitate the safe introduction and certification of new 
vehicle designs equipped with automated driving systems in a separate 
rulemaking.\105\ NHTSA is also looking across all FMVSS to address the 
applicability and appropriateness of safety messaging (telltales, 
indicators, and warnings) in new vehicle designs without conventional 
driver controls.\106\ Additionally, NHTSA notes that manufacturers are 
free to design their vehicles to have the malfunction detection 
notification be communicated directly to the ADS, a remote assistant or 
service personnel, as a redundant means of communication. Such 
redundancy is permissible in situations that a manufacturer believes it 
is necessary.
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    \105\ https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202310&RIN=2127-AM00.
    \106\ https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202310&RIN=2127-AM07.
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3. Sensor obstructions and testing
    NHTSA proposed that the driver must be warned in all instances of 
malfunctions, including malfunctions caused solely by sensor 
obstructions. The NPRM also proposed that during track testing of the 
AEB system all sensors used by the system and any part of the vehicle 
immediately ahead of the sensors, such as plastic trim, the windshield, 
etc., would be free of debris or obstructions. NHTSA stated that it was 
considering requirements pertaining to specific failures and including 
an accompanying test procedure.
Comments
    The Alliance stated that it is important that NHTSA define a finite 
set of scenarios that could be reasonably defined as a malfunction, 
should the agency decide to regulate in this area, to ensure that 
relevant scenarios are being addressed, and that other factors that may 
influence AEB performance are evaluated independently. Mobileye 
recommended performing full blockage camera/radar testing as in the 
Euro-NCAP Assisted Driving protocol. ZF also suggested testing by 
obstructing sensors. Rivian recommended that NHTSA adopt detailed 
procedures that can be performed on the test track and are 
representative of relatively high frequency occurrence in actual use 
cases. ZF commented that malfunction indicator light testing could be 
done by deliberately blocking for radar to simulate snow accumulation, 
or a piece of tape for cameras to simulate a lens blockage.
Agency Response
    After considering the comments, NHTSA is not making any further 
specifications of failures that would be tested. As is customary with 
NHTSA's standards, the laboratory compliance test procedures will 
specify how NHTSA intends to run its compliance test regarding 
illumination of a malfunction telltale.

H. Procedure for Testing Lead Vehicle AEB

    This section describes the lead vehicle AEB performance tests 
adopted by this final rule. After considering the comments to the NPRM, 
NHTSA has adopted the proposed procedures with a few changes. Some 
minor parameters

[[Page 39737]]

and definitions were modified and various definitions were added, to 
clarify details of the test procedures. Additionally, to increase the 
practicability of running the tests, a third manual brake application 
controller option, a force only feedback controller, has been added. 
The force feedback controller is substantially similar to the hybrid 
controller with the commanded brake pedal position omitted, leaving 
only the commanded brake pedal force application.
    This section responds to the comments and explains NHTSA's reasons 
for adopting the provisions set forth in this final rule. For the 
convenience of readers, a list of the test specifications can be found 
in the appendix A to this final rule preamble.
    The lead vehicle AEB performance tests require a vehicle to 
automatically brake, or supplement insufficient manual braking, when 
tested during daylight under three specific test scenarios. The 
scenarios involve a stopped lead vehicle, a slower-moving lead vehicle, 
and a decelerating lead vehicle. The performance criterion for all AEB 
tests involving a lead vehicle is full collision avoidance, meaning the 
subject vehicle must not contact the lead vehicle.
    The lead vehicle AEB tests include parameters necessary to fully 
define the initial test conditions in each scenario. Key test 
parameters for the lead vehicle AEB tests include the travel speed of 
both the subject vehicle and lead vehicle, the initial headway between 
the subject vehicle and the lead vehicle, the deceleration of the lead 
vehicle, and any manual brake application made to the subject vehicle. 
For each test run conducted under each of the scenarios, NHTSA will 
select the subject vehicle speed (VSV), lead vehicle speed 
(VLV), headway, and lead vehicle deceleration from the 
ranges specified in the standard.\107\
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    \107\ In instances where an FMVSS includes a range of values for 
testing or performance requirements, 49 CFR 571.4 states that the 
word any, used in connection with a range of values, means generally 
the totality of the items or values, any one of which may be 
selected by NHTSA for testing, except where clearly specified 
otherwise.
---------------------------------------------------------------------------

    There will be testing under two conditions. In one condition, NHTSA 
will test without any manual brake application. This would simulate a 
scenario where a driver does not intervene at all in response to the 
FCW or impending collision. In the other condition, NHTSA will test 
with manual brake application that will not be sufficient to avoid the 
crash. Not only will the second condition ensure that the AEB will 
supplement the manual braking when needed, it also provides a way to 
ensure that an application of insufficient manual braking will not 
suppress automatic braking in circumstances where automatic braking is 
initiated before the manual brake application is used.
1. Scenarios
    Many commenters suggested including additional scenarios in lead 
vehicle AEB testing.\108\ Many commenters urged NHTSA to include lead 
vehicle AEB testing in the dark to increase the benefits of the rule. 
The Lidar Coalition commented that it supports testing AEB in the 
darkest realistic conditions possible. It stated that a test procedure 
in dark conditions would evaluate AEB and PAEB technologies in the 
real-world scenarios where these systems are most needed because of 
diminished visibility. Forensic Rock state that they found differences 
in the performance of a specific vehicle's AEB system during the day as 
compared to testing under the same conditions at night and that to 
comprehensively evaluate the performance of AEB systems, daytime and 
nighttime tests should be conducted under the same closing speeds. 
Advocates suggested that NHTSA evaluate and present data demonstrating 
that the exclusion of testing lead vehicle (vehicle-to-vehicle) AEB 
under dark conditions is not limiting the performance level demanded by 
the proposed rule nor needlessly jeopardizing safety.
---------------------------------------------------------------------------

    \108\ These commenters included Luminar, Forensic Rock, Consumer 
Reports, Applied, Rivian, Advocates, Adsky and the Lidar Coalition.
---------------------------------------------------------------------------

    In response, NHTSA appreciates the interest in including additional 
scenarios to potentially assess AEB systems under a wider range of 
potential real-world situations. NHTSA does not, however, include 
further tests in this final rule. The decision to include a particular 
test scenario depends on various factors, including the safety benefit 
resulting from a requirement, the practicability of meeting the 
requirement, the practicality and safety of conducting a test, and, in 
accordance with E.O. 12866, the likelihood that market forces will 
incentivize manufacturers to provide the needed performance absent the 
requirement. NHTSA at present does not have sufficient supporting data 
to assess the need for, practicability of, or practicalities involved 
with adding darkness test scenarios to the lead vehicle AEB tests. This 
is in contrast to the PAEB test, which includes darkness test 
scenarios.
    There is not enough data supporting a finding for a safety need for 
a darkness test. The test scenarios of this rule broadly represent real 
world situations by sampling the most common types of light vehicle 
rear-end crashes. In NHTSA's latest testing described earlier in this 
document, the agency observed that vehicle performance during the dark 
ambient tests were largely consistent with those produced during the 
daylight tests (in the absence of a regulation). The dark- compared to 
day-contact results observed for a given test speed were identical or 
nearly identical for several of the vehicles tested. Where impacts 
occurred, the impact speeds were very similar. Additionally, as 
detailed in the safety problem section of this preamble, 51 percent of 
rear end crash fatalities occur during daylight, and injury and 
property-damage-only rear-end crashes were reported to have happened 
overwhelmingly during daylight, at 76 percent for injury rear-end 
crashes and 80 percent for property-damage-only rear-end crashes.
    Some data indicate that there may not be a technical need for a 
darkness test to reap the benefits of lead vehicle AEB in darkness. As 
part of this final rule, NHTSA is specifying minimum performance 
requirements for pedestrian avoidance in dark conditions. The agency 
believes that systems that can identify, and respond to, a pedestrian 
in the roadway at night could also possibly detect lead vehicle 
taillamps and other reflective surfaces that distinguish a vehicle from 
the surrounding visual landscape. The agency also believes a radar 
sensor will perform the same regardless of the lighting condition. As 
such, NHTSA believes an AEB system could be highly effective at 
classifying the rear of a lead vehicle in a dark condition, even 
without an explicit regulation requiring such performance. Only the 
daylight condition was proposed for lead vehicle AEB testing, and this 
sole lighting condition is maintained in this final rule.
    Luminar, Forensic Rock, Consumer Reports, and Aptiv suggest the 
agency expand testing with additional overlaps (the measurement of 
deviation of the lead vehicle centerline and the subject vehicle 
centerline) for lead vehicle testing. Luminar stated that a 50 percent 
overlap in car-to-car scenario is used in both US and Euro NCAP testing 
and suggested that NHTSA should consider 50 percent overlap which, the 
commenter believed, is a common, achievable, car-to-car test scenario. 
Forensic Rock suggests expanding the testing to include a 25-50% 
overlap condition would ensure that the

[[Page 39738]]

performance of these systems included more than just pure collinear 
crash scenarios.
    In response, NHTSA has not included test scenarios with an overlap 
less than 100 percent (although a tolerance on the travel path of the 
subject vehicle is included). A rear-end crash as defined in the FARS 
database is ``a collision in which one vehicle collides with the rear 
of another vehicle.'' \109\ Even at the higher speeds used in testing, 
a change of the overlap during testing from 100 percent to 50 percent 
or 25 percent would result in only a marginal change in the position of 
the lead vehicle in the field of view of the sensors. The proposed 
overlap for lead vehicle AEB testing is consistent with NHTSA's NCAP 
test procedures for CIB and DBS, the IIHS test procedure, as well as 
UNECE Regulation No. 152.\110\ The agency does not have the necessary 
information to demonstrate practicality and need for a regulation that 
adopts scenarios that include a broad range of overlap.
---------------------------------------------------------------------------

    \109\ https://www-fars.nhtsa.dot.gov/Help/
Terms.aspx#:~:text=Rear%2Dend%20Collision,The%20Rear%20Of%20Another%2
0Vehicle. Accessed November 21st, 2023 at 3:22 p.m.
    \110\ National Highway Traffic Safety Administration (Oct., 
2015), Crash Imminent Brake System Performance Evaluation for The 
New Car Assessment Program. Available at: https://www.regulations.gov/document/NHTSA-2015-0006-0025; National Highway 
Traffic Safety Administration (Oct., 2015), Dynamic Brake Support 
Performance Evaluation Confirmation Test for The New Car Assessment 
Program. Available at: https://www.regulations.gov/document/NHTSA-2015-0006-0026; Insurance Institute for Highway Safety (Oct., 2013), 
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; and UN 
Regulation No 152--Uniform provisions concerning the approval of 
motor vehicles with regard to the Advanced Emergency Braking System 
(AEBS) for M1 and N1 vehicles [2020/1597] (OJ L 360 30.10.2020, p. 
66, ELI: https://data.europa.eu/eli/reg/2020/1597/oj).
---------------------------------------------------------------------------

    Some commenters suggest that NHTSA should consider adding 
additional testing scenarios from EuroNCAP, such as the head-on 
scenarios and left turn across path. Consumer Reports suggested NHTSA 
incorporate additional scenarios such as a curved travel path, 
scenarios involving challenges posed by environmental conditions, and 
circumstances in which the lead vehicle is revealed suddenly or is not 
aligned straight when in front of the subject vehicle.
    In response, this final rule requires lead vehicle AEB systems that 
will prevent or mitigate rear-end crashes of light vehicles and is 
based on the research and other data demonstrating the efficacy and 
practicability of these systems. The data and technologies for test 
scenarios representing crashes other than a rear-end crash are not yet 
available to support possible inclusion in an FMVSS.
    Applied stated that NHTSA should include additional scenarios and 
elements through virtual testing procedures. It stated that modeling 
and simulation technologies allow for a vehicle to be put through a 
much more expansive set of testing scenarios and elements than what are 
possible in real-world testing and may allow to vastly increase the 
number of tests that can be run creating a much greater pool of data to 
evaluate a vehicle.
    In response, while virtual test scenarios involving modeling and 
simulation may be employed, and are employed, by manufacturers in 
developing lead vehicle AEB systems, such testing is not suitable for 
NHTSA's compliance testing of AEB systems at this time. Virtual testing 
has the potential to provide many benefits and advancements to motor 
vehicle safety. There are challenges, however, in using virtual 
assessments in agency compliance tests. The agency must be assured that 
the virtual scenarios it was running are representative of the real 
world and that the test results it obtained would be the same as those 
obtained in tests of an actual vehicle. Neither condition currently 
exists. Also, virtual test environments are reliable only if they have 
been appropriately validated. Right now, NHTSA does not have the 
research available to support the development of a simulator designed 
for the purposes of testing compliance with this rule. Though 
simulation testing is a method that NHTSA is very interested in from a 
research perspective, it is not yet an approach that is ready for NHTSA 
use in compliance testing.\111\
---------------------------------------------------------------------------

    \111\ There are also several practical challenges that prevent 
NHTSA from using virtual testing to determine compliance with the 
FMVSS. NHTSA's goal is to independently purchase vehicles available 
on the market without notification to the manufacturer (or anyone) 
that it is purchasing a particular vehicle. This helps make sure 
that the product that NHTSA is testing is one that consumers of that 
product would also purchase. If NHTSA were to obtain vehicles 
directly from manufacturers for compliance testing, NHTSA may not be 
as confident about the independence of its testing results. Also, 
AEB systems are proprietary systems. If NHTSA needs capabilities and 
access to the technicalities of the AEB system to conduct virtual 
testing, confidential business information issues may arise.
---------------------------------------------------------------------------

    After considering the comments, this final rule adopts the three 
track test scenarios, which are lead vehicle stopped, lead vehicle 
moving and lead vehicle decelerating, as proposed in the NPRM.
2. Subject Vehicle Speed Ranges
    The proposed speed ranges were selected based on the speeds at 
which rear-end crashes tend to happen, while considering two primary 
factors. The first factor is the practical ability of AEB technology to 
consistently operate and avoid contact with a lead vehicle. NHTSA's 
2020 and 2023 research testing indicate that the selected speed ranges 
for the various scenarios are within the capabilities of current 
production vehicles. NHTSA proposed speed ranges to ensure AEB system 
robustness. To illustrate, during the agency's AEB research testing, 
two vehicles performed better at higher speeds (48 km/h or 30 mph) than 
at lower speeds (40 km/h or 25 mph) in the lead vehicle stopped tests, 
which suggests that a range of speeds should be used in FMVSS No. 
127.\112\
---------------------------------------------------------------------------

    \112\ https://www.regulations.gov/document/NHTSA-2021-0002-0002.
---------------------------------------------------------------------------

    The second factor is the practical limits of safely conducting 
track tests of AEB systems. Based on the available data, a majority of 
fatalities and injuries from rear-end crashes occur at posted speeds up 
to 97 km/h (60 mph). Due to the tendency of fatalities and injuries to 
increase as the vehicle travel speed increases, NHTSA proposed AEB 
system testing at the highest speeds at which NHTSA can safely and 
repeatably conduct tests. If a system does not intervene as required 
and the subject vehicle collides with the lead vehicle test device, it 
should do so in a manner that will not injure test personnel or 
demolish the laboratory's equipment and set-up.
Comments Seeking To Increase Testing Speeds To Increase Potential 
Safety Benefits
    Many government entities, consumer interest groups, private 
individuals and others suggested that NHTSA consider exploring ways to 
increase test speeds.\113\ Many suggested lead-vehicle AEB tests above 
100 km/h (~60 mph) for the stopped lead vehicle and slower-moving lead 
vehicle scenarios, and 80 km/h (~50 mph) for the decelerating lead 
vehicle scenarios. These commenters point to the increased risk of 
crashes as well as fatalities and serious injuries resulting from 
crashes as speeds rise, and some believed that a requirement to meet 
higher test speeds is practicable. Forensic Rock stated that if a 
private accident reconstruction firm can find suitable track length to 
conduct

[[Page 39739]]

high closing speed tests, NHTSA should be able to as well. NTSB stated 
that test scenarios be designed to best reflect real world operating 
conditions as NTSB investigations have shown there is a need to 
consider systems' performance in other crash-relevant scenarios 
including unusual vehicle profiles and configurations encountered in 
real-world conditions.
---------------------------------------------------------------------------

    \113\ These commenters included the cities of Philadelphia, 
Nashville, and Houston, the Richmond Ambulance Authority, DRIVE 
SMART Virginia, NACTOA, the Lidar Coalition, Consumer Reports, 
Forensic Rock, and Luminar.
---------------------------------------------------------------------------

Agency Response
    After considering the comments, NHTSA declines to increase the test 
speeds proposed in the NPRM. The agency explained in the NPRM that 
NHTSA proposed what it believed to be the highest practicable and 
reasonable testing speeds. Testing speeds are bound by important 
practicability matters and practical limitations, such as the safety of 
the testing personnel, vehicle and test equipment damage, and the 
repeatability of testing and test validity. Forensic Rock suggested 
adding equipment such as ``deer/cattle guards'' to the subject vehicle 
during testing. NHTSA believes such an approach is untenable because 
such equipment would still not protect testing equipment and would 
alter the ``real-world'' condition of the vehicle.
    NHTSA limited the maximum test speeds for lead vehicle AEB to no 
more than a maximum 80 km/h (50 mph) speed differential. NHTSA is 
encouraged by Luminar and Forensic Rock's testing at speeds higher than 
the NPRM, but, with regard to Luminar's comment that the systems they 
tested performed at speeds up to 120 km/h, the agency's limit for the 
testing speed was determined based on factors including safety need and 
practicability, and not just on AEB performance. While NHTSA is 
currently researching other testing scenarios for AEB, the agency does 
not have the needed information regarding practicability and the need 
for a higher speed regulation to include a broader speed range at this 
time.
Comments Suggesting Different Approaches
    Several commenters suggested NHTSA should take a hybrid approach 
and reduce speeds for a no-contact requirement while allowing contact 
at a higher speed. The Alliance, Toyota and others suggested NHTSA 
implement a hybrid approach that maintains no-contact requirements for 
lower-mid-range speeds while permitting compliance if acceptable speed 
reductions that reduce the risk of serious injury can be achieved in 
higher-speed scenarios. It stated that such an approach would align 
with the approach implemented by other international bodies, such as 
UNECE Regulation No. 152, where no contact is required up to 40 km/h 
and various levels of maximum impact speeds are allowed from 42 km/h up 
to 60 km/h.\114\ A number of other commenters suggested reducing the 
range of testing speeds and allowing contact above certain testing 
speeds.\115\
---------------------------------------------------------------------------

    \114\ https://unece.org/transport/documents/2023/06/standards/un-regulation-no-152-rev2. Other commenters supported harmonizing 
with UNECE Regulation No. 152, including ASC, Ford, Mitsubishi, and 
Nissan.
    \115\ These commenters included HATCI, Nissan, ZF, and Aptiv.
---------------------------------------------------------------------------

    The Alliance stated that the hybrid approach would ensure that 
vehicle speeds are reduced to a level where crashworthiness features 
can provide an additional layer of protection for reducing the severity 
of occupant and pedestrian injury outcomes by lowering the overall 
impact speed. Volkswagen provided an analysis, which it stated is not 
statistically significant, which showed that vehicles on the road today 
can protect their occupants from severe injuries of MAIS 3+ even with 
collision speeds up to 50 km/h. Toyota recommended an approach that 
vehicle-to-lead vehicle target contact be allowed ``at a speed low 
enough that the crash would be highly unlikely to be fatal or to result 
in serious injury.'' Honda also considered NHTSA's crash injury 
estimations for the risk of severe injury or fatality in frontal 
crashes to suggest a hybrid type approach.
Agency Response
    The commenters support a hybrid approach where collision avoidance 
would be required only up to 42 km/h (26.1 mph) and speed reduction (a 
mitigated collision) permitted at speeds above 42 km/h (26.1 mph) 
during testing. NHTSA does not find this approach acceptable. The 
agency's intent is to prevent crashes at the highest practicable speeds 
and the proposed limits in testing speeds reflect this.
    Using the speed limit as a proxy for traveling speed, the data 
presented earlier in this document show that about 60 percent of fatal 
rear-end crashes were on roads with a speed limit of 97 km/h (60 mph) 
or lower. That number is 73 percent for injury rear-end crashes and 78 
percent for property-damage-only rear-end crashes. Out of the total 
rear-end crash population, only about 1 percent of fatalities, 5 
percent of injuries and 7 percent of property-damage-only crashes 
happen where the speed limit is 40 km/h (25 mph) or less. If NHTSA were 
to require collision avoidance only for crashes up to 40 km/h (25 mph), 
in NHTSA's view only a fraction of fatalities and injuries would be 
avoided when so many more motorists could benefit. Such an outcome 
would fall short of meeting the need for safety, as meeting the 
proposed test speeds is practicable. As detailed in the research 
section, the 2023 Toyota Corolla Hybrid was able to avoid collision 
under all testing conditions up to the maximum proposed testing speed 
requirement for lead vehicle stopped and lead vehicle moving. That same 
vehicle, when tested for the lead vehicle decelerating scenario with a 
12 m headway and 0.5g lead vehicle deceleration, was able to avoid 
collision in all trials when tested at 50 km/h and was able to avoid 
collision on two trials and incur impact speeds of approximately 5 km/h 
and below on the other three trials when tested at 80 km/h (50 mph). If 
NHTSA were not to require collision avoidance during testing at speeds 
up to 100 km/h (62 mph), the majority of fatal rear-end crashes would 
not be prevented.
    NHTSA is providing a five-year lead time to push development of the 
technology while providing time to foster the evolution of it to 
achieve AEB's life-saving potential. Four out of the six vehicles 
tested avoided collision during agency testing at 50 km/h subject 
vehicle to 50 km/h lead vehicle and 12 m and the other two avoided in 
four out of the five trials. Considering that current AEB systems seem 
somewhat detuned at higher speeds because they were not designed to 
this requirement, the agency is encouraged that when engineered to meet 
this requirement, AEB will be able to avoid collision in a similar 
fashion as they do now under the 50 km/h condition.
    The injury curves and thresholds provided by the commenters show 
that below 40 km/h (25 mph), there is a reduced probability of AIS3+ 
injury. With AEB, there is the potential to prevent the crash from 
occurring in the first place, i.e., to completely mitigate the risk of 
injury. The technology has proven capable of avoiding collisions during 
testing at higher speeds. With the potential of AEB technology, its 
rapid evolution, and the significant lead time this final rule is 
providing to allow for maturation and deployment of AEB, NHTSA has 
decided to maintain the no-contact requirement and speed limits at the 
levels proposed in the NPRM.
    As another approach, Honda suggested to test only at what they 
state are worst case scenarios that pose the highest risk of injury 
(i.e., impact relative speed) and present the most challenging 
situations for AEB systems to react quickly (i.e., time to impact). 
Honda stated that after evaluating

[[Page 39740]]

various combinations within the proposed headway distance and lead 
vehicle deceleration ranges, the worst-case scenarios are for impact 
relative speed of 72 km/h, time to collision (TTC) of 2.1 sec with a 
lead vehicle deceleration of 0.5 g, at both the 12 m and 40 m headway 
distances at 50 or 80 km/h.
    In response, NHTSA does not believe that ``worst case'' scenario 
testing is appropriate for this standard in this final rule. In past 
NHTSA tests, vehicles sometimes avoided contacting the vehicle test 
device at higher speed tests but contacted it at lower speeds. A range 
of tests is necessary to better ensure satisfactory performance of the 
systems in the real world.
Some Commenters Suggest Reduced Speeds and Repeat Trials To Avoid What 
They See as Potential Negative Consequences
    A number of commenters believed that having to meet the higher end 
of the proposed speed range will increase the likelihood of negative 
consequences. Several commenters believed that the higher end of the 
proposed speed range will increase the likelihood of false 
positives.\116\ Porsche and Volkswagen stated that doubling the 
relative velocity at which no contact is required, as compared to UNECE 
Regulation No. 152, may impact the robustness of the system in real-
world performance, potentially leading to increased instances of 
premature or unnecessary braking in the real-world. Aptiv stated that 
due to the possibility of false positives, NHTSA should reduce testing 
speeds to 50 km/h (31 mph) and allow repeat trials. Mobileye stated 
that the proposed requirement will necessitate hardware updates or 
replacement, and preferred a speed reduction requirement, based on a 2 
out of 3 test runs. HATCI stated that NHTSA should follow the AEB 
voluntary commitment requirements.\117\
---------------------------------------------------------------------------

    \116\ These commenters included, ASC, Mobileye, Bosch, Ford, 
Mitsubishi, Honda, the Alliance, Porsche, Volkswagen, HATCI, Rivian, 
Bosch, and Aptiv.
    \117\ The voluntary commitment included automatic braking system 
performance (CIB only) able to achieve a specified average speed 
reduction over five repeated trials when assessed in a stationary 
lead vehicle test conducted at either 19 or 40 km/h (12 or 25 mph). 
To satisfy the performance specifications in the voluntary 
commitment, a vehicle would need to achieve a speed reduction of at 
least 16 km/h (10 mph) in either lead vehicle stopped test, or a 
speed reduction of 8 km/h (5 mph) in both tests.
---------------------------------------------------------------------------

Agency Response
    One reason the commenters requested lowering the upper speed range 
for a no-contact requirement was the concern that false activations 
would increase. In the NPRM, NHTSA stated that the proposed testing 
requirements are practicable and are intended to avoid and mitigate the 
most crashes. In the NPRM, NHTSA expressed that AEB systems are 
undergoing rapid advancement and have been able to achieve collision 
avoidance at higher testing speeds without major updates. Since the 
publication of the NPRM, NHTSA research has confirmed that a vehicle 
(the 2023 Toyota Corolla Hybrid) was able to avoid collision under all 
testing conditions up to the maximum proposed testing speed requirement 
for lead vehicle stopped and lead vehicle moving. That same vehicle, 
when tested for the lead vehicle decelerating scenario with a 12 m 
headway and 0.5 g lead vehicle deceleration, was able to avoid 
collision in all trials when tested at 50 km/h and was able to avoid 
collision on two trials and incur impact speeds of approximately 5 km/h 
and below on the other three trials when tested at 80 km/h (50 mph).
    This vehicle's ability to pass these tests demonstrate that the 
proposed requirements are practicable and the technology is still 
evolving. As stated in the NPRM, the expectation for the tested AEB 
production systems (which were not designed to meet these requirements) 
was not that they would pass all trials; rather, it was to inform the 
agency on the practicability of the proposed testing speeds. The fact 
that a current AEB system is already capable of meeting the AEB 
requirements confirms the agency's assumption that current AEB systems 
can be further developed within the lead time provided.
    Another area of concern expressed by the commenters was sensor 
range performance. Honda and Bosch both had concerns about requiring no 
contact when testing at higher speeds as current AEB systems sensor 
range makes it difficult for the system to discern objects far enough 
to achieve no contact and mitigate false positives. In previous agency 
testing that informed development of the NPRM, for the vehicle that 
performed the best--according to the publicly available information 
from the manufacturer--the upgrades to the AEB system from the previous 
generation included, among others, improved sensor range.\118\ As shown 
by the evolution of the Toyota system, and based on the testing results 
from the other vehicles which also show significant advancement in 
collision avoidance, NHTSA is confident that current systems, given 
sufficient development time, can be engineered to avoid contact and 
mitigate false positives in a similar manner as the Toyota system.
---------------------------------------------------------------------------

    \118\ https://www.jdpower.com/cars/shopping-guides/what-is-toyota-safety-sense, accessed November 13, 2023.
---------------------------------------------------------------------------

    The request for further development time was raised by the majority 
of industry commenters, and, as discussed later in this preamble, NHTSA 
agrees and is providing more time to meet this final rule. Based on the 
comments received, it seems that the main solution currently employed 
by manufacturers to mitigate false positives is to detune the system at 
higher speeds (consistent with current UNECE requirements). Euro NCAP, 
while not a regulation, employs similar testing at similar speeds as 
proposed in the NPRM (and adopted by this final rule), and many 
vehicles achieve a full score on Euro NCAP testing due to their 
collision avoidance capabilities. This information further reinforces 
NHTSA's assessment that the proposed testing speeds are practicable and 
deployable in the real world with sufficient lead time.
    Ford stated that harsh braking to avoid high speed collisions can 
result in rear end collisions based on an internal controllability 
study with randomly selected drivers in Germany. Based on that study 
Ford stated there is an increase in rear end collisions resulting from 
AEB activation above differential speeds of 60 km/h (37.5 mph).
    In response, NHTSA was unable to find this study as Ford did not 
provide any data on it. Thus, NHTSA was unable to evaluate the 
relevance of Ford's statement to the current rule. The agency observes, 
however, the proposed requirements do not require hasher braking than 
currently demonstrated by vehicles compliant with FMVSS No. 135. 
Further, if all vehicles were equipped with AEB systems conforming to 
this final rule, it is plausible that no crash would happen.
Comments About Increased Costs as New Hardware is Needed
    Mobileye stated that for the stopped lead vehicle, the majority of 
AEB systems in vehicles today will need a new safety strategy and may 
need hardware updates/replacements. Therefore, Mobileye states, the 
assumption that all vehicles have the necessary hardware is not 
correct.
Agency Response
    In response, NHTSA concurs that the cost estimates in the NPRM 
underestimated the incremental hardware costs associated with this 
final rule. Accordingly, this final rule has

[[Page 39741]]

adjusted the estimates presented in the NPRM to include the costs 
associated with software and hardware improvements, compared to the 
baseline condition. Incremental costs reflect the difference in costs 
associated with all new light vehicles being equipped with AEB with no 
performance standard (the baseline condition) relative to all light 
vehicles being equipped with AEB that meets the performance 
requirements specified in this final rule. The Final Regulatory Impact 
Analysis (FRIA) provides a detailed discussion of the benefits and 
costs of this final rule.
Comments About the Effect of Test Speed on Evasive Steering
    When a driver is alerted to an impending crash, the driver may 
manually intervene by, for example, applying the vehicle's brakes or 
making an evasive steering maneuver, to avoid or mitigate the crash. 
Several commenters believed that the agency should ensure that all 
final test conditions (especially at higher test speeds) would preserve 
steering intervention or other intentional driving behavior regarding 
the TTC intervention times.
    A number of commenters believed that at higher testing speeds, AEB 
could interfere with evasive steering maneuvers.\119\ Honda stated that 
AEB should only intervene when a collision is otherwise unavoidable and 
is designed to intervene as late as possible to mitigate injury and not 
interfere with evasive or normal driver steering maneuvers. Honda 
stated that differentiating between those situations where steering is 
more appropriate than emergency braking is critical when considering 
the unintended consequences of AEB. Honda believed that, under the 
proposed speeds, AEB intervention will be forced to occur before the 
driver might steer, hindering the driver's appropriate and intended 
response in real-world higher speed scenarios.
---------------------------------------------------------------------------

    \119\ These commenters included ASC, Mobileye, Bosch, the 
Alliance, HATCI, Ford, Mitsubishi, Porsche and ITS America.
---------------------------------------------------------------------------

    The Alliance stated that, based on a NHTSA study,\120\ the time 
required to avoid impact by steering or braking are equal at 
approximately 35 kph and 0.61 seconds and that above 35 kph, avoidance 
though braking begins to require increasingly more time than steering. 
Drivers are generally more likely to initiate braking to avoid striking 
an object at speeds below 44 kph and are more likely to initiate 
steering to avoid impact above 44 kph. The Alliance stated that the 
driver will typically initiate their maneuver before 1.7 seconds TTC 
and therefore, any ``no-contact'' requirement for AEB at higher speeds 
will necessitate activating AEB before the driver has an opportunity to 
steer around the threat when a steering maneuver would be more 
effective. Similarly, Toyota stated that NHTSA should define a maximum 
speed for the lead vehicle AEB testing with no manual brake 
application, of no greater than 60 km/h for the ``no-contact'' 
requirement, due to the potential effect of evasive steering and the 
timing of AEB activation.
---------------------------------------------------------------------------

    \120\ Forward Collision Warning Requirements Project Final 
Report--Task 1 (DOT HS 809 574)--January 2003.
---------------------------------------------------------------------------

Agency Response
    NHTSA has considered the comments but does not find the arguments 
relating to evasive steering compelling. AEB intervention is a last 
resort crash avoidance maneuver, and it does not seem reasonable to 
assume that a driver who is inattentive until moments before a crash 
will reengage and be able to perform a safe steering maneuver that 
would not jeopardize other traffic participants. The information 
provided by Honda, Toyota, and the Alliance seem to consider only the 
timing required for a vehicle to brake to a complete stop versus the 
timing of a steering maneuver, without considering any other factors. 
Such factors as vehicle dynamics, traffic conditions, and traffic 
participants all influence the safety benefit of a steering avoidance 
maneuver. While NHTSA does not encourage aggressive and unsafe driving 
behavior as shown in that example, we do note that because the test 
procedures involve manual braking, disengagement of AEB cannot happen 
solely due to brake application. Nothing in our standard, however, 
requires a manufacturer to suppress steering. A manufacturer, outside 
of the testing requirements, may elect to detune or disengage the AEB 
system based on an emergency steering maneuver as long as they meet all 
the AEB requirements.
    The type of roadway (two lane, divided, interstate) is an important 
factor in assessing whether a steering maneuver is appropriate, as is 
the traffic on such roadways. It seems unreasonable to expect that, 
except for very specific situations such as when an adjacent lane 
exists and is empty, a disengaged driver could perform any type of 
steering maneuver safer than stopping in the lane.
    In normal driving situations, rear end crashes frequently happen in 
heavy traffic where crash avoidance maneuvers from automatic or manual 
steering could cause the vehicle to either depart the road, collide 
with a vehicle in the adjacent lane, or, on an undivided two-lane road, 
cause a head-on frontal crash. Further, research referenced by Porsche 
in their comments shows that overwhelmingly, drivers either brake, or 
brake and steer, when presented with a surprise obstacle catapulted 
from the side.\121\ In this research, when the obstacle was presented 
to the drivers at a TTC of 1.5s, with the adjacent lane free of 
obstacles and the drivers had the opportunity to avoid a collision by 
steering alone, 43 percent of participants attempted to avoid by 
braking alone. The other 57 percent of participants tried to avoid the 
collision by braking and steering, while no participant tried to avoid 
contact by steering alone.
---------------------------------------------------------------------------

    \121\ Emergency Steer and Brake Assist--A Systematic Approach 
for System Integration of Two Complementary Driver Assistance 
Systems (Eckert, Continental AG, Paper Number 11-0111), https://www-esv.nhtsa.dot.gov/Proceedings/22/files/22ESV-000111.pdf.
---------------------------------------------------------------------------

    At a TTC of 2.0 s, 46 percent of participants tried to avoid by 
braking alone, 38 percent by braking and steering, and 15 percent by 
steering alone, while at a TTC of 2.5s 72 percent of participants tried 
to avoid by braking only, 14 percent tried to avoid by braking and 
steering, and 14 percent tried to avoid by steering alone.
    This research found that only at TTCs later than two seconds did 
drivers attempt to avoid only by steering alone, which suggests that 
drivers were not comfortable steering to avoid the presented object at 
the speed they were traveling without braking, further reinforcing the 
agency's assertion that braking in lane is appropriate. Looking at 
these results and considering that this research was performed with a 
surprise object catapulted from the side (which induces a preference 
for drivers to avoid by steering), it is clear that drivers are more 
inclined to brake in an emergency. Additionally, drivers brake even as 
they attempt a steering maneuver, which can lead to unstable vehicle 
dynamics. This serves to reinforce the agency's findings that a brake 
in the lane maneuver, even if it occurs early, before a TTC of 1.5s, is 
the safest, most appropriate, maneuver.
    The other situation where steering may be more appropriate, 
according to the commenters, is an engaged driver who consciously 
decides to avoid by steering. The steering avoidance maneuver by an 
engaged driver as shown by HATCI in their comment would still present a 
higher safety risk than a brake in the lane maneuver. In that example, 
a vehicle avoids the lead vehicle by cutting in front of a vehicle

[[Page 39742]]

on the adjacent lane. NHTSA fails to understand how such a maneuver is 
safe for any of the vehicles involved, especially considering the 
likelihood that other vehicles would be in the adjacent lanes. A 
subject vehicle darting out of its lane into an adjacent lane could 
result in a different type of crash.
3. Headway
Comments
    A key test parameter for the lead vehicle AEB tests is the initial 
headway \122\ between the subject vehicle and the lead vehicle. Several 
vehicle and equipment manufacturers opposed the proposed headway 
conditions (12 m at 80 km/h) in decelerating lead vehicle AEB 
tests.\123\ They stated that the proposed headway requirement is not 
practical because the short headway values at high relative speeds go 
beyond the capabilities of current AEB systems. Volkswagen, Porsche, 
Rivian, and others argued that the low headway conditions at high 
relative speeds may increase false positive rates, leading to phantom 
braking because earlier braking means the system looks further ahead, 
both in space and in time. (Hence, commenters stated, the probability 
for a collision is estimated at a lower accuracy value and this may 
lead to a false positive activation.)
---------------------------------------------------------------------------

    \122\ Headway refers to the distance or interval of time between 
vehicles moving in the same direction on the same route.
    \123\ These commenters included Volkswagen, Porsche, Mitsubishi, 
Rivian, Honda, MEMA, Bosch, and Mobileye.
---------------------------------------------------------------------------

    Many commenters believed the 12 m proposed headway at 80 km/h is a 
very close following distance that would equate to an unsafe following 
distance in the real world and that AEB systems are not designed to 
account for this type of ``misuse'' by the driver. In addition, they 
believed that compliance with a no-contact requirement would require 
immediate emergency braking at maximum deceleration, which, the 
commenters stated, would result in an uncontrollable safety hazard for 
following traffic. Volkswagen and Porsche suggested removing the 12 m 
headway at the 80 km/h scenario from the decelerating lead vehicle 
tests and aligning with the requirements of UNECE Regulation No. 
152.\124\ Similarly, Mitsubishi suggested 23 m as the minimum headway 
because the proposed minimum headway distance (12 m) is considered 
close enough to issue an FCW even with minimal deceleration of the 
subject vehicle. MEMA and Bosch suggested a headway greater than 16 m 
and a time gap greater than 0.2 seconds at 80 km/h to create a more 
representative test scenario that resembles a constant following 
distance. Mobileye stated that the headway of the 12 m in decelerating 
lead vehicle test scenario at 80 km/h is around 0.5 s which, the 
commenter believed, was not realistic because research data showed that 
the median headway time across 10 different sites was 1.74 s.
---------------------------------------------------------------------------

    \124\ That regulation currently requires full collision 
avoidance up to 40 km/h relative speed between the subject and lead 
vehicle.
---------------------------------------------------------------------------

Agency Response
    The agency disagrees with Volkswagen and other manufacturers that 
the lower bound (i.e., 12 m) of the headway range is not practicable 
for the current AEB systems at a high speed (e.g., 80 km/h). NHTSA 
discussed in the NPRM that 4 out of 11 vehicles in the agency's 2020 
AEB research met the no-contact requirement of this rule when the 
subject vehicle and lead vehicle were traveling at 72.4 km/h (45 mph) 
with an initial headway of 13.8 m (45 ft). The deceleration of the lead 
vehicle was 0.3 g. This research also included decelerating lead 
vehicle testing at 56.3 km/h (35 mph) with a deceleration rate of 0.5 
g.
    In the NPRM, NHTSA tentatively concluded that the current lead 
vehicle AEB systems would be able to meet the most stringent headway 
requirement (i.e., 12 m) if their perception software was properly 
tuned for the higher lead vehicle deceleration (0.5 g). The agency's MY 
2023 AEB research supports this.\125\ The test results demonstrated 
that one of the six vehicles was able to meet the requirements of this 
standard in all five trials at 80 km/h with the initial headway of 12 m 
and the lead vehicle deceleration of 0.5 g. Another vehicle was also 
able to meet the test requirements in 2 out of 5 trials for the same 
test speeds.
---------------------------------------------------------------------------

    \125\ NHTSA's 2023 Light Vehicle Automatic Emergency Braking 
Research Test Summary, available in the docket for this final rule 
(NHTSA-2023-0021).
---------------------------------------------------------------------------

    In their comment, Honda stated that the worst-case scenarios for 
impact relative speed (72 km/h) are accomplished with a lead vehicle 
deceleration of 0.5 g at the 12 m headway distance. Given the 
performance of these two vehicles in the most difficult testing 
scenario, NHTSA continues to believe that the headway specifications of 
this final rule--any distance between 12 m (39.4 ft) and 40 m (131.2 
ft)--are within the capabilities of the AEB systems designed to comply 
with this final rule.
    As for the potential increase of false positive rate raised by 
Volkswagen, Porsche and Rivian, false positive activation that causes 
an unreasonable risk to safety is a defect issue. Vehicle manufacturers 
are responsible for mitigating and resolving any defects in their 
vehicle products. Here, the concern is based on a hypothetical 
situation where a vehicle at a high speed with a small headway (e.g., 
12 m) may prematurely activate the AEB system--forcing initiation of 
early braking--when there is not a true risk of an imminent collision. 
At 80 km/h (50 mph), a headway of 12 m is uncomfortably close to a 
crash imminent situation and the agency feels strongly that it is 
difficult even for an attentive driver to react properly to avoid a 
crash in this scenario, especially with a lead vehicle braking above 
0.3g. It is up to manufacturers to design their AEB systems to deal 
with situations where the driver is following close to the vehicle in 
front of it, and the lead vehicle decelerates between 0 and 0.3 g. They 
must determine what is a false positive and what is an actual positive.
    As for replacing the current range requirements for headway with 
discrete values, NHTSA disagrees with Honda and Volkswagen that the 
range requirements require infinite number tests and cause unreasonable 
test burden to manufacturers. The agency noted in the NPRM that the use 
of a range of potential values allows NHTSA to ensure that AEB system 
performance remains consistent, as conditions--in this case headway--
vary within the bounds of the range. NHTSA has observed that some lead 
vehicle AEB systems performed well under high speed or shorter headway 
scenarios, but did not perform as well under lower speed or longer 
headway scenarios. This type of performance inconsistency is why the 
agency proposed a range of values, and not just discrete values.
    The current range headway provides manufacturers an understanding 
of the performance the FMVSS requires. Manufacturers have the ability 
and flexibility to decide how they can certify that a given AEB system 
complies with the requirements contained in this final rule. This 
includes the number and types of tests needed to ensure that an AEB 
system works throughout the proposed range. The agency is providing 
notice of how we test a vehicle's compliance. For these reasons, NHTSA 
believes that the headway range requirements do not cause an 
unreasonable test burden.
    Accordingly, NHTSA declines to amend the range of headway 
specifications in decelerating lead vehicle AEB tests. This final rule 
adopts that the headway specifications in

[[Page 39743]]

decelerating lead vehicle AEB tests to include any distance between 12 
m (39.4 ft) and 40 m (131.2 ft) as proposed in the NPRM.
4. Lead Vehicle Deceleration
    The decelerating lead vehicle scenario is meant to assess the AEB 
performance when the subject vehicle and lead vehicle initially are 
travelling at the same constant speed in a straight path and the lead 
vehicle begins to decelerate. NHTSA's proposed lead vehicle AEB tests 
included parameters for the deceleration of the lead vehicle.
    Honda expressed concern that the proposed rule included a broad 
range of parameters for lead vehicle deceleration (ranging from 0.3 to 
0.5 g). It further stated that testing a theoretically infinite number 
of combinations within the proposed range is impractical. Honda 
suggested that the proposed range of deceleration values should be 
replaced with discrete nominal test values for lead vehicle AEB 
deceleration tests.
    In response to Honda, NHTSA believes that the targeted average 
deceleration is best represented by a bounded range, rather than a 
discrete value, to better evaluate vehicle performance. During agency 
testing, NHTSA has observed vehicles that may perform well at the upper 
and lower bounds of a performance range, yet inconsistently perform in 
the middle of a performance range. The agency believes that specifying 
a bounded range of 0.3 g to 0.5 g will better ensure consistent 
performance of AEB systems in real world situations than if a discrete 
value were specified. Further, the test procedures of this rule provide 
information regarding how the agency will conduct tests. Manufacturers 
have the flexibility to certify the compliance of their vehicles using 
reasonable care, and are not required to conduct testing as the agency 
does if the vehicle passes when tested by NHTSA as specified in the 
standard. Therefore, this final rule adopts the average deceleration 
range proposed in the NPRM.
    Humanetics commented that the provision related to ``targeted 
deceleration'' should state that the deceleration is maintained until 
the speed is below a target value (such as 1 km/h) and that the 
regulatory text ``250 ms prior to coming to a stop'' in proposed 
S7.5.3a should be replaced with ``the lead vehicle speed is reduced to 
1 km/h.''
    NHTSA disagrees with the comment. When determining the targeted 
average deceleration, the agency has specified that the targeted 
deceleration will occur within 1.5 sec of lead vehicle braking onset, 
giving the lead vehicle time to reach the desired deceleration. As the 
vehicle comes to a stop, the acceleration profile becomes noisy and is 
not reflective of the actual deceleration observed through most of the 
test. Thus, the agency proposed that the last 250 milliseconds (ms) of 
the vehicle braking before coming to a stop are not used in the 
calculation of the targeted average deceleration. Changing this 
threshold to be a speed measurement, as suggested by Humanetics, would 
change the end of test parameter to allow for contact and would not 
address the noise in the deceleration as the vehicle comes to a stop. 
(This metric is consistent with how NCAP currently performs AEB 
testing.) NHTSA concludes that the metric does not need additional 
clarification and thus declines to replace the current time-based 
provision with a speed-based protocol.
5. Manual Brake Application
    NHTSA proposed lead vehicle AEB performance tests that included 
parameters for the manual brake application made to the subject 
vehicle.
    NHTSA received several comments from vehicle and equipment 
manufacturers on the provisions. Porsche and Volkswagen stated that 
NHTSA should provide additional clarity specific to the brake robot 
application, particularly regarding proposed S10 specific to the set-up 
and calibration of the braking robot and the rate of brake pedal 
application. Hyundai suggested removing the manual braking tests and 
replacing them by a statement in FMVSS No. 127 to the effect that, ``A 
driver's manual activation of the brake pedal shall not impair the 
operation or effectiveness of AEB.'' ASC sought further clarification 
regarding the manual brake application profile. Humanetics believed 
that the tolerance was too tight in proposed S10.4 that brake pedal 
force is to be maintained within 10 percent of the commanded brake 
pedal force. Humanetics encouraged NHTSA to adopt a wider tolerance, 
such as allowing an applied force within 25 percent of the commanded 
force, while also allowing shorter duration forces (less than 200 ms) 
that may exceed the 25 percent tolerance.
    This final rule adopts the NPRM's proposed specifications for the 
manual braking conditions. It also includes a third brake control 
option that a manufacturer may choose.
    The agency disagrees with Hyundai that the purpose of the manual 
braking conditions can be achieved by the suggested statement. The 
tests with manual braking application are different from the lead 
vehicle AEB tests without manual braking. First, manual braking tests 
are conducted at a higher range of subject vehicle speed, at any 
subject vehicle speed between 70 km/h (43 mph) and 100 km/h (62 mph) 
for both the stopped and slower-moving lead vehicle scenarios, than 
that of corresponding AEB tests without manual braking application. 
Second, the tests with manual braking application represent two 
different real-world situations. The first represents a driver that 
reacts to the FCW and re-engages in the driving task by applying the 
brake (although with insufficient force to prevent a collision). In 
this case, the vehicle must be capable of recognizing that the driver 
has failed to provide adequate manual braking and supplement it with 
automated braking force. The second represents a driver who re-engages 
very late in the AEB event. The test ensures that the act of late 
manual braking does not disrupt or disengage crash imminent braking 
functionality.
    The language suggested by the commenter considers only this second 
condition and not the first. Additionally, Hyundai did not provide a 
metric for ensuring that this performance could be met using their 
proposed language. Therefore, NHTSA declines to remove the manual 
braking test conditions in the lead vehicle AEB tests of this final 
rule.
    Regarding the specifications for the braking robot, the agency 
notes that both Porsche and Volkswagen requested more detail but 
neither explained the issues they faced, or what is needed in terms of 
additional information. Both manufacturers have experienced braking 
robots in other AEB testing. In the proposal, NHTSA stated that either 
a displacement braking controller or a hybrid braking controller 
(braking robot) could be used, at the manufacturer's discretion, and 
proposed requirements for the performance of these two styles of 
controllers. Additionally, the agency imposed no limitations on how 
manufacturers can self-certify. Thus, manufacturers, who have the best 
knowledge of their AEB systems, are free to choose a braking method 
(type of braking controller, human test driver, etc.) that best serves 
their needs to certify their vehicles. As Porsche recognized, various 
brake robots are available with different specifications. A 
manufacturer can easily select the one that is most appropriate for 
testing its AEB system. Therefore, NHTSA concludes it is unnecessary to 
specify a single brake controller or braking robot.
    ASC sought further clarification regarding the tests that require 
manual brake application on the manual brake

[[Page 39744]]

application profile. It specifically highlighted the time for driver 
reaction, movement of foot brake pedal application, and build system 
pressure. They also highlighted that 1.2 seconds after an FCW would be 
a typical driver response time according to Euro NCAP.
    As stated in the proposal, brake pedal application onset occurs 1.0 
 0.1 second after the forward collision warning onset, 
thus, the driver response time is approximately one second. The agency 
does not have data showing that a reaction time of 1.2 is more 
appropriate. Specifics such as the movement of foot brake pedal 
application and system pressure are best not stipulated as absolutes, 
as they may change based off each brake system and in-vehicle brake 
controller. The agency believes it has provided sufficient notice for 
manufacturers to understand how NHTSA will test.
    ASC also sought information on how the agency determines brake 
pedal application onset. NHTSA does not believe that specifying a 
minimum brake pedal displacement, along with a minimum level of force 
applied to the pedal is necessary. To displace the pedal at all 
requires a minimum amount of force. The agency believes that 11 N (2.5 
lbf) of force is small enough to be easily achieved by a driver or 
controller, and large enough to show intent to brake. Thus, the agency 
is not adopting a change to the brake pedal application onset.
    ASC highlighted that NHTSA had not considered braking systems using 
force feedback. The agency agrees that a force only feedback controller 
will provide another useful method of brake application. As such, the 
final rule includes this third brake control option that a manufacturer 
may choose. It is substantially similar to the hybrid controller with 
the commanded brake pedal position omitted, leaving only the commanded 
brake pedal force application. The force feedback brake pedal 
application applies the force that would result in a mean deceleration 
of 0.4 g in the absence of AEB activation.
6. Testing Setup and Completion
    The NPRM proposed that the subject vehicle and lead vehicle speeds 
are maintained within 1.6 km/h, the travel paths do 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. MEMA and ASC 
suggested that the lane positioning requirements should be harmonized 
with UNECE Regulation No. 152, e.g., 0.2 m not 0.3 m permitted lateral 
variance. Humanetics suggested that NHTSA use more strict tolerances 
for the subject vehicle, to increase repeatability. Humanetics also 
stated that as the yaw rate is quite a noisy signal, a filter should be 
used for the lead and subject vehicles. Humanetics further suggested 
that the agency should consider currently accepted tolerances to test 
speeds and other test parameters in defining these FMVSS tests.
    In response, NHTSA disagrees with the commenters that a tighter 
tolerance is needed. The agency's specification is in line with 
previous NHTSA testing. As for requiring a smaller tolerance for 
vehicle speed and providing additional tolerances for a target carrier, 
the agency disagrees with Humanetics that the tolerance specified is 
excessively large for attaining repeatable and reliable testing. NHTSA 
does not have any data showing that manufacturers cannot meet these 
tolerances, nor that the tolerances proposed induce testing failures. 
Additionally, requiring a tighter tolerance is not representative of 
expected on road conditions. Accordingly, the agency does not see value 
in providing tighter tolerances.
    NHTSA also notes that the agency proposed tolerances for where the 
lead vehicle will be positioned and operated during the performance 
tests. NHTSA is concerned that adding more tolerances to the carrier 
system that drives the vehicle test device would overly constrain the 
testing set up. Lastly, ISO 19206-7 is in draft form and is yet to be 
finalized. As such, it would be premature to incorporate the document 
into this final rule. Given the above, the agency declines to change 
lane positioning requirements or adopt additional tolerancing.
    Regarding test completion, the NPRM proposed that, ``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.'' The Alliance stated that, for the 
slower-moving vehicle scenario, imposing a full braking requirement may 
not be appropriate if the target/lead vehicle were to continue to move 
(or if a stopped vehicle were to move again under real-world 
conditions). The commenter suggested that test completion be defined as 
``the instance when the subject vehicle speed is equal or less than the 
lead vehicle speed without making contact with the lead vehicle, or 
when the subject vehicle makes contact with the lead vehicle.''
    In response, NHTSA notes that the NPRM addressed the Alliance's 
concern in the proposed test procedures in proposed S7.4.4. This final 
rule adopts the proposed test completion criteria--``test run is 
complete when the subject vehicle speed is less than or equal to the 
lead vehicle speed''--for slower moving lead AEB tests as proposed.
    Bosch suggested NHTSA consider setting parameters to define a 
``valid run'' with respect to pedal and steering inputs to maintain 
tolerance on approach. Bosch stated that they encountered testing cases 
where an overly narrow definition of the calibration tolerances of the 
robot has interfered with the system reaction. Bosch also commented 
that, depending on the robot mode and type of vehicle brakes utilized, 
interference with the ADAS systems may occur. Bosch suggested the 
adoption of tolerances outlined in UNECE Regulation No. 152 for 
performance testing, with the aim of promoting standardized and 
realistic evaluations of automotive safety systems.
    In response to Bosch's suggestion to define what a valid run is, 
NHTSA highlights the position and speed specifications for testing as 
stated in the NPRM that 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. 
Additionally, 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. Bosch provided no 
additional information as to the inadequacy of NHTSA's proposed 
specifications for how the lead vehicle and subject vehicle respond 
prior to subject vehicle braking. Additionally, Bosch did not identify 
specific inadequacies in the braking controllers specified for use with 
manual braking
    As for the proposed triggering times/TTCs (related to the 
``beginning of tests''), the ASC stated that different test procedures 
in the NPRM specify different triggering times/TTCs (e.g., three (3) 
seconds in S7.5.2, four (4) seconds in S8.2). ASC suggested that the 
trigger time period be standardized for all test scenarios.
    The agency disagrees with this TTC suggestion. NHTSA selected 
appropriate test procedures, including triggering times, for each test 
scenario based on its unique features. For example, a three-second 
triggering time in a decelerating lead vehicle AEB test (S7.5.2) is 
selected to provide sufficient time to align a subject vehicle with a 
lead vehicle and to set a proper headway between the vehicles. On the 
other hand, a four-second triggering time in a PAEB test (S8.2) is 
selected to estimate an initial headway between a subject vehicle and

[[Page 39745]]

a pedestrian surrogate. As such, these triggering times represent 
unique features of two different tests. There are reasons not to 
standardize a triggering time to use across all lead vehicle and 
pedestrian AEB test scenarios.
    ASC sought clarification on the accelerator pedal release process 
when the vehicle cruise control is active. In response, as stated in 
the NPRM, when cruise control is active the pedal release process is 
omitted as the accelerator pedal is already released. The agency 
expects an equivalent level of crash avoidance or mitigation regardless 
of whether cruise control is active.
7. Miscellaneous Comments
    Mobileye stated that in some cases of target deceleration, the 
robot deceleration will be enough, or close enough, to avoid a 
collision. Mobileye stated that, in cases where the collision speed is 
very small, the AEB system can cause a nuisance event by a slight 
modification of the braking power by the driver. Mobileye suggested a 
more deterministic approach for these test scenarios which will result 
in a collision speed above 10 kph when using the robot 0.4 g 
deceleration.
    In response, NHTSA does not specify the level of deceleration that 
the AEB system needs employ to safely bring the vehicle to a stop. In 
fact, during testing, the agency has observed that while some vehicles 
employ late and harsh braking as described by Mobileye, more refined 
AEB systems do not perform in such a manner.\126\ As shown by Mobileye, 
to resolve the example they provided, only a slight additional 
deceleration, to further reduce the subject vehicle speed of 6.3 km/h, 
is needed to avoid the collision without harsh braking.
---------------------------------------------------------------------------

    \126\ https://www.regulations.gov/document/NHTSA-2021-0002-0002.
---------------------------------------------------------------------------

    Bosch suggested NHTSA consider employing the term ``stationary 
vehicle'' as used in the UNECE Regulation No. 152 specification, 
instead of ``stopped,'' to promote uniformity and consistency in 
automotive safety terminology with existing standards and 
specifications. Bosch believed the distinction is crucial for some AEB 
systems as ``stopped'' vehicle implies that the vehicle was in motion 
immediately before the sensors have detected the Vehicle Under Test 
(VUT). Bosch suggested using the term ``stationary'' instead of 
``stopped'' to align with existing standards and avoid any potential 
misinterpretations about the VUT as moving.
    NHTSA does not agree with Bosch that the term ``stopped lead 
vehicle'' should be amended to ``stationary vehicle.'' The standard's 
test procedures clearly specify how the lead vehicle test device is 
placed (see, S7.3.2 of the proposed regulatory text) (``the lead 
vehicle is placed stationary with its longitudinal centerline 
coincident to the intended travel path'') and does not lend itself to 
potential misinterpretations. The term stopped, used in this 
requirement, is consistent with the agency's practices in previous AEB 
research and in the current U.S. NCAP.
    NHTSA received several comments regarding test speeds as applied to 
vehicles equipped with ADS. The Alliance, AVIA and Zoox suggested that 
compliance testing be limited to the maximum speed that an ADS-equipped 
vehicle can achieve within its operational design domain. AVIA 
commented that some ADS-equipped vehicles have top speeds below those 
required in the Lead Vehicle AEB Collision Avoidance test parameters, 
and therefore suggested modifying the test parameters such that they 
can be met when an ADS-equipped vehicle operates at its highest speed 
if that speed is lower than the originally proposed subject and lead 
vehicle speeds. Zoox commented that an ADS may ``refuse'' to drive at 
80 km/h at a following distance of 12 m or at 80 kph between two parked 
cars because this behavior does not align with its more conservative 
driving parameters.
    In response, by including a maximum speed of 90 mph in this final 
rule, NHTSA is not requiring that manufacturers design their vehicles 
to be capable of driving 90 mph. Similarly, NHTSA is not requiring that 
Zoox design its ADS to operate at 90 mph. Instead, NHTSA may test the 
vehicle at the maximum speed the vehicle can achieve in its operational 
design domain. However, if the speed limitation in Zoox's vehicles are 
solely due to ADS programming and the vehicle itself is not speed 
limited, then Zoox must certify compliance to all speeds up to the 
maximum speed its vehicles are capable of being driven. As an example, 
if Zoox's ADS is programmed to drive at speeds up to 45 mph, but the 
vehicle has functionality that would allow it to be driven at speeds up 
to 90 mph, then Zoox must certify that AEB operates as required by this 
final rule at speeds up to 90 mph.
    Regarding proposed subject vehicle specifications, an anonymous 
commenter stated that they found some of the procedures and criteria to 
be unclear or confusing in the NPRM. They stated that NHTSA should 
provide more diagrams and figures to clarify the test procedures and 
criteria.
    In response, NHTSA believes that the NPRM provided sufficient 
information to the public to understand the requirements of the 
proposed standard. The agency included many figures, diagrams, and 
tables, that highlighted and explained key information. These figures, 
coupled with the detailed testing scenarios and test track conditions, 
adequately describe the rulemaking and the performance NHTSA is 
requiring by issuing FMVSS No. 127.

I. Procedures for Testing PAEB

    This section describes the pedestrian AEB performance tests adopted 
by this final rule. After considering the comments to the NPRM, NHTSA 
has adopted the proposed procedures tests with a few minor revisions to 
some parameters and definitions, to clarify details of the test 
procedures. Importantly, NHTSA has increased the lead time to meet the 
requirements by providing a five-year lead time.
    This section responds to the comments and explains NHTSA's reasons 
for adopting the provisions set forth in this final rule. For the 
convenience of readers, a list of the test specifications can be found 
in appendix B to this final rule preamble.
    The pedestrian AEB performance tests require AEB systems to provide 
a forward collision warning (FCW) and automatically apply the service 
brakes at all forward speeds above 10 km/h (6 mph) to avoid an imminent 
collision with a pedestrian.\127\
---------------------------------------------------------------------------

    \127\ The FCW and brake application need not be sequential.
---------------------------------------------------------------------------

    The test scenarios required for PAEB evaluation fall into three 
groups of scenarios based on how NHTSA will apply the pedestrian test 
device--crossing path, stationary and along path. For each test 
conducted under the testing scenarios, there are the following 
provisions within those testing scenarios: (1) pedestrian crossing 
(right or left) relative to an approaching subject vehicle; (2) subject 
vehicle overlap (25% or 50%); \128\ (3) pedestrian obstruction (Yes/
No); and, (4) pedestrian speed (stationary, walking, or running) 
(VP).
---------------------------------------------------------------------------

    \128\ Overlap describes the location of the point on the front 
of the subject vehicle that would contact a pedestrian if no braking 
occurred. It refers to the percentage of the subject vehicle's 
overall width that the pedestrian test mannequin traverses. It is 
measured from the right or the left (depending on which side of the 
subject vehicle the pedestrian test mannequin originates).
---------------------------------------------------------------------------

    NHTSA will select further parameters from a subject vehicle speed 
range (VSV) and the lighting condition (daylight, lower 
beams or upper beams). The

[[Page 39746]]

subject vehicle's travel path in each of the test scenarios is 
straight.
1. Scenarios
Request To Add Scenarios
    Many commenters suggested additional scenarios in PAEB 
testing.\129\ Commenters urged NHTSA to include test devices 
representative of bicyclists and other vulnerable road users (VRUs), 
such as motorcyclists. A number of commenters recommended expanding 
additional scenarios involving pedestrians, such as older adult 
pedestrians who may walk slower than 3 mph, persons with disabilities, 
a running adult from the left scenario with dark lower beam or upper 
beam, pedestrians crossing from both directions, or pedestrians 
traveling against traffic.
---------------------------------------------------------------------------

    \129\ These commenters included NTSB, Advocates, the League, 
AMA, APBP, NSC, Forensic Rock, Consumer Reports, CAS, Radian Labs, 
AARP, NSC, America Walks, APBP, AARP, United spinal, Radian Labs, 
Adasky, VRUSC, AFB, Humanetics, and PVA.
---------------------------------------------------------------------------

    NHTSA is highly interested in having PAEB address more scenarios, 
road users, and pedestrians than the scenarios covered by this final 
rule. NHTSA explained in the NPRM that the agency is actively 
conducting research to characterize, among other matters, the 
performance of AEB systems in response to bicycles and motorcycles, in 
both daylight and darkness conditions. However, the state of knowledge 
is not at the point where NHTSA can proceed with including bicycle and 
motorcycle surrogates in the new standard at this time. To illustrate, 
preliminary testing discussed in the NPRM identified issues with the 
design of the bicycle and motorcycle surrogates and their effect on the 
vehicles under test, indicating a need to learn more about these 
devices.\130\ NHTSA is continuing its research to learn more, and 
present and future studies may well result in efforts to define test 
procedures, refine the bicycle and motorcycle surrogate devices, and 
characterize AEB system performance for possible incorporation into the 
FMVSS.
---------------------------------------------------------------------------

    \130\ This report is expected to be completed within 2024.
---------------------------------------------------------------------------

    NHTSA proceeded with this rulemaking because it has the information 
needed to support an NPRM and final rule on the pedestrian behaviors 
addressed by the rule. Less is known about additional pedestrian 
behaviors to which commenters refer. NHTSA does not have the research 
necessary to determine well-reasoned and practicable performance 
requirements for the full range of travel behaviors pedestrians employ. 
Because developing the technical underpinnings and assessing the 
feasibility of potential further countermeasures need more time, NHTSA 
is adopting the PAEB test procedures proposed in the NPRM as a sound 
first step.
Request To Remove PAEB Scenarios
    The Alliance requested that NHTSA not include the test of the 
stationary pedestrian test in nighttime conditions (S8.4). The Alliance 
stated that an analysis of real-world data from NHTSA's FARS database 
showed that fewer than 5 percent of stationary pedestrian crashes occur 
in dark, or low light, conditions, which is substantially lower than 
the other scenarios evaluated in the NPRM. The Alliance stated that the 
complexity in designing countermeasures is increased, particularly for 
vision-based systems, in discerning non-moving objects that may 
resemble the human form in low light conditions at high speed. The 
Alliance expressed concerns that this requirement would force the 
installation of additional sensors to verify the presence of an object 
in the roadway. The Alliance stated that this scenario has additional 
cost implications and underscores that meeting the requirements of the 
rule is not as straightforward as the agency suggested.
    Similarly, MEMA questioned if crash data support the stationary 
pedestrian test, because the commenter believed it is unlikely a 
pedestrian would be completely stationary and without movement in any 
real-world condition. MEMA further stated that this test increases the 
probability of false activation from other stationary roadside objects. 
MEMA suggested that the moving along path scenario addresses real-world 
scenarios.
    In response, NHTSA declines this request to eliminate the 
stationary pedestrian in nighttime conditions test. The commenters 
addressed the size and existence of the safety problem, with the 
Alliance providing an analysis showing that the standing pedestrian 
scenario comprises 5 percent (479 lives) of unlit nighttime crashes 
between 2014 and 2021. The unlit nighttime testing is designed to test 
a worst-case scenario, where there is no appreciable light other than 
that generated by the vehicle to aid in the detection of a 
pedestrian.\131\ While the stationary position of the pedestrian test 
mannequin adds to the challenge of the test, real pedestrians encounter 
these potential dual dangers of darkness and stillness every day in the 
real world. NHTSA testing, discussed in the NPRM, has shown that AEB 
performance is reduced when testing the stationary scenario as compared 
to the along path scenario. Given the certainty that there are 
pedestrians outside in the dark each day, the likelihood that they may 
be stationary at times and not always in motion when a vehicle 
approaches, and the certainty of their vulnerable status vis-[agrave]-
vis the vehicle (even low-speed vehicle impacts with pedestrians can 
result in fatalities and serious injuries), NHTSA believes that 
eliminating the test would not be reasonable. This is particularly so 
given that meeting the requirement is practicable.\132\ Further, even 
if the agency accepts the Alliance analysis and interprets in a similar 
manner ``standing'' as equivalent to stationary during PAEB testing, 
NHTSA believes that the almost 50 annual fatalities over 8 years of 
data lends support for adopting the proposed test.
---------------------------------------------------------------------------

    \131\ NHTSA expects that this performance will also be 
representative of, and beneficial to, nighttime conditions where 
brighter ambient light conditions exist.
    \132\ NHTSA's 2023 testing demonstrated that six out of six 
vehicles were able to fully meet the stationary requirements in both 
daylight and upper beam nighttime scenarios. The testing showed that 
half of the vehicles tested also were able to fully meet the 
proposed requirements for the lower beam nighttime scenario.
---------------------------------------------------------------------------

    Ford believed that some tests are redundant and requested their 
removal. Ford recommends the removal of daytime 50 percent overlap 
crossing use cases as this will be 25 percent redundant with crossing 
use cases, as well as removing either the in-path stationary or moving 
scenarios which, the commenter believed, are redundant to each other.
    In response, NHTSA does not agree the tests are redundant. Testing 
with a 25 percent overlap is more stringent than the 50 percent overlap 
test, as the pedestrian is exposed to the vehicle for a shorter amount 
of time. However, the 50 percent overlap test assesses a different 
scenario than the 25 percent overlap test. In the 50 percent overlap 
test, the vehicle comes upon the pedestrian later in the event. NHTSA 
is retaining the 50 percent overlap test, and the other mentioned 
tests, to ensure that PAEB systems are tuned to detect pedestrians 
across a wide and reasonable range in the roadway.
Lack of Dynamic Brake Support (DBS) Testing in PAEB Scenarios
    Unlike for lead vehicle AEB, NHTSA did not propose that the AEB 
system supplement the driver's brake input with a dynamic brake support 
system. This is because NHTSA believes that, due to the sudden 
succession of events in a potential collision between a

[[Page 39747]]

vehicle and a pedestrian, particularly for the pedestrian crossing path 
scenarios, a driver is unlikely to have enough time to react to the 
crash imminent event, and the vehicle will brake automatically without 
driver input. Further, NHTSA stated that it anticipates that AEB system 
designs would include DBS.
    Advocates commented that NHTSA should either state that manual 
braking alone is insufficient to interrupt the AEB functionality or 
include testing of DBS functionality in the PAEB scenarios. AARP 
commented that it is important that the PAEB system function regardless 
of the characteristics of the vehicle's driver, and testing should 
reflect predictable variations such as those that result from the 
characteristics of older drivers.
    In response, NHTSA is declining to add a manual braking test for 
pedestrians in this final rule. As stated in the NPRM, NHTSA expects 
that manufacturers will include this functionality when approaching a 
pedestrian. While the agency does not test PAEB with manual brake 
application, it does not make any distinction as to when AEB is 
required based on manual brake application. Thus, an AEB system tested 
for manual brake application under lead vehicle AEB testing will 
function in the same manner when approaching a pedestrian.
    The agency also decided to test PAEB only without manual brake 
application due to the timing of crashes involving pedestrians, as it 
is not realistic to expect a quick enough response from a driver when 
presented with a warning to mitigate a collision under the proposed 
testing scenarios. NHTSA testing for lead vehicle AEB is premised on 
data that often an engaged driver does not brake enough to avoid a 
collision when presented with an FCW. However, the timing of a crossing 
path pedestrian scenario in some cases does not afford the ability to 
warn a driver and wait for a driver response. This difference between 
the lead vehicle and pedestrian crash scenarios renders requiring a 
manual brake application inappropriate for PAEB.\133\ As such, the 
agency is declining to add a manual braking test for pedestrians at 
this time.
---------------------------------------------------------------------------

    \133\ NHTSA is also mindful that implementing similar manual 
braking test scenarios for PAEB as for lead vehicle AEB may increase 
the likelihood of false positives when the systems are driven on the 
road. At 60 km/h (37.3 mph) automatic braking would need to occur at 
a minimum distance to the pedestrian of 20.25 meters with a 0.7g 
stop, which is a TTC of 1.21 sec, and it takes the vehicle 2.4 sec 
to stop. A pedestrian traveling with a walking speed of 5 km/h (3.1 
mph) would cover 3.36 meters in this time, which puts that 
pedestrian 3.8 meters from the center of an average vehicle in the 
25 percent overlap scenario, or about 2.9 meters from the side of 
the vehicle. In an urban setting, this would place the pedestrian in 
the buffer zone between the sidewalk and the travel lane, indicating 
the intent to cross the street. In this scenario the pedestrian 
would be a further 1.38 meters away in case of a warning issued 1 
second prior to the minimum TTC described above, or more with a 
longer warning. This would place a pedestrian outside the buffer 
zone and solidly on the sidewalk. Adding additional time for a 
forward collision warning and driver reaction time increases the 
likelihood of false alerts, as it becomes increase difficult to 
determine the pedestrian's intent the further outside the travel 
lane the pedestrian is. Because of this, NHTSA proposed requiring, 
``The vehicle must automatically apply the brakes and alert the 
vehicle operator such that the subject vehicle does not collide with 
the pedestrian test mannequin when tested using the procedures in S8 
under the conditions specified in S6.''
---------------------------------------------------------------------------

Lack of 25 Percent Overlap for PAEB Scenarios in Dark Conditions
    Several comments suggested including PAEB performance tests with 25 
percent overlap in dark conditions. Advocates requested that testing 
requirements at 25 percent overlap be included in the proposal, as a 
quarter of the vehicles tested by NHTSA in a limited study included 
such capability. Luminar stated the proposed PAEB testing overlap is 
arbitrary since the NPRM proposes PAEB testing at 25 percent overlap, 
but only 50 percent overlap for other scenarios, including some 
nighttime tests.
    In response, as discussed in the NPRM, NHTSA declined to add the 25 
percent overlap scenario for nighttime pedestrian AEB because it is not 
practicable at speeds relevant to the safety problem. The final rule 
has more benefits when pedestrian avoidance is tested at a more 
stringent and higher speed 50 percent overlap scenario.
    NHTSA disagrees with Luminar that the overlap scenarios are 
arbitrary. UNECE Regulation No. 152 specifies the pedestrian target's 
positioning at the same location as a 50 percent overlap scenario. Euro 
NCAP also uses impact locations of 25, 50, and 75 percent. NHTSA still 
views testing at high speeds with a 25 percent overlap during nighttime 
scenarios as not practicable. The agency views setting higher speed 
tests for crossing path with a 50 percent overlap at night as merited 
and more appropriate for this final rule than specifying lower max 
speeds for a 25 percent overlap at night. Accordingly, NHTSA is 
declining to add a scenario for a high-speed test with a 25 percent 
overlap during nighttime condition.
Lack of Turning Scenarios
    Several commenters recommended the inclusion of turning scenarios 
as part of the PAEB test requirements, i.e., expanding the testing 
conditions to evaluate pedestrian during right and left turns of the 
subject vehicle.\134\ Luminar stated that turning real word traffic 
conditions that mimic common pedestrian encounters in which the 
subject's movement partially or momentarily obscured and performance of 
crash avoidance technology in these scenarios is achievable. Some 
commenters stated that turning car-to-pedestrian AEB testing is 
performed as part of Euro NCAP.
---------------------------------------------------------------------------

    \134\ These commenters included Forest Rock, Luminar, APBP, NSC, 
the Coalition, Consumer Reports, and AARP.
---------------------------------------------------------------------------

    In response, this final rule adopts the tests as proposed based on 
the research and other data demonstrating the efficacy and 
practicability of systems meeting the crossing path, stationary and 
along path scenarios. The data and technologies for test scenarios 
representing other crashes have not been analyzed as to their merit for 
inclusion in a possible FMVSS (as discussed throughout this document, 
rear-end crashes have been analyzed).
    NHTSA included pedestrian AEB in turning from the left and turning 
from the right as a potential regulatory alternative for a more 
stringent rule. While commenters pointed out that Euro NCAP and other 
world NCAP programs offer some turning scenarios, NHTSA does not have 
sufficient information to propose or finalize incorporating a turning 
scenario at this time. NHTSA is not selecting this alternative in this 
final rule, however, and will consider conducting additional research 
and adopting requirements for turns in a future rulemaking, as 
appropriate. As discussed in the NPRM, NHTSA focused on the practicable 
scenarios that have the largest impact on the safety problem. While 
turning scenarios are responsible for around 48 percent of the total 
crash population for pedestrians, NHTSA crash data shows that 90 
percent of fatal pedestrian-vehicle crashes, and 52 percent of the 
total pedestrian-vehicle crash population are covered under the 
standard NHTSA has developed.\135\ In contrast, NHTSA data found that 
the turning right and turning left scenarios were found to only account 
for 1 percent and 4 percent of pedestrian fatalities, respectively.
---------------------------------------------------------------------------

    \135\ Mikio Yanagisawa, Elizabeth D. Swanson, Philip Azeredo, 
and Wassim Najm (2017, April) Estimation of potential safety 
benefits for pedestrian crash avoidance/mitigation systems (Report 
No. DOT HS 812 400) Washington, DC: National Highway Traffic Safety 
Administration, p xiii.

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[[Page 39748]]

2. Subject Vehicle Speed Ranges
Increase PAEB Testing Speeds
Comments
    NHTSA received many comments requesting the agency to increase the 
test speed of the vehicle.\136\ Commenters generally stated that since 
the most common speed limit for a road where a pedestrian is killed is 
45 mph, PAEB testing speeds should be increased above the proposed 
speeds (they generally did not suggest a maximum testing speed).
---------------------------------------------------------------------------

    \136\ These commenters included the cities of Philadelphia, 
Nashville and Houston, the Richmond Ambulance Authority, Drive Smart 
Virginia, Teledyne, the Lidar Coalition, Luminar, Consumer Reports, 
Forensic Rock, Luminar, COMPAL, and NACTO.
---------------------------------------------------------------------------

Agency Response
    In response, as explained in the earlier section for lead vehicle 
testing speeds, NHTSA has bounded the testing speeds after considering 
practicability and other issues. These practicability concerns include, 
among others, the performance that can reasonably be achieved in the 
lead time provided for the final rule, the safety need that can be 
addressed, the safety of the testing personnel, and the practicalities 
of conducting a test that can be run repeatably and consistently 
without damaging lab equipment, to preserve the integrity and validity 
of the test data. NHTSA proposed and is adopting the highest 
practicable testing speeds. Accordingly, NHTSA has decided not to 
increase the test speeds for PAEB in this final rule. NHTSA considered, 
and is currently researching, other testing scenarios for PAEB, so more 
will be known about the future about the practicability and 
reasonableness of higher test speeds.
Reduce PAEB Testing Speeds
Comments
    NHTSA received many comments from manufacturers and others 
requesting the agency to decrease the test speed of the vehicle.\137\ 
Some manufacturers commented that NHTSA should permit low impact speeds 
when testing PAEB above certain testing speeds (when testing 30 km/h 
(19 mph) and above).
---------------------------------------------------------------------------

    \137\ These commenters included the Alliance, Honda, Mobileye, 
Mitsubishi, Porsche, Volkswagen, Nissan, Toyota, and Aptiv.
---------------------------------------------------------------------------

    Like their comments on the lead vehicle speed tests, the Alliance 
and others suggested a hybrid approach that would permit some level of 
contact with the pedestrian test device for speeds above, e.g., 30 km/h 
(19 mph). These commenters stated that providing full crash avoidance 
at higher speeds may not always be practicable due to increased 
potential for false positives under real world conditions. 
Additionally, the Alliance stated that the PAEB system must have 
sufficient information upon which to base its decision to apply braking 
force. The high testing speeds and no-contact requirement may force the 
AEB system to be too aggressive particularly in view of what can be 
unpredictable movement of pedestrians in and around the roadway 
environment. Honda suggested when PAEB is tested between 50 km/h and 65 
km/h (31 mph to 40 mph), NHTSA should allow low speed contact up to 15 
km/h (9.3 mph). Honda stated that the basis for the suggested speed 
threshold is that according to pedestrian injury data in the U.S., the 
risk of severe injury or fatality in pedestrian crashes below 15 km/h 
is highly unlikely.
    The Alliance expressed concern about false positives or bad actors 
seeking to manipulate the AEB system into activating by imitating the 
act of entering the roadway environment. Mitsubishi was concerned about 
pedestrians who are about to jaywalk but stop due to approaching cars. 
The commenter stated that this behavior may lead to unnecessary 
activation and induce unintended consequences as current technology 
cannot predict pedestrian behavior with 100% accuracy. The Alliance and 
others stated that impact speeds of 25 km/h (16 mph) should be allowed 
as such impact speeds would have a reasonable safety outcome when the 
crash speed was mitigated from a higher speed testing. Some commenters 
stated that NHTSA should harmonize with UNECE Regulation No. 152, where 
impact speeds up to 40 km/h (25 mph) are allowed.
Agency Response
    NHTSA is adopting the proposed testing speed ranges with a no-
contact requirement and is not permitting repeat trials.
    The commenters' main arguments in support of reducing the PAEB 
testing speeds are the potential increase in the likelihood of false 
positives due to difficulties in detecting pedestrians and classifying 
pedestrian action (such as intention to enter the roadway). In general, 
the commenters suggested allowing some level of pedestrian contact at 
above certain reduced speeds, ranging from 30 km/h to 50 km/h (10 mph 
to 31 mph), with most commenters suggesting around 40 km/h (25 mph) as 
the maximum speed for a no-contact requirement.
    NHTSA proposed testing requirements that can be met, and that can 
avoid as many crashes, and mitigate as much harm, as practicable. For 
PAEB, NHTSA seeks to avoid crashes at the highest practicable speeds 
because of the vulnerability of a pedestrian in a vehicle crash. 
Vehicle contact with a pedestrian can be fatal or result in serious 
injury with potential long-term effects. NHTSA scrutinizes hybrid 
approaches, such as that of the Alliance, that incorporate as part of 
its framework the vehicle's hitting a pedestrian because the risk of 
injury to a pedestrian in a vehicle crash is so great. After reviewing 
the comments and other information, NHTSA does not believe that 
striking a pedestrian is an acceptable safety outcome given the 
availability of technologies that can prevent any kind of contact in 
the test scenarios.
    Using the speed limit as a proxy for traveling speed, the data 
presented in the previous section of this document show that about 50 
percent of pedestrian fatalities, and about 57 percent of injuries, 
occur on roads with a speed limit of 65 km/h (40 mph) or less. NHTSA 
believes an upper speed limit less than 65 km/h (40 mph) for a no-
contact PAEB requirement would not be appropriate when test data on the 
performance of current vehicles show the practicability of meeting the 
proposed limits, particularly when more lead time is provided for the 
technology to evolve.
    The injury curves and thresholds provided by some of the commenters 
show that below 25 km/h, there is a reduced probability of AIS3+ and 
MAIS3+ injury compared to impacts at greater speeds. However, the 
safety problem that PAEB can mitigate exists mainly at speeds above 40 
km/h. Given that AEB, when developed to meet a no-contact requirement, 
could help mitigate the occurrence of pedestrian impacts up to 65 km/h 
(40 mph), NHTSA believes it unreasonable to set the no-contact limit at 
speeds at just a 40 km/h (25 mph) threshold.
    As demonstrated by NHTSA testing, the technology has already proven 
effective at avoiding collisions at speeds up to 65 km/h (40 mph). As 
detailed in the research section, NHTSA found that a vehicle (the 2023 
Toyota Corolla Hybrid) was able to avoid collision under all testing 
conditions up to the maximum proposed testing speeds requirement for 
all PAEB testing scenarios and speeds.\138\ In addition,

[[Page 39749]]

four of the six vehicles tested achieved collision avoidance up to the 
proposed maximum speeds in almost all scenarios-some even in the most 
challenging dark lower beam scenarios. Additionally, another vehicle 
was able to achieve collision avoidance at all tested speeds in 3 
scenarios.
---------------------------------------------------------------------------

    \138\ NHTSA's 2023 Light Vehicle Pedestrian Automatic Emergency 
Braking Research Test Summary, available in the docket for this 
final rule (NHTSA-2023-0021).
---------------------------------------------------------------------------

    NHTSA believes that the practicability of meeting the PAEB 
requirements of this final rule is demonstrated by the test data 
showing the performance of the 2023 Toyota Corolla Hybrid that passed 
all scenarios, and that of the several other vehicles that almost 
passed all scenarios. These test results are even more noteworthy 
because the tested vehicles did not have AEB systems designed to meet 
the requirements of proposed FMVSS No. 127. They were not prototypes or 
vehicles specially engineered to the specifications of the proposed 
standard for research purposes. To be clear, these were production 
vehicles already in the marketplace. The fact that current vehicles not 
particularly engineered to meet the new standard's requirements could 
meet them as designed, or with slight modification, further 
demonstrates the practicability of this final rule. Because current AEB 
systems are already capable of meeting the AEB requirements, NHTSA's 
assumption is confirmed that manufacturers will be able to meet the 
requirements of FMVSS No. 127 with the lead time provided, without 
major upgrades while mitigating excessive false positives or other 
unintended consequences.
    Several commenters also believed that repeated trials should be 
allowed during PAEB testing. In response, NHTSA notes that the agency 
does not usually incorporate repeated trials in its vehicle compliance 
program. NHTSA's position has been to conduct a compliance test and, if 
an apparent noncompliance results, the agency should pursue the matter 
with the vehicle manufacturer without having to run a repeated trial. 
NHTSA's view is that the vehicle manufacturer is responsible for 
certifying the compliance of its vehicles and for ensuring the basis of 
its certification is sufficiently robust such that each vehicle will 
pass the test when tested by NHTSA. The agency acknowledges that for 
many years, NCAP testing (and other testing around the world) has 
encompassed repeated test trials to populate information about AEB in 
the consumer information program. NHTSA took the repeated trial 
approach in NCAP only because it was for a technology that was new or 
being developed. For more mature systems with a substantial record of 
real-world use, a single test run is preferable. A single test approach 
provides the agency the confidence that the performance it is 
regulating will perform as consistently as possible in the real world.
    Regarding the comments received relating to AEB perception,\139\ 
pedestrian detection, and classification, the MY 2023 vehicles tested 
for PAEB were generally able to avoid collision in all scenarios and at 
the majority of higher testing speeds. These vehicles are in production 
and on the road, demonstrating that solutions have been engineered to 
the PAEB perception in the real world. The engineering solutions have 
also accounted for no-contact testing performance. Also, Euro NCAP, 
while not a regulation, employs similar testing at similar speeds as 
the requirements in this final rule and many vehicles achieve a full 
score on Euro NCAP testing due to their collision avoidance 
capabilities. This performance further reinforces NHTSA's assessment 
that meeting the testing speeds of this final rule are practicable.
---------------------------------------------------------------------------

    \139\ The performance of each AEB system depends on the ability 
of the system to use sensor data to appropriately detect and 
classify forward objects. The AEB system uses this detection and 
classification to decide if a collision is imminent and then avoid 
or mitigate the potential crash. Manufacturers and suppliers of AEB 
systems have worked to address unnecessary AEB activations through 
techniques such as sensor fusion, which combines and filters 
information from multiple sensors, and advanced predictive models.
---------------------------------------------------------------------------

Evasive Steering (PAEB)
Comments
    For the small overlap (25% test conditions), Porsche stated the 
last point to steer is much closer to the pedestrian than the last 
point to brake and the proposed test speeds may increase the likelihood 
for emergency braking engagement that may often be perceived by the 
customer as a false activation in scenarios where the driver is aware 
of the pedestrian on the road and planning to steer around them. 
Porsche stated that this dilemma is similar to high speed AEB for lead 
vehicles, but occurs at lower speeds, as small overlap pedestrian 
scenarios are harder to detect and predict.
Agency Response
    In response, after considering the comments, and similar to its 
assessment of comments regarding lead vehicle evasive steering, the 
agency is not persuaded that evasive steering is an acceptable 
avoidance maneuver during testing. As thoroughly discussed previously, 
such factors as vehicle dynamics, traffic conditions and traffic 
participants all influence the safety benefit of a steering avoidance 
maneuver. A steering maneuver, as an avoidance maneuver, may not be as 
safe as a brake-in-lane maneuver, particularly in an urban environment. 
In any event, like for the lead vehicle situation, a manufacturer, 
outside of the testing requirements, may elect to detune or disengage 
the AEB system based on an emergency steering maneuver as long as the 
vehicle meets all the AEB requirements.
3. Pedestrian Test Device Speed
Comments
    AARP and ASC commented on the proposed pedestrian test device 
speeds. AARP suggested that NHTSA consider whether testing the adult 
pedestrian scenarios at a walking speed of 3.1 mph (5 km/h) is 
sufficient to improve safety for those who walk at slower speeds. ASC 
stated that IIHS, and UNECE Regulation No. 152 and No. 131, require a 
speed of less than or equal to 5 km/h, which is representative of a 
walking adult pedestrian.
Agency Response
    In response, NHTSA believes that the proposed crossing path test 
speed of 5 km/h (3.1 mph) for walking adult scenarios reasonably 
addresses the safety of adult pedestrians, including those who walk at 
slower speeds. Higher pedestrian test device walking speeds are more 
challenging for AEB systems. The longer a pedestrian is in the roadway, 
the more time a vehicle has to identify, classify, and avoid striking 
the pedestrian. NHTSA proposed that tests be performed at 5 km/h (3.1 
mph) and 8 km/h (5 mph), as these speeds are representative of able-
bodied adults walking and running. The agency expects that 
manufacturers will not turn pedestrian avoidance off at pedestrian 
speeds below those tested but will instead design systems that detect 
pedestrians moving at speeds lower than 5 km/h (3.1 mph) and avoid 
them. Further, the agency also included in the requirements testing 
with stationary pedestrian test devices, so that PAEB performs under 
three distinct pedestrian test mannequin speed scenarios (0 km/h, 5 km/
h and 8 km/h). Therefore, NHTSA declines to include additional tests 
with pedestrian surrogate speeds lower than 5 km/h (3.1 mph) based on 
the absence of a safety need to do so.
    In response to ASC, NHTSA notes that the 8 km/h (5 mph) test speed 
is used in the pedestrian crossing from the left scenario. It is 
representative of an able-bodied pedestrian running. This

[[Page 39750]]

performance test was proposed in the NPRM to ensure that pedestrian 
avoidance occurs in as wide a range of scenarios as is practicable. 
Data from NHTSA's testing of six model year 2023 vehicles showed that 
four of the six vehicles were able to meet the performance levels 
proposed in the NPRM. Based on the above, NHTSA concludes this test 
scenario is practical and appropriate for inclusion in the final rule. 
The agency also expects that if manufacturers can meet this performance 
for pedestrians crossing from the left at 8 km/h (5 mph), they can also 
avoid slower moving pedestrians, because in general the slower moving 
scenario poses a less demanding performance condition.
    After considering the comments, the final rule adopts the 5 km/h (3 
mph) speed for walking adult scenarios and the 8 km/h (5 mph) speed for 
running adult scenarios in crossing path PAEB tests, as proposed in the 
NPRM.
4. Overlap
    Bosch commented on NHTSA's use of the term ``overlap'' in the NPRM. 
Overlap is a term used to describe the location of the point on the 
front of the subject vehicle that would make contact with a pedestrian 
if no braking occurred. The NPRM defined overlap as the percentage of 
the subject vehicle's overall width that the pedestrian test mannequin 
traverses. It is measured from the right or the left, depending on the 
side of the subject vehicle where the pedestrian test mannequin 
originates.
    NHTSA proposed to use two overlaps for testing: a 25 percent 
overlap and a 50 percent overlap. The agency proposed the minimum 
overlap of 25 percent to allow for the test mannequin to fully be in 
the path of the subject vehicle. The agency also explained that the 
overlap determines the available time for the AEB system to detect and 
react when a collision with the test mannequin is imminent--a 50 
percent overlap allows for more time than a 25 percent overlap. As for 
tolerances, the NPRM proposed that for each test run, the actual 
overlap would have to be within 0.15 m of the specified overlap.
    Bosch did not object to the meaning of the term, the values 
proposed, or the tolerance provided for overlap, but suggested that 
NHTSA consider using the phrase ``percentage of the vehicle's width,'' 
rather than ``overlap.'' The commenter believed that the phrase 
accurately describes the lateral distance between the person in front 
of the vehicle and is terminology used by Euro NCAP. Bosch further 
stated that a similar approach by NHTSA would promote consistency and 
comparability in AEB performance evaluation across the industry.
    In response, NHTSA declines to change the term ``overlap.'' The 
agency believes that the term overlap used in the proposal, and 
``percent vehicle width'' used in Euro NCAP, are synonymous and not in 
conflict. Furthermore, the use of ``overlap'' is consistent with 
NHTSA's use of terms in its crashworthiness regulations, NHTSA's NCAP 
program, and NHTSA's practices in previous PAEB research. In addition, 
the definition of ``overlap'' in S8.1.2--the percentage of the subject 
vehicle's overall width--already includes the phrase put forth by 
Bosch.
5. Light Conditions
    This final rule adopts the proposed requirements in the NPRM to 
specify compliance testing of AEB systems in daylight and dark 
conditions. The conditions ensure performance in a wide range of 
ambient light conditions. For daylight testing, the ambient 
illumination at the test site is not less than 2,000 lux. This minimum 
level approximates a typical roadway light level on an overcast day. 
The acceptable range also includes any higher illumination level 
including levels associated with bright sunlight on a clear day. For 
PAEB testing in darkness, the ambient illumination at the test site 
must be no greater than 0.2 lux. This value approximates roadway 
lighting in dark conditions without direct overhead lighting with 
moonlight and low levels of indirect light from other sources, such as 
reflected light from buildings and signage.
Comments
    NHTSA received many comments to the proposed light conditions. 
Consumer advocacy groups and others generally support the proposed PAEB 
tests in daylight and darkness (with lower and upper beam) 
conditions.\140\ NSC and GHSA emphasize that 75 to 77 percent of 
pedestrian fatalities occur in darkness or after dark, regardless of 
whether artificial lighting was present. GHSA also states that 
disadvantaged communities are overrepresented in pedestrian fatalities. 
Consumer Reports is supportive of PAEB in dark conditions based on the 
overrepresentation of nighttime pedestrian crashes among the total.
---------------------------------------------------------------------------

    \140\ These commenters included NSC, NTSB, GHSA, Consumer 
Reports, Forensic Rock, the Lidar Coalition, ZF, and COMPAL.
---------------------------------------------------------------------------

    With respect to the use of headlamps during PAEB testing, Consumer 
Reports believes there does not appear to be a significant advantage of 
testing with the upper beams if the system already meets the 
requirements with the lower beams, and, that there is no guarantee that 
drivers will use the upper beams. In addition, Consumer Reports 
anticipates an increasing number of vehicles will be offered with 
adaptive driving beam (ABD) technology that can be used rather than 
lower beam and upper beams, and suggests that NHTSA's AEB tests test 
with ADB. Therefore, Consumer Reports suggests NHTSA replace the lower 
and upper beam language with language referring to the ``lowest level 
of active illumination,'' or similar, and require that the system pass 
the test at this level of lighting. Some equipment manufacturers 
expressed support for the proposed PAEB tests in daylight and darkness 
conditions, stating that infra-red sensors would increase safety for 
dark lighting conditions.
    The Lidar Coalition expressed strong support for the proposed 
testing of PAEB in low light conditions with no overhead lighting and 
only lower beams activated. The commenter states that NHTSA is 
correctly focusing on addressing the largest portion of pedestrian 
fatalities on U.S. roadways. The Lidar Coalition suggests that NHTSA 
prioritize testing in the darkest realistic conditions possible. The 
commenter states that the proposed test procedure in dark conditions 
will evaluate PAEB technologies in the real-world scenarios where the 
commenter believes these systems are most needed, when the human eye 
falls short. The Lidar Coalition states the Insurance Institute for 
Highway Safety found that in darkness conditions, camera and radar 
based PAEB systems fail in every instance to detect pedestrians. They 
additionally referenced the GHSA finding that in an evaluation of 
roadway fatalities in 2020, 75% of pedestrian fatalities occur at 
night.
    COMPAL supports a finding of a safety need for PAEB under dark 
condition and higher speeds (greater than 60 km/h (37.5 mph)), and 
believes that placing infrared sensors as a forward-looking sensor in 
PAEB testing can improve AEB functionality in challenging situations, 
such as testing for the crossing child obstructed scenario and the 
crossing adult running from the left. It states that infrared sensors 
should not be considered an emerging technology and that they work well 
in sun glare and darkness conditions and can detect a pedestrian much 
further than typical headlamps.
    Vehicle manufacturers and equipment manufacturers generally oppose 
the proposed PAEB dark test conditions with only low beams because of 
the

[[Page 39751]]

limited ability to illuminate pedestrians. The Alliance, Ford, Nissan, 
Toyota, Honda, MEMA, Mobileye and Adasky support the idea of allowing 
the use of the advanced lighting technology (such as ADB headlamps) if 
available on the model as standard equipment, or to incorporate the use 
of streetlights to simulate urban traffic conditions. The Alliance 
argues that allowing all dark lighting conditions to be tested with the 
advanced lighting features activated aligns with NHTSA's considerations 
for similar testing in the proposed NCAP upgrade and further promotes 
the adoption of these advanced lighting systems. Porsche states that 
the required nighttime PAEB performance requirements at the higher 
relative speeds is likely to exceed the technical capabilities of many 
current AEB system hardware. MEMA states that, in dark environments 
without streetlights, the lower beams would not be active because upper 
beams provide a better view, so this lower beam test is not depicting a 
real driving situation.
    Ford and Nissan also state that the lighting requirements in FMVSS 
No. 108 impact feasibility and practicability in testing certain low 
light PAEB tests. Similarly, Honda commented that the primary sensor 
for detecting pedestrian targets is the camera, which relies on optical 
information. Honda state this exceeds the recognition capability and 
reliability range of current camera systems and will lead to excessive 
false activations.
Agency Response
    After considering the comments, NHTSA has determined there is a 
safety need for the dark testing requirement, given the number of 
nighttime pedestrian fatalities and IIHS's finding that several AEB 
systems that performed well in daylight performed poorly in dark 
conditions. The agency has adopted the dark lighting requirements as 
proposed. However, as explained in the discussion below, NHTSA concurs 
that more time is needed to meet the dark lighting conditions. This 
final rule provides five years of lead time to do the additional 
engineering work needed to bring poorer performing AEB systems to a 
level where they can meet this final rule's requirements.
    Consumer Reports commented that testing with upper beam may be 
redundant if the system already meets the requirements with the lower 
beam. While this might be true for some systems, agency testing 
performed for the NPRM showed inconsistent performance while testing 
with the upper beam.\141\ In rare cases, vehicles performed better with 
lower beams illuminated than with upper beam. NHTSA is adopting an 
upper beam test to assure the functionality of the AEB system when the 
driver uses the upper beam.
---------------------------------------------------------------------------

    \141\ https://www.regulations.gov/docket/NHTSA-2023-0021/document (last accessed 12/8/2023).
---------------------------------------------------------------------------

    Forensic Rock, Lidar Coalition, COMPAL and ZF, appear to assert 
that all scenarios should be tested under dark and daylight condition, 
or that testing should be performed in the darkest realistic condition. 
NHTSA does not concur with that view, as the agency must consider, 
among other matters, the safety problem being addressed (to ensure the 
FMVSSs appropriately address a safety need), and the practicability and 
capabilities of the technology. NHTSA has assessed the tests and 
performance requirements adopted in this final rule to ensure each 
satisfies the requirements for FMVSS established in the Safety Act. 
Some tests did not pass NHTSA's assessment and were not proposed. To 
illustrate, the test results for the crossing scenarios at 25% overlap 
at night indicate meeting the test is impracticable at this time.\142\ 
Similarly, the obstructed child scenario depicts a situation that very 
rarely occurs at night (as noted by ZF as well), so NHTSA did not 
propose testing for such a scenario at night as not practical or 
reasonable.\143\
---------------------------------------------------------------------------

    \142\ https://www.regulations.gov/docket/NHTSA-2023-0021/document.
    \143\ Id.
---------------------------------------------------------------------------

    Many commenters believe that testing should be allowed with the 
adaptive driving beam (ADB) active. NHTSA disagrees. NHTSA does not 
require ADB, whereas the lower beam and upper beam are required by the 
FMVSSs on the vehicle. Further, even if an ADB system were installed on 
the vehicle, a driver may not use it. NHTSA does not believe it 
appropriate to tie the life-saving benefits associated with AEB to a 
technology (ADB) that a driver may or may not use on a trip.
    Additionally, ADB still employs the lower beam and upper beam, and 
merely switches automatically to the lower beam at times appropriate to 
do so. Thus, even if a driver has ADB operational, if the ADB reverts 
to a lower beam on a large portion of the beam area, in effect the 
operating conditions would be lower beam only, which, under the 
commenters' suggested approach, would not have been assessed with AEB. 
Testing PAEB with ADB on could, under the commenters' suggested testing 
conditions, essentially amount to the agency only testing the upper 
beam condition. Such an outcome would be undesirable from a safety 
standpoint, as most drivers rarely use their upper beams when operating 
vehicles at night. IIHS test data of 3,200 isolated vehicles (where 
other vehicles were at least 10 or more seconds away) showed that only 
18 percent had their upper beams on.\144\ At one unlit urban location, 
IIHS data showed that upper beam use was less than 1 percent. IIHS 
found that even on rural roads, drivers used their upper beams less 
than half of the time they should have for maximum safety, on average. 
Testing during daylight and dark with lower beam and upper beam 
provides confidence that in urban dark lighted environment, PAEB will 
perform even with only the lower beam operational.
---------------------------------------------------------------------------

    \144\ https://www.iihs.org/news/detail/few-drivers-use-their-high-beams-study-finds (last accessed 11/18/2023).
---------------------------------------------------------------------------

    NHTSA understands that lower beam testing scenarios may require 
better lowlight cameras and may require improved recognition algorithms 
for the lower performing AEB systems, which is why the agency is 
affording manufacturers additional time to engineer such systems up to 
FMVSS No. 127 performance. NHTSA's testing conducted for the NPRM 
indicated that the proposed PAEB dark scenarios represent ambitious, 
yet achievable performance criteria.\145\ The latest agency research, 
detailed in this notice, on six model year 2023 vehicles found that in 
the scenario where the pedestrian is approaching from the right, five 
of the six vehicles tested were able to meet the performance 
requirements for the upper beam lighting condition, and four of the six 
were able to meet the lower beam lighting condition. In the scenario 
where the pedestrian is stationary, all vehicles were able to meet the 
upper beam light condition, and three of the six vehicles were able to 
meet the lower beam testing condition. The final nighttime scenario, 
with the pedestrian moving along the vehicle's path, four vehicles met 
the performance requirements for the upper beam condition, and a single 
vehicle met the lower beam condition. The 2023 Toyota Corolla was able 
to avoid collision in two instances and had impact speeds of about 5 
km/h or less in the other three tests.
---------------------------------------------------------------------------

    \145\ https://www.regulations.gov/docket/NHTSA-2023-0021/document (last accessed 12/8/2023).
---------------------------------------------------------------------------

    These data indicate the practicability of meeting the PAEB tests 
proposed in the NPRM. Although not all manufacturers can currently 
certify to

[[Page 39752]]

all dark tests, AEB technologies are evolving rapidly, with significant 
improvements occurring even in the last year or two of NHTSA's AEB 
research program. NHTSA is providing five years for further development 
and integration of the technology into the new vehicle fleet. The 
agency adopts the upper and lower beam conditions as proposed in the 
NPRM without change, except for providing more lead time to meet the 
standard's requirements.
    As for Honda's concerns about the sensors that they use, i.e., 
cameras, NHTSA is aware of different sensor combinations capable of 
detecting pedestrian mannequins, as is evidenced by the higher 
performing vehicles identified during NHTSA testing. While Honda's 
current generation cameras may have recognition capability and 
reliability range challenges, other sensors and sensor combinations do 
not. NHTSA is not required to limit performance requirements to what 
one particular manufacturer using specific sensors is capable of doing 
at a given point in time. If Honda faces the challenges it describes, 
then software and possibly hardware updates may be necessary for Honda 
to meet the require performance.
6. Testing Setup
Pedestrian, Obstructed Running Child, Crossing Path From the Right
    In the test of an obstructed running child crossing from the right, 
an obstructed child pedestrian test device moves in the vehicle's 
travel path from the right of the travel path. The pedestrian surrogate 
crosses the subject vehicle's travel path from in front of two stopped 
vehicle test devices (VTDs). The VTDs are parked to the right of the 
subject vehicle's travel path, in the adjacent lane, at 1.0 m (3 ft) 
from the side of the subject vehicle. The VTDs are parked one after the 
other and are facing in the same direction as the subject vehicle. The 
subject vehicle must avoid collision with the child pedestrian 
surrogate without manual brake input.
Comments and Agency Responses
    Porsche, Volkswagen, FCA, and ASC commented on the proposed 
obstructed pedestrian scenario in PAEB performance tests. Porsche and 
Volkswagen stated that the distance between the pedestrian test dummy 
and the farthest obstructing vehicle is not specified in the proposed 
regulation (i.e., S8.3.3). The commenters believe this is critical to 
be defined because the level of obstruction of the child test dummy can 
only be defined by this distance. If multiple distances are required to 
reflect full and partial obstruction, then each specific test scenario 
should be defined.
    In response, NHTSA agrees with the commenters that the proposed 
testing setup should have, but did not, include the distance between a 
pedestrian test mannequin and the obstructing vehicle device positioned 
further from a subject vehicle. In this final rule, NHTSA adopts the 
following regulatory text language to clarify the test setup for the 
obstructed pedestrian crossing scenario: ``[t]he frontmost plane of the 
vehicle test device furthermost from the subject vehicle is located 1.0 
 0.1 m from the parallel contact plane (to the subject 
vehicle's frontmost plane) on the pedestrian test mannequin.''
    ASC stated that the vehicles obstructing the mannequin should be 
specified. The commenter believes that due to the large size of common 
vehicles sold in the US (e.g., pick-ups and sport utility vehicles), 
specific vehicle models or types should be defined for this test 
configuration.
    In response, the agency disagrees with ASC that NHTSA should 
specify models or types of the obstructing vehicles. The regulatory 
text specifies that two vehicle test devices are used as an obstruction 
in obstructed pedestrian crossing tests and the text also provides the 
dimensional specifications and other measurements of the vehicle test 
device. Therefore, the standard includes sufficient information 
specifying the obstructing vehicles to ensure repeatable and 
reproducible testing.
    FCA commented that the obstruction vehicles in the research testing 
were a Honda Accord and Toyota Highlander and every research test used 
this combination of real vehicles as obstructions, but that there was 
no data in the NPRM or the research about how these scenarios react or 
correlate to the vehicle test devices proposed for the FMVSS at 
S8.3.3(g). FCA expressed concern that this could lead to added 
practicability or other concerns for the associated test condition.
    In response, NHTSA highlights the additional testing performed. In 
this course of this testing, NHTSA evaluated using real vehicles, the 
4Active vehicle test device, and the ABD test device.\146\ The agency 
found no appreciable differences in performance between real vehicles 
and either vehicle test device. Thus, NHTSA believes that using the 
vehicle test device in the obstructed child crossing scenario is 
practicable and reasonable.
---------------------------------------------------------------------------

    \146\ ``NHTSA's 2023 Light Vehicle Automatic Emergency Braking 
Research Test Summary'' Available in the docket for this final rule 
(NHTSA-2023-0021).
---------------------------------------------------------------------------

    With respect to Bosch's suggestion that the maximum allowed travel 
path deviation needs to be specified as \1/8\th of the subject vehicle 
width and not the 0.3 m allowed in the proposal, the agency agrees in 
general that the tolerance for the expected point of contact should be 
from the subject vehicle and not the lane. Thus, in the proposal, the 
tolerance for the expected contact point was specified as the 
difference between the actual overlap and the specified overlap. This 
tolerance was specified and is finalized independent of the vehicle's 
position in the lane. The NPRM's proposed regulatory text stated: ``For 
each test run, the actual overlap will be within 0.15 m of the 
specified overlap.'' This is a tighter tolerance than Bosch suggested 
(\1/8\th of the average vehicle width is approx. 0.22 m). As such, the 
agency does not believe this will allow the situation Bosch proposed 
(where 25 percent overlap can be mistaken for a 50 percent overlap, and 
50 percent overlap can be mistaken for 25 percent overlap from the 
left) to occur.
    FCA suggested that NHTSA should consider using a standard road 
width and simply positioning the pedestrian mannequins across 
percentages of the lane, as this would be indicative of a position in 
the real world. FCA stated that NHTSA intended to position pedestrians 
according to ratios derived from the overall width of each vehicle, but 
that this set up can be overly complicated.
    NHTSA disagrees with FCA that applying mannequin positions--
described as percentages of the width of a standard test lane--would 
simplify test procedures. First, the agency is not aware of a standard 
test lane specification that is universally accepted for PAEB tests, 
and which can represent various types of roads in the real-world. Such 
roads would include lanes marked by two lines on highways, lanes marked 
by only one line in urban residential sections, and lanes without any 
marking in rural areas. Second, applying a same mannequin position 
within the test lane for all PAEB tests could cause unnecessary 
confusion because it might result in different overlap scenarios for 
different sizes of subject vehicles. For example, a pedestrian 
mannequin positioned at a certain percentage of the lane width may be 
appropriate for a 25 percent overlap test with a full-size pickup 
truck. However, such positioning may result in an invalid test with a 
small compact car--for example, a Fiat 500--since a mannequin at the 
same lateral

[[Page 39753]]

position within the test lane may not make a contact with such a small 
subject vehicle. Therefore, NHTSA declines to adopt a mannequin 
position that is defined by lane width and not percent overlap.

J. Procedures for Testing False Activation

    This section describes the false activation performance tests 
adopted by this final rule. These tests are sometimes referred to as 
``false-positive'' tests. After considering the comments to the NPRM, 
NHTSA has adopted the proposed procedures tests with little change. 
This section responds to the comments and explains NHTSA's reasons for 
adopting the provisions set forth in this final rule. For the 
convenience of readers, a list of the test specifications can be found 
in appendix C to this final rule preamble.
    This final rule adopts the two proposed false activation testing 
scenarios--the steel trench plate test and the vehicle pass-through 
scenario. Both tests are performed during daylight. Testing is 
performed with manual brake application and without manual brake 
application. The performance criterion is that the AEB system must not 
engage the brakes to create a peak deceleration of more than 0.25 g 
additional deceleration than any manual brake application would 
generate (if used).
Comments
    NHTSA received comments both supporting and opposing the proposed 
false activation tests. Commenters in favor of including the tests in 
FMVSS No. 127 include: Consumer Reports, Advocates, the Lidar 
Coalition, AAA, Bosch, Porsche, and CAS. Consumer Reports states that 
it is important to limit false activations to maximize safety and 
consumer acceptance. AAA supported the steel trench plate test, stating 
that it is important to ensure that increased system sensitivity does 
not occur at the expense of unnecessary braking. CAS suggested the 
addition of a third test involving a railroad crossing. The Lidar 
Coalition stated that false positive tests are important for evaluating 
both sensing modalities and perception systems, as well as the 
interplay between both pieces of an effective AEB and PAEB system.
    NHTSA also received comments opposing inclusion of one or both of 
the tests. Volkswagen recommended eliminating the proposed false 
activation tests from the rule, believing the tests have no comparable 
real-world relevance. Luminar expressed similar concern about real-
world similarity.
Agency Response
    After considering the comments, NHTSA has decided to maintain the 
false positive testing scenarios for AEB proposed in the NPRM. The 
proposed false activation tests establish only a baseline for system 
functionality and are by no means comprehensive, nor sufficient to 
eliminate susceptibility to false activations. However, the tests are a 
means to establish at least a minimum threshold of performance in the 
standard.
    NHTSA expects that vehicle manufacturers will design AEB systems to 
thoroughly address the potential for false activations.\147\ Previous 
implementations of other technologies have shown that manufacturers 
have a strong incentive to mitigate false positives. Vehicles that have 
excessive false positive activations may pose an unreasonable risk to 
safety and may be considered to have a safety-related defect. NHTSA 
understands from industry comments to this rulemaking and others that 
industry generally designs their systems to minimize false 
activations.\148\
---------------------------------------------------------------------------

    \147\ 88 FR 38632 at 38696.
    \148\ In response to a 2022 NCAP Request for Comment, the 
Alliance stated in their comments to the 2022 NCAP notice where 
NHTSA requested comment on the inclusion of false positive tests in 
NCAP 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, in response to the same 2022 NCAP notice, Honda stated 
that vehicle manufacturers must already account for false positives 
when considering marketability and HMI. These comments are available 
in this docket https://www.regulations.gov/document/NHTSA-2023-0020-0001.
---------------------------------------------------------------------------

    Nonetheless, NHTSA is including the false activation tests in this 
final rule because NHTSA has seen evidence of false activations in 
those scenarios and because NHTSA expects that the scenario might be 
particularly challenging for AEB systems. Thus, the agency does not 
agree to remove or add additional test scenarios or conditions to the 
test scenarios at this time. NHTSA is including the tests in FMVSS No. 
127 to establish a reasonable minimum when it comes to false activation 
assessment and mitigation; the agency may add to the tests in the 
future if the need arises.
    CR commented that a 0.25g deceleration threshold is too high, 
stating that a ``0.25g braking event is noticeable by passengers and 
could confuse or distract the driver.'' In response, the requirement is 
for peak additional deceleration, not for average deceleration. In 
other words, the deceleration that Consumer Reports is describing would 
likely not meet the requirement. Consumer Reports is referring to a 
brief, not sustained, brake pulse, which would be noticeable. The 0.25g 
peak deceleration threshold was chosen as an obvious indication of 
external braking that is easily measurable by testing equipment.
    Bosch supported the proposed steel trench plate properties for the 
steel trench plate test but suggested that the orientation of the plate 
be accurately aligned within a tolerance, e.g., aligning the leading 
edge of the plate 90 degrees plus or minus 0.5 degrees to the 
centerline of the test vehicle.
    In response, NHTSA does not agree with Bosch that a tolerance is 
appropriate for positioning of the steel plate, particularly such a low 
tolerance as 0.5 degrees. The steel plate false activation test is an 
established test which has been performed without a specific tolerance 
for the alignment of the steel plate for an extended period without any 
indication that the lack of a tolerance influences the outcome of the 
tests. Further, Bosch has not provided any data in support of their 
suggestion, and NHTSA does not have any data suggesting that any slight 
misalignment of the steel plate influences the results.
    Porsche stated that they support the false positive tests with some 
suggested improvements. Porsche stated that they suggest modifying the 
pass-through test lateral distance gap in S9.3.1(b) to be in relation 
to the exterior of the vehicle body instead of the front wheels. 
Porsche also suggested adding a test matrix table to section S8.1. 
Volkswagen suggested that NHTSA better define the test scenarios, such 
as with regard to the exterior dimensions of the stationary vehicles in 
the pass-through gap test and whether there is a manual brake 
application in either test.
    In response, while Porsche states that the gap between the vehicles 
should be measured based on the exterior of the vehicles, not the 
wheels, the commenter did not provide any data or reasoning for the 
suggestion. Volkswagen suggests that more detail should be given on the 
exterior dimensions of the stationary vehicles but also did not provide 
any supporting data or reasoning. NHTSA had evaluated these 
requirements when developing the NPRM and found them to be sufficient. 
Accordingly, the agency is not revising how the space between the 
vehicles is measured and how we specify the dimensions of the two 
stationary vehicles.
    Porsche and Volkswagens both state it is unclear whether testing is 
to be done with and without manual brake application. In response, 
NHTSA notes

[[Page 39754]]

that in the NPRM, NHTSA specifically states that it would test vehicles 
with and without manual application. While the agency does not believe 
a table is needed specifying the key parameters when testing for lead 
vehicle and PAEB, NHTSA agrees that the proposed regulatory text was 
not clear on this topic. Thus, the agency has revised the regulatory 
text for the steel plate and for the pass-through test to be clear that 
testing is conducted with manual brake application and without manual 
brake application.

K. Track Testing Conditions

1. Environmental Test Conditions
Lighting Conditions
    Under this final rule, NHTSA will test AEB systems in daylight for 
lead vehicle AEB and PAEB testing, as well as in darkness for PAEB 
testing. The light conditions ensure performance in a wide range of 
ambient light conditions. For all daylight testing, the ambient 
illumination at the test site is not less than 2,000 lux, which 
approximates the minimum light level on a typical roadway on an 
overcast day. To better ensure test repeatability, testing may not be 
performed while the intended travel path is such that the heading angle 
of the vehicle is less than 25 degrees with respect to the sun and 
while the solar elevation angle is less than 15 degrees. The intensity 
of low-angle sunlight can create sensor anomalies that may lead to 
unrepeatable test results.
    For PAEB darkness testing, the ambient illumination at the test 
site must be no greater than 0.2 lux. This value approximates roadway 
lighting in dark conditions without direct overhead lighting with 
moonlight and low levels of indirect light from other sources. This 
darkness level accounts for the effect ambient light has on AEB 
performance, particularly for camera-based systems. It ensures robust 
performance of all AEB systems, regardless of what types of sensors are 
used.
Comments
    NHTSA received several comments on the lighting conditions,\149\ 
particularly the proposed ambient illumination requirement (i.e., any 
level at or below 0.2 lux) for darkness PAEB testing.
---------------------------------------------------------------------------

    \149\ These commenters included HATCI, MEMA, Bosch, Mitsubishi, 
and AAA.
---------------------------------------------------------------------------

    HATCI and others believe that NHTSA should use nighttime lighting 
conditions for PAEB testing that are more characteristic of urban 
environments. HATCI states that NHTSA would use the same specification 
for lower and upper beams, 0.2 lux, but that an ambient environment of 
0.2 lux is extremely dark and is unlikely to be representative of real-
world conditions in an urban area. HATCI stated that since 82% of the 
pedestrian fatalities occur in urban areas, these environmental 
conditions should be reflected in the test procedures. HATCI suggests 
that the agency should include overhead lights as it is more 
representative of the urban environment. The commenters state that 
additional lighting, including streetlights, would align lighting 
conditions with Euro NCAP. In contrast, AAA believes NHTSA should 
refrain from allowing testing under artificially bright overhead 
lighting for PAEB system performance requirements in darkness 
conditions.
Agency Response
    After considering the comments submitted about the lighting 
conditions, NHTSA has decided to adopt the proposed lighting conditions 
for several reasons. First, the agency is finalizing the proposed 
lighting conditions because they present the most challenging, but 
practicable, lighting conditions for PAEB systems. Because they will be 
able to meet the most challenging condition, PAEB will be able to 
perform well in situations with more light, like roads that have 
streetlights. Although NHTSA agrees with commenters that 0.2 lux may 
not be representative of urban scenarios at night, the agency disagrees 
with HATCI, MEMA, Bosch, and Mitsubishi that testing should be 
conducted with lighting conditions that mimic urban areas. Testing in 
dark conditions, below 0.2 lux, represents the worst lighting case, 
where pedestrians are most at risk.\150\
---------------------------------------------------------------------------

    \150\ For the proposed PAEB testing in darkness, the ambient 
illumination at the test site must be no greater than 0.2 lux. This 
value approximates roadway lighting in dark conditions without 
direct overhead lighting with moonlight and low levels of indirect 
light from other sources, such as reflected light from buildings and 
signage.
---------------------------------------------------------------------------

    Second, testing during daylight and dark with lower beams and upper 
beams provides confidence that in urban dark lighted environments, PAEB 
will perform even if the agency does not test under such a condition
    In addition, the agency conducted confirmatory testing that 
indicates that the proposed lighting conditions represented ambitious, 
yet achievable conditions. The agency conducted additional research on 
the performance of the AEB systems of six model year 2023 vehicles when 
approaching a pedestrian. The darkness testing occurred with less than 
0.2 lux of ambient lighting. In the scenario where the pedestrian is 
approaching from the right, five of the six vehicles tested were able 
to meet the performance requirements for the upper beam lighting 
condition, and four of the six were able to meet the lower beam 
lighting condition. In the scenario where the pedestrian is stationary, 
all vehicles were able to meet the upper beam light condition, and 
three of the six vehicles were able to meet the lower beam testing 
condition. The final nighttime scenario, with the pedestrian moving 
along the vehicle's path, four vehicles met the performance 
requirements for the upper beam condition, and a single vehicle met the 
lower beam condition. NHTSA believes that this data show that testing 
with the ambient light below 0.2 lux is practicable. For the above 
reasons, NHTSA believes the lighting conditions adopted by this final 
rule best ensure that PAEB systems work in all environments where 
pedestrians are at the highest safety risk.
    As for the proposed PAEB daylight testing conditions, several 
sensor suppliers suggested that the agency should reconsider the 
sunlight glare avoidance requirement (i.e., not driving toward or away 
from the sun--less than 25 degrees in vertical and 15 degrees in 
horizontal directions). Adasky and the Lidar Coalition stated that the 
NHTSA should include additional real world environmental conditions, 
such as direct sunlight.
    In response, the agency agrees with Luminar that there is a safety 
issue on the road when drivers operate in direct sunlight. However, the 
agency does not have enough test data to assess the statements from 
manufacturers of lidar systems (Adasky, Luminar, The Lidar Coalition) 
on the efficacy of LIDAR systems and potential sensor saturation by 
testing in direct sunlight. Additionally, NHTSA believes that, if 
research is warranted to assess the accuracy of the companies' 
assertions, that would delay this rulemaking. Thus, NHTSA declines to 
change the final rule as requested.
Ambient Temperature
    This final rule adopts the proposed specification that the ambient 
temperature in the test area be between 0 Celsius (32 [deg]F) and 40 
Celsius (104 [deg]F) during AEB testing. This ambient temperature range 
matches the range specified in NHTSA's safety standard for brake system 
performance and is representative of the wide range of conditions that 
AEB-equipped vehicles encounter. As explained in the NPRM,

[[Page 39755]]

while AEB controls and sensors can operate at lower temperatures, the 
limiting factor here is the braking performance.
Comments
    FCA commented that, given the only proposed outcome is ``no 
contact'' and passing results in the research data are often less than 
one meter, brake stopping performance and variation become crucial. FCA 
stated that because of this, testing at temperature becomes a primary 
concern. FCA suggested that if NHTSA believes braking performance at 
hot temperatures is the worst case, it should make that explanatory 
statement. However, if NHTSA believes braking is worst case at cold 
temperatures, it should assess AEB performance at the freezing point 
minimum temperature. Otherwise, it should limit the regulatory testing 
to a much more modest range to accommodate the existing data.
Agency Response
    In response, NHTSA notes that FCA did not provide the testing range 
that it believes would be acceptable, or explain its concern about 
aspects of the proposed range. NHTSA believes that braking performance 
would be relatively unaffected by outside temperature because the 
procedures specify that there will be an initial braking temperature 
which ensures that the brakes are warm when tested, and has specified a 
burnishing procedure to ensure that the brakes perform consistently. 
The final rule specifies a testing range consistent with the ranges 
included in the existing braking standards applying to the vehicles 
subject to FMVSS No. 127. Those testing temperatures have worked well 
in those braking standards, and NHTSA is unaware of information 
indicating they would be unacceptable for this rule. Accordingly, NHTSA 
adopts the ambient temperature range proposed in the NPRM without 
change.
Wind Conditions
    This final rule adopts the proposed specification that the maximum 
wind speed during AEB compliance testing be no greater than 10 m/s (22 
mph) for lead vehicle avoidance tests and 6.7 m/s (15 mph) for 
pedestrian avoidance tests. Excessive wind during testing could disturb 
the test devices in various ways. For example, high wind speeds could 
affect the ability of the VTD to maintain consistent speed and/or 
lateral position, or could while cause the pedestrian mannequin to bend 
or sway unpredictably.
Comments
    Bosch and Zoox are concerned with testing up to the proposed 
maximum wind speed. Bosch states that the testing equipment is not able 
to consistently maintain stability in windy conditions. Bosch and MEMA 
suggest using language similar to UNECE R152 which specifies testing 
only when there is no wind present that is liable to affect the 
results. Zoox suggests reducing the maximum test wind speed from 10 m/s 
to 5 m/s for all AEB testing.
Agency Response
    NHTSA declines to adopt the suggested changes. The wind speeds 
included in the proposal and adopted in this final rule have long been 
used by the agency in AEB testing and testing of other systems in the 
FMVSS. As stated in the NPRM, these are the same maximum wind speeds 
specified for AEB tests in the agency's AEB NCAP test procedures and 
PAEB draft research test procedure without problems. The wind speed 
specified for lead vehicle avoidance tests is also in line with the 
maximum wind speed specified for passenger vehicles in FMVSS No. 126, 
``Electronic stability control systems for light vehicles.'' The 
specification has been workable for many years.
    Commenters did not explain the basis for characterizing the 
proposed wind speeds as windy conditions, or what winds could affect 
test results. They provided no information showing that the proposed 
wind speeds would affect braking performance and test equipment 
stability. NHTSA believes that the UNECE R152 approach would not be 
helpful, as it is open-ended about wind speeds. It would not provide 
manufacturers with notice of the wind speeds under which the agency 
would test. NHTSA believes its approach of specifying the specific 
range of wind speeds, as opposed to leaving it open ended and undefined 
like UNECE R152, provides notice about the test conditions under which 
compliance testing would be conducted and more assurance about what 
NHTSA considers a valid test. The agency therefore adopts the 
provisions for wind speed without change.
Precipitation
    NHTSA adopts the proposed specification that NHTSA will not conduct 
AEB compliance tests during periods of precipitation, including rain, 
snow, sleet, or hail. The presence of precipitation could influence the 
outcome of the tests because wet, icy, or snow-covered pavement has 
lower friction. Conducting a test under those conditions also poses 
risks to lab personnel. Additionally, the presence of precipitation 
like rain, snow, sleet, or hail, makes it much more difficult to 
reproduce a friction level with good precision. That is, even if NHTSA 
were able to run a particular test on a pavement with precipitation, 
replicating the same test conditions may not be possible.
Comments
    Consumer Reports stated that the variation of AEB performance in 
different conditions is why this additional testing is needed. It noted 
that in its experience evaluating vehicles' wet-road braking 
performance, it is feasible to establish objective test procedures for 
conditions in which the ground is wet.
Agency Response
    In response, NHTSA does not have the information necessary to 
demonstrate that such testing would be possible for compliance testing. 
NHTSA is encouraged that Consumer Reports conducts wet pavement testing 
because such testing can add to the agency's knowledge in this area. 
NHTSA encourages Consumer Reports to share more detailed information 
about its wet-road braking to possibly provide a foundation for future 
NHTSA research.
Visibility
    This final rule adopts the proposed specification that AEB 
performance tests will be conducted when visibility at the test site is 
unaffected by fog, smoke, ash, or airborne particulate matter. Reduced 
visibility in the presence of fog or other particulate matter is 
difficult to reproduce in a manner that produces repeatable test 
results. While NHTSA considered a minimum visibility range during the 
development of the proposal, the agency proposed a limitation on the 
presence of conditions that would obstruct visibility during AEB 
testing. NHTSA sought comment on whether to adopt a minimum visibility 
range.
Comments
    ASC, ZF, and MEMA supported the proposed visibility conditions for 
AEB testing. ASC, MEMA and ZF stated that defining minimum visibility 
ranges would be challenging due to current sensor performance and 
creating repeatable test conditions.
    Other commentators requested a minimum visibility requirement and 
gave suggestions on how to create a minimum visibility definition. The 
Alliance stated that this should be objectively defined. Mobileye 
suggests that a minimum level of visibility could

[[Page 39756]]

be defined as the visibility that allows a human driver to see the 
target within 5 seconds time to collision. Bosch and FCA states that 
NHTSA should establish a precise and comprehensive definition for 
``visibility'' (e.g., that visibility will be greater than 1 km, 0.5 
km, etc.). Bosch and Volkswagen state that the test must ensure that 
the horizontal visibility range will allow the target to be clearly 
observed throughout the test. Aptiv and Consumer Reports recommend 
adding additional testing to account for real-world conditions such as 
sun glare, rain, fog and smoke.
Agency Response
    NHTSA adopts the provisions proposed in the NPRM without change, 
for the reasons provided in the proposal. The agency agrees with 
commenters that there may be merits to having an objective way to 
measure visibility, but defining a minimum visibility range that is 
objective is challenging, as noted by ASC, ZF, and MEMA. Bosch 
suggested requiring visibility be measured as greater than ``X'' 
kilometers, similar to NCAP programs,\151\ and Mobileye suggested an 
approach.
---------------------------------------------------------------------------

    \151\ Euro NCAP specifies visibility of at least 1 km (0.62 
miles) and NHTSA's NCAP specifies 5 km (3.1 miles).
---------------------------------------------------------------------------

    NHTSA will further consider the pros and cons of these and other 
approaches and determine whether to consider them in a future 
rulemaking. For now, it does not appear that the commenters' requested 
changes to the visibility metric proposed in the NPRM present a better 
measurement than the limitation on the presence of conditions that 
would obstruct visibility. Therefore, NHTSA will adopt the provisions 
described in the NPRM.
2. Road/Test Track Conditions
Surface
    This final rule adopts the proposed specification that NHTSA will 
test on a dry, uniform, solid-paved surface with a peak friction 
coefficient (PFC) of 1.02 when measured using an ASTM F2493 standard 
reference test tire, in accordance with ASTM E1337-19 at a speed of 
64.4 km/h (40 mph), without water delivery.\152\ Surface friction is a 
critical factor in testing systems that rely heavily on brake system 
performance testing, such as AEB. 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.
---------------------------------------------------------------------------

    \152\ ASTM E1337-19, Standard Test Method for Determining 
Longitudinal Peak Braking Coefficient (PBC) of Paved Surfaces Using 
Standard Reference Test Tire.
---------------------------------------------------------------------------

Comments
    MEMA supports the test track surface having a peak friction 
coefficient of 1.02. AAA recommended, based on previous testing, that 
there should be some tolerance allowed in terms of peak friction 
coefficient to allow for a greater number of closed-course facilities 
to be suitable for confirmation testing. FCA asked for clarification, 
as they see a maximum Roadway Friction Coefficient (RFC) but no mention 
of any minimum RFC. In addition, FCA suggested adopting a similar 
calculation for over speed/under speed tests within FMVSS No. 127 as in 
FMVSS No. 135. The Alliance commented that NHTSA should define the 
tolerance for the required test track surface with maximum and minimum 
friction coefficients. It stated that such a tolerance would ensure 
fairness when conducting tests across different test facilities, reduce 
the cost/burden associated with maintaining a test surface having a 
specific PFC, particularly since this value can change over time, and 
is consistent with NCAP's Crash Avoidance test procedures.
Agency Response
    NHTSA first addressed this issue in the final rule upgrading the 
motorcycle brake system standard published in 2012.\153\ NHTSA stated 
that, by specifying a single PFC, the intent is not to specify testing 
only on surfaces with that PFC. Rather, the intent is to set a target 
PFC that acts as a reference point. Manufacturers who choose to conduct 
on-track testing to certify their vehicles can use test surfaces with 
any PFC below the specified level to ensure compliance at the specified 
level. On the other hand, NHTSA, and laboratories conducting compliance 
tests, would use surfaces having a PFC at or above the target PFC to 
allow a reasonable margin for friction variations and other test 
surface variables.
---------------------------------------------------------------------------

    \153\ 77 FR 51650 (Aug. 24, 2012).
---------------------------------------------------------------------------

    This approach of specifying PFC without tolerance is consistent 
with how surface peak friction coefficients are specified in FMVSS No. 
121, ``Air Brake Systems,'' FMVSS No. 135, ``Light Vehicle Brake 
Systems,'' and in FMVSS No. 126, ``Electronic Stability Control 
Systems. FMVSS No. 126 mandates Electronic Stability Control (ESC) 
systems on light vehicles, and establishes test procedures to ensure 
that ESC systems meet minimum requirements. In the rulemaking that 
established FMVSS No. 126, NHTSA originally proposed a tolerance around 
the surface PFC specification, but ultimately specified a single PFC 
for the test surface in the final rule. The agency explained that, 
although the proposed tolerance was an attempt to increase objectivity, 
such a tolerance created the possibility of compliance tests for FMVSS 
No. 126 being performed on lower friction coefficient surfaces than 
those for other braking standards, which is not the intention. NHTSA 
explained that while it is unlikely that any facility has a surface 
with exactly that friction coefficient, compliance testing for other 
braking standards is performed on a surface with a PFC slightly higher 
than the specification, which has more adhesion and creates a margin 
for clear enforcement. Here, as in the ESC final rule, NHTSA will use 
consistent compliance test conventions across all FMVSSs when 
specifying surface PFC.
Slope
    This final rule adopts the proposed specification that NHTSA's test 
surface will have a consistent slope between 0 and 1 percent. The slope 
of the road surface can affect the performance of an AEB-equipped 
vehicle.\154\ The slope also influences the dynamics and layout 
involved in the AEB test scenarios.
---------------------------------------------------------------------------

    \154\ Kim, H. et al., Autonomous Emergency Braking Considering 
Road Slope and Friction Coefficient, International Journal of 
Automotive Technology, 19, 1013-1022 (2018).
---------------------------------------------------------------------------

Comments
    MEMA and Bosch commented, suggesting language from FMVSS No. 135 
stating that the test surface has no more than a 1% gradient in the 
direction of testing and no more than a 2% gradient perpendicular to 
the direction of testing.
Agency Response
    In response, NHTSA has not made the requested change. The agency's 
proposed specification did not specify that this is consistent in only 
the direction of travel. The agency might test on a surface that is not 
necessarily a defined lane, so, much like with ESC testing, the surface 
could be 1% in the direction of travel or normal to the direction of 
travel.
    NHTSA provides the public with information on how the agency will 
conduct compliance tests, but manufacturers are not required to certify 
their vehicles using the tests in the FMVSS. Testing on a surface that 
is less flat could be more stringent, and manufacturers are free to 
test on a more stringent surface than what the agency

[[Page 39757]]

uses.\155\ Therefore, the agency does not see a need for the suggested 
change.
---------------------------------------------------------------------------

    \155\ The manufacturer must exercise due care in making its 
certification. While manufacturers are not required to follow the 
tests in the FMVSSs, manufacturers seek to ensure that their 
vehicles will meet the FMVSS when NHTSA tests them according to the 
test procedures in the FMVSSs.
---------------------------------------------------------------------------

Markings
    This final rule adopts the proposed specification that, in NHTSA's 
tests, within 2 m of the intended travel path, the road surface can be 
unmarked, or marked with one, or two lines of any configuration or 
color, at NHTSA's option. If lines are used, they must be straight, 
and, in the case of two lines, they must be parallel to each other and 
the distance between them must be from 2.7 m to 4.5 m. Vehicles 
equipped with AEB often are equipped with other advanced driver 
assistance systems, such as lane-centering technology, which detects 
lane lines. Those systems may be triggered by the presence of road 
markings, potentially leading to unrepeatable results.
Comments
    In its comment, Bosch recommended including surface conditions such 
as grade lane markings, surrounding clearance areas, and acceptable 
target object specifications to enhance the accuracy and reliability of 
the testing process in each scenario. Zoox recommended specific 
markings for the regulation. It suggests text stating: ``The road 
surface within 2 m of the intended travel path is marked with two solid 
lines (yellow on the left, white on the right) that are straight, 
parallel to each other, and at any distance from 2.7 m to 4.5m.'' Zoox 
believes that, in the scenarios prescribed and with the variety of 
permissible lane markings, an ADS may drive around the obstruction 
instead of stopping in lane. It recommends specifying lane markings 
consistent with the Manual on Uniform Traffic Control Devices (MUTCD).
Agency Response
    NHTSA disagrees with the recommendation by Bosch and Zoox to change 
the lane marking specifications for the compliance test. Fully marking 
the lane would simulate a vehicle traveling on new, well-marked 
roadways, which reduces the representativeness of test of the real-
world. Lane markings across the country vary in terms of existence, 
quality, and placement. Many rural roads have little to no lane 
markings, older roads may have degraded or missing lane markings, and 
even new roadways may have lane markings that are not yet present. The 
provision that states that NHTSA has flexibility in how the lanes are 
marked puts manufacturers on notice that they must consider all roadway 
types when designing their AEB system, not just road with newly marked 
lines. The most commonly encountered lane marking colors are white and 
yellow; however, there are areas where vehicles may encounter other 
colors. The MUTCD states that markings are to be yellow, white, red, 
blue, or purple. Less common situations include E-ZPass lanes that are 
marked with purple/white lane markings. In general NHTSA does not 
believe that lane markings/colors have a technical effect on AEB 
performance, however specifying that lane lines used may be any color 
ensures that AEB performance will not vary based on lane marking color 
faded color.
    NHTSA believes it is important to the real-world efficacy of AEB 
systems that AEB be designed to consider a wide variety of lane 
markings that it is reasonable to assume the systems may encounter in 
the real world. NHTSA is concerned that reducing the types of lane 
markings they need to consider would work against NHTSA's goals of 
ensuring the robustness of AEB systems and the safety benefits AEB can 
attain. Therefore, the agency will adopt the provisions described in 
the NPRM without change.
Subject Vehicle Conditions
    This final rule adopts the proposed specification about the subject 
vehicle conditions during testing relating to the following topics: AEB 
initialization, tires, subject vehicle brakes, fluids and propulsion 
battery charge, user adjustable settings, headlamps and subject vehicle 
loading. Where the agency received no comments a particular topic, it 
is not discussed below. All proposals are adopted for the reasons 
discussed in the NPRM.
AEB System State and Initialization
    In the NPRM, NHTSA proposed that testing not be conducted if the 
AEB malfunction telltale is illuminated or any of the sensors used by 
the AEB systems are obstructed. NHTSA proposed that AEB systems would 
be initialized before each series of performance tests to ensure the 
AEB system is in a ready state for each test trial. This is because the 
electronic components of an AEB system, including sensors and 
processing modules, may require a brief interval following each 
starting system cycle to reset to their default operating state. It 
also may be necessary for an AEB-equipped vehicle to be driven at a 
minimum speed for a period of time prior to testing so that the 
electronic systems can self-calibrate to a default or baseline 
condition, and/or for the AEB system to become active.
    The proposed initialization procedure specifies that, once the test 
vehicle starting system is cycled on, it will remain on for at least 
one minute and the vehicle is driven at a forward speed of at least 10 
km/h (6 mph) before any performance trials commence. This procedure 
also ensures that no additional driver actions are needed for the AEB 
system to be in a fully active state.
    In its comment, Porsche suggested that vehicles should be brought 
to operating temperature before testing is begun. NHTSA disagrees with 
this suggestion for several reasons. First, it is NHTSA's position that 
the AEB system should be functional regardless of the vehicle's 
operating temperature because to choose otherwise could lead to 
unnecessary and concerning real-world limitations. The agency believes 
that specifying that the vehicle will be started and running for at 
least one minute prior to test initiation is more than sufficient for 
the manufacturer to have a functional AEB system. In the real world, 
vehicles often travel at the speeds proposed shortly after the driver 
powers the vehicle on. NHTSA requires brakes, lights, and 
crashworthiness devices, like seat belts and air bags, to work when the 
vehicle is turned on. In the same manner, the vehicle must meet FMVSS 
No. 127 when turned on. NHTSA is providing a brief initiation state for 
the AEB system to reset to a default operating state, but extending 
that state to the period suggested by Porsche would be contrary to the 
need for safety.
    NHTSA believes the one-minute initiation period is generous in the 
context of the FMVSSs. There is a risk that drivers will not wait a 
minute to start driving. These drivers likely expect all vehicle 
system, especially safety systems, to be ready to operate once the 
vehicle is turned on. Porsche did not provide sufficient justification 
for its suggestion to extend that time. Based on these the above 
factors, NHTSA is not accepting Porsche's suggestion.
    MEMA, Volkswagen, Porsche, and Bosch commented that the agency 
should adopt the pre-test conditioning process from UNECE Regulation 
No. 152 where, if requested by the manufacturer, the vehicle can be 
driven a maximum of 100 km (62.1 miles) to initialize the sensor 
system.
    NHTSA also disagrees with this suggestion for the reasons discussed 
in the previous paragraph. This suggestion

[[Page 39758]]

presents issues similar to those flagged in the previous paragraph, 
namely that the system should be available and functioning as soon as 
possible after vehicle start up and that a failure to do that could be 
very confusing to drivers and result in a failure to provide the safety 
benefits it should. For the reasons explained in this section, this 
final rule adopts the provisions proposed in the NPRM without change.
Brake Burnishing
    To maximize test repeatability, this final rule adopts the proposed 
specification that subject vehicle brakes be burnished prior to AEB 
performance testing according to the specifications of either S7.1 of 
FMVSS No. 135, Light vehicle brake systems, which applies to passenger 
vehicles with GVWR of 3,500 kilograms or less, or to the specifications 
of S7.4 of FMVSS No. 105, which applies to passenger vehicles with GVWR 
greater than 3,500 kilograms. Since AEB capability relies upon the 
function of the service brakes on a vehicle, it is reasonable and 
logical that the same pre-test conditioning procedures that apply to 
service brake performance evaluations should also apply to AEB system 
performance evaluations.
Comments
    In comments, MEMA, Volkswagen, Porsche, and Bosch suggest that the 
agency adopt the pre-test conditioning process from UNECE Regulation 
No. 152 in that the vehicle can undergo a series of brake activations 
to burnish the brake system.
Agency Response
    In response, NHTSA agrees with commenters that properly burnishing 
the brake system is important, but NHTSA does not believe that it must 
adopt this aspect of UNECE Regulation No. 152 to accomplish that. NHTSA 
believes that the proposed brake burnishing procedures that are 
consistent with both FMVSS No. 135 and FMVSS No. 105 properly burnish 
the brake system, depending on the test vehicle's GVWR. Additionally, 
commenters did not provide NHTSA with any evidence that the brake 
burnishing procedures the agency proposed are improper for burnishing 
brakes or are otherwise unacceptable for any reason. NHTSA is not 
adopting the changes and will adopt the provisions proposed in the NPRM 
without change.
Brake Temperature
    This final rule adopts the proposed specification that the subject 
vehicle service brakes be maintained at an average temperature between 
65[deg] C (149 [deg]F) and 100[deg] C (212 [deg]F) measured as an 
average of the brakes on the hottest axle. This temperature range, 
which is the same as the range specified in FMVSS No. 135, is important 
for consistent brake performance and test repeatability.
Comments
    In comments, MEMA, Volkswagen, Porsche, and Bosch suggest that 
NHTSA adopt the pre-test conditioning process from UNECE Regulation No. 
152, specifically, that the average temperature of the service brakes 
on the hottest axle should be between 65-100 degrees C prior to each 
test run. Zoox also recommends that the hottest axle on the service 
brakes should be between 65-100 degrees C prior to testing, and that 
the agency should use FMVSS No. 135 as a guide for warming the vehicle 
brakes.
Agency Response
    In response, NHTSA points out that the commenters refer to initial 
brake temperatures tested according to the procedure in FMVSS No. 135, 
and appear to be supporting NHTSA's proposed provisions notwithstanding 
reference to UNECE Regulation No. 152. The procedure in FMVSS No. 135 
more rigorously specifies how and where temperature is measured than 
the equivalent in UNECE Regulation No. 152. NHTSA concurs and is 
adopting the provisions as proposed in the NPRM
User Adjustable Settings
    This final rule adopts the proposed specification that NHTSA may 
test user adjustable settings such as engine braking, regenerative 
braking, and those associated with FCW, at any available setting state. 
Furthermore, adaptive and traditional cruise control may be used in any 
selectable setting during testing. The agency may test vehicles with 
any cruise control or adaptive cruise control setting to make sure that 
these systems do not disrupt the ability of the AEB system to stop the 
vehicle in crash imminent situations. However, for vehicles that have 
an ESC off switch, NHTSA will keep ESC engaged for the duration of the 
test.
Comments
    In its comments, HATCI stated that NHTSA should test the vehicles 
using the default settings to represent real-world driving conditions 
because HATCI's research indicates that consumers do not typically 
change the settings. Bosch commented that the regenerative brakes add 
too much variability to the vehicle performance. Therefore, Bosch 
stated that the regenerative braking feature of a car, if equipped with 
one, should be overridden for the duration of AEB testing. AAA 
expressed concern that the proposal to allow vehicle testing with any 
cruise control setting would introduce too many variables into the 
testing scenario. AAA recommended the agency test all vehicles with the 
latest AEB setting and/or test all vehicles with and without the cruise 
control activated.
Agency Response
    The purpose of the ``any'' user adjustable parameter is to ensure 
that driver-activated settings do not negatively impact AEB 
performance. NHTSA seeks to avoid a situation where use of a setting 
reduces the requisite performance of AEB when tested according to the 
parameters of S7, S8, and S9. NHTSA also sought to incorporate the word 
``any'' into the standard to make clear that NHTSA has wide latitude to 
adjust the settings in a compliance test, in accordance with 49 CFR 
571.4. That section states: ``The word any, used in connection with a 
range of values or set of items in the requirements, conditions, and 
procedures of the standards or regulations in this chapter, means 
generally the totality of the items or values, any one of which may be 
selected by the Administration for testing, except where clearly 
specified otherwise.''
    NHTSA did not receive any comments indicating that the agency's 
approach to ensure AEB performance would be problematic. Vehicle 
manufacturers will have to assure that their designs do not negative 
affect the performance of AEB and may have more of a certification 
burden to assure such performance. The burden is reasonable, though, to 
assure that AEB systems work properly when other systems are engaged. 
Therefore, the agency is adopting the provisions proposed in the NPRM 
without change.
Loading
    This final rule adopts the proposed specification that NHTSA will 
load the subject vehicle with not more than 277 kg (611 lbs.), which 
includes the sum of any vehicle occupants and any test equipment and 
instrumentation. The agency proposed this specification for load 
because tests of the fully loaded vehicles are already required and 
conducted under exiting FMVSSs, such as FMVSS No. 135, ``Light vehicle 
brake systems,'' to measure the maximum brake capacity of a vehicle.

[[Page 39759]]

Comments
    NHTSA received comments from MEMA and ASC recommending that the 
agency harmonize with procedures of UNECE R151 and R152, and Euro NCAP. 
Those procedures specify a maximum load of 200 kg.
Agency Response
    In response, NHTSA declines to adopt the suggested change. NHTSA 
derives the subject vehicle load of 277 kg (611 lbs.) from agency 
testing, which uses the provision in NHTSA's NCAP test procedures. 
Most, if not all, vehicle manufacturers are familiar with NCAP's 
procedures and have designed their vehicles in accordance with them. As 
explained in the NPRM, the stopping performance of a fully loaded 
vehicle is already assessed under FMVSS No. 135. Commenters supporting 
the UN Regulations maximum load of 200 kg gave little technical support 
or rationale as to why that maximum load was preferred to the 277 kg 
proposed load. It is not apparent to NHTSA whether or the degree to 
which the 77 kg difference would change the test results. Therefore, 
given the information available to the agency, NHTSA is adopting the 
proposal.

L. Vehicle Test Device

    This final rule adopts specifications for a VTD to be used for 
compliance testing for the lead vehicle requirements. The GVT is a 
full-sized harmonized surrogate vehicle developed to test crash 
avoidance systems. 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, the VTD specified in this final rule 
will be used as a lead vehicle, pass through vehicle, and obstructing 
vehicle during testing. This final rule adopts all the specifications 
in the NPRM.
    This final rule specifies that the vehicle test device is 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.'' \156\ The vehicle test 
device is a tool that NHTSA will use in compliance tests to measure the 
performance of AEB systems required by FMVSS No. 127.
---------------------------------------------------------------------------

    \156\ https://www.iso.org/standard/70133.html. May 2021.
---------------------------------------------------------------------------

1. General Description
    In the NPRM, NHTSA provided background on the agency's purpose and 
rationale for proposing the VTD.\157\ The VTD provides a sensor 
representation of a passenger motor vehicle. 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.
---------------------------------------------------------------------------

    \157\ 88 FR 38632 at 38705.
---------------------------------------------------------------------------

    NHTSA received several comments on the proposed test device, all of 
which were generally supportive. Bosch, AAA, Rivian, the Alliance, and 
Ford all generally supported use of the proposed GVT across all AEB 
systems. AAA stated that the GVT is easy to use and provides 
versatility that allows for the evaluation of many realistic vehicle 
interaction. Rivian recommended NHTSA align the GVT device with the 
device used by Euro NCAP.
    Forensic Rock, on the other hand, recommends higher speed targets 
that can withstand high closing speed tests with minimal damage to the 
vehicles. In response, NHTSA will continuously monitor the development 
of AEB technologies and test devices associated with system 
performance. If a need arises for new test devices, NHTSA can assess 
and respond to the situation at that time.
2. Definitions
    The proposal defined a ``vehicle test device'' as a test device 
that simulates a passenger vehicle for the purpose of testing AEB 
system performance and defined a vehicle test device carrier as a 
movable platform on which a lead vehicle test device may be attached 
during compliance testing.
    Bosch recommended the definition of ``vehicle test device'' be 
changed to ``a test device with the appearance and radar 
characteristics that, together with the vehicle test device carrier, 
simulates a passenger vehicle for the purpose of testing automatic 
emergency brake system performance.''
    In response, NHTSA has considered the difference in the proposed 
definition for the ``vehicle test device'' and the definition suggested 
by Bosch and believes there to be no utility difference. The definition 
suggested by Bosch contains two areas of distinction from that of the 
proposed rule. First, Bosch suggested adding the phrase ``with the 
appearance and radar characteristics.'' While the specifications 
contain appearance and radar characteristics, such details are not 
needed within the definition to fulfill the purpose of a definition, 
which is to provide clarity as to what items are included and excluded 
from the term. The agency has decided to keep the definition broad and 
specify the technical details in the body of the regulation.
    Second, the definition suggested by Bosch provides that only the 
combination of the vehicle test device and the vehicle test device 
carrier represent a passenger vehicle. While the specifications provide 
details of the carrier device, those details are minimal and are 
primarily designed to minimize the carrier's appearances. One 
limitation of Bosch's suggestion would be that only the combination of 
the vehicle test device and the carrier would be usable for testing at 
a definition level. Not all tests require movement of the vehicle test 
device and as such, these tests could be conducted without a carrier 
(provided that the vehicle test device meet the specifications without 
the carrier). Considering that the appearance of the carrier is to be 
minimal, such flexibility of testing provides advantages for compliance 
testing. Accordingly, the agency is finalizing the definition of 
vehicle test device as proposed in the NPRM.
3. Sideview Specification
    NHTSA proposed to establish specifications applicable to only the 
rear-end of the vehicle test device. The proposal sought comment on 
whether the specifications for the vehicle test device should include 
sides of the vehicle, as well as the rear-end, and proposed potentially 
including the specifications from ISO 19206-3:2021.
Comments
    Advocates, MEMA, ZF, and Bosch all support specification of 
sideview, so the AEB can address cross traffic in the future. MEMA and 
ZF also recommend angled rear view (30 degrees, for example) 
representing a vehicle making a right-hand turn. Advocates suggested 
that any shortcomings established with specifications of rear view 
should also be addressed by NHTSA for side view. Bosch stated that for 
test cases in which the sides of the vehicle are within the signal 
detection of the radars and/or sensors, the sides need to be included.
Agency Response
    In response, NHTSA is not adopting turning scenarios or other 
scenarios where the side of the vehicle test device is critical to the 
outcome of the test. All lead vehicle scenarios, with the single 
exception of the false activation pass-through test, align the subject 
vehicle with the vehicle test device longitudinally along each 
centerline. Similar to the pass-through test, the obstructed pedestrian 
test that utilizes the vehicle test device aligns the subject

[[Page 39760]]

vehicle with vehicle test device longitudinally, with offsetting 
centerlines. Thus, no tests finalized in this final rule are dependent 
on the side view characteristics of the vehicle test device. If, in the 
future, tests are added that include side view interactions, the agency 
will consider additional specifications to the vehicle test device. For 
this final rule, the agency has finalized the rear-view characteristics 
only and has not added any view characteristics other than 180 degrees.
4. Field Verification Procedure
    The NPRM did not specify in-the-field verifications be performed to 
assess whether the radar cross section falls within the acceptability 
corridor throughout the life of the device. NHTSA sought comment 
regarding the adoption of the optional field verification procedure 
provided in ISO 19206-3:2021, Annex E, Section E.3.
Comments
    Bosch commented in support of the utilization of the optimal field 
verification procedure provided in ISO 19206-3:2021, Annex E, Section 
E.3, and further suggests the inclusion of suitable parts of the Annex 
C.
Agency Response
    In response, the field verification procedure is not included in 
this final rule. NHTSA testing has shown that the radar cross section 
of a new GVT and a ``used'' GVT manufactured by at least one company 
fall consistently within the specified corridor incorporated by 
reference from ISO 19206-3:2021.\158\ The field verification procedure 
alone does not fully demonstrate that the vehicle test device is within 
the specifications outlined in this rule. Accordingly, while the agency 
may informally use the field verification test to provide a general 
indication of the state of the vehicle test device, such a procedure is 
not appropriate for the test procedure.
---------------------------------------------------------------------------

    \158\ Assessing the Effect of Wear on Vehicle Test Device Radar 
Return Characteristics, available in the docket for this final rule 
(NHTSA-2023-0021).
---------------------------------------------------------------------------

5. Dimensional Specification
    NHTSA proposed that the rear silhouette and the rear window be 
symmetrical about a shared vertical centerline and that representations 
of the taillamps, rear reflex reflectors, and tires also be symmetrical 
about the surrogate's centerline. Further, the license plate 
representation was proposed to have a width of 300  15 mm 
and a height of 150  15 mm, and be mounted with a license 
plate holder angle within the range described in 49 CFR 571.108, 
S6.6.3.1. Lastly, NHTSA proposed that the VTD representations be 
located within the minimum and maximum measurement values specified in 
columns 3 and 4 of Table A.4 of ISO 19206-3:2021 Annex A. The tire 
representations are to be located within the minimum and maximum 
measurement values specified in columns 3 and 4 of Table A.3 of ISO 
19206-3:2021 Annex A. Additional clarification of terms was included in 
the NPRM stating that ``rear light'' means ``taillamp,'' 
``retroreflector'' means ``reflex reflector,'' and ``high centre 
taillight'' means ``high-mounted stop lamp.''
Comments
    In their comments, Ford, Porsche, and FCA all agree with NHTSA that 
the vehicle test device should be based on specifications defined in 
ISO 19206-3:2021. AAA and Adasky, alternatively, suggests that NHTSA 
re-assess the proposed requirement to be consistent with subcompact and 
compact cars, given the increased popularity of larger crossovers, 
SUVs, and light-duty trucks. Adasky recommends that the influences of 
hood height and A-pillar be included in the vehicle test device 
property definition.
Agency Response
    In response, NHTSA has adopted the specification as proposed. Most 
commentors agreed with the use of ISO 19206-3:2021, which NHTSA 
proposed as appropriate in the NPRM. The agency does not have 
information to support adopting a change at this time. The agency would 
also point out that including the hood height and A pillar is 
unnecessary for front to rear crashes because they are not visible from 
the rear of the test device, which is the orientation for all tests.
6. Visual and Near Infrared Specification
    NHTSA proposed that the vehicle test device rear representation 
colors be within the ranges specified in Tables B.2 and B.3 of ISO 
19206-3:2021 Annex B. The proposal also specified that the infrared 
properties of the vehicle test device be within the ranges specified in 
Table B.1 of ISO 19206-3:2021 Annex B 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 Annex B. Lastly, NHTSA 
proposed that the rear reflex reflectors, and at least 50 cm\2\ of the 
taillamp representations, of the vehicle test device be grade DOT-C2 
reflective sheeting as specified in 49 CFR 571.108, S8.2.
    NHTSA received no comments on this proposal. The agency has adopted 
the provision for the reasons provided in the NPRM.
7. Radar Reflectivity
    NHTSA proposed that the radar cross section of the vehicle test 
device is to be measured while attached to the carrier (robotic 
platform). NHTSA also proposed that the radar reflectivity of the 
carrier platform be less than 0 dBm\2\ for a viewing angle of 180 
degrees at a distance of 5 to 100 m, when measured according to the 
radar measurement procedure specified in C.3 of ISO 19206-3:2021 Annex 
C for fixed-angle scans. The proposal also stated that the rear bumper 
area, as shown in Table C.1 of ISO 19206-3:2021 Annex C, contributes to 
the target radar cross section. NHTSA proposed that the radar cross 
section be assessed using a 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 0.6 m, 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). The proposal stated that a minimum of 92 percent of 
the filtered data points of the surrogate radar cross section for the 
fixed vehicle angle, variable range measurements be within the radar 
cross section boundaries defined in Section C.2.2.4 of ISO 19206-3:2021 
Annex C for a viewing angle of 180 degrees when measured according to 
the radar measurement procedure specified in C.3 of ISO 19206-3:2021 
Annex C for fixed-angle scans. Lastly, the proposed rule stated that 
between 86 to 95 percent of the vehicle test device spatial radar cross 
section reflective power be within the primary reflection region 
defined in Section C.2.2.5 of ISO 19206-3:2021 Annex C, when measured 
according to the radar measurement procedure specified in Section C.3 
of ISO 19206-3:2021 Annex C using the angle-penetration method.
Comments
    In their comments, ZF and ASC both consider the tolerance of +/- 
10dBm\2\ to be quite high. ZF noted that information derived might be 
misleading (e.g., object classification). In addition, ZF, ASC, 
Mobileye, and MEMA recommend including acceptable Radar Cross Section 
(RCS) ranges for the rear and the side of the VTD. While ZF, ASC, and 
MEMA suggest using the same RCS corridor values as specified in ISO 
19206-3:2021, Mobileye suggests setting the bars at the lower RCS 
values (e.g., -10dBsm for VRU, 0dBsm or below for

[[Page 39761]]

motorcycle). Mobileye also suggests including lateral edge errors as 
critical metrics because identifying the lateral edges of the object 
lowers risk of false association with camera or other sensors. Bosch 
recommends amending the radar reflectivity specifications because, 
``The radar reflectivity of the carrier platform alone 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 Section C.3 of ISO 19206-3:2021 Annex C for fixed-angle scans.''
Agency Response
    The agency disagrees with the suggested revision to the radar 
reflectivity for the carrier, as the carrier radar characteristics are 
important when attached to the VTD, not the carrier by itself for the 
purposes of testing AEB. Testing the carrier alone fails to take into 
account the actual interface between the VTD and the carrier system.
    Regarding the RCS range, the agency believes that both values are 
needed to set appropriate bounds of what is acceptable RCS for the VTD 
to match real world vehicles. The vehicle tests using two different 
sensors documented in the ISO 19206-3:2021 Figure C.17 and C.18 show 
that the vehicles tested varied within +/- 10dBm\2\. Thus, permitting 
the vehicle test device to vary within this tolerance provides real-
world application for the various vehicles on the road. In addition, 
lateral error tolerances are included in the test set-up 
specifications.
    NHTSA is not adding turning scenarios to this proposal, and 
therefore the agency believes that side presentation specifications are 
not needed. NHTSA is finalizing the radar reflectivity specifications 
for the vehicle test device as proposed in the NPRM.
8. List of Actual Vehicles
    In addition to the vehicle test device specifications, NHTSA sought 
comment on specifying a set of real vehicles to be used as vehicle test 
devices in AEB testing. NHTSA also sought comment on the utility and 
feasibility of 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. Additionally, NHTSA sought 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.
Comments
    Advocates and Bosch both generally support the development of a 
list of possible real vehicles that could be used for testing in 
addition to the GVT. While Bosch suggests that NHTSA reference the 
relevant parts of ISO 19206-3:2021 if using a set of real vehicles, 
Advocates recommend that NHTSA consider the most frequently registered 
vehicles in the US over some lookback period with an established 
timeline.
    In contrast, Rivian, Alliance, ASC, ZF, and MEMA all oppose using 
real vehicles. ZF, MEMA, and ASC state high cost and risk of injury to 
human subjects in performing high-speed AEB tests. ASC and ZF added 
that the advantages of testing with real vehicles compared to soft 
vehicle targets is not clear. Furthermore, ZF and MEMA mention that the 
tests that involve a soft target could serve as a real vehicle test if 
combined with documentation provided by the OEM.
    The Alliance notes test repeatability and reproducibility 
challenges due to potential differences in vehicles selected for 
testing and that repairs may be expensive and time-consuming if contact 
occurs. It also notes that the current GVT is correlated to real world 
vehicles through collaborative global government/industry testing and 
verification. Rivian stated that using representative test devices, as 
opposed to real vehicles, reduces test burdens on manufacturers and 
poses lesser risk of injury if AEB fails to avoid a crash during the 
test procedure. ASC and ZF believe that vehicles with AEB systems 
should be able to detect a wide range of vehicles and suggests that if 
NHTSA decides to develop its own, more US-fleet representative GVT 
target, then it should be compliant with the ISO standard.
Agency Response
    NHTSA agrees that the VTD specifications provide sufficient 
flexibility in appearance that creating a list of vehicles for testing 
is not likely to increase the safety impacts of the rule. NHTSA also 
agrees that there are concerns over the cost of testing with real 
vehicles, and, that there are potential safety risks to test operators. 
NHTSA believes that the GVT is representative of a genuine 
vehicle,\159\ and does not believe that the increased costs of adding a 
documentation requirement for manufacturers to show this is warranted 
at this time. Accordingly, the agency is not adopting a list of real 
vehicles for testing at this time.
---------------------------------------------------------------------------

    \159\ Overall, the AEB system sensors interpret the SSV appears 
to sensors as a genuine vehicle. Nearly all vehicle manufacturers 
and many suppliers have assessed how the SSV appears to the sensors 
used for their AEB systems. The results of these scans have been 
very favorable. 80 FR 68615, NCAP RFC, Docket No. NHTSA-2015-0006.
---------------------------------------------------------------------------

M. Pedestrian Test Devices

    This final rule adopts specifications for two pedestrian test 
devices to be used for compliance testing for the PAEB requirements. 
The two pedestrian test devices each consist of a test mannequin and a 
motion apparatus (carrier system) that positions the test mannequin 
during a test. NHTSA's specifications for pedestrian test mannequins 
represent a 50th percentile adult male and a 6- to 7-year-old child. 
NHTSA has incorporated by reference specifications from three ISO 
standards.
1. General Description
    The Adult Pedestrian Test Mannequin (APTM) provides a sensor 
representation of a 50th percentile adult male and consists of a head, 
torso, two arms and hands, and two legs and feet. The Child Pedestrian 
Test Mannequin (CPTM) provides a sensor representation of a 6- to 7-
year-old child and consists of a head, torso, two arms and hands, and 
two legs and feet. The arms of both test mannequins are posable but 
will not move during testing. The legs of the test mannequins will 
articulate and will be synchronized to the forward motion of the 
mannequin.
    In the NPRM, NHTSA provided background on the agency's purpose and 
rationale for proposing the test devices and the history of the devices 
and their use,\160\ including previous NHTSA Federal Register notices 
that have solicited input from the public on test procedures that 
include the use of these pedestrian test devices either in current or 
past form (i.e., articulated vs. non-articulated legs).
---------------------------------------------------------------------------

    \160\ 88 FR at 38702.
---------------------------------------------------------------------------

    NHTSA received many comments on the proposal, all of which were 
generally supportive. Commenters generally supported the use of the ISO 
19206-2:2018 mannequins as these are already validated and readily 
available. SAE noted that its mannequin prototypes had limited testing 
in the test track and deferred to NHTSA's understanding of the new 
standard to know which pedestrian mannequin would be most appropriate 
for the regulation. The commenters also supported harmonizing with 
international standards, such as UNECE Regulation No. 152, as a 
baseline for mannequin specifications, and with ISO

[[Page 39762]]

19206-2:2018 regarding the PAEB mannequins.
    In response, NHTSA is adopting the relevant parts of ISO 19206-
2:2018 and ISO 19206-4:2020, as specified in the NPRM. ISO 19206 has a 
larger body of research testing to support its test devices than SAE 
J3116, and using ISO 19206 is consistent with international standards 
like UNECE Regulation No. 152.
    For the mannequin carrier system, Bosch suggested adoption of the 
ISO 19206-7 specifications and test hardware to specify the carrier 
system used to move the pedestrian test mannequin. Bosch further 
recommended revising the definitions of the adult and child mannequins 
to refer to the carrier systems. NHTSA is declining to make these 
changes. Because ISO 19206-7 is still in draft form, NHTSA believes it 
is premature to consider it for adoption. Regarding the carrier system, 
it is a modular system designed to move the child and adult test 
mannequins. As such, NHTSA believes that the definition of the carrier 
system should lie outside the definition of either mannequin. It is 
also more appropriate to specify how the carrier system can affect 
sensor representations of the mannequins, rather than specify it as 
part of a mannequin.
    The American Foundation for Blind (AFB) recommended NHTSA use the 
most inclusive and effective mannequins that will reduce road injuries 
and deaths among people with disabilities, including women, adults with 
short stature, and cyclists. Some commenters suggest that NHTSA use 
pedestrian test mannequins using mobility assistive devices, such as 
wheelchairs (motorized and non-motorized), walkers, motorized scooters, 
or canes.
    In response, NHTSA is interested in additional pedestrian test 
devices outside of the child and adult pedestrian test mannequins, 
including those that reflect the broad diversity among the American 
public. At this time, however, there is a need for more development, 
research, and testing for pedestrian test mannequins that are using 
mobility assistive devices. NHTSA intends to monitor the progress of 
these devices as they are developed and standardized, for possible 
inclusion in the standard at a future date.
2. Dimensions and Posture
    The APTM and the CPTM have basic body dimensions and proportions 
specified in ISO 19206-2:2018. All commenters responding to the 
proposed dimensions agreed with the proposal. The agency is adopting 
the proposal for the reasons provided in the NPRM.
    A number of commenters responded to NHTSA's question asking whether 
use of the 50th percentile adult male test mannequin would ensure PAEB 
systems will react to small adult females and other pedestrians other 
than mid-size adult males. Consumer Reports (CR) supported NHTSA's 
proposal to use a pedestrian test mannequin representing a 50th-
percentile adult male and one representing a six- to seven-year-old 
child, stating it is critical to use both mannequins in PAEB testing to 
account for a range of human proportions. The commenter believed it is 
especially important to use the child mannequin to provide adequate 
protection for children and other shorter individuals, particularly 
from impacts involving large vehicles that have tall hoods or that 
otherwise have limited frontal visibility.
    Several commenters (Advocates, AARP, ZF, Consumer Reports, and 
MEMA) suggested including an adult female mannequin and the child 
mannequin in all tests. NHTSA is unaware of any standards providing 
specifications for a 5th percentile adult female test mannequin, or of 
any consumer information programs testing with such a device.
    The Alliance stated that the proposed child and adult test devices 
should provide a reasonable assessment across a broad spectrum of 
occupant sizes.\161\ AAA recommended not including the child test 
mannequin for all testing scenarios, as this would increase testing 
burdens. AAA suggested that, as an alternative, NHTSA could test some 
scenarios with the smaller SAE pedestrian test mannequin.
---------------------------------------------------------------------------

    \161\ The Alliance supported using a child test mannequin in 
daytime scenarios only, and not also in the nighttime scenario. 
NHTSA discussed this comment in separate section.
---------------------------------------------------------------------------

    After reviewing the comments, NHTSA is satisfied that the currently 
proposed pedestrian test mannequins provide a reasonable representation 
of the pedestrian crash population for purposes of issuing this final 
rule. In its comment to the NPRM, IIHS stated that evidence does not 
demonstrate that current PAEB systems are tuned only to the adult male 
mannequin. This rulemaking does not expand the mannequins used in new 
FMVSS No. 127, or expand how the child dummy is used, because NHTSA 
does not have the body of research necessary to support such changes 
for this final rule.
    FCA noted that there are no dimensional tolerances on the 
pedestrian test device. In response, NHTSA's testing has not shown an 
issue with the dimensions specified in the NPRM. Further, the 
locational bounds of the pedestrian test mannequin are specified in the 
individual test scenarios. Thus, the agency is not adopting additional 
tolerances on the dimensional specification of the pedestrian test 
mannequins. SAE responded to NHTSA's comment on shoe height, stating 
that the overall mannequin height on the sled is representative of the 
overall height of real pedestrians with shoes.
3. Visual Properties
    The mannequins will have specified features for the depictions of 
hair, skin tone, clothing, and the like. The features are specified in 
the ISO standards incorporated by reference into FMVSS No. 127 by this 
final rule. The incorporated ISO standards provide needed 
specifications for these features, but they also allow NHTSA to 
harmonize with specifications for test mannequins in use by Euro NCAP.
    Because specifications for test mannequin skin color are not found 
in ISO 19206-2:2018, NHTSA is incorporating by reference the bicyclist 
mannequin specifications for color and reflectivity found in ISO 19206-
4:2020, ``Road vehicles--test devices for target vehicles, vulnerable 
road users and other objects, for assessment of active safety 
functions--Part 4: Requirements for bicyclists targets.'' Although this 
standard provides requirements for bicyclist test devices, NHTSA is 
referencing it for color and reflectivity for the prescribed adult and 
child test mannequins because the specifications are workable for use 
with the ISO standard for pedestrian test devices. NHTSA is specifying 
that the test mannequins be of a color that matches a specified range 
of skin colors representative of very dark to very light complexions. 
The mannequins must also have standardized properties that represent 
hair, facial skin, hands, and other features, and must have a 
standardized long-sleeve black shirt, blue long pants, and black shoes.
    Commenters (AARP, Safe Kids Worldwide (SKW), Safe Kids in 
Autonomous Vehicles Alliance (SKAVA), Luminar, and private citizens) 
supported NHTSA's effort to ensure PAEB detect pedestrians of all skin 
colors. The agency agrees with the commentors that sensors should 
detect skin tones other than light skin tones.
    Luminar did not support the white face, black shirt, and blue pants 
on mannequins. While NHTSA understands that the commenter would like to 
see testing outside of the

[[Page 39763]]

specifications identified in the NPRM, the agency does not have the 
body of knowledge necessary to objectively specify clothing outside of 
the black shirt and blue pants. Furthermore, commenters did not provide 
data demonstrating that current PAEB systems do not already detect a 
wide array of skin tones. The proposal includes a range of colors 
(based on ISO 19206-4_2020 standard) for skin, face, and hands. NHTSA 
encourages manufacturers to consider designing their systems to detect 
all pedestrians, including those wearing various clothing colors.
4. Radar Properties
    The radar reflectivity characteristics of the pedestrian test 
device approximates that of a pedestrian of the same size when 
approached from the side or from behind. Radar cross section 
measurements of the pedestrian test mannequins must fall within the 
upper and lower boundaries shown in Annex B, section B.3, figure B.6 of 
ISO 19206-2:2018 when tested in accordance with the measure procedure 
in Annex C, section C.3 of ISO 19206-2:2018.
    In response to Bosch, this final rule adopts the newer ISO 19206-
3:2021 instead of ISO 19206-2:2018 in determining the upper and lower 
boundaries for an object for radar cross-section measurements. The 
proposed procedure in Annex C, section C.3 of ISO 19206-2:2018 is 
specific for pedestrian targets; however, recent testing performed by 
the agency indicates that the three position measurement specified in 
Annex C, section C.3 of ISO 19206-3:2021 provides more reduction in 
multi-path reflections and offers more accurate radar cross section 
values. This testing confirms the recommendation from Bosch to adopt 
the measurement procedure in Annex C, section C.3 of ISO 19206-3:2021. 
Therefore, the agency is adopting the new version of the ISO standard.
5. Articulation Properties
    This final rule adopts the proposal that the legs of the pedestrian 
test device be in accordance with, and as described in, Annex D, 
section D.2 and illustrated in Figures D.1, D.2, and D.3 of ISO 19206-
2:2018. For the test scenarios involving a moving pedestrian, the legs 
of the pedestrian test mannequin will articulate to simulate a walking 
motion. A test mannequin that has leg articulation when in motion more 
realistically represents an actual walking or running pedestrian. For 
test scenarios involving a stationary pedestrian, the legs of the 
pedestrian test mannequin remain at rest (i.e., simulate a standing 
posture).
    Commenters to this issue supported the pedestrian test mannequin 
with articulation characteristics. The Alliance agreed that mannequins 
equipped with articulate moving legs are more representative of actual 
pedestrians than mannequins with stationary legs. While agreeing with 
the NPRM, Aptiv noted that even when people are standing next to a 
road, they move in some way (e.g., body micro-movement) and so NHTSA 
may want to add some upper body movement to the stationary pedestrian 
test mannequin. Porsche supported the adoption of articulated dummies, 
explaining that the articulated motion is required because of the 
``micro doppler'' effect, which is an important consideration for radar 
sensors.
    NHTSA has adopted the proposal for the articulation properties of 
the legs. The agency is not adding pedestrian micro-movement to the 
articulation requirements as there are currently no consensus standards 
available for pedestrian micro-movement and NHTSA does not testing 
experience with mannequins of that type.
6. Comments on Thermal Characteristics
    In addition to the characteristics specified in the proposal 
presented in the NPRM, NHTSA requested comments on whether test 
mannequins should have thermal characteristics. Several commenters 
\162\ responding to the NPRM discussed the merits of thermal 
characteristics in the pedestrian test mannequins. Owl AI and Teledyne 
explained that thermal imaging can capture infrared radiation emitted 
by pedestrians in the 8-14[mu]m (long wave) band, which allows for 
pedestrians to be easily distinguished from other objects. AAA 
supported inclusion of thermal specifications, especially for nighttime 
testing.
---------------------------------------------------------------------------

    \162\ Commenters included Advocates, Adasky, Owl AI, Teledyne, 
and AAA.
---------------------------------------------------------------------------

    NHTSA currently does not have the body of research necessary to 
develop test protocols that support the inclusion of thermally active 
pedestrian test mannequins but concurs this matter may be a topic for 
future consideration. NHTSA will continue to monitor the development of 
thermally active pedestrian test mannequins so that the agency can 
explore their use in the future.
N. Miscellaneous Topics
    Advocates, ZF, AAA, Rivian, Volkswagen, AARP, the National 
Associations of Mutual Insurance Companies, and ASC suggested a 
requirement that vehicle manufacturers provide information in owners' 
manuals and elsewhere describing how the AEB system works, and its 
capabilities and its limitations. SEMA suggested a requirement that 
specific information such as diagnostic codes and calibration 
information be shared with consumers, MEMA suggested web links to 
information, and NADA suggested using a QR code on the Monroney label. 
SEMA also requested that NHTSA provide a system of information about 
AEB to aftermarket suppliers.
    In contrast, the Alliance and Hyundai opposed new information 
requirements about AEB, suggesting that information is already provided 
in the absence of a regulation. Additionally, the Alliance stated it is 
unaware of the safety impacts of providing AEB information to 
consumers.
    This final rule has not adopted additional information 
requirements. The agency concludes that the primary safety impacts from 
AEB is the functionality itself. While information regarding the 
capabilities and limitations of the AEB system may be generally useful, 
AEB as required by this rule is a last second intervention system. 
Thus, a driver's basic driving technique should not change based on the 
capabilities or even the existence of AEB (aside from heeding the 
warning of the malfunction indicator to attend to a problem with the 
AEB system).
    FCA believed that the proposed requirements overly focus 
performance on the vehicle's braking system and not on the output of 
the sensing and perception capacity of the AEB system. FCA further 
stated that it could be possible to focus the regulatory requirement 
solely onto the AEB system (i.e., the sensors and perception system) by 
defining a perception mandate for output signals for time to warn or 
the BRAKE! Command. FCA further asserted that this output could be 
derived from fleet averages, equations of motion, and that as vehicle 
performance improves, the timing could be revised accordingly.
    In response, NHTSA declines FCA's suggestion to directly regulate 
the sensing and perception systems directly instead of the ability of 
the entire system to avoid crashes. This FMVSS is created with 
important safety goals in mind to address significant safety problems 
that this technology can resolve. For this rule, the safety problems 
are rear-end crashes and crashes involving pedestrians struck by the 
front of a vehicle. The performance requirements (avoiding contact with 
a lead vehicle and pedestrian) address

[[Page 39764]]

this safety problem in an effective and expeditious manner. They are 
solidly supported and informed by data from years of agency and 
industry research, the voluntary commitment and NCAP, substantial 
collaborative work between entities, and NHTSA's close monitoring of 
AEB development and maturation. A new approach specifying a particular 
time to collision based on the information from the perception system 
is not supported by the current stated of knowledge and would take 
years to research and develop.
    FCA commented that NHTSA did not provide a baseline or compliance 
assessment of the front lighting equipment installed in the research 
vehicles, so manufacturers are unaware of the performance level of the 
lighting relative to the FMVSS No. 108 range. For example, the vehicles 
may have been equipped with optional lighting packages within the 
product lineup, which may have enhanced performance. FCA also noted 
that lighting was not included in the technical assessment or economic 
analysis in the proposal. FCA expressed that NHTSA should have 
knowledge regarding the high cost of modern lighting systems and 
importantly, how much lead time would be needed to develop them, and 
that performance requirements should not prohibit otherwise compliant 
lighting systems. Finally, it stated that if improved lighting is 
mandatory for AEB nighttime performance objectives, FMVSS No. 108 
should be reconfigured in a separate rulemaking.
    In response, NHTSA's performance-oriented approach in this final 
rule directly addresses the safety problem while providing 
manufacturers the most flexibility in designing vehicles to meet FMVSS 
No. 127. Improved lighting is not a requisite of the final rule. A 
manufacturer may choose to create a robust perception system that 
initiates braking sooner, have a lesser performing perception system 
and equip the vehicle with robust brakes, have a high performing 
headlighting system to help achieve the performance required, or 
implement another means of meeting the standard. Because FMVSS No. 127 
is a performance standard, manufacturers decide what countermeasures 
makes the most sense for them to meet the standard, and the marketplace 
can continue to drive innovation while achieving positive safety 
outcomes.

O. Effective Date and Phase-In Schedule

    NHTSA proposed that all requirements be phased in within four years 
of publication of a final rule. Under the proposal, all AEB-equipped 
vehicles would be required to meet all requirements associated with 
lead vehicle AEB within three years. NHTSA also proposed that all PAEB-
equipped vehicles would be required to meet all daylight test 
requirements for PAEB within three years. For PAEB performance in 
darkness, NHTSA proposed lower maximum test speed thresholds that would 
have to be met within three years for some specified test procedures. 
Under the proposal, all vehicles would be required to meet the minimum 
performance requirements with higher darkness test speeds four years 
after the publication of a final rule. Small-volume manufacturers, 
final-stage manufacturers, and alterers would be provided an additional 
year of lead time for all requirements.
    NHTSA requested comments on the proposed lead time for meeting the 
proposed 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.
Comments
    In general, manufacturers, suppliers, and industry advocacy groups 
asserted that more time is needed to meet the performance requirements 
in the NPRM. In contrast, safety advocates and municipalities requested 
that the proposed requirements be implemented sooner.
    More specifically, the Alliance cited concerns over the 
practicability of no contact, the NPRM's underestimation of the 
software and hardware changes needed to facilitate crash avoidance at 
higher speeds, and the complexity of addressing false positives all 
within a short lead time. They expressed that it cannot be known 
whether systems can achieve the proposed requirements through software 
upgrades until a comprehensive system review, analysis, and synthesis 
has been performed by manufacturers. Further, they expressed that the 
proposed timeline could disrupt vehicle developments already underway 
as it may require revisiting previous hardware and software design 
decisions and redesigning systems expected to impact or be impacted by 
the AEB/PAEB system. In addition, they stated that existing vehicle 
electrical architectures may not be capable of handling the additional 
or upgraded sensors, additional communication bandwidth and processing 
power to upgrade the vehicle ADAS system to the proposed level of 
performance.
    The Alliance, Mitsubishi, Honda, and Nissan proposed a compliance 
date starting seven years or more after the issuance of a final rule 
for large volume manufacturers, and the Alliance suggested an 
additional four years for small volume manufacturers. The Alliance 
proposed an alternative compliance schedule that begins five years 
after the issuance of a final rule but noted that this would not 
address the outstanding technical issues and unintended consequences 
that they outlined in their comments.
    Volkswagen and Porsche suggested a phased-in compliance process 
where a certain percentage of the fleet would be required to comply 
over a period of several years until 100 percent of the fleet was 
required to comply with the final rule. The Alliance and Nissan 
suggested that if the agency considered its proposal to harmonize with 
UNECE Regulation No. 152, compliance could occur sooner. Porsche and 
Volkswagen suggested that compliance with UNECE Regulation No. 152 
could be considered for end-of-production lines or as part of a phase-
in.
    Bosch recommended a stepwise regulatory timeline, observing that 
speeds up to 60 km/h are achievable as proposed in the NPRM, but 
additional time would be necessary for testing at higher speeds. 
Mobileye suggested a similar approach.
    Advocates stated that the agency should require a more aggressive 
schedule for compliance given the baseline inclusion of the components 
for AEB systems in new vehicles. In addition, Advocates stated that 
they oppose any further extension of the proposed compliance dates in 
the NPRM. The NTSB encouraged NHTSA to consider reducing the timeline 
for the rule's effective dates to expedite deployment as some 
manufacturers may be able to achieve some of the performance 
requirements immediately. Consumer Reports suggested that all 
requirements, other than darkness pedestrian avoidance requirements, be 
effective no later than one year after issuing a final rule. For 
darkness pedestrian avoidance requirements, Consumer Reports stated 
that NHTSA should set the compliance timeline at no more than two years 
after publication of a final rule. NAMIC and IIHS stated that, based on 
recent IIHS test data, manufacturers have made dramatic progress in 
PAEB programs in a short time, and recommended a one-year phase-in. 
Finally, NACTO, Richmond Ambulance Authority, DRIVE SMART Virginia, the 
city of Philadelphia, the city of Houston, and the Nashville DOT 
recommended that NHTSA have the higher speed pedestrian avoidance tests 
in dark conditions required on the same timeline as the daytime 
scenarios.

[[Page 39765]]

Agency Response
    The agency finds the arguments for additional lead time compelling. 
For the reasons discussed below, this final rule requires that 
manufacturers comply with all provisions of this final rule at the end 
of the five-year period starting the first September 1 after this 
publication, or September 1, 2029. Most vehicles sold today do not meet 
all of the requirements set forth in this final rule, and many may not 
be easily made compliant with all of the requirements established in 
this final rule. While NHTSA recognizes the urgency of the safety 
problem, NHTSA also recognizes that the requirements of this final rule 
are technology-forcing. The agency believes that the requirements are 
crucial in ensuring the safety in the long run, but we are extending 
the schedule to avoid significantly increasing the costs of this rule 
by requiring that manufacturers conduct expensive equipment redesigns 
outside of the normal product cycle. Because of the normal product 
development cycle, it is likely that there will be significant market 
penetration of complying systems as they are developed prior to the 
effective date of this rule.
    While some commenters suggested that the proposed lead time is 
practicable if the agency reduced the stringency of this final rule's 
requirements, such an approach would result in a substantial decrease 
in the expected benefits of this rule in the long run. A lead time of 
five years provides manufacturers with the ability to fully integrate 
the AEB system into vehicles in line with the typical design cycle in 
many cases. Such a process permits manufacturers to fully design 
systems that minimize the false activations that industry has expressed 
concern about, yet still provide the level of performance required by 
this rule. NHTSA believes a five-year lead time fully balances safety 
considerations, the capabilities of the technology, and the practical 
need to engineer systems that fully comply with this final rule.
    Note that as discussed in the Regulatory Flexibility Act section of 
the document, NHTSA is giving certain small manufacturers and alterers 
an additional year of lead time to comply with this rule.
Safety Act
    Under 49 U.S.C. 30111(d), a standard may not become effective 
before the 180th day after the standard is prescribed or later than one 
year after it is prescribed, unless NHTSA finds, for good cause shown, 
that a different effective date is in the public interest and publishes 
a reason for the finding. A 5-year compliance period is in the public 
interest because most vehicles will require upgrades of hardware or 
software to meet the requirements of this final rule. To require 
compliance with this standard outside of the normal development cycle 
would significantly increase the cost of the rule because vehicles 
cannot easily be made compliant with the requirements of this final 
rule outside of the normal vehicle design cycle.

IV. Summary of Estimated Effectiveness, Cost, and Benefits

    The requirements specified in this final rule for Lead Vehicle AEB 
address rear-impact crashes. Between 2016 and 2019, an average of 1.12 
million rear-impact crashes involving light vehicles occurred annually. 
These crashes resulted in an annual average of 394 fatalities, 142,611 
non-fatal injuries, and approximately 1.69 million property-damage-only 
vehicles (PDOVs).
    In specifying the requirements for Lead Vehicle AEB, the agency 
considered the number of fatalities and non-fatal injuries resulting 
from crashes that could potentially be prevented or mitigated given the 
current capabilities of this technology. As a result, the requirements 
specified for Lead Vehicle AEB consider the need to address this safety 
issue by ensuring that these systems have sufficient braking authority 
to generate speed reductions that can prevent or mitigate real-world 
crashes.
    The requirements specified in the final rule for PAEB address 
crashes in which a light vehicle strikes a pedestrian. Between 2016 and 
2019, an average of approximately 23,000 crashes that could potentially 
be addressed by PAEB occurred annually. These crashes resulted in an 
annual average of 2,642 fatalities and 17,689 non-fatal injuries.
    In specifying the requirements for PAEB, the agency considered the 
number of fatalities and non-fatal injuries resulting from crashes that 
could potentially be prevented or mitigated given the current 
capabilities of this technology. As a result, the requirements 
specified for PAEB consider the need to address this safety issue by 
ensuring that these systems have sufficient braking authority to 
generate speed reductions that can prevent or mitigate real-world 
crashes with pedestrians.
    The target population for the lead vehicle AEB analysis includes 
two-vehicle, rear-end light vehicle crashes and their resulting 
occupant fatalities and non-fatal injuries. FARS is used to obtain the 
target population for fatalities and CRSS is used to obtain the target 
population for property-damage-only crashes and occupant injuries. The 
target population includes two-vehicle light-vehicle to light-vehicle 
crashes in which the manner of collision is a rear-end crash and the 
first harmful event was a collision with a motor vehicle in transport. 
Further refinement includes limiting the analysis to crashes where the 
striking vehicle was traveling straight ahead prior to the collision at 
a speed less than 90.1 mph (145 km/h) and the struck vehicle was either 
stopped, moving, or decelerating.
[GRAPHIC] [TIFF OMITTED] TR09MY24.023

    The target population for the PAEB analysis considered only light 
vehicle crashes that included a single vehicle and pedestrian in which 
the first injury-causing event was contact with a pedestrian. The area 
of initial impact was limited to the front of the vehicle, specified as 
clock points 11, 12, and 1, and the vehicle's pre-event movement was 
traveling in a straight line.
    These crashes were then categorized as either the pedestrian 
crossing the vehicle path or along the vehicle path. The crashes are 
inclusive of all light, road surface, and weather conditions to capture 
potential crashes, fatalities, and injuries in real world conditions. 
Data

[[Page 39766]]

elements listed as ``unknown'' were proportionally allocated, as 
needed.
[GRAPHIC] [TIFF OMITTED] TR09MY24.024

A. Benefits

    As a result of the requirements for Lead Vehicle AEB and PAEB 
specified in this final rule, we estimate that 362 fatalities and more 
than 24,000 non-fatal MAIS 1-5 injuries will be mitigated over the 
course of one vehicle model year's lifetime.
[GRAPHIC] [TIFF OMITTED] TR09MY24.025

B. Costs

    The agency estimated the incremental costs associated with this 
final rule, which has been adjusted from the estimates presented in the 
NPRM to include the costs associated with software and hardware 
improvements, compared to the baseline condition. Incremental costs 
reflect the difference in costs associated with all new light vehicles 
being equipped with AEB with no performance standard (the baseline 
condition) relative to all light vehicles being equipped with AEB that 
meets the performance requirements specified in this final rule.
    As common radar and camera systems are used across Lead Vehicle AEB 
and PAEB systems, functionality can be achieved through upgraded 
software for most of the affected vehicles. Therefore, the agency 
accounts for the incremental cost associated with a software upgrade 
for all new light vehicles. Although the majority of new light vehicles 
would be able to achieve the minimum performance requirement without 
adding additional hardware to their current AEB systems, a small 
percentage would need to add either an additional camera or radar. 
Based on the prevalence of mono-camera systems in our test data and in 
NCAP reporting data, as well as a discussion with Bosch, this analysis 
estimated that approximately five percent of new light vehicles would 
require additional hardware.\163\ Therefore, in addition to software 
costs, the agency also accounts for the incremental cost for five 
percent of new light vehicles would add additional hardware (radar) to 
their existing AEB systems in order to meet the requirements specified 
in this final rule. Taking into account both software and hardware 
costs, the total annual

[[Page 39767]]

cost associated with this final rule is approximately $354.06 million 
in 2020 dollars.
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    \163\ Ex Parte Docket Memo and Presentation_Bosch, available at: 
https://www.regulations.gov/document/NHTSA-2023-0021-1058.
[GRAPHIC] [TIFF OMITTED] TR09MY24.026

C. Net Impact

    The Benefits associated with this final rule, which are measured in 
fatalities prevented and non-fatal injuries reduced, were converted 
into equivalent lives saved. Under this final rule, the cost per 
equivalent life saved ranges from $0.55 million and $0.68 million. 
Therefore, the final rule is considered to be cost-effective. To 
calculate net benefits, both measures must be represented in 
commeasurable units. Therefore, total benefits are translated into 
monetary value. When discounted at three and seven percent, the net 
benefits associated with the final rule are $7.26 billion and $5.82 
billion, respectively. Furthermore, when discounted at three and seven 
percent, the benefit cost ratios associated with the final rule are 
21.51 and 17.45, respectively. Therefore, this final rule is net 
beneficial. Overall, the agency's analyses indicate that society will 
be better off as a result of the final rule.
[GRAPHIC] [TIFF OMITTED] TR09MY24.027

[GRAPHIC] [TIFF OMITTED] TR09MY24.028

[GRAPHIC] [TIFF OMITTED] TR09MY24.029


[[Page 39768]]



V. Regulatory Notices and Analyses

Executive Orders 12866, 13563, and 14094 and DOT Regulatory Policies 
and Procedures

    The agency has considered the impact of this rulemaking action 
under Executive Order (E.O.) 12866, E.O. 13563, E.O. 14094, and the 
Department of Transportation's regulatory procedures. This rulemaking 
is considered ``(3)(f)(1) significant'' and was reviewed by the Office 
of Management and Budget under E.O. 12866, ``Regulatory Planning and 
Review,'' as amended by E.O. 14094, ``Modernizing Regulatory Review.'' 
It is expected to have an annual effect on the economy of $200 million 
or more. NHTSA has prepared a regulatory impact analysis that assesses 
the cost and benefits of this rule, which has been included in the 
docket listed at the beginning of this rule. The benefits, costs, and 
other impacts of this rule are summarized in the final regulatory 
impact analysis.

Regulatory Flexibility Act

    The Regulatory Flexibility Act of 1980, as amended, requires 
agencies to evaluate the potential effects of their proposed and final 
rules on small businesses, small organizations, and small governmental 
jurisdictions. The Small Business Administration's regulations at 13 
CFR part 121 define a small business, in part, as a business entity 
``which operates primarily within the United States.'' (13 CFR 
121.105(a)). No regulatory flexibility analysis is required if the head 
of an agency certifies that the rule will not have a significant 
economic impact on a substantial number of small entities. The SBREFA 
amended the Regulatory Flexibility Act to require Federal agencies to 
provide a statement of the factual basis for certifying that a rule 
will not have a significant economic impact on a substantial number of 
small entities.
    NHTSA has considered the effects of this final rule under the 
Regulatory Flexibility Act.
    The RIA discusses the economic impact of the rule on small vehicle 
manufacturers, of which NHTSA is aware of 12. NHTSA believes that this 
rule would not have a significant economic impact on these 
manufacturers. The vehicles produced by manufacturers listed in RIA can 
roughly be grouped into three classes: (1) luxury/ultra-luxury 
vehicles; (2) alternative electric vehicles; and (3) modified vehicles 
from other manufacturers. For luxury/ultra-luxury vehicles, any 
potential incremental compliance costs would not impact demand. 
Similarly, we would expect alternative electric vehicles to offer 
amenities meeting or exceeding the established market alternatives, 
including effective AEB and PAEB systems. Lastly, regarding final stage 
manufacturers, NHTSA is aware that these manufacturers buy incomplete 
vehicles from first-stage manufacturers. Then these vehicles are 
modified from larger manufacturer stock that would already be 
compliant. Therefore, there would be no incremental compliance costs.
    As noted in the NPRM, much of the work developing and manufacturing 
AEB system components would be conducted by suppliers. Although the 
final certification would be made by the manufacturer, the NPRM 
proposed allowing for one additional year for small-volume 
manufacturers to comply with any requirement. That approach is similar 
to the approach we have taken in other rulemakings in recognition of 
manufacturing differences between larger and smaller manufacturers. As 
the countermeasures are developed, AEB suppliers would likely supply 
larger vehicle manufacturers first, before small manufacturers. In the 
proposed rule, NHTSA recognized this and maintained the agency's 
position that small manufacturers need additional flexibility, so they 
have time to obtain the equipment and work with the suppliers after the 
demands of the larger manufacturers are met.
    The difference between the proposal and what is finalized in this 
rule is that NHTSA is no longer pursuing different lead-times based on 
the technology or phase-in schedules. Rather, the agency is providing 
all manufacturers with two extra years of lead time for lead vehicle 
AEB and one extra year of lead time for the most stringent requirements 
for PAEB (i.e., 5 years of lead time regardless of technology). The 
rule adopts a 5-year lead time for all requirements and all 
manufacturers to ensure that the public attains lead vehicle AEB and 
PAEB safety benefits as soon as practicable. Small volume manufacturers 
would not have to comply for six years due to the additional year 
provided to them.
    This rule may also affect final stage manufacturers, many of whom 
would be small businesses. While it is NHTSA's understanding that final 
stage manufacturers rarely make modifications to a vehicle's braking 
system and instead rely upon the pass-through certification provided by 
a first-stage manufacturers, as with small-volume manufacturers, final 
stage manufacturers would be provided with one additional year to 
comply with any requirement.
    NHTSA received comments on the Regulatory Flexibility Act analysis 
included in the NPRM. One commenter asserted that NHTSA did not 
adequately consider the additional burden for small volume 
manufacturers and the unique design characteristics that would present 
additional compliance challenges for small manufacturers. The unique 
design considerations include low ground clearance, bumper 
characteristics that would require mounting radar very close to the 
ground, thereby requiring additional engineering to manage increased 
sensor signal noise, the general shape of the bumper, and the materials 
used for the bumper. This commenter said that the combination of these 
factors raises the risk of false positives and/or angular distortion of 
the target object in vertical and horizontal plane. Another commenter 
raised concerns about the engineering challenges faced by manufacturers 
of ``SuperCars'' and concern that these manufacturers would revert to 
seeking exemptions instead of pursuing FMVSS compliance.
    In response to these comments, NHTSA notes that it has extended the 
lead time for all manufacturers to 5 years in this final rule. As 
proposed, final stage manufacturers and small-volume manufacturers 
would receive an additional year to comply, thus giving those entities 
6 years to comply with this final rule. NHTSA believes that 6 years is 
sufficient time for even the smallest manufacturers to design and 
conform their products to this FMVSS, or seek an exemption if they have 
grounds under one of the bases listed in 49 CFR part 555.
    I certify that this final rule would not have a significant 
economic impact on a substantial number of small entities. Additional 
information concerning the potential impacts of this rule on small 
entities is presented in the RIA accompanying this rule.

National Environmental Policy Act

    The National Environmental Policy Act of 1969 (NEPA) \164\ 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.\165\ The Council on Environmental Quality (CEQ) directs Federal 
agencies to prepare an environmental assessment for a proposed action 
``that is not likely to

[[Page 39769]]

have significant effects or when the significance of the effects is 
unknown.'' \166\ 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.'' \167\
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    \164\ 42 U.S.C. 4321-4347.
    \165\ 42 U.S.C. 4332(2)(C).
    \166\ 40 CFR 1501.5(a).
    \167\ 40 CFR 1501.5(c).
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    This section serves as NHTSA's Final Environmental Assessment (EA). 
In this Final EA, NHTSA outlines the purpose and need for the 
rulemaking, a reasonable range of alternative actions the agency 
considered through rulemaking, the projected environmental impacts of 
these alternatives. NHTSA did not receive any comments on the Draft EA.

Purpose and Need

    This final rule sets forth the purpose of and need for this action. 
In this final rule, NHTSA is adopting a new FMVSS to require AEB 
systems on light vehicles capable of reducing the frequency and 
severity of both lead vehicle rear-end (lead vehicle AEB) and 
pedestrian crashes (PAEB). 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 with a lead vehicle or pedestrian. This final rule promotes 
NHTSA's goal to reduce the frequency and severity of crashes described 
in the summary of the crash problem discussed earlier in the final 
rule, and advances DOT's January 2022 National Roadway Safety Strategy 
that identified requiring AEB, including PAEB technologies, on new 
passenger vehicles as a key Departmental action to enable safer 
vehicles. This final rule also responds to a mandate under the 
Bipartisan Infrastructure Law (BIL) directing the Department to 
promulgate such a rule.

Alternatives

    NHTSA considered four 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 with systems that meet minimum specified performance 
requirements, and manufacturers would continue to add AEB systems 
voluntarily. However, because the BIL directs NHTSA to promulgate a 
rule that would require that all passenger vehicles be equipped with an 
AEB system, NHTSA cannot adopt the no action alternative. Alternative 1 
considers requirements specific to lead vehicle AEB only. Alternative 2 
includes the lead vehicle AEB requirements in Alternative 1 and a 
requirement in which PAEB is only required to function in daylight 
conditions. Alternative 3, the selected alternative, considers 
requirements for lead vehicle AEBs and PAEB requirements in both 
daylight and darkness conditions. Alternative 4 considers a more-
stringent requirement in which PAEB would be required to provide 
pedestrian protections in turning scenarios (no change to the lead 
vehicle AEB requirements in the final rule).
    NHTSA also considered other options, including the International 
Organization for Standardization (ISO) standards, SAE International 
standards, the Economic Commission for Europe (ECE) standards, test 
procedures used by NHTSA's New Car Assessment Program (NCAP) and Euro 
NCAP, which are described above in this preamble and accompanying 
appendices. In the final rule, NHTSA incorporates aspects of the test 
procedures and standards mentioned here, but departs from them in 
numerous and significant ways.

Environmental Impacts of the Proposed Action and Alternatives

    This final rule is anticipated to result in the employment of 
sensor technologies and sub-systems on light vehicles that work 
together to sense when a vehicle is in a crash imminent situation, to 
automatically apply the vehicle brakes if the driver has not done so, 
and to apply more braking force to supplement the driver's braking if 
insufficient. This final rule is also anticipated to improve safety by 
mitigating the number of fatalities, non-fatal injuries, and property 
damage that would result from crashes that could potentially be 
prevented or mitigated because of AEB. As a result, the primary 
environmental impacts \168\ that could potentially result from this 
rulemaking are associated with: greenhouse gas emissions and air 
quality, socioeconomics, public health and safety, solid waste/property 
damage/congestion, and hazardous materials. Consistent with CEQ 
regulations and guidance, this EA discusses impacts in proportion to 
their potential significance. The effects of the final rule that were 
analyzed further are summarized below.
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    \168\ NHTSA anticipates that this rulemaking 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.
---------------------------------------------------------------------------

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 greenhouse gas emissions or air 
quality impacts from criteria pollutant emissions. Atmospheric 
greenhouse gases (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 greenhouse gas 
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 cause an increase in vehicle fuel consumption and 
emissions. An AEB system requires the following hardware: sensing, 
perception, warning hardware, and electronically modulated braking 
subsystems.\169\ As discussed in the preamble and the RIA, NHTSA 
anticipates that under the no action alternative and Alternatives 1-3, 
the majority of vehicles subject to the rulemaking would already have 
all of the hardware capable of meeting the requirements by the 
effective date of a final rule. For all alternatives, NHTSA assumes 
that manufacturers will need

[[Page 39770]]

time to build code that analyses the frontal view of the vehicle (i.e., 
manufacturers would need to upgrade the software for the perception 
subsystem) in a way that achieves the requirements of this final rule. 
Furthermore, approximately five percent of vehicles would add 
additional hardware such as a camera or radar. In addition to those 
costs, Alternative 4 includes an assumption that two cameras would be 
added; however, based on weight assumptions included in studies cited 
in the RIA, that weight impact would be minimal. The incremental weight 
associated with a stereo camera module is 785 g (1.73 lbs.) and for the 
entire camera and radar fused system is 883 g. (1.95 lbs.). NHTSA has 
previously estimated that a 3-4-pound increase in vehicle weight is 
projected to reduce fuel economy by 0.01 mpg.\170\ Accordingly, 
Alternatives 1-3 would not have any fuel economy penalty for 95 percent 
of vehicles subject to the rulemaking because no hardware would be 
added. The potential impact on fuel economy for those five percent that 
would add an additional hardware would be negligible as it would 
potentially be under a pound when considering half the weight of either 
the stereo camera module or camera and radar fused system or under two 
pounds based on the stereo camera module. Similarly, Alternative 4 
would potentially have a negligible fuel economy penalty as the 
potential incremental weight would be under two pounds based on the 
stereo camera module.
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    \169\ Automatic actuation of a vehicle's brakes requires more 
than just technology to sense when a collision is imminent. In 
addition to the sensing system, hardware is needed to apply the 
brakes without relying on the driver to depress the brake pedal. The 
automatic braking system relies on two foundational braking 
technologies--electronic stability control to automatically activate 
the vehicle brakes and an antilock braking system to mitigate wheel 
lockup. Not only do electronic stability control and antilock 
braking systems enable AEB operation, these systems also modulate 
the braking force so that the vehicle remains stable while braking 
during critical driving situations where a crash with a vehicle or 
pedestrian is imminent.
    \170\ Final Regulatory Impact Analysis, Corporate Average Fuel 
Economy for MYs 2012-2016 Passenger Cars and Light Trucks, Table IV-
5 (March 2010).
---------------------------------------------------------------------------

    Pursuant to the Clean Air Act (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). The 
NAAQS include ``primary'' standards and ``secondary'' standards. 
Primary standards are intended to protect public health with an 
adequate margin of safety. Secondary standards are set at levels 
designed to protect public welfare by accounting for the effects of air 
pollution on vegetation, soil, materials, visibility, and other aspects 
of the general welfare. Under the General Conformity Rule of the 
CAA,\171\ 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). The General Conformity Rule does not, 
however, require a conformity determination for Federal ``rulemaking 
and policy development and issuance,'' such as this action.\172\ 
Therefore, NHTSA has determined it is not required to perform a 
conformity analysis for this action.
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    \171\ 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).
    \172\ 40 CFR 93.153(c)(2)(iii).
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Socioeconomics

    The socioeconomic impacts of the rulemaking would be primarily felt 
by vehicle manufacturers, light vehicle drivers, passengers, and 
pedestrians on the road that would otherwise be killed or injured in 
light vehicle crashes. NHTSA conducted a detailed assessment of the 
economic costs and benefits of establishing the new rule in its RIA. 
The main economic benefits come primarily from the reduction in 
fatalities and non-fatal injuries (safety benefits). Reductions in the 
severity of motor 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 RIA that would affect these parties include software 
and some hardware costs and property damage savings. Overall, 
Alternative 1 is anticipated to have societal net benefits of $3.40 to 
$4.28 billion, Alternative 2 is anticipated to have societal net 
benefits of $4.23 to $5.30 billion, Alternative 3 (the selected 
alternative) is anticipated to have societal net benefits of $5.82 to 
$7.26 billion, and Alternative 4 is anticipated to have societal net 
benefits of $4.18 to $5.73 billion. The RIA discusses this information 
in further detail.

Public Health and Safety

    The affected environment for public health and safety includes 
roads, highways and other driving locations used by all light vehicle 
drivers, other drivers, 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 RIA, 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 four action alternatives. Under Alternative 1, it is 
expected that the addition of a less stringent requirement that only 
specifies requirements for lead vehicle AEB would result each year in 
314 to 388 equivalent lives saved. Under Alternative 2, it is expected 
that the less-stringent requirement, in which PAEB is only required to 
function in daylight conditions, would result each year in 384 to 473 
equivalent lives saved. Under Alternative 3 (the selected alternative), 
it is expected that the regulatory option would result each year in 517 
to 638 equivalent lives saved. Finally, under Alternative 4, it is 
expected that the addition of more stringent requirements in which PAEB 
would be required to provide pedestrian protections in turning 
scenarios would result each year in 555 to 684 equivalent lives saved. 
The RIA 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.
    NHTSA's rulemaking is projected to reduce the amount and severity 
of light vehicle crashes, and therefore may reduce the quantity of 
solid waste, hazardous materials, and other property damage generated 
by light vehicle crashes in the United States. The addition of an AEB 
system may also result in reduced damage to the vehicles and property, 
as well as reduced travel delay costs due to congestion. This is 
especially the case in ``property-damage-only'' crashes, where no 
individuals are injured or killed in the crash, but there may be damage 
to the vehicle or whatever is impacted by it. NHTSA estimates that 
based off data from 2016-2019 alone, an average of 1.12 million rear-
impact crashes involving light vehicles occurred

[[Page 39771]]

annually. These crashes resulted in an annual average of 394 
fatalities, 142,611 non-fatal injuries, and approximately 1.69 million 
PDOVs.
    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 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.
    The addition of an AEB system may also result in reduced post-crash 
environmental effects from congestion. As discussed in the RIA, 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 has recognized that motor vehicle crashes result in congestion 
that has both socioeconomic and environmental effects. These 
environmental effects include ``wasted fuel, increased greenhouse gas 
production, and increased pollution as engines idle while drivers are 
caught in traffic jams and slowdowns.'' \173\ NHTSA's monetized 
benefits therefore include a quantified measure of congestion 
avoidance. NHTSA did not calculate congestion effects specifically for 
each regulatory alternative; however, because comprehensive costs are a 
discrete cost applied to non-fatal injuries and fatalities at the same 
rate, we can conclude that there are increasing benefits associated 
with fewer crashes, and specifically decreased congestion, as the 
monetized benefits increase across regulatory alternatives. To the 
extent that any regulatory option for AEB results in fewer crashes and 
accordingly higher monetized benefits, there would be fewer congestion-
related environmental effects.
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    \173\ 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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    NHTSA has tentatively concluded that under the agency's rulemaking, 
the economic benefits resulting from improved safety outcomes, property 
damage savings, fuel savings, and GHG reductions would limit the 
negative environmental impacts caused by additional solid waste/
property damage due to crashes because of the crashes that will be 
avoided due to the requirements of this rule. Similarly, while the 
potential degree of hazardous materials spills prevented due to the 
reduction of crash severity and crash avoidance expected from the 
rulemaking has not specifically been analyzed in the RIA or final rule, 
the addition of the AEB system is projected to reduce the amount and 
severity of light vehicle crashes and may improve the environmental 
effects with respect to hazardous material spills. While the RIA does 
not specifically quantify these impact categories, in general NHTSA 
believes the benefits would increase relative to the crashes avoided 
and would be relative across the different alternatives. The RIA 
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.

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 
actions regardless of what agency (Federal or non-Federal) or person 
undertakes such other actions.'' \174\ NHTSA notes that the public 
health and safety, solid waste/property damage/congestion, air quality 
and greenhouse gas emissions, socioeconomic, and hazardous material 
benefits identified in this EA were based on calculations described in 
the RIA, in addition to other NHTSA actions and studies on motor 
vehicle safety as described in the preamble. 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.
---------------------------------------------------------------------------

    \174\ 40 CFR 1508.1(g)(3).
---------------------------------------------------------------------------

    NHTSA's and other parties' past actions that improve the safety of 
light vehicles, as well as future actions taken by the agency or other 
parties that improve the safety of light vehicles, could further reduce 
the severity or number of crashes involving light vehicles. Any such 
cumulative improvement in the safety of light vehicles would have an 
additional effect in reducing injuries and fatalities and could reduce 
the quantity of solid and hazardous materials generated by crashes. To 
the extent that this rule may have some minimal impact on fuel economy 
for the small percentage of vehicles where additional hardware may be 
required, NHTSA would consider that impact when setting maximum 
feasible fuel economy standards.'' \175\
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    \175\ 49 U.S.C. 32902(f), which states that we consider the 
effect of other motor vehicle standards of the Government on fuel 
economy in the max feasible discussion.
---------------------------------------------------------------------------

Agencies and Persons Consulted

    This preamble describes the various materials, persons, and 
agencies consulted in the development of the final rule. NHTSA invited 
public comments on the contents and tentative conclusions of the Draft 
EA. No public comments addressing the Draft EA were received. 
Furthermore, none of the public comments that were received addressed 
any issues related to the human environment that would be relevant to 
the Final EA.

Finding of No Significant Impact

    Although this rule is anticipated to result in additional FMVSS 
requirements for light vehicle manufacturers, AEB systems have already 
largely been introduced by manufacturers voluntarily. The addition of 
regulatory requirements (depending on the regulatory alternative) to 
standardize the AEB systems in all vehicle models is anticipated to 
result in negligible or no fuel economy and emissions penalties (i.e., 
five percent of vehicles would require additional hardware, but the 
added weight is negligible), increasing socioeconomic and public safety 
benefits as the alternatives get more stringent, and an increase in 
benefits from the reduction in solid waste, property damage, and 
congestion (including associated traffic level impacts like reduction 
in energy consumption and tailpipe pollutant emissions) from fewer 
vehicle crashes across the regulatory alternatives.
    Based on the Final EA, NHTSA concludes that implementation of any 
of the alternatives considered for the proposed action, including the 
selected alternative, will not have a significant effect on the human 
environment and that a ``finding of no significant impact''

[[Page 39772]]

is appropriate. This statement constitutes the agency's ``finding of no 
significant impact,'' and an environmental impact statement will not be 
prepared.\176\
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    \176\ 40 CFR 1501.6(a).
---------------------------------------------------------------------------

Executive Order 13132 (Federalism)

    NHTSA has examined this rule pursuant to Executive Order 13132 (64 
FR 43255, August 10, 1999) and concluded that no additional 
consultation with States, local governments, or their representatives 
is mandated beyond the rulemaking process. The agency has concluded 
that this rule will not have sufficient federalism implications to 
warrant consultation with State and local officials or the preparation 
of a federalism summary impact statement. The rule does 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 compliance 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. The 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. 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 Orders 13132 and 12988, NHTSA has considered 
whether this 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 (i.e., the language and 
structure of the regulatory text) and objectives of this rule and finds 
that this rule, like many NHTSA rules, would prescribe only a minimum 
safety standard. As such, NHTSA does not intend this rule to preempt 
state tort law that would effectively impose a higher standard on motor 
vehicle manufacturers. 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.

Executive Order 12988 (Civil Justice Reform)

    When promulgating a 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 that the preemptive effect of 
this rulemaking is discussed above in connection with Executive Order 
13132. 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.

Executive Order 13045 (Protection of Children From Environmental Health 
and Safety Risks)

    Executive Order 13045, ``Protection of Children from Environmental 
Health and Safety Risks,'' (62 FR 19885; April 23, 1997) applies to any 
proposed or final rule that: (1) Is determined to be ``economically 
significant,'' as defined in E.O. 12866, and (2) concerns an 
environmental health or safety risk that NHTSA has reason to believe 
may have a disproportionate effect on children. If a rule meets both 
criteria, the agency must evaluate the environmental health or safety 
effects of the rule on children, and explain why the rule is preferable 
to other potentially effective and reasonably feasible alternatives 
considered by the agency.
    This rule is not expected to have a disproportionate health or 
safety impact on children. Consequently, no further analysis is 
required under Executive Order 13045.

Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et. seq., as added by 
the Small Business Regulatory Enforcement Fairness Act of 1996, 
generally provides that before a rule may take effect, the agency 
promulgating the rule must submit a rule report, which includes a copy 
of the rule, to each House of the Congress and to the Comptroller 
General of the United States. NHTSA will submit a report containing 
this rule and other required information to the U.S. Senate, the U.S. 
House of Representatives, and the Comptroller General of the United 
States prior to publication of the rule in the Federal Register. 
Because this rule meets the criteria in 5 U.S.C. 804(2), it will be 
effective sixty days after the date of publication in the Federal 
Register.

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 rule.

[[Page 39773]]

National Technology Transfer and Advancement Act

    Under the National Technology Transfer and Advancement Act of 1995 
(NTTAA) (Pub. L. 104-113), all Federal agencies and departments shall 
use technical standards 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) developed or adopted by voluntary consensus 
standards bodies, such as the International Organization for 
Standardization and SAE International. The NTTAA directs us to provide 
Congress, through OMB, explanations when we decide not to use available 
and applicable voluntary consensus standards.
    NHTSA is incorporating by reference ISO and ASTM standards into 
this rule. NHTSA considered several ISO standards and has opted to use 
ISO 19206-3:2021 to specify the vehicle test device and a combination 
of ISO 19206-2:2018 and ISO 19206-4:2020 to specify the test 
mannequins. 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 International Recommended Practice J3087, 
``Automatic emergency braking (AEB) system performance testing,'' which 
defines the conditions for testing AEB and FCW systems. This standard 
defines test conditions, test targets, test scenarios, and measurement 
methods, but does not provide performance criteria. There is 
considerable overlap in the test setup and conditions between this rule 
and the SAE standard including the basic scenarios of lead vehicle 
stopped, slower moving, and decelerating. This SAE recommended practice 
is substantially similar to the existing NCAP test procedures and this 
rule.
    NHTSA also considered SAE International Standard J3116, ``Active 
Safety Pedestrian Test Mannequin Recommendation,'' which provides 
recommendations for the characteristics of a surrogate that could be 
used in testing of active pedestrian safety systems. As proposed, NHTSA 
incorporates the ISO standard because the ISO standard specifications 
are more widely adopted than the SAE Recommended Practice.
    In appendix B of the NPRM's preamble, NHTSA described several 
international test procedures and regulations the agency considered for 
use in this rule. This rule has substantial technical overlap with 
UNECE Regulation No. 131 and UNECE Regulation No. 152. This rule and 
the UNECE regulations both specify a forward collision warning and 
automatic emergency braking. Several lead vehicle AEB scenarios are 
nearly identical, including the lead vehicle stopped and lead vehicle 
moving scenarios. The pedestrian crossing path scenario specified in 
UNECE Regulation No. 152 is also substantially similar to this rule. As 
discussed in the preamble, this rule differs from the UNECE standards 
in the areas of maximum test speed and the minimum level of required 
performance. This rule uses higher test speeds and a requirement that 
the test vehicle avoid contact, both of which are more stringent than 
the UNECE regulations and more reflective of the safety need in the 
United States. NHTSA expects that 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), 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. At the final rule 
stage, regulations require that the agency seek formal approval, 
summarize the material that it incorporates by reference in the 
preamble of the final rule, discuss the ways that the materials are 
reasonably available to interested parties, and provide other specific 
information to the Office of the Federal Register.
    In this rule, NHTSA incorporates by reference six documents into 
the Code of Federal Regulations, ASTM E1337-19, Standard Test Method 
for Determining Longitudinal Peak Braking Coefficient (PBC) of Paved 
Surfaces Using Standard Reference Test Tire, is already incorporated by 
reference elsewhere in 49 CFR part 571. 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 also incorporates by reference SAE J2400 Human Factors in 
Forward Collision Warning System: Operating Characteristics and User 
Interface Requirements, into part 571. SAE J2400 is an information 
report intended as a starting point of reference for designers of 
forward collision warning systems. NHTSA incorporates this document by 
reference solely to specify the location specification and symbol for a 
visual forward collision warning.
    NHTSA incorporates by reference four ISO standards into 49 CFR part 
596. The first of these standards is ISO 3668:2017(E), Paints and 
varnishes--Visual comparison of colour of paints. This document 
specifies a method for the visual comparison of the color of paints 
against a standard. This method will be used to verify the color of 
certain elements of the pedestrian test mannequin NHTSA will use in 
PAEB testing. Specifically, NHTSA will use these procedures to 
determine that the color of the hair, torso, arms, and feet of the 
pedestrian test mannequin is black and that the color of the legs are 
blue.
    NHTSA incorporates by reference ISO 19206-2:2018(E), Road 
vehicles--Test devices for target vehicles, vulnerable road users and 
other objects, for assessment of active safety functions--Part 2: 
Requirements for pedestrian targets. This document addresses the 
specification for a test mannequin. It is designed to resemble the 
characteristics of a human, while ensuring the safety of the test 
operators and preventing damage to subject vehicles in the event of a 
collision during testing. NHTSA references many, but not all, of the 
specifications of ISO 19206-2:2018, as discussed earlier in the 
preamble of this rule.
    NHTSA also incorporates 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. Like the 
test mannequin described in the prior paragraph, 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 
references many, but not all, of the specifications of ISO 19206-
3:2021, as discussed earlier in the preamble of this rule.
    Finally, NHTSA incorporates by reference ISO 19206-4:2020(E), Road 
vehicles--test devices for target vehicles,

[[Page 39774]]

vulnerable road users and other objects, for assessment of active 
safety functions--Part 4: Requirements for bicyclists targets. This 
standard describes specifications for bicycle test devices 
representative of adult and child sizes. NHTSA will not use a bicycle 
test device during testing for this final rule. Rather, this standard 
is incorporated by reference solely because it contains specifications 
for color and reflectivity, including skin color, that NHTSA is 
applying to its pedestrian test mannequin.
    All standards incorporated by reference in this rule are available 
for review at NHTSA's headquarters in Washington, DC, and for purchase 
from the organizations promulgating the standards (see 49 CFR 517.5 for 
contact information). The ASTM standard presently incorporated by 
reference into other NHTSA regulations is also available for review at 
ASTM's online reading room.\177\
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    \177\ https://www.astm.org/products-services/reading-room.html.
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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, of more than 
$100 million annually (adjusted annually for inflation with base year 
of 1995). Adjusting this amount by the implicit gross domestic product 
price deflator for 2021 results in an estimated current value of $165 
million (2021 index value of 113.07/1995 index value of 68.60 = 1.65). 
The assessment may be included in conjunction with other assessments, 
as it is for this rule in the RIA.
    A rule on lead vehicle AEB and PAEB is not likely to result in 
expenditures by State, local or tribal governments of more than $100 
million annually. However, it is estimated to result in the estimated 
expenditure by automobile manufacturers and/or their suppliers of $354 
million annually (estimated to be an average of approximately $23 per 
light vehicle annually). This average estimated cost impacts reflects 
that the estimated incremental costs depend on a variety of lead 
vehicle AEB hardware and software that manufacturers plan to install 
(in vehicles used as ``baseline'' for the cost estimate). The final 
cost will greatly depend on choices made by the automobile 
manufacturers to meet the lead vehicle AEB and PAEB test requirements. 
These effects have been discussed in the RIA developed in support of 
this final rule.
    The Unfunded Mandates Reform Act requires the agency to select the 
``least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule.'' As an alternative, the 
agency considered a full-vehicle dynamic test to evaluate the 
capability of lead vehicle AEB and PAEB systems to prevent crashes or 
mitigate the severity of crashes. Based on our experience on conducting 
vehicle tests for vehicles equipped with lead vehicle AEB and PAEB 
where we utilize a reusable surrogate target crash vehicle and test 
mannequins instead of conducting the test with an actual vehicle as the 
target, we determined that full vehicle-to-vehicle crash tests can have 
an undesired amount of variability in vehicle kinematics. Unlike 
vehicle-to-vehicle tests, the lead vehicle AEB and PAEB tests with a 
surrogate target vehicle is conducted in a well-controlled test 
environment, which results in an acceptable amount of variability. In 
addition, the agency's lead vehicle AEB and PAEB tests with surrogate 
target vehicle and pedestrian were able to reveal deficiencies in the 
system that resulted in inadequate system capability in detecting and 
activating the brakes. Therefore, we concluded that a full vehicle-to-
vehicle test would not achieve the objectives of the rule.
    In addition, the agency evaluated data across a broad range of test 
scenarios in an effort to identify the maximum range of test speeds at 
which it is feasible for test vehicles to achieve a no-contact result. 
The range of feasible speeds for no contact identified in the review 
was specified as the mandated range in the rule. Thus, there are no 
alternative test procedures available that would improve the ability of 
manufacturers to achieve no-contact results. In turn, the agency 
concluded that lead vehicle AEB and PAEB systems designed to meet the 
no-contact requirement at speeds outside the ranges specified in the 
rule would not achieve the objectives of the rule.

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 
requested public comment on the ``regulatory approaches taken by 
foreign governments'' concerning the subject matter of this rulemaking. 
NHTSA received many comments expressing that NHTSA should either align 
or adopt existing international regulations. As discussed above, while 
NHTSA has adopted aspects of these regulations, it has rejected others 
because of the stringency of the regulations due to the reasons 
discussed in further detail in various parts of the preamble and 
National Technology Transfer and Advancement Act section.

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. It expresses NHTSA's view that, even with invalidated 
portions or applications disregarded, remaining portions and 
applications can still function sensibly.

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 Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

VI. Appendices to the Preamble

A. Appendix A: Description of the Lead Vehicle AEB Test Procedures 
Stopped Lead Vehicle

Test Parameters
    The stopped lead vehicle scenario consists of the vehicle traveling 
straight ahead, at a constant speed, approaching a stopped lead vehicle 
in its path. The vehicle must be able to avoid contact with the stopped 
lead vehicle. The testing is at any subject vehicle speed

[[Page 39775]]

between 10 km/h and 80 km/h with no manual brake application and 
between 70 km/h and 100 km/h with manual brake application.
Test Conduct Prior to FCW Onset
    Prior to the start of a test, the lead vehicle is placed with its 
longitudinal centerline coincident to the intended travel path and with 
no specific limitations on how a subject vehicle may be driven prior to 
the test start. As long as the specified initialization procedure is 
executed, a subject vehicle may be driven under any conditions 
including any speed and direction, and on any road surface, for any 
elapsed time prior to reaching the point where a test trial begins. As 
the subject vehicle approaches the rear of the lead vehicle, 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. Furthermore, beginning when the 
headway corresponds to L0, the subject vehicle heading is 
maintained with minimal steering input such that the subject vehicle 
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. The purpose of these test tolerances is to 
assure test practicability and repeatability of results.
Test Conduct After FCW Onset
    During each test, the subject vehicle accelerator pedal is released 
in response to the FCW. The procedure states that the accelerator pedal 
is released at any rate and is fully released within 500 milliseconds 
for subject vehicles tested without cruise control active. The 
accelerator release procedure ensures consistent release of the 
accelerator and assures test repeatability. The accelerator pedal 
release can be omitted from tests of vehicles with cruise control 
actively engaged because there is no driver input to the accelerator 
pedal in that case. The AEB performance requirements are the same for 
vehicles with and without cruise control engaged, and AEB systems must 
provide an equivalent level of crash avoidance or mitigation regardless 
of whether cruise control is active.
    For testing without manual brake application, no manual brake 
application is made until one of the test completion criteria is 
satisfied. For tests that include manual brake application, the service 
brakes are applied at 1.0  0.1 second after FCW.
Test Completion Criteria
    Any test 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.
Slower-Moving Lead Vehicle
Test Parameters
    The slower-moving lead vehicle scenario involves the subject 
vehicle traveling straight ahead at constant speed, approaching a lead 
vehicle traveling at a slower speed in the subject vehicle path. NHTSA 
will test at the same two subject vehicle speed ranges as the stopped 
lead vehicle scenario depending on the manual brake application. The 
lead vehicle speed is 20 km/h.
Test Conduct Prior to FCW Onset
    Prior to the start of a test trial 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.
    As the subject vehicle approaches the rear of the lead vehicle, 
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. Furthermore, beginning 
when the headway corresponds to L0, the subject vehicle and 
lead heading are to be maintained with minimal steering input such that 
the subject vehicle 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.
Test Conduct After FCW Onset
    Similar to the stopped lead vehicle test, the subject vehicle 
accelerator pedal is released in response to the FCW. The procedure 
states that the accelerator pedal is released at any rate and is fully 
released within 500 milliseconds for subject vehicles tested without 
cruise control active. The accelerator pedal release can be omitted 
from tests of vehicles with cruise control actively engaged due to the 
lack of driver input to the accelerator pedal.
    For testing without manual brake application, no manual brake 
application is made until one of the test completion criteria is 
satisfied. For testing with manual brake application, the service brake 
application occurs at 1.0  0.1 second after FCW onset.
Test Completion Criteria
    Any 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.
Decelerating Lead Vehicle
Test Parameters
    The decelerating lead vehicle scenario is meant to assess the AEB 
performance when the subject vehicle and lead vehicle initially are 
travelling at the same constant speed in a straight path and the lead 
vehicle begins to decelerate. NHTSA tests under two basic setups for 
this scenario, one where both the subject vehicle and lead vehicle 
initial travel speed (VSV = VLV) is 50 km/h and 
another where both vehicles travel at 80 km/h. For both testing speeds, 
NHTSA tests with, and without, manual brake application, at any headway 
between 12 m and 40 m and at any lead vehicle deceleration between 0.3 
g and 0.5 g.
Test Conduct Prior to Lead Vehicle Braking Onset
    Up to 3 seconds prior to the start of a test trial there are no 
specific limitations on how a subject vehicle may be driven. Between 3 
seconds prior and the lead vehicle braking onset, 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. During this same time interval, the subject 
vehicle follows the lead vehicle at the testing headway distance 
between 12 m and 40m. While the subject vehicle follows the lead 
vehicle from 3 seconds prior and lead vehicle brake onset, the subject 
vehicle and lead vehicle speeds are maintained within 1.6 km/h and 
their travel paths do not deviate more than 0.3 m laterally from the 
centerline of the lead vehicle. The speed is to be maintained with 
minimal and smooth accelerator pedal inputs and the and yaw rate of the 
subject vehicle may not exceed 1.0 deg/s.
Test Conduct After Lead Vehicle Braking Onset
    The lead vehicle is decelerated to a stop with a targeted average 
deceleration of any value between 0.3g and 0.5g. The targeted 
deceleration magnitude is to be achieved within 1.5 seconds of lead 
vehicle braking onset and maintained until 250 ms prior to coming to a 
stop. Similar to the lead vehicle tests, during each test trial, the 
subject vehicle accelerator pedal is released in response to the FCW 
and fully released within 500 milliseconds.
    In the same manner as the slower lead vehicle tests, when testing 
without

[[Page 39776]]

manual brake application, no manual brake application is made until one 
of the test completion criteria is satisfied. For testing with manual 
brake application, the service brake application occurs at 1.0  0.1 second after FCW onset.
Test Completion Criteria
    Any 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, similarly to the 
stopped lead vehicle tests.
Headway Calculation
    For the scenarios where the headway is not specified (stopped lead 
vehicle and slower lead vehicle) 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 = 5.0
Travel Path
    The intended travel path is the target path for a given test 
scenario and is identified by the projection onto the road surface of 
the frontmost point of the subject vehicle located on its longitudinal, 
vertical center plane. The subject vehicle's actual travel path is 
recorded and compared to the intended path.
    The intended subject vehicle travel path is coincident with the 
center of a test lane whenever there are two edge lines marking a lane 
on the test track surface. If there is only one lane line (either a 
single or double line) marked on the test track, the vehicle path will 
be parallel to it and offset by 1.8 m (6 ft) to one side (measured from 
the inside edge of the line).
Subject Vehicle (Manual) Brake Application Procedures
    Subject vehicle brake application is performed through either 
displacement or hybrid feedback at the manufacturer's choosing. The 
subject vehicle brake application procedures are consistent with the 
manual brake applications defined in NHTSA's NCAP test procedures for 
DBS performance assessment. The procedure is to begin with the subject 
vehicle brake pedal in its natural resting position with no preload or 
position offset.
Displacement Feedback Procedure
    For the displacement feedback procedure, the commanded brake pedal 
position is the brake pedal position that results in a mean 
deceleration of 0.4 g in the absence of AEB system activation. 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. 
The pedal displacement controller depresses the pedal at a rate of 254 
mm/s 25.4 mm/s to the commanded brake pedal position. The 
standard allows for the pedal displacement controller to overshoot the 
commanded position by any amount up to 20 percent. In the event of an 
overshoot, it may be corrected within 100 ms. 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.
Hybrid Brake Pedal Feedback Procedure
    For the hybrid brake pedal feedback procedure, the commanded brake 
pedal application is the brake pedal position and a subsequent 
commanded brake pedal force that results in a mean deceleration of 0.4 
g in the absence of AEB system activation. The hybrid brake pedal 
application procedure follows the displacement application procedure, 
but instead of maintaining the achieved brake pedal displacement, the 
controller starts to control the force applied to the brake pedal (100 
ms after pedal displacement occurs and any overshoot is corrected). The 
hybrid controller applies a pedal force of at least 11.1 N and 
maintains the pedal force 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.
Force Feedback Procedure
    For the force feedback procedure, the commanded brake pedal 
application is the brake pedal force that results in a mean 
deceleration of 0.4 g in the absence of AEB system activation. The mean 
deceleration is the deceleration over the time from when the commanded 
brake pedal force is first achieved to 250 ms before the vehicle comes 
to a stop. The force controller achieves the commanded brake pedal 
force within 250 ms. The application rate is unrestricted. The force 
controller may overshoot the commanded force by up to 20 percent. If 
such an overshoot occurs, it is corrected within 250 ms from when the 
commanded force is first achieved. The force controller applies a pedal 
force of at least 11.1 N from the onset of the brake application until 
the end of the test.

B. Appendix B: Description of the PAEB Test Procedures

Test Parameters
    The PAEB performance tests require a vehicle to avoid a collision 
with a pedestrian test device by applying the brakes automatically 
under certain test-track scenarios during daylight and darkness (with 
lower beam and with upper beams activated). Similar to the lead vehicle 
AEB performance test requirements, NHTSA adopted a no-contact 
requirement as a performance metric. The test scenarios for PAEB 
evaluation fall into three groups of scenarios based on the actions of 
the pedestrian test device--crossing path, stationary and along path. 
For each test conducted under the testing scenarios, NHTSA adopted the 
following options within those testing scenarios: (1) pedestrian 
crossing (right or left) relative to an approaching subject vehicle, 
(2) subject vehicle overlap (25% or 50%), (3) pedestrian obstruction 
(Yes/No), and (4) pedestrian speed stationary, walking, or 
running(VP). Further parameters when approaching a 
pedestrian are selected from a subject vehicle speed range 
(VSV) and the lighting condition (daylight, lower beams or 
upper beams). As opposed to lead vehicle AEB track testing, manual 
brake application by the driver is not a parameter of the test 
scenarios for PAEB.
    Similarly to the lead vehicle AEB testing, NHTSA specifies that the 
travel path in each of the test scenarios be straight. For PAEB 
testing, the intended travel path of the subject vehicle is a straight 
line originating at the location corresponding to a headway of 
L0.
    NHTSA specifies that if the road surface is marked with a single or 
double lane line, the intended travel path be 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.
    For each PAEB test run, the headway (L0), in meters, between the 
front plane of the subject vehicle and a parallel contact plane on the 
pedestrian test mannequin providing 4.0 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 VP-y is the component of 
speed of the pedestrian test mannequin in m/s in the direction of the 
intended travel path:

L0 = TTC0 x (VSV-VP-y)
TTC0 = 4.0
    Overlap describes the location of the point on the front of the 
subject vehicle that would make contact with the

[[Page 39777]]

pedestrian test mannequin (PTM) if no braking occurred and is the 
percentage of the subject vehicle's overall width that the pedestrian 
test mannequin traverses. It identifies the point on the subject 
vehicle that would contact a test mannequin within the subject vehicle 
travel path if the subject vehicle were to maintain its speed without 
braking, and it is measured from the right or the left (depending on 
the side of the subject vehicle where the pedestrian test mannequin 
originates).
Pedestrian Crossing Path
Test Parameters--Unobstructed From the Right
    The unobstructed crossing path from the right scenario consists of 
the subject vehicle traveling straight at a constant speed towards the 
adult PTM, which enters its travel path (perpendicular to the vehicle's 
travel path) from the right side of the vehicle. The subject vehicle 
must be able to avoid contact with the pedestrian test mannequin 
crossing its path. NHTSA specifies testing the unobstructed crossing 
path scenario from the right with a 25% and 50% overlap during daylight 
and a 50% overlap for darkness with independent tests with the lower 
and upper beams activated. The subject vehicle testing speed is any 
speed between 10 km/h and 60 km/h, while the PTM speed is 5km/h.
Pedestrian Test Mannequin--Unobstructed From the Right
    An adult PTM is used for this scenario and NHTSA specifies that the 
PTM is to be secured to a moving apparatus so that it faces the 
direction of motion at 4.0  0.1 m to the right of the 
subject vehicle's intended travel path. The PTM's leg articulation is 
to start on apparatus movement and stops when the apparatus stops. The 
PTM speed is 5 km/h.
Test Parameters--Unobstructed From the Left
    The unobstructed crossing path from the left scenario consists of 
the subject vehicle traveling straight at a constant speed towards the 
adult PTM, which enters its travel path (perpendicular to the vehicle's 
travel path) from the left side of the vehicle. The subject vehicle 
must be able to avoid contact with the pedestrian test mannequin 
crossing its path. NHTSA will test the unobstructed crossing path 
scenario from the left with a 50% overlap during daylight. The subject 
vehicle testing speed is any speed between 10 km/h and 60 km/h, while 
the PTM speed is 8 km/h.
Pedestrian Test Mannequin--Unobstructed From the Left
    An adult PTM is used for this scenario, and NHTSA specifies that 
the PTM be secured to a moving apparatus so that it faces the direction 
of motion at 6.0  0.1 m to the left of the intended travel 
path. The PTM's leg articulation is to start on apparatus movement and 
stops when the apparatus stops. As this simulates a running adult 
pedestrian, the PTM speed is 8 km/h.
Test Parameters--Obstructed From the Right
    The obstructed crossing path from the right scenario consists of 
the subject vehicle traveling straight at a constant speed towards a 
child PTM, which enters its travel path (perpendicular to the travel 
path) from the right side of the vehicle. The child PTM crosses the 
subject vehicle's travel path from in front of two stopped VTDs. The 
VTDs are parked to the right of the subject vehicle's travel path, in 
the adjacent lane, at 1.0 m (3 ft) from the side of the subject vehicle 
(tangent with the right outermost point of the subject vehicle when the 
subject vehicle is in the intended travel path). The VTDs are parked 
one after the other and are facing in the same direction as the subject 
vehicle. One VTD is directly behind the other, separated by 1.0  0.1 m. The subject vehicle must be able to avoid contact with 
the child PTM crossing its path. NHTSA specifies testing this scenario 
with a 50% overlap during daylight. The subject vehicle testing speed 
is any speed between 10 km/h and 50 km/h, while the child PTM speed is 
5 km/h.
Pedestrian Test Mannequin--Obstructed From the Right
    A child PTM is used for the obstructed scenario. NHTSA specifies 
that the child PTM is secured to a moving apparatus so that it faces 
the direction of motion at 4.0  0.1 m to the right of the 
intended travel path. The PTM's leg articulation is to start on 
apparatus movement and stops when the apparatus stops. This scenario 
simulates a running child pedestrian and the child PTM speed is 5 km/h.
Test Conduct Prior to FCW or Vehicle Braking Onset
    NHTSA specifies that, as the subject vehicle approaches the 
crossing path of the PTM, beginning when the headway corresponds to 
L0, the subject vehicle speed be maintained within 1.6 km/h 
of the test speed with minimal and smooth accelerator pedal inputs. 
Furthermore, beginning when the headway corresponds to L0, 
the subject vehicle heading is to be maintained with minimal steering 
input such that the subject vehicle 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. Prior to the 
start of a test trial, as long as the specified initialization 
procedure is executed, a subject vehicle may be driven under any 
conditions including any speed and direction, and on any road surface, 
for any elapsed time prior to reaching the point where a test trial 
begins. For all tests, there is no specific limitations on how a 
subject vehicle is driven prior to the start of a test trail, in the 
same manner as for the lead vehicle trials.
    The PTM apparatus is to be triggered at a time such that the 
pedestrian test mannequin meets the intended overlap. The agency 
specifies that the PTM achieve its intended speed within 1.5 m after 
the apparatus begins to move and maintains its intended speed within 
0.4 km/h until the test completion criteria is satisfied.
Test Conduct After Either FCW or Vehicle Braking Onset
    NHTSA specifies that after FCW or vehicle braking 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.
    During testing, no manual brake application is permitted and the 
PTM continues to move until one of the test completion criteria is 
satisfied.
Test Completion Criteria
    NHTSA specifies that any test run is complete when the subject 
vehicle comes to a complete stop without making contact with the PTM, 
when the PTM is no longer in the forward path of the subject vehicle, 
or when the subject vehicle makes contact with the PTM.
Stationary Pedestrian
Test Parameters
    The stationary pedestrian scenario consists of the subject vehicle 
traveling straight at a constant speed towards the adult PTM, which is 
stationary at an overlap of 25%, facing away from the approaching 
subject vehicle. The subject vehicle must be able to avoid contact with 
the stationary PTM during daylight and darkness with lower beam and 
upper beam. The subject vehicle testing speed is any speed between 10 
km/h and 55 km/h.
Pedestrian Test Mannequin
    An adult PTM is used for this scenario and NHTSA specifies that the 
PTM be stationary and face away from

[[Page 39778]]

the subject vehicle. The pedestrian test mannequin legs remain still.
Test Conduct Prior to FCW or Vehicle Braking Onset
    NHTSA specifies that as the subject vehicle approaches the 
stationary PTM, beginning when the headway corresponds to 
L0, the subject vehicle speed be maintained within 1.6 km/h 
of the test speed with minimal and smooth accelerator pedal inputs. 
Furthermore, beginning when the headway corresponds to L0, 
the subject vehicle heading is to be maintained with minimal steering 
input such that the subject vehicle 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. Similarly to 
the other tests, the subject vehicle may be driven under any conditions 
including any speed and direction, and on any road surface, for any 
elapsed time prior to reaching the point where a test trial begins.
Test Conduct After Either FCW or Vehicle Braking Onset
    NHTSA specifies that after FCW or vehicle braking 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. No manual braking is permitted during 
testing until one of the test completion criteria is satisfied.
Test Completion Criteria
    NHTSA specifies that any test run is complete when the subject 
vehicle comes to a complete stop without making contact with the PTM or 
when the subject vehicle makes contact with the PTM.
Pedestrian Moving Along the Path
Test Parameters
    The pedestrian moving along path scenario consists of the subject 
vehicle traveling straight at a constant speed towards an adult PTM 
moving away from the vehicle. The PTM is moving at 5 km/h at an overlap 
of 25%, facing away on the same travel path as the vehicle. The PTM's 
movement is parallel to and in the same direction as the subject 
vehicle. The subject vehicle must be able to avoid contact with the 
moving PTM during daylight and darkness with lower beam and upper beam. 
The subject vehicle testing speed is any speed between 10 km/h and 65 
km/h.
Test Conduct Prior to FCW or Vehicle Braking Onset
    NHTSA specifies that as the subject vehicle approaches the moving 
PTM, 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. Furthermore, 
beginning when the headway corresponds to L0, the subject 
vehicle heading is to be maintained with minimal steering input such 
that the subject vehicle 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. Similarly to the other 
tests the subject vehicle may be driven under any conditions including 
any speed and direction, and on any road surface, for any elapsed time 
prior to reaching the point where a test trial begins.
    The PTM is to be secured to a moving apparatus triggered any time 
after the distance between the front plane of the subject vehicle and a 
parallel contact plane on the pedestrian test mannequin corresponds to 
L0. The specifications state that the PTM achieve its 
intended speed within 1.5 m after the apparatus begins to move and 
maintain its intended speed within 0.4 km/h until one of the test 
completion criteria is satisfied.
Test Conduct After Either FCW or Vehicle Braking Onset
    NHTSA specifies that after FCW or vehicle braking 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. No manual braking is permitted during 
testing until one of the test completion criteria is satisfied.
Test Completion Criteria
    NHTSA specifies that any test run is complete when the subject 
vehicle slows to a speed below that of the PTM without making contact 
with the PTM, or when the subject vehicle makes contact with the PTM.

C. Appendix C: Description of the False Activation Test Procedures

Test Parameters
Headway Calculation
    NHTSA specifies that for each test run conducted, 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 a 5.0 
second, 2.1 second, and 1.1 second 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) m
TTC 0 = 5.0 s
TTC 2.1 = 2.1 s
TTC 1.1 = 1.1 s
Steel Trench Plate
Test Parameters
    The steel trench plate false activation scenario involves the 
subject vehicle approaching at 80 km/h a steel plate, commonly used in 
road construction, placed on the surface of a test track in its 
intended travel path. The steel trench plate is positioned flat on the 
test surface so that its longest side is parallel to the vehicle's 
intended travel path and horizontally centered on the vehicle's 
intended travel path. The steel plate presents no imminent danger, and 
the subject vehicle can safely travel over the plate without harm. 
NHTSA specifies testing with and without manual brake application.
Test Conduct
    The procedure states that as the subject vehicle approaches the 
steel trench plate, the subject vehicle speed shall be maintained 
within 1.6 km/h of the test speed with minimal and smooth accelerator 
pedal inputs beginning when the headway corresponds to L0. 
Furthermore, beginning when the headway corresponds to L0, 
the subject vehicle heading is to be maintained with minimal steering 
input such that the subject vehicle 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. If an FCW 
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 tests performed with the subject vehicle's cruise control active.
    For testing without manual brake application, no manual brake 
application is made until one of the test completion criteria is 
satisfied. For testing with manual brake application, 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. The service brake application occurs at 
headway L1.1.
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.

[[Page 39779]]

Pass-through Test
Test Parameters
    The pass-through test simulates the subject vehicle approaching at 
80 km/h vehicle test devices 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 and the travel 
path is free of obstacles. NHTSA tests with and without manual brake 
application.
Test Conduct
    The procedure states that as the subject vehicle approaches the gap 
between the two vehicle test devices, beginning when the headway 
corresponds to L0, the subject vehicle speed be maintained 
within 1.6 km/h of the test speed with minimal and smooth accelerator 
pedal inputs. Furthermore, beginning when the headway corresponds to 
L0, the subject vehicle heading is to be maintained with 
minimal steering input such that the subject vehicle 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. 
If an FCW 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.
    For testing without manual brake application, no manual brake 
application is made until one of the test completion criteria is 
satisfied. For testing with manual brake application, 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. The service brake application occurs at 
headway L1.1.
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.

List of Subjects

49 CFR Part 571

    Imports, Incorporation by reference, Motor vehicle safety, Motor 
vehicles, Rubber and rubber products.

49 CFR Part 595

    Motor vehicle safety, Motor vehicles.

49 CFR Part 596

    Automatic emergency braking, Incorporation by reference, Motor 
vehicles, Motor vehicle safety, Test devices.
    In consideration of the foregoing, NHTSA amends 49 CFR chapter V as 
follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
1. 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
2. Amend Sec.  571.5 by:
0
a. Revising paragraph (d)(35);
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) * * *
    (35) 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; 571.127; 571.135; 
571.136; 571.500.
* * * * *
    (l) * * *
    (49) SAE J2400, ``Human Factors in Forward Collision Warning 
Systems: Operating Characteristics and User Interface Requirements,'' 
August 2003 into Sec.  571.127.
* * * * *

0
3. Add Sec.  571.127 to read as follows:


Sec.  571.127  Standard No. 127; Automatic emergency braking systems 
for light vehicles.

    S1. Scope. This standard establishes performance requirements for 
automatic emergency braking (AEB) systems for light 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 passenger cars and to 
multipurpose passenger vehicles, trucks, and buses with a gross vehicle 
weight rating (GVWR) of 4,536 kilograms (10,000 pounds) or less.
    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 11 N of force has been 
applied to 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 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 subject vehicle's frontmost 
plane normal to its centerline and as applicable: the vehicle test 
device's rearmost plane normal to its centerline; a parallel contact 
plane (to the subject vehicle's frontmost plane) on the pedestrian test 
mannequin; and the leading edge of the steel trench plate.
    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 0.05 g due to brake application.
    Masked threshold is the quietest level of a signal that can be 
perceived in the presence of noise.
    Pedestrian test mannequin is a device used during AEB testing, when 
approaching pedestrians, meeting the specifications of subpart B of 49 
CFR part 596.
    Small-volume manufacturer means an original vehicle manufacturer 
that produces or assembles fewer than 5,000 vehicles annually for sale 
in the United States.
    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.
    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

[[Page 39780]]

longitudinal vertical center plane, as the subject vehicle travels 
forward.
    Subject vehicle braking onset is the point at which the subject 
vehicle achieves a deceleration of 0.15 g due to the automatic control 
of the service brakes.
    Vehicle test device is a device meeting the specifications set 
forth in subpart C of 49 CFR part 596.
    S5. Requirements.
    (a) Except as provided in S5(b), vehicles manufactured on or after 
September 1, 2029 must meet the requirements of this standard.
    (b) The requirements of S5(a) do not apply to small-volume 
manufacturers, final-stage manufacturers, and alterers until one year 
after the dates specified in S5(a).
    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 that provides an 
auditory and visual signal to the driver of an impending collision with 
a lead vehicle. The system must operate under the conditions specified 
in S6 when traveling at any forward speed that is greater than 10 km/h 
(6.2 mph) and less than 145 km/h (90.1 mph).
    (a) Auditory signal.
    (1) The auditory signal must have a high fundamental frequency of 
at least 800 Hz.
    (2) The auditory signal must have a tempo in the range of 6-12 
pulses per second and a duty cycle in the range of 0.25-0.95.
    (3) The auditory signal must have a minimum intensity of 15-30 dB 
above the masked threshold.
    (4) In-vehicle audio that is not related to a safety purpose or 
safety system (i.e., entertainment and other audio content not related 
to or essential for safe performance of the driving task) must be 
muted, or reduced in volume to within 5 dB of the masked threshold 
during presentation of the FCW auditory signal.
    (b) Visual signal.
    (1) The visual signal must be located within an ellipse that 
extends 18 degrees vertically and 10 degrees horizontally of the driver 
forward line of sight based on the forward-looking eye midpoint 
(Mf) as described in S14.1.5. of Sec.  571.111.
    (2) The visual signal must include the crash pictorial symbol in 
SAE J2400, 4.1.16, incorporated by reference (see Sec.  571.5).
    (3) The visual signal 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, that applies 
the service brakes automatically when a collision with a lead vehicle 
is imminent. The system must operate under the conditions specified in 
S6 when the vehicle is traveling at any forward speed that is greater 
than 10 km/h (6.2 mph) and less than 145 km/h (90.1 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 under the conditions specified in S6. 
The forward collision warning is not required if adaptive cruise 
control is engaged.
    S5.2. Requirements when approaching pedestrians.
    S5.2.1. Forward collision warning. A vehicle is required to have a 
forward collision warning system, as defined in S4, that provides an 
auditory and visual signal to the driver of an impending collision with 
a pedestrian. The system must operate under the conditions specified in 
S6 when the vehicle is traveling at any forward speed that is greater 
than 10 km/h (6.2 mph) and less than 73 km/h (45.3 mph). The forward 
collision warning system must meet the auditory signal and visual 
signal requirements specified in S5.1.1.
    S5.2.2. Automatic emergency braking. A vehicle is required to have 
an automatic emergency braking system, as defined in S4, that applies 
the service brakes automatically when a collision with a pedestrian is 
imminent when the vehicle is under the conditions specified in S6 and 
is traveling at any forward speed that is greater than 10 km/h (6.2 
mph) and less than 73 km/h (45.3 mph).
    S5.2.3. Performance test requirements. The vehicle must provide a 
forward collision warning and apply the brakes automatically such that 
the subject vehicle does not collide with the pedestrian test mannequin 
when tested using the procedures in S8 under the conditions specified 
in S6.
    S5.3. False activation. The vehicle must not automatically apply 
braking that results in peak additional deceleration that exceeds what 
manual braking would produce by 0.25 g or greater, when tested using 
the procedures in S9 under the conditions specified in S6.
    S5.4. Malfunction detection and controls.
    S5.4.1 The system must continuously detect system malfunctions, 
including performance degradation caused solely by sensor obstructions. 
If the system detects a malfunction, or if the system adjusts its 
performance such that it will not meet the requirements specified in 
S5.1, S5.2, or S5.3, the system must provide the vehicle operator with 
a telltale notification.
    S5.4.2 Except as provided in S5.4.2.1 and S5.4.2.2, the 
manufacturer must not provide a control that will place the AEB system 
in a mode or modes in which it will no longer satisfy the performance 
requirements of S5.1, S5.2, and S5.3.
    S5.4.2.1 The manufacturer may provide a control to allow AEB 
deactivation that is securely activated, provided the manufacturer 
enables such activation exclusively in a vehicle owned by a law 
enforcement agency.
    S5.4.2.2 The manufacturer may allow AEB deactivation to occur 
during low-range four-wheel drive configurations, when the driver 
selects ``tow mode,'' or when another vehicle system is activated that 
will have a negative ancillary impact on AEB operation.
    S5.4.3 The vehicle's AEB system must always return to the 
manufacturer's original default AEB mode that satisfies the 
requirements of S5.1, S5.2, and S5.3 at the initiation of each new 
ignition cycle, unless the vehicle is in a low-range four-wheel drive 
configuration selected by the driver on the previous ignition cycle 
designed for low-speed, off-road driving.
    S6. Test conditions.
    S6.1. Environmental conditions.
    S6.1.1. Temperature. The ambient temperature is any temperature 
between 0 [deg]C and 40 [deg]C.
    S6.1.2. Wind. The maximum wind speed is no greater than 10 m/s (22 
mph) during lead vehicle avoidance tests and 6.7 m/s (15 mph) during 
pedestrian avoidance tests.
    S6.1.3. Ambient lighting.
    (a) Daylight testing.
    (1) The ambient illumination on the test surface is any level at or 
above 2,000 lux.
    (2) 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.
    (b) Dark testing.
    (1) The ambient illumination on the test surface is any level at or 
below 0.2 lux.
    (2) Testing is performed under any lunar phase.
    (3) Testing is not performed while driving toward the moon such 
that the horizontal angle between the moon and a vertical plane 
containing the centerline of the subject vehicle is less

[[Page 39781]]

than 25 degrees and the lunar 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 may not be used.
    S6.2.2. Surface friction. The road test surface produces a peak 
friction coefficient (PFC) of 1.02 when measured using an 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 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 S5.4 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 Sec.  571.105.
    (b) Vehicles subject to Sec.  571.135 are burnished in accordance 
with S7.1 of Sec.  571.135.
    S6.3.5. Brake temperature. The average temperature of the service 
brakes on the hottest axle of the vehicle during testing, measured 
according to S6.4.1 of Sec.  571.135, is between 65[deg]C and 100[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.
    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. Headlamps.
    (a) Daylight testing is conducted with the headlamp control in any 
selectable position.
    (b) Darkness testing is conducted with the vehicle's lower beams 
active and separately with the vehicle's upper beams active.
    (c) Prior to performing darkness testing, headlamps are aimed 
according to the vehicle manufacturer's instructions. The weight of the 
loaded vehicle at the time of headlamp aiming is within 10 kg of the 
weight of the loaded vehicle during testing.
    S6.3.13. Subject vehicle loading. The vehicle load, which is the 
sum of any vehicle occupants and any test equipment and 
instrumentation, does not exceed 277 kg. The load does not cause the 
vehicle to exceed its GVWR or any axle to exceed its GAWR.
    S6.3.14. 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. Adult pedestrian test mannequin is specified in 49 CFR part 
596, subpart B.
    S6.4.3. Child pedestrian test mannequin is specified in 49 CFR part 
596, subpart B.
    S6.4.4. 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 2 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 in 
table 1 to S7.1.

                                            Table 1 to S7.1--Test Parameters When Approaching a Lead Vehicle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Speed (km/h)
                                     -----------------------------------------       Headway (m)       Lead vehicle decel (g)   Manual brake application
                                                VSV                  VLV
--------------------------------------------------------------------------------------------------------------------------------------------------------
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.

[[Page 39782]]

 
Decelerating Lead Vehicle...........  50.....................              50  Any 12-40.............  Any 0.3-0.5...........  No.
                                      50.....................              50  Any 12-40.............  Any 0.3-0.5...........  Yes.
                                      80.....................              80  Any 12-40.............  Any 0.3-0.5...........  No.
                                      80.....................              80  Any 12-40.............  Any 0.3-0.5...........  Yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    S7.2. Headway calculation. For each test run conducted under S7.3 
and S7.4, the headway (L0), in meters, providing 5.0 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:
Equation 1 to S7.2

L0 = TTC0 x (VSV-VLV)
TTC0 = 5.0

    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 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 S10. 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) 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.
    (d) 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.
    (e) Beginning when the headway corresponds to L0, the 
subject vehicle and lead vehicle headings are be 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 the 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 S10. 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 3 seconds prior to lead vehicle braking onset, the 
subject vehicle is be driven at any speed, in any direction, on any 
road surface, for any amount of time.
    (b) Between 3 seconds 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 12 m and 40 m.
    (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.

[[Page 39783]]

    (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 onset of forward collision warning.
    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 0.5g. 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 S10. 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. Testing when approaching a pedestrian.
    S8.1. Setup.
    S8.1.1. General.
    (a) For reference, table 2 to S8.1.1 specifies the pedestrian test 
mannequin direction of travel, overlap, obstruction condition and speed 
(VP), the subject vehicle speed (VSV), and the 
lighting condition for each test that may be conducted.
    (b) The intended travel path of the vehicle is a straight line 
originating at the location corresponding to a headway of 
L0.
    (c) 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.
    (d) For each test run conducted, the subject vehicle speed 
(VSV) will be selected from the range specified in table 2 
to S8.1.1.

                                            Table 2 to S8.1.1--Test Parameters When Approaching a Pedestrian
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Speed (km/h)
                                         Direction            Overlap           Obstructed       ------------------------------------ Lighting condition
                                                                                                          VSV               VP
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pedestrian Crossing Road........  Right.................              25  No....................  Any 10-60.........               5  Daylight
                                  Right.................              50  No....................  Any 10-60.........               5  Daylight
                                                                                                                                      Lower Beams
                                                                                                                                      Upper Beams
                                  Left..................              50  No....................  Any 10-60.........               8  Daylight
                                  Right.................              50  Yes...................  Any 10-50.........               5  Daylight
Stationary Pedestrian...........  Right.................              25  No....................  Any 10-55.........               0  Daylight
                                                                                                                                      Lower Beams
                                                                                                                                      Upper Beams
Pedestrian Moving Along the Path  Right.................              25  No....................  Any 10-65.........               5  Daylight
                                  ......................  ..............  ......................  ..................  ..............  Lower Beams
                                                                                                                                      Upper Beams
--------------------------------------------------------------------------------------------------------------------------------------------------------

    S8.1.2. Overlap. As depicted in figure 1 to this section, overlap 
describes the location of the point on the front of the subject vehicle 
that would make contact with a pedestrian if no braking occurred. 
Overlap is the percentage of the subject vehicle's overall width that 
the pedestrian test mannequin traverses. It is measured from the right 
or the left, depending on the side of the subject vehicle where the 
pedestrian test mannequin originates. For each test run, the actual 
overlap will be within 0.15 m of the specified overlap.
    S8.1.3. Pedestrian test mannequin.
    (a) For testing where the pedestrian test mannequin is secured to a 
moving apparatus, the pedestrian test mannequin is secured so that it 
faces the direction of motion. The pedestrian test mannequin leg 
articulation starts on apparatus movement and stops when the apparatus 
stops.
    (b) For testing where the pedestrian test mannequin is stationary, 
the pedestrian test mannequin faces away from the subject vehicle, and 
the pedestrian test mannequin legs remain still.
    S8.2. Headway calculation. For each test run conducted under S8.3, 
S8.4, and S8.5, the headway (L0), in meters, providing 4.0 
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 VP-y is the 
component of speed of the pedestrian test mannequin in m/s in the 
direction of the intended travel path:
Equation 2 to S8.2
    L0 = TTC0 x (VSV - VP-y)
    TTC0 = 4.0

    S8.3. Pedestrian crossing road.
    S8.3.1. Test parameters and setup (unobstructed from right).
    (a) The testing area is set up in accordance with figure 3 to this 
section.
    (b) Testing is conducted in the daylight or darkness conditions, 
except that testing with the pedestrian at the 25 percent overlap is 
only conducted in daylight conditions.
    (c) Testing is conducted using the adult pedestrian test mannequin.
    (d) The movement of the pedestrian test mannequin is perpendicular 
to the subject vehicle's intended travel path.
    (e) The pedestrian test mannequin is set up 4.0  0.1 m 
to the right of the intended travel path.
    (f) The intended overlap is 25 percent from the right or 50 
percent.
    (g) The subject vehicle test speed is any speed between 10 km/h and 
60 km/h.
    (h) The pedestrian test mannequin speed is 5 km/h.
    S8.3.2 Test parameters and setup (unobstructed from left).
    (a) The testing area is set up in accordance with figure 4 to this 
section.
    (b) Testing is conducted in the daylight condition.
    (c) Testing is conducted using the adult pedestrian mannequin.

[[Page 39784]]

    (d) The movement of the pedestrian test mannequin is perpendicular 
to the intended travel path.
    (e) The pedestrian test mannequin is set up 6.0  0.1 m 
to the left of the intended travel path.
    (f) The intended overlap is 50 percent.
    (g) The subject vehicle test speed is any speed between 10 km/h and 
60 km/h.
    (h) The pedestrian test mannequin speed is 8 km/h.
    S8.3.3. Test parameters and setup (obstructed).
    (a) The testing area is set up in accordance with figure 5 to this 
section.
    (b) Testing is conducted in the daylight condition.
    (c) Testing is conducted using the child pedestrian test mannequin.
    (d) The movement of the pedestrian test mannequin is perpendicular 
to the intended travel path.
    (e) The pedestrian test mannequin is set up 4.0  0.1 m 
to the right of the intended travel path.
    (f) The intended overlap is 50 percent.
    (g) Two vehicle test devices are secured in stationary positions 
parallel to the intended travel path. The two vehicle test devices face 
the same direction as the intended travel path. One vehicle test device 
is directly behind the other separated by 1.0  0.1 m. The 
frontmost plane of the vehicle test device furthermost from the subject 
vehicle is located 1.0  0.1 m from the parallel contact 
plane (to the subject vehicle's frontmost plane) on the pedestrian test 
mannequin. The left side of each vehicle test device is 1.0  0.1 m to the right of the vertical plane parallel to the 
intended travel path and tangent with the right outermost point of the 
subject vehicle when the subject vehicle is in the intended travel 
path.
    (h) The subject vehicle test speed is any speed between 10 km/h and 
50 km/h.
    (i) The pedestrian test mannequin speed is 5 km/h.
    S8.3.4. Test conduct prior to forward collision warning or subject 
vehicle braking onset.
    (a) 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.
    (b) The subject vehicle approaches the crossing path of the 
pedestrian test mannequin.
    (c) 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.
    (d) Beginning when the headway corresponds to L0, the 
subject vehicle heading is maintained with minimal steering inputs such 
that the subject vehicle's 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 prior to any 
automated braking onset.
    (e) The pedestrian test mannequin apparatus is triggered at a time 
such that the pedestrian test mannequin meets the intended overlap, 
subject to the criteria in S8.1.2. The pedestrian test mannequin 
achieves its intended speed within 1.5 m after the apparatus begins to 
move and maintains its intended speed within 0.4 km/h until the test 
completion criteria of S8.3.6 are satisfied.
    S8.3.5. Test conduct after either forward collision warning or 
subject vehicle braking onset.
    (a) After forward collision warning or subject vehicle braking 
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.
    (b) No manual brake application is made until the test completion 
criteria of S8.3.6 are satisfied.
    (c) The pedestrian mannequin continues to move until the completion 
criteria of S8.3.6 are satisfied.
    S8.3.6. Test completion criteria. The test run is complete when the 
subject vehicle comes to a complete stop without making contact with 
the pedestrian test mannequin, when the pedestrian test mannequin is no 
longer in the path of the subject vehicle, or when the subject vehicle 
makes contact with the pedestrian test mannequin.
    S8.4. Stationary pedestrian.
    S8.4.1. Test parameters and setup.
    (a) The testing area is set up in accordance with figure 6 to this 
section.
    (b) Testing is conducted in the daylight or darkness conditions.
    (c) Testing is conducted using the adult pedestrian test mannequin.
    (d) The pedestrian mannequin is set up at the 25 percent right 
overlap position facing away from the approaching vehicle.
    (e) The subject vehicle test speed is any speed between 10 km/h and 
55 km/h.
    (f) The pedestrian mannequin is stationary.
    S8.4.2. Test conduct prior to forward collision warning or subject 
vehicle braking onset.
    (a) 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.
    (b) The subject vehicle approaches the pedestrian test mannequin.
    (c) 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.
    (d) Beginning when the headway corresponds to L0, the 
subject vehicle heading is maintained with minimal steering inputs such 
that the subject vehicle's 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 prior to any 
automated braking onset.
    S8.4.3. Test conduct after either forward collision warning or 
subject vehicle braking onset.
    (a) After forward collision warning or subject vehicle braking 
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 
with vehicles with cruise control active.
    (b) No manual brake application is made until the test completion 
criteria of S8.4.4 are satisfied.
    S8.4.4. Test completion criteria. The test run is complete when the 
subject vehicle comes to a complete stop without making contact with 
the pedestrian test mannequin, or when the subject vehicle makes 
contact with the pedestrian test mannequin.
    S8.5. Pedestrian moving along the path.
    S8.5.1. Test parameters and setup.
    (a) The testing area is set up in accordance with figure 7 to this 
section.
    (b) Testing is conducted in the daylight or darkness conditions.
    (c) Testing is conducted using the adult pedestrian test mannequin.
    (d) The movement of the pedestrian test mannequin is parallel to 
and in the same direction as the subject vehicle.
    (e) The pedestrian test mannequin is set up in the 25 percent right 
offset position.
    (f) The subject vehicle test speed is any speed between 10 km/h and 
65 km/h.
    (g) The pedestrian test mannequin speed is 5 km/h.
    S8.5.2. Test conduct prior to forward collision warning or subject 
vehicle braking onset.
    (a) 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.
    (b) The subject vehicle approaches the pedestrian test mannequin.
    (c) 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.

[[Page 39785]]

    (d) Beginning when the headway corresponds to L0, the 
subject vehicle heading is maintained with minimal steering inputs 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 prior to any automated braking onset.
    (e) The pedestrian test mannequin apparatus is triggered any time 
after the distance between the front plane of the subject vehicle and a 
parallel contact plane on the pedestrian test mannequin corresponds to 
L0. The pedestrian test mannequin achieves its intended 
speed within 1.5 m after the apparatus begins to move and maintains its 
intended speed within 0.4 km/h until the test completion criteria of 
S8.5.4 are satisfied.
    S8.5.3. Test conduct after either forward collision warning or 
subject vehicle braking onset.
    (a) After forward collision warning or subject vehicle braking 
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.
    (b) No manual brake application is made until the test completion 
criteria of S8.5.4 are satisfied.
    S8.5.4. Test completion criteria. The test run is complete when the 
subject vehicle slows to speed below the pedestrian test mannequin 
travel speed without making contact with the pedestrian test mannequin 
or when the subject vehicle makes contact with the pedestrian test 
mannequin.
    S9. False AEB activation.
    S9.1. Headway calculation. For each test run to be conducted under 
S9.2 and S9.3, the headway (L0, L2.1, L1.1), in meters, 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:
Equation 3 to S9.1
Lx = TTCx x (VSV)
TTC0 = 5.0
TTC2.1 = 2.1
TTC1.1 = 1.1

    S9.2. Steel trench plate.
    S9.2.1. Test parameters and setup.
    (a) The testing area is set up in accordance with figure 8 to this 
section.
    (b) The steel trench plate is secured flat on the test surface so 
that its longest side is parallel to the vehicle's intended travel path 
and horizontally centered on the vehicle's intended travel path.
    (c) The subject vehicle test speed is 80 km/h.
    (d) Testing is conducted with manual brake application and without 
manual brake application.
    (e) Testing is conducted during daylight.
    S9.2.2. Test conduct.
    (a) 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.
    (b) The subject vehicle approaches the steel trench plate.
    (c) 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.
    (d) 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.
    (e) 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.
    (f) For tests where no manual brake application occurs, manual 
braking is not applied until the test completion criteria of S9.2.3 are 
satisfied.
    (g) 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.
    (h) For tests where manual brake application occurs, the service 
brakes are applied as specified in S10. The brake application pedal 
onset occurs at headway L1.1.
    S9.2.3. 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.
    S9.3. Pass-through.
    S9.3.1. Test parameters and setup.
    (a) The testing area is set up in accordance with figure 9 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 is conducted with manual brake application and without 
manual brake application.
    (e) Testing is conducted during daylight.
    S9.3.2. Test conduct.
    (a) 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.
    (b) The subject vehicle approaches the gap between the two vehicle 
test devices.
    (c) 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.
    (d) 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.
    (e) 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.
    (f) For tests where no manual brake application occurs, manual 
braking is not applied until the test completion criteria of S9.3.3 are 
satisfied.
    (g) 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.
    (h) For tests where manual brake application occurs, the service 
brakes are applied as specified in S10. The brake application onset 
occurs when the headway corresponds to L1.1.
    S9.3.3. 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.
    S10. Subject vehicle brake application procedure.
    S10.1. The procedure begins with the subject vehicle brake pedal in 
its natural resting position with no preload or position offset.
    S10.2. At the option of the manufacturer, either displacement 
feedback, hybrid feedback, or force feedback control is used.
    S10.3. Displacement feedback procedure. For displacement feedback, 
the commanded brake pedal position is the brake pedal position that 
results in a mean deceleration of 0.4 g in the absence of AEB system 
activation.

[[Page 39786]]

    (a) The mean deceleration is the deceleration over the time from 
the brake pedal achieving the commanded position to 250 ms before the 
vehicle comes to a stop.
    (b) The pedal displacement controller displaces the brake 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 250 ms from when the commanded position is first 
achieved.
    (d) The achieved brake pedal position is any position within 10 
percent of the commanded position from 250 ms after the commanded brake 
pedal position is first achieved to the end of the test.
    S10.4. 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 0.4 g in the absence of AEB system 
activation.
    (a) The mean deceleration is the deceleration over the time from 
the brake pedal achieving the commanded position to 250 ms before the 
vehicle comes to a stop.
    (b) The hybrid controller displaces the brake 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 250 ms from then the commanded position is first 
achieved.
    (d) The hybrid controller begins to control the force applied to 
the brake pedal and stops controlling pedal displacement within 100 ms 
after the commanded brake pedal displacement occurs.
    (e) The hybrid controller applies a pedal force of at least 11.1 N 
from the onset of the brake application until the end of the test.
    (f) The average pedal force is maintained within 10 percent of the 
commanded brake pedal force from 350 ms after commended pedal 
displacement occurs until test completion.
    S10.5. Force feedback procedure. For force feedback, the commanded 
brake pedal application is the brake pedal force that results in a mean 
deceleration of 0.4 g in the absence of AEB system activation.
    (a) The mean deceleration is the deceleration over the time from 
when the commanded brake pedal force is first achieved to 250 ms before 
the vehicle comes to a stop.
    (b) The force controller achieves the commanded brake pedal force 
within 250 ms. The application rate is unrestricted.
    (c) The force controller may overshoot the commanded force by any 
amount up to 20 percent. If such an overshoot occurs, it is corrected 
within 250 ms from when the commanded force is first achieved.
    (d) The force controller applies a pedal force of at least 11.1 N 
from the onset of the brake application until the end of the test.
    (e) The average pedal force is maintained within 10 percent of the 
commanded brake pedal force from 250 ms after commended pedal force 
occurs until test completion.
BILLING CODE 4910-59-P

Figure 1 to Sec.  571.127--Percentage Overlap Nomenclature
[GRAPHIC] [TIFF OMITTED] TR09MY24.030


[[Page 39787]]



Figure 2 to Sec.  571.127--Setup for Lead Vehicle Automatic Emergency 
Braking
[GRAPHIC] [TIFF OMITTED] TR09MY24.031


[[Page 39788]]



Figure 3 to Sec.  571.127--Setup for Pedestrian, Crossing Path, Right
[GRAPHIC] [TIFF OMITTED] TR09MY24.032


[[Page 39789]]



Figure 4 to Sec.  571.127--Setup for Pedestrian, Crossing Path, Left
[GRAPHIC] [TIFF OMITTED] TR09MY24.033


[[Page 39790]]



Figure 5 to Sec.  571.127--Setup for Pedestrian, Obstructed
[GRAPHIC] [TIFF OMITTED] TR09MY24.034


[[Page 39791]]



Figure 6 to Sec.  571.127--Setup for Pedestrian Along-Path Stationary
[GRAPHIC] [TIFF OMITTED] TR09MY24.035


[[Page 39792]]



Figure 7 to Sec.  571.127--Setup for Pedestrian Along-Path Moving
[GRAPHIC] [TIFF OMITTED] TR09MY24.036

Figure 8 to Sec.  571.127--Steel Trench Plate
[GRAPHIC] [TIFF OMITTED] TR09MY24.037


[[Page 39793]]



Figure 9 to Sec.  571.127--Pass-through
[GRAPHIC] [TIFF OMITTED] TR09MY24.038

BILLING CODE 4910-59-C

PART 595--MAKE INOPERATIVE EXEMPTIONS

0
4. The authority citation for part 595 continues to read as follows:

    Authority:  49 U.S.C. 322, 30111, 30115, 30117, 30122 and 30166; 
delegation of authority at 49 CFR 1.95.

0
5. Amend Sec.  595.4 by adding the definition of ``Manufacturer'' in 
alphabetical order to read as follows:


Sec.  595.4  Definitions.

* * * * *
    Manufacturer is defined as it is in 49 U.S.C. 30102(a).
* * * * *

0
6. Add subpart D to read as follows:

Subpart D--Modifications to Law Enforcement Vehicles


Sec.  595.9  Automatic emergency braking.

    A manufacturer, dealer, or motor vehicle repair business that 
modifies a vehicle owned by a law enforcement agency to provide a means 
to temporarily deactivate an AEB system is exempted from the ``make 
inoperative'' prohibition in 49 U.S.C. 30122 to the extent that such 
modification affects the motor vehicle's compliance with 49 CFR 
571.127, S5.4.2. Modifications that would take a vehicle out of 
compliance with any other Federal motor vehicle safety standards, or 
portions thereof, are not covered by this exemption.

0
7. 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--Pedestrian Test Devices
596.7 Specifications for pedestrian test devices.
596.8 [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 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, such as 49 CFR 
571.127.


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.
    Adult pedestrian test mannequin (APTM) means a test device with the 
appearance and radar cross section that simulates an adult pedestrian 
for the purpose of testing automatic emergency brake system 
performance.
    Child pedestrian test mannequin (CPTM) means a test device with the 
appearance and radar cross section that stimulates a child pedestrian 
for the purpose of testing automatic emergency brake system 
performance.
    Pedestrian test device(s) means an adult pedestrian test mannequin 
and/or a child pedestrian test mannequin.
    Pedestrian test mannequin carrier means a movable platform on which 
an adult pedestrian test mannequin or child pedestrian test mannequin 
may be attached during compliance testing.
    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.


Sec.  596.5  Matter incorporated by reference.

    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 and 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 or email [email protected]. The 
material may be obtained from the source(s) in the following paragraph 
of this section.
    (a) 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: https://www.iso.org/.

[[Page 39794]]

    (1) ISO 3668:2017(E), Paints and varnishes--Visual comparison of 
colour of paints, Third edition, 2017-05 (ISO 3668:2017); into Sec.  
596.7.
    (2) ISO 19206-2:2018(E), Road vehicles--Test devices for target 
vehicles, vulnerable road users and other objects, for assessment of 
active safety functions--Part 2: Requirements for pedestrian targets, 
First edition, 2018-12 (ISO 19206-2:2018); into Sec.  596.7.
    (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 (ISO 19206-3:2021); into Sec.  596.10.
    (4) ISO 19206-4:2020(E), Test devices for target vehicles, 
vulnerable road users and other objects, for assessment of active 
safety functions -Part 4: Requirements for bicyclist targets, First 
edition, 2020-11 (ISO 19206-4:2020); into Sec.  596.7.
    (b) [Reserved]

Subpart B--Pedestrian Test Devices


Sec.  596.7  Specifications for pedestrian test devices.

    (a) Explanation of usage. The words ``recommended,'' ``should,'' 
``can be,'' or ``should be'' appearing in sections of ISO 19206-2:2018 
(incorporated by reference, see Sec.  596.5), referenced in this 
section, are read as setting forth specifications that are used.
    (b) Explanation of usage. The words ``may be,'' or ``either'' used 
in connection with a set of items appearing in sections of ISO 19206-
2:2018 (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) Specifications for the pedestrian test devices--(1) General 
description. The adult pedestrian test mannequin (APTM) provides a 
sensor representation of a 50th percentile adult male and consist of a 
head, torso, two arms and hands, and two legs and feet. The child 
pedestrian test mannequin (CPTM) provides a sensor representation of a 
6- to 7-year-old child and consists of a head, torso, two arms and 
hands, and two legs and feet. The arms of the APTM and CPTM are 
posable, but do not move during testing. The legs of the APTM and CPTM 
articulate and are synchronized to the forward motion of the mannequin.
    (2) Dimensions and posture. The APTM has basic body dimensions and 
proportions specified in Annex A, table A.1 in ISO 19206-2:2018 
(incorporated by reference, see Sec.  596.5). The CPTM has basic body 
dimensions and proportions specified in Annex A, table A.1 in ISO 
19206-2:2018 (incorporated by reference, see Sec.  596.5).
    (3) Visual properties--(i) Head. The head has a visible hairline 
silhouette by printed graphic. The hair is black as defined in Annex B 
table B.2 of ISO 19206-4:2020, as tested in accordance with ISO 
3668:2017 (both incorporated by reference, see Sec.  596.5).
    (ii) Face. The head does not have any facial features (i.e., eyes, 
nose, mouth, and ears).
    (iii) Skin. The face, neck and hands have a skin colored as defined 
Annex B, table B.2 of ISO 19206-4:2020 (incorporated by reference, see 
Sec.  596.5).
    (iv) Torso and arms. The torso and arms are black as defined in 
Annex B table B.2 of ISO 19206-4:2020, as tested in accordance with ISO 
3668:2017 (both incorporated by reference, see Sec.  596.5).
    (v) Legs. The legs are blue as defined in Annex B table B.2 of ISO 
19206-4:2020, as tested in accordance with ISO 3668:2017 (both 
incorporated by reference, see Sec.  596.5).
    (vi) Feet. The feet are black as defined in Annex B table B.2 of 
ISO 19206-4:2020, as tested in accordance with ISO 3668:2017 (both 
incorporated by reference, see Sec.  596.5).
    (4) Infrared properties. The surface of the entire APTM or CPTM are 
within the reflectivity ranges specified in Annex B section B.2.2 of 
ISO 19206-2:2018, as illustrated in Annex B, figure B.2 (incorporated 
by reference, see Sec.  596.5).
    (5) Radar properties. The radar reflectivity characteristics of the 
pedestrian test device approximates that of a pedestrian of the same 
size when approached from the side or from behind.
    (6) Radar cross section measurements. The radar cross section 
measurements of the APTM and the CPTM is within the upper and lower 
boundaries shown in Annex B, section B.3, figure B.6 of ISO 19206-
2:2018 when tested in accordance with the measure procedure in Annex C, 
section C.3, Scenario 2 Fixed Angle Scans of ISO 19206-3:2021 with a 
measurement range of 4m to 40m (incorporated by reference, see Sec.  
596.5).
    (7) Posture. The pedestrian test device has arms that are posable 
and remain posed during testing. The pedestrian test device is equipped 
with moving legs consistent with standard gait phases specified in 
Section 5.6 of ISO 19206-2:2018 (incorporated by reference, see Sec.  
596.5).
    (8) Articulation properties. The legs of the pedestrian test device 
are in accordance with, and as described in, Annex D, section D.2 and 
illustrated in Figures D.1, D.2, and D.3 of ISO 19206-2:2018 
(incorporated by reference, see Sec.  596.6).


Sec.  596.8  [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) Explanation of usage. The words ``recommended,'' ``should,'' 
``can be,'' or ``should be'' appearing in sections of ISO 19206-3:2021 
(incorporated by reference, see Sec.  596.5), referenced in this 
section, are read as setting forth specifications that are used.
    (b) Explanation of usage. The words ``may be,'' or ``either,'' used 
in connection with a set of items appearing in sections of ISO 19206-
3:2021 (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 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 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.''

[[Page 39795]]

    (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 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 
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 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 Section C.3 of ISO 19206-3:2021 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 
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 radar cross section boundaries 
defined in Section C.2.2.4 of ISO 19206-3:2021 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 
Section C.3 of ISO 19206-3:2021 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 Annex C 
(incorporated by reference, see Sec.  596.5) when measured according to 
the radar measurement procedure specified in Section C.3 of ISO 19206-
3:2021 Annex C (incorporated by reference, see Sec.  596.5) using the 
angle-penetration method.

    Issued in Washington, DC, under authority delegated in 49 CFR 
1.95 and 501.5.
Sophie Shulman,
Deputy Administrator.
[FR Doc. 2024-09054 Filed 5-8-24; 8:45 am]
BILLING CODE 4910-59-P