Hours of Service of Drivers, 71247-71270 [E7-24238]

Agencies

• Federal Motor Carrier Safety Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 72, Number 241 (Monday, December 17, 2007)]
[Rules and Regulations]
[Pages 71247-71270]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-24238]


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DEPARTMENT OF TRANSPORTATION

Federal Motor Carrier Safety Administration

49 CFR Parts 385 and 395

[Docket No. FMCSA-2004-19608]
RIN-2126-AB14


Hours of Service of Drivers

AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT.

ACTION: Interim final rule (IFR); request for comments.

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SUMMARY: FMCSA amends the Federal Motor Carrier Safety Regulations 
effective December 27 to allow commercial motor vehicle (CMV) drivers 
up to 11 hours of driving time within a 14-hour, non-extendable window 
from the start of the workday, following 10 consecutive hours off duty 
(11-hour limit). This interim rule also allows motor carriers and 
drivers to restart calculations of the weekly on-duty time limits after 
the driver has at least 34 consecutive hours off duty (34-hour 
restart). An IFR is necessary to prevent disruption to enforcement and 
compliance with the hours-of-service (HOS) rules when the stay expires, 
as well as possible effects on the timely delivery of essential goods 
and services. This IFR will ensure that a familiar and uniform set of 
national rules governs motor carrier transportation, while FMCSA 
gathers public comments on all aspects of this interim final rule, 
conducts peer review of our analysis, and considers the appropriate 
final rule that addresses the issues identified by the Court. FMCSA is 
fully committed to issuing a final rule in 2008.

DATES: This rule is effective December 27, 2007. Comments must be 
received on or before February 15, 2008.

ADDRESSES: You may submit comments identified by Federal Docket 
Management System Number FMCSA-2004-19608 by any of the following 
methods:
     Web Site: https://www.regulations.gov. Follow the 
instructions for submitting comments on the Federal electronic docket 
site.
     Fax: 1-202-493-2251.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, Room W12-140, 1200 New Jersey Avenue, SE., Washington, 
DC 20590-0001.
     Hand Delivery: Ground Floor, Room W12-140, DOT Building, 
1200 New

[[Page 71248]]

Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m. e.t., 
Monday through Friday, except Federal holidays.
    Instructions: All submissions must include the Agency name and 
docket number or Regulatory Identification Number (RIN) for this 
rulemaking. For detailed instructions on submitting comments and 
additional information on the rulemaking process, see the Public 
Participation heading below. Note that all comments received will be 
posted without change to https://www.regulations.gov, including any 
personal information provided. Please see the Privacy Act heading 
below.
    Docket: For access to the docket to read background documents or 
comments received, go to https://www.regulations.gov at any time or to 
the ground floor, room W12-140, DOT Building, New Jersey Avenue, SE., 
Washington, DC, between 9 a.m. and 5 p.m. e.t., Monday through Friday, 
except Federal holidays.
    Privacy Act: Anyone is able to search the electronic form of all 
comments received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (65 FR 19477-78) or you may visit https://
docketsinfo.dot.gov.
    Public participation: The https://www.regulations.gov Web site is 
generally available 24 hours each day, 365 days each year. You can get 
electronic submission and retrieval help and guidelines under the 
``help'' section of the https://www.regulations.gov Web site and also at 
the DOT's https://docketsinfo.dot.gov Web site. If you want us to notify 
you that we received your comments, please include a self-addressed, 
stamped envelope or postcard or print the acknowledgement page that 
appears after submitting comments online.
    Comments received after the comment closing date will be included 
in the docket, and we will consider late comments to the extent 
practicable. FMCSA may, however, issue a final rule at any time after 
the close of the comment period.

FOR FURTHER INFORMATION CONTACT: Mr. Thomas Yager, Driver and Carrier 
Operations; or MCPSD@dot.gov. Telephone (202) 366-4325. Office hours 
are from 7:45 a.m. to 4:15 p.m., e.t., Monday through Friday, except 
Federal holidays.

SUPPLEMENTARY INFORMATION: 

Table of Contents

A. Legal Basis for the Rulemaking
B. Why This Interim Final Rule Is Necessary
C. Background
D. FMCSA's Response to the Court's Decision
E. Evaluation of Issues Concerning the Regulatory Impact Analysis
F. Evaluation of Recent Safety and Operational Data Under the 11-
Hour and 34-Hour Rules
G. Regulatory Analyses and Notices

A. Legal Basis for the Rulemaking

    This rule is based on the authority of the Motor Carrier Act of 
1935 and the Motor Carrier Safety Act of 1984.
    The Motor Carrier Act of 1935 provides that ``The Secretary of 
Transportation may prescribe requirements for (1) qualifications and 
maximum hours of service of employees of, and safety of operation and 
equipment of, a motor carrier; and, (2) qualifications and maximum 
hours of service of employees of, and standards of equipment of, a 
motor private carrier, when needed to promote safety of operation'' [49 
U.S.C. 31502(b)].
    The hours-of-service (HOS) regulations adopted in this interim rule 
pertain directly to the ``maximum hours of service of employees of * * 
* a motor carrier [49 U.S.C. 31502(b)(1)] and the ``maximum hours of 
service of employees of * * * a motor private carrier'' [49 U.S.C. 
31502(b)(2)]. The adoption and enforcement of such rules was 
specifically authorized by the Motor Carrier Act of 1935. This rule 
rests squarely on that authority.
    The Motor Carrier Safety Act of 1984 provides concurrent authority 
to regulate drivers, motor carriers, and vehicle equipment. It requires 
the Secretary of Transportation to ``prescribe regulations on 
commercial motor vehicle safety. The regulations shall prescribe 
minimum safety standards for commercial motor vehicles.'' Although this 
authority is very broad, the Act also includes specific requirements: 
``At a minimum, the regulations shall ensure that (1) commercial motor 
vehicles are maintained, equipped, loaded, and operated safely; (2) the 
responsibilities imposed on operators of commercial motor vehicles do 
not impair their ability to operate the vehicles safely; (3) the 
physical condition of operators of commercial motor vehicles is 
adequate to enable them to operate the vehicles safely; and (4) the 
operation of commercial motor vehicles does not have a deleterious 
effect on the physical condition of the operators'' [49 U.S.C. 
31136(a)].
    This rule is based on the authority of the 1984 Act and addresses 
the specific mandates of 49 U.S.C. 31136(a)(2), (3), and (4). Section 
31136(a)(1) of 49 U.S.C. deals almost entirely with the mechanical 
condition of commercial motor vehicles (CMVs), a subject not included 
in this rulemaking. The phrase ``operated safely'' in paragraph (a)(1) 
refers primarily to the safe operation of the vehicle's equipment, but 
to the extent it encompasses safe driving, this rule also addresses 
that mandate.
    Before prescribing any regulations, the Federal Motor Carrier 
Safety Administration (FMCSA) must also consider their ``costs and 
benefits'' [49 U.S.C. 31136(c)(2)(A) and 31502(d)]. Those factors are 
also discussed in this interim rule.

B. Why This Interim Final Rule Is Necessary

    After the United States Court of Appeals for the District of 
Columbia Circuit (the Court or D.C. Circuit) decision in Owner-Operator 
Independent Drivers Association, Inc. v. Federal Motor Carrier Safety 
Administration, 494 F.3d 188 (D.C. Cir. 2007), FMCSA carefully analyzed 
the current situation to determine the appropriate action to take in 
response to the decision. It is important to note that the D.C. Circuit 
found fault with various procedures related to the Agency's adoption of 
the 11-hour limit and the 34-hour restart, but not with their 
substance. This analysis included a review of the safety data 
concerning motor carrier operations, particularly with respect to 
fatigue-related fatal crashes. The discussion below further explains 
the analysis and reasoning that has led FMCSA to determine this IFR is 
necessary to ensure that a familiar and uniform set of national rules 
governs motor carrier transportation, while FMCSA gathers public 
comments and information and considers the appropriate final rule, 
which FMSCA is fully committed to issuing in 2008.
    We found that the 2005 rule has maintained highway safety outcomes 
while enhancing operational flexibility for the motor carrier industry. 
Every alternative, including immediate restoration of a 10-hour driving 
limit with no 34-hour restart, entails a risk of disrupting that 
achievement. As mentioned above, in the years since 2003, when the 11-
hour driving limit and 34-hour restart provision were adopted (along 
with the critically important 10-hour minimum daily off-duty period), 
there has been no upward trend in the number of fatal crashes as a 
whole or fatigue-related fatal crashes in particular. In fact, the 2006 
fatality rate per 100 million vehicle miles traveled (VMT) by 
combination unit trucks (mostly standard tractor-trailer

[[Page 71249]]

combinations) is the lowest since the Department of Transportation 
began keeping such statistics over 30 years ago. The percentage of 
large truck fatal crashes where the driver was coded as fatigued has 
remained essentially the same since 2003, despite small fluctuations. 
Similarly, the percentage of large-truck fatalities in the 11\th\ hour 
of driving where the driver was coded as fatigued has remained below 
the average of the years 1991-2002 since 2003. The D.C. Circuit found 
fault with various procedures related to the Agency's adoption of the 
11-hour limit and the 34-hour restart, but not with their substance. 
These provisions are part of an effective safety rule and must be 
preserved while the Department addresses the issues identified by the 
Court.
    We then examined the alternatives available to the Agency in light 
of the Court's decision and our statutory responsibilities. We believe, 
based on reading the Court's decision in conjunction with the current 
text of the regulation, that there is strong likelihood of confusion 
regarding what HOS rules will be in effect on December 27, 2007, when 
the Court's mandate issues. For example, drivers and motor carriers 
could read the Court's decision to vacate certain provisions of the 
2005 HOS rule in light of 49 CFR 395.0 and conclude that there is no 
daily driving limit in effect. Alternatively, issuance of the Court's 
mandate could be viewed as an immediate restoration of the former 10-
hour driving limit with no 34-hour restart. Regardless of how the 
Court's action is interpreted, we are certain that issuance of the 
mandate will lead to sufficient confusion and uncertainty concerning 
what HOS rules govern, and result in poor compliance by the motor 
carrier industry, as well as reduced and inconsistent enforcement by 
Federal and State officials. FMCSA provides grants to States that agree 
to adopt and enforce State laws or regulations compatible with the 
Federal safety regulations. Some adopt Federal rules by reference, 
while others require the legislature to enact a special measure 
adopting the Federal rule; many allow an administrative agency to adopt 
a rule, but only after publishing a notice and giving the public a 
chance to comment. Because of wide variations in adoption procedures 
and schedules, States have three years to adopt such regulations. In 
order to respond adequately to the Court's procedural concerns we 
believe that, to respond to the Court's decision, we need to issue an 
IFR, with an opportunity for public comment, to ensure there will not 
be a patchwork of laws across the nation--with some States enforcing a 
10-hour limit while others enforce no limit, and still others retained 
the 2005 limits--without a clear general understanding of what Federal 
regulation is in place . Undoubtedly, this would create confusion, 
inconsistency, and have an unpredictable impact on safety, since law 
enforcement may reduce its enforcement as a result of varying State 
laws. To remain legal, each driver would need to know the HOS limits in 
each State where he or she operated; this is simply impractical. 
Drivers could not be sure how their actions in one State would be 
treated in a State with a different HOS regime; officers might reduce 
their enforcement efforts to avoid the perception of unfairness. 
Uncertainty is the enemy of enforcement and compliance; it can only 
impair highway safety. This IFR will ensure that a familiar, uniform 
set of national rules govern motor carrier transportation, while FMCSA 
gathers additional public comments on all aspects of this interim final 
rule, conducts peer review of our analysis, and considers an 
appropriate final rule that addresses the issues identified by the 
Court. FMCSA is fully committed to issuing a final rule in 2008.
    Additionally, an immediate restoration of a 10-hour driving limit 
with no restart provision or entirely eliminating the daily driving 
limit would cause disruption and transition costs. The affidavits of 
motor carrier officials filed by American Trucking Associations, Inc. 
(ATA) in support of its stay motion in the D.C. Circuit (and described 
in more detail below) bear witness to the recruitment, training, 
operational, and equipment costs motor carriers would face, amounting 
in the aggregate to scores and perhaps hundreds of millions of dollars. 
The costs are not merely transitional, however. Our failure to issue an 
IFR could inflict a loss of scheduling flexibility on the industry and 
ultimately raise the cost of highway transportation. There could also 
be adverse safety implications, as new and inexperienced drivers are 
hired to handle loads that could not consistently be delivered in the 
absence of the provisions vacated by the Court. New drivers are less 
safe than veteran operators and would inevitably become involved in 
crashes that a more experienced driver population would avoid. The 
costs of added crashes are very substantial. The IFR avoids all of 
these problems.
    The IFR will also allow FMCSA and commenters to the docket 
additional time to evaluate more recent data and determine the 
appropriate final hours of service rule while avoiding shifting the 
requirements back and forth. Although our analysis indicates these 
policies are the right ones to adopt on an interim basis, FMCSA 
specifically requests comment on all the conclusions reached in this 
preamble and Regulatory Impact Analysis (RIA). FMCSA is also submitting 
its analysis to peer review. FMCSA is committed to issuing in 2008 a 
final rule fully responding to all comments to this IFR.
    For example, with respect to the 11-hour driving limit and the 34-
hour restart, the more recent data continue to support them. Although 
the D.C. Circuit raised concerns with the Agency's treatment of the 
Trucks Involved in Fatal Accidents (TIFA) data for crashes that 
occurred beyond the 11th hour in the 2005 rule, the Agency has employed 
a more sophisticated analysis discussed below that shows a lower risk 
from driving in the 11th hour than under FMCSA's earlier method. The 
modeling of time on task (TOT) developed for the 2005 rule was complex 
and comprehensive and remains the best available study of its kind. The 
D.C. Circuit faulted the Agency for failing to make this model 
available for notice and comment; this IFR corrects that oversight, and 
the RIA provides a more detailed explanation of the Agency's methods. 
Analysis of further data collected for the Virginia Tech Transportation 
Institute (VTTI) operational study supports the preliminary results 
described in the 2005 rule: There is no increase in ``critical 
incidents'' (a surrogate for crash risk) in the 11th hour of driving. 
FMCSA's very recent survey data show that, while the 11th hour and the 
34-hour restart provisions are being used more often than in 2005, 
virtually no one attempts to use every minute of driving or on-duty 
time theoretically allowed by the regulations, just as the Agency 
predicted in the 2005 rule. Furthermore, the analysis of fatigue-
related crashes by day of the week, described in detail later in the 
preamble, also supports the belief that the 34-hour restart is not 
resulting in increases in fatigue-related fatal crashes. FMCSA is not 
required to demonstrate that constant, maximum utilization of the HOS 
rules is as safe as the pre-2003 rules, when operational constraints 
(heavy traffic, shortages of parking and truck driver sleeping 
facilities, waiting time at terminals, eating and refueling, etc.) make 
it impossible to achieve that degree of utilization except for brief 
periods. The 2005 rule analyzed the safety implications of the HOS 
rules in

[[Page 71250]]

the real world, and all of the safety data for subsequent years have 
borne out the Agency's conclusion that the rule skillfully and 
successfully combines safety with operational benefits. These are the 
outcomes this IFR seeks to maintain.

C. Background

    The HOS rules limit the number of hours a driver may operate a 
commercial motor vehicle (CMV) during each workday, the length of the 
workday within which driving may occur, the minimum off-duty period 
before starting the next workday, and the cumulative number of on-duty 
hours during the work week after which a CMV may not be driven. The 
rules also allow for the use of a sleeper berth to accumulate the 
equivalent of 10 consecutive hours off duty. Prior to April 2003, FMCSA 
and its predecessor agencies limited driving time to 10 hours within a 
15-hour, extendable workday or window. In practice, the 15-hour window 
could be substantially longer than 15 hours because miscellaneous off-
duty periods were not counted as part of the 15 hours. Drivers were 
required to have at least 8 consecutive hours off duty prior to the 
beginning of a new 15-hour duty window. Drivers using a sleeper berth 
could split their time in the sleeper berth into two separate periods 
to accumulate the equivalent of 8 consecutive hours off duty provided 
neither period was less than 2 hours. Drivers working for a carrier 
that operated 6 days each week could not drive CMVs after 60 hours on 
duty in a 7 consecutive-day period; drivers working for a carrier that 
operated CMVs 7 days each week and which chose to operate under an 
alternate work schedule to the 60-hour rule, could not drive CMVs after 
70 hours on duty in an 8 consecutive-day period. In practice, drivers 
on certain schedules could ``run out'' of available on-duty time within 
a few days and be forced to go off duty for approximately 3 full days 
before being allowed to drive again, regardless of whether the driver 
may have fully recovered from the work demands in a shorter period of 
time.
    In April 2003, FMCSA published a final rule that changed the 
requirements for drivers of property-carrying CMVs. (68 FR 22456, April 
28, 2003) (``2003 Rule'') Driving was limited to 11 hours within a 14-
hour, non-extendable window after coming on duty, following 10 
consecutive hours off duty (known as the 11-hour limit). Although the 
60- and 70-hour rules were unchanged, drivers could restart the 
calculation during any weekly time period after they took 34 
consecutive hours off duty (known as the 34-hour restart provision). 
Drivers using sleeper berths were allowed to continue to split the 
mandatory off duty period, with the minimum period in the sleeper berth 
being 2 hours. (Drivers of passenger-carrying CMVs are still required 
to operate under the pre-2003 rules.)
    The 2003 rule contained several provisions that, when taken 
together, improved the opportunity for drivers to obtain restorative 
sleep, thus decreasing the likelihood of driver fatigue. For example, 
among the most significant provisions, the rule established a 14-hour, 
non-extendable window within which a driver could drive up to 11 hours, 
following a 10 consecutive hour off-duty period. This provision moved 
drivers toward a work-rest schedule that more closely matched the 
natural circadian cycle of 24 hours and gave drivers the opportunity to 
obtain the 7 to 8 hours of uninterrupted sleep per day that most adults 
need. The 34-hour restart provision also gave drivers the opportunity 
for two 8-hour sleep periods, which research has shown can overcome 
cumulative fatigue associated with sleep deprivation. Because the duty 
period within which an operator could drive was more limited than under 
the pre-2003 rule and because the rest period was long enough to 
provide an opportunity for 7 to 8 hours of uninterrupted sleep time, 
FMCSA concluded it was safe and reasonable to extend the number of 
hours an operator could drive within the 14-hour window from 10 hours 
to 11 hours. The 34-hour restart provision also gave drivers and 
carriers operational flexibility and an improved quality of life, 
particularly for long haul operations, where the 7- and 8-day limits 
may limit flexibility by forcing drivers to go off duty for periods 
longer than necessary to fully recover from a typical work week. FMCSA 
concluded that the 14-hour rule and the mandatory 10-hour off-duty 
period improved safety while providing operational flexibility that the 
11 hours of driving time and the 34-hour restart provide.
    In April 2004, the Court overturned the 2003 rule on the grounds 
that FMCSA did not address the issue of driver health, as required by 
49 U.S.C. 31136(a)(4). (Public Citizen v. FMCSA, 374 F.3d 1209, D.C. 
Cir. 2004) The Court also indicated that it had concerns about the 
rationale for other provisions in the rule. However, to avoid industry 
disruption and burden on the States, Congress enacted section 7(f) of 
the Surface Transportation Extension Act of 2004. This section provided 
that the 2003 rule would remain in effect until a new final rule 
addressed the Court's issues or until September 30, 2005, whichever 
occurred first.
    After reviewing the decision and considering the concerns raised by 
the Court, FMCSA decided to re-propose the rule as originally published 
in 2003 and to seek public comments. (70 FR 3339, Jan. 24, 2005) On 
August 25, 2005, FMCSA published a final HOS rule that retained most of 
the provisions of the 2003 rule. (70 FR 49978, Aug. 25, 2005) (``2005 
Rule'') The Agency significantly strengthened the 2003 rule by 
requiring drivers using sleeper berths to spend at least 8 but less 
than 10 consecutive hours in the sleeper berth and take an additional 2 
hours either off duty or in the sleeper berth. The new requirement 
provided drivers the opportunity to obtain 7 to 8 hours of 
uninterrupted sleep each day. Also, the Agency required that the 
shorter sleeper berth period be counted against the 14-hour on-duty 
limit decreasing the extent to which the workday could be extended. The 
2005 rule also provided relief to some short-haul operations using 
lighter trucks.
    The purpose of the HOS rules is to reduce the likelihood of driver 
fatigue and of fatigue-related crashes. Although the rules that existed 
before 2004 (the effective year of the 2003 rule) allowed less daily 
driving time than the 2003 and 2005 rules (10 hours versus 11 hours), 
the driving could occur 15 hours or more after the driver started 
working without any opportunity for intervening restorative rest or 
sleep, and followed a shorter minimum rest period (8 hours versus 10 
hours). The change to a 14-hour non-extendable window and a 10-hour 
rather than an 8-hour rest period was intended to limit the period in 
which a driver could operate a CMV and provide the driver with a work 
schedule that was consistent with the normal 24-hour biological clock. 
The 2005 rule did not limit the number of hours a driver can perform 
work other than driving, but if a driver worked after the 14th hour, he 
or she must take at least 10 consecutive hours off duty after finishing 
work before again operating a CMV. The change to a 10-hour off-duty 
requirement also recognized that drivers may do other things in their 
off-duty time besides sleeping; the 10-hour break gives them an 
opportunity to obtain the 7 to 8 hours of sleep most people need to be 
rested and to carry out other day-to-day personal activities. The 34-
hour restart provision provides drivers with an opportunity to obtain 
two 8-hour rest periods, which research indicates can overcome 
cumulative sleep deprivation. Similarly, the 2005 change to the sleeper 
berth provisions eliminated the

[[Page 71251]]

practice of splitting time in the sleeper berth into increments that 
were too short to provide an opportunity for 7 to 8 consecutive hours 
of sleep.
    FMCSA addressed the issue of driver health in the 2005 rule, as 
required by 49 U.S.C. 31136(a)(4). In preparing the 2005 rule, FMCSA 
researched both U.S. and international health and fatigue studies and 
consulted with Federal safety and health experts. In addition, FMCSA 
asked the Transportation Research Board (TRB) of the National Academies 
to contract with a research team of experts in the field of health and 
fatigue to prepare a summary of relevant literature through the TRB 
Commercial Truck and Bus Safety Synthesis Program. The literature 
review was conducted using two teams of health and transportation 
experts to identify and summarize the available research literature 
relevant to the 2005 rule. This review included research findings that 
discussed the relationship between the hours a commercial motor vehicle 
driver works, drives, and the structure of the work schedule (on-duty/
off-duty cycles, time-on-task, especially time in continuous driving, 
sleep time, etc.), and the impact on his/her health. The research 
studies cited in this interim rule are included in the List of 
References in the 2005 final rule (70 FR 49978, at 50067). Copies or 
abstracts are in the docket referenced at the beginning of this notice.
    FMCSA re-affirms its findings on driver health outlined in the 2005 
final rule. For a complete discussion of the health of drivers 
operating under the HOS rules, see the August 25, 2005 final rule (70 
FR 49978, at 49982).
    Public Citizen and others challenged the August 2005 rule on 
several grounds, as did the Owner-Operator Independent Drivers 
Association (OOIDA). On July 24, 2007, the Court rejected OOIDA's 
arguments, which focused on the sleeper berth provision, but accepted 
part of Public Citizen's arguments and vacated the 11-hour driving time 
and 34-hour restart provisions (Owner-Operator Independent Drivers 
Association, Inc. v. Federal Motor Carrier Safety Administration, 494 
F.3d 188 (D.C. Cir. 2007)). Public Citizen challenged the provisions on 
four grounds. First, Public Citizen contended that FMCSA's actions were 
inconsistent with the Administrative Procedure Act (APA) requirement 
for notice and comment rulemaking because the Agency did not disclose 
in time for comment the methodology of a model central to the Agency's 
justification for the rule. Second, when the methodology was disclosed, 
FMCSA did not provide an explanation for some of its critical elements, 
thus rendering the rule arbitrary and capricious. Third, FMCSA's 
treatment of a number of other safety considerations was also arbitrary 
and capricious. Finally, Public Citizen argued that the rule failed to 
protect driver health. The Court vacated the rule provisions based on 
the first two arguments and did not address the last two.
    The Court concluded that FMCSA did not satisfy the APA's 
requirements because the Agency failed to provide an opportunity for 
public comment on the methodology of the Agency's operator-fatigue 
model, which FMCSA used to assess the costs and benefits of alternative 
changes to the HOS rules. In particular, the Court found the Agency had 
not adequately disclosed and made available for review the 
modifications it made to the 2003 operator-fatigue model to account for 
time-on-task effects in the 2005 analysis. The Court concluded that the 
methodology the Agency used changed and did not remain constant from 
2003 to 2005 because the time-on-task element in the model was new and 
constituted the Agency's response to a defect in its previous 
methodology. The Court listed several elements of the process by which 
the Agency calculated the impact of time-on-task that it held could not 
have been anticipated and that were not disclosed in time to allow for 
public comment.
    The Court also found, turning to Public Citizen's second argument, 
that FMCSA did not provide an adequate explanation for certain critical 
elements in the model's methodology. As its basis for vacating the 
increase in the daily driving limit from 10 to 11 hours, the Court 
found arbitrary and capricious what it described as FMCSA's ``complete 
lack of explanation for an important step in the Agency's analysis,'' 
i.e., the manner in which it had plotted crash risk as a function of 
time-on-task/hours of driving. The Court also found that FMCSA failed 
to provide an explanation for its method for calculating risk relative 
to average driving hours in determining its estimate of the increased 
risk of driving in the 11th hour. As its basis for vacating the 34-hour 
restart provision, the Court found that FMCSA also provided no 
explanation for the failure of its operator-fatigue model to account 
for cumulative fatigue due to the increased weekly driving and working 
hours permitted by the 34-hour restart provision.
    Based on these two findings, the Court found it unnecessary to 
reach Public Citizen's other two arguments. In addition, the Court 
rejected three additional challenges to the 2005 Rule raised by OOIDA.
    In an order filed on September 28, 2007, the Court granted a 90-day 
stay of the mandate. The Court directed that issuance of the mandate be 
withheld until December 27, 2007.

D. FMCSA's Response to the Court's Decision

    This rulemaking addresses the issues that were identified by the 
Court in overturning two provisions of the 2005 rule. It seeks comment 
on the methodology of the model central to the justification for this 
IFR. It is based on the Agency's evaluation of new safety and 
operational data, additional analysis and modeling of the relationship 
between hours of driving and fatigue-related large truck crashes, 
discussion of the concept of cumulative fatigue in the context of 
driving activity, and the collection and evaluation of new data on the 
benefits and costs of the 11-hour driving limit and the 34-hour restart 
provisions. As an additional step to ensure the soundness of the 
Agency's analytical methods, we are subjecting our analysis to peer 
review.
    By re-adopting the 11-hour limit and the 34-hour restart, the 
Agency's intent is to allow motor carriers and drivers to combine work-
rest schedules that follow the optimal 24-hour circadian cycle (10 
hours off duty and 14 hours on duty) while maintaining highway safety 
with operational flexibility. By adopting these rules as interim, the 
Agency is seeking to avoid significant and costly disruption of 
existing industry compliance and State enforcement practices while 
ensuring that the actions and underlying safety analysis are available 
for comment from all interested parties before issuing a final rule. In 
the meantime, this will ensure that an uninterrupted safety regime 
remains in place with State enforcement laws, policies, and personnel.
    The 2005 rule includes a provision stating that ``[a]ny regulations 
on hours of service of drivers in effect before April 28, 2003, which 
were amended or replaced by the final rule adopted on April 28, 2003 
[69 FR 22456] are rescinded and not in effect'' (Sec.  395.0). Because 
the D.C. Circuit did not address this provision, either in OOIDA v. 
FMCSA or in its response to FMCSA's response in support of ATA's motion 
for a stay, the Agency must now adopt an IFR to forestall the 
significant confusion that would otherwise occur in the motor carrier 
industry, interfering with efforts to restore an orderly HOS regime.
    The two provisions being adopted in this rule, on an interim basis, 
are part of a broader, critical set of five HOS

[[Page 71252]]

provisions included in this IFR. The other three critical provisions of 
the 2005 rule are: (1) The increase in the minimum off-duty period from 
8 consecutive hours to 10 consecutive hours to ensure drivers have an 
opportunity to obtain up to 8 hours of sleep; (2) the establishment of 
a 14-hour, non-extendable window from the start of the workday within 
which all driving must be completed; and (3) the modification of the 
sleeper-berth rule to require an 8-hour sleeper berth period, thereby 
ensuring that drivers have an opportunity to obtain up to 8 hours of 
uninterrupted sleep. These provisions function along with the 11-hour 
limit and the 34-hour restart provision to protect against degradation 
of driver's cognitive or psychomotor skills due to fatigue.
    Section E describes additional analysis conducted since 2005 that 
validates the modeling relied upon by the Agency to examine the 
relationship between the risk of a fatigue-related large truck crash 
during the 11th hour of driving. It also addresses cumulative fatigue 
as it relates to the driving and restart provisions. In its analysis of 
the 34-hour restart provisions being adopted in this IFR, the Agency 
re-examined the research pertaining to long work hours and sought 
additional research completed after the 2005 rule. The Agency found no 
new research that addressed the relationship of long work hours to 
motor-vehicle driving safety.
    Safety data collected and analyzed since the 2003 HOS rule became 
effective, described below in Section F, address the impact of the 11-
hour driving limit and the 34-hour restart provisions and validate the 
Agency's argument that safety has been maintained under these 
provisions. The Agency has collected new operational data, described in 
Section F, that support its prior conclusions with regard to the cost-
benefit analysis of the 11-hour driving limit and the 34-hour restart 
provision. These data also suggest that reverting to the pre-2003 rule 
10-hour driving limit and eliminating the 34-hour restart provisions 
would be significantly disruptive to drivers, carriers, and to the 
States where most of the enforcement of HOS violations occur. It would 
also be disruptive to the safe and efficient movement of freight and 
cause delays in the delivery of essential goods and services to the 
American people.

E. Evaluation of Issues Concerning the Regulatory Impact Analysis

    The D.C. Circuit's 2007 decision held that FMCSA failed to provide 
an adequate opportunity for review of certain aspects of the RIA. The 
Agency is providing a 60-day opportunity for review and comment on the 
RIA supporting this interim rule and the interim rule itself. Since the 
public has submitted comment on many aspects of this analysis in 
previous rulemakings, and given the Agency's desire to issue a final 
rule in a timely fashion, FMCSA believes 60 days is an adequate amount 
of time to afford the public opportunity for comment.
    The Court also held that the Agency had not provided an adequate 
explanation for two critical elements of the model in the RIA 
accompanying the 2005 rule: (1) The analysis of time-on-task; and (2) 
the analysis of how the 34-hour restart affected cumulative fatigue. 
This section addresses these two topics. First, in support of this 
interim rule the Agency has reevaluated how the effects of extended 
driving hours (i.e., time-on-task or TOT) were taken into account in 
its cost-benefit model. This section summarizes how, in the RIA 
accompanying this rule, the Agency has responded to questions about the 
TOT analysis raised by Public Citizen and the Court in its July 2007 
opinion. FMCSA's careful analysis uncovered several necessary 
revisions, but the net effects of these revisions are minor. Second, 
this section addresses the issue of cumulative fatigue and describes 
the Agency's conclusion, based on recent crash data and operational 
data, that there is no evidence that the 34-hour restart provision has 
led to harmful cumulative fatigue.

Original Analysis

    The goal of the Agency's 2005 analysis was to assess the change in 
fatigue-related crash risks that would result from eliminating driving 
in an 11th hour of driving. Assuming motor carriers will still deliver 
the same volume of freight even without the 11th hour, FMCSA concluded 
that driving that could not be completed in the 11th hour would be 
completed by additional drivers in somewhat shorter trips. Crashes, 
including some that are fatigue-related, will occur in those shorter 
trips. The 2005 RIA calculated the average fatigue-related crash rate 
in trips that allow the 11th hour compared to the rate in the 
replacement trips that do not.
    A TOT effect was added to the fatigue model by establishing a 
function relating TOT and the percentage of crashes attributable to 
fatigue, relative to typical fatigue levels, and using that relative 
risk to scale up the fatigue crash risk for hours with above-average 
fatigue. The model was then calibrated by scaling the results to bring 
the average fatigue crash risk in the baseline in line with the rate 
projected for long-haul driving in earlier modeling of the impacts of 
the 2003 rule.
    To find the relationship between TOT and fatigue, FMCSA used Trucks 
Involved in Fatal Accidents (TIFA) data from 1991 through 2002 (A 
general discussion of the TIFA data set can be found later in this IFR 
under section F's subheading ``Trucks Involved in Fatal Accidents 
(TIFA) Data''). For each TOT level from the first hour through the 
12th, FMCSA computed the average percentage of crashes caused by 
fatigue. Few data points were available for TOT levels beyond the 12th 
hour, not least because it was illegal, in most cases, to drive past 10 
hours during this time period. To use the limited data on fatigue 
percentages at high TOT levels without introducing too much 
variability, FMCSA pooled the data for all crashes beyond 12 hours: we 
constructed an observation that assigned the average percent fatigue 
related crashes to the average TOT for all crashes beyond 12 hours, and 
used this as an additional data point in the analysis. Specifically, 
the average percentage of fatigue-related crashes for these crashes was 
24.75 percent; and the average TOT was 16.7 hours.
    A regression analysis included this combined data point and showed 
a clear pattern of increasing fatigue-crash percentages at high TOT 
levels, as shown in Exhibit 1. A cubic function fit the data well, 
including the final, combined point.
    From Exhibit 1, it appears that the data point for the 11th hour by 
itself lies well above the general pattern of most of the data. In the 
years from 1991 through 2002 during which the data were collected, 
driving beyond 10 hours violated the HOS rules. There were two 
exceptions when driving beyond 10 hours would not have violated the HOS 
rules. First, driving beyond 10 hours would not have violated the HOS 
rules when the driver was driving in intrastate commerce under State 
HOS rules. Second, driving beyond 10 hours would not have violated the 
HOS rules when the driver was driving under the Federal adverse driving 
conditions \1\ exception, 49 CFR 395.1(b)(1), which by its very nature 
suggests a more stressful work environment at the time of the 11th hour 
of driving. Thus, the only drivers represented were those who were 
willing to violate the rules or who were exempt from the rule and may,

[[Page 71253]]

therefore, have been unusually fatigued for reasons other than TOT.
---------------------------------------------------------------------------

    \1\ ``Adverse driving conditions'' means snow, sleet, fog, other 
adverse weather conditions, a highway covered with snow or ice, or 
unusual road and traffic conditions, none of which were apparent on 
the basis of information known to the person dispatching the run at 
the time it was begun.
---------------------------------------------------------------------------

    As shown in exhibit 1, the model's predicted relative risk at the 
11th hour is lower than the raw percent of fatigue related crashes at 
the 11th hour. This is not surprising, however, given the standard 
errors of the estimates at the longer driving times. There were 94 
crashes in the 11th hour in the data set; even if the predicted value 
of about 7 percent fatigue is correct, a random selection of 94 crashes 
would frequently show 9 or more due to fatigue.
[GRAPHIC] [TIFF OMITTED] TR17DE07.007

    Using the cubic function, FMCSA calculated the probability that a 
crash at a given TOT would be coded as fatigue-related. In order to 
calculate the impacts of allowing the 11th hour of driving, FMCSA then 
had to take these results and apply them to a model of what would 
happen to driving patterns with and without the 11th hour provision. 
FMCSA used these modeling results to calculate a TOT ``adjustment 
factor'' to calculate a total risk of fatigue-related large truck 
crashes, incorporating both TOT and non-TOT fatigue risk factors. In 
order to scale the effects, in the modeling, each fatigue probability 
for TOT levels of 8 hours or more was divided by a measure of the 
average fatigue probability across the first 11 hours, as seen in the 
TIFA data. This was simply to prepare the TOT results for use in the 
overall model, and is explained in more detail in the RIA. If properly 
performed, this rescaling should not affect the results of the analysis 
of each option, since the relative relationship of fatigue-related risk 
to driving hours is unaffected by the scaling factor. In the 2003 
model, for TOT less than 8 hours, no incremental fatigue risk was 
calculated on the grounds that for these hours fatigue was at or below 
average. As discussed later on in this preamble, the lack of adjustment 
for the hours before 8 biased the results, and needed to be addressed 
in revising the analysis.
    This approach created fatigue adjustment factors. For each hour of 
driving that was modeled, the predicted fatigue crash levels in the 
absence of a TOT effect were multiplied by these factors.
    This analysis was used to calculate the reduction in crash risks 
resulting from eliminating the 11th hour. In a model run that allowed 
the 11th hour, some hours of driving would fall into the 11th hour; 
their predicted non-TOT-adjusted fatigue crash likelihoods would be 
multiplied by a factor greater than 1.0, based on the modeling results, 
which would increase the values to reflect the higher fatigue levels 
expected at high TOT levels. In runs that eliminated the 11th hour, the 
predicted non-TOT fatigue crash risks would be multiplied by generally 
smaller TOT multipliers, and so the predicted average crash risk would 
be lower than in the run that allowed the 11th hour. Using this method, 
and calibrating the model so that the baseline run would show 7 percent 
fatigue-related crashes, FMCSA found that eliminating the 11th hour 
would reduce crash-related damages by about 0.3 percent, worth about 
$60 million annually.

Challenges to the Analysis

    In the 2007 challenge by Public Citizen, the original analysis was 
disputed in several ways. First, petitioners questioned the use of a 
function that combined the data points beyond 12 hours and treated them 
as though they fell near the 17th, rather than at some other point on 
the graph (e.g., at the 13th hour). Second, the reason for dividing the 
predicted fatigue levels from the TOT function by the average fatigue-
related crash rate was questioned. Third, the value used to adjust the 
total crash risk to the fatigue-related crash risk was criticized as 
being based on TOT hours 1-11, rather than the hours 1-10 that would be 
allowed in the alternative that eliminated the 11th hour. FMCSA's 
responses to these challenges, and the revisions to the analysis that 
were made as a consequence, are explained here.
    Statistical Approach. FMCSA's basic approach of fitting a function 
to the entire range of TOT hours rather than relying on the percentage 
of crashes at

[[Page 71254]]

a particular hour is a widely accepted statistical method. Relying on 
the percentage of fatigue crashes for individual TOT hours would 
subject the analysis to great uncertainty, because random factors can 
cause large changes in measured percentages of small numbers. The data 
used in the 2005 analysis, for example, shows that in the 13th hour, 25 
percent of fatal crashes are fatigue-related, while the 14th hour shows 
0 percent fatigue crashes; the 11th hour shows 9.6 percent, while the 
12th shows only 8.7 percent. Further, data can vary across years. For 
example, in data and analysis explained below, in 2004 there was not a 
single fatigue-related fatal crash in the 11th hour. None of these 
widely varying values are precise measures of what would be seen if 
more observations were available. If TOT affects fatigue crash risks, 
it is more likely to be due to an underlying tendency to become more 
fatigued with longer periods of driving than to the individual effects 
of particular hours of driving. The need to fit a function to the data, 
extrapolating from the large volumes of crash experience at low TOT 
levels, was in fact recognized by the Court in its 2004 decision:

    The mere fact that the magnitude of time-on-task effects is 
uncertain is no justification for disregarding the effect entirely. 
The agency, for example, could have extrapolated the time-on-task 
effects of driving longer hours using crash-risk data derived from 
drivers who drove for shorter periods of time. (Public Citizen v. 
FMCSA, 374 F.3d 1209, D.C. Cir. 2004, Slip opinion at 16)

FMCSA believes the use of a combined data point at the average TOT and 
average fatigue crash risk along with the use of a cubic function were 
reasonable approaches to the need to fit a function and use the limited 
data available for high TOT values. Moreover, in reassessing this 
model, we have evaluated the suggestions made by Public Citizen and 
found that they would have been inappropriate. Specifically, Public 
Citizen suggested a method by which the average crash risk shown in the 
data for longer driving hours could have been combined and then placed 
at 13 hours for the purposes of modeling. If fatigue goes up steadily 
with TOT, one would expect the average fatigue percentage of crashes at 
and beyond 13 hours will be higher than the fatigue percentage at 
exactly 13 hours. Thus, combining all the high-TOT data at 13 hours 
would have biased upward the estimated relationship between TOT and 
fatigue-related crash risk.
    It is true that FMCSA did not use more recent statistical modeling 
techniques that utilize all of the individual observations of crashes 
across all TOT levels, but rather aggregated observations at specific 
hours of TOT to calculate and model those percentages. \2\ One flaw in 
the original approach is that the cubic functional form allows for 
fatigue percentages that are greater than 100 percent or less than 
zero, which are outside the range of possible values for fatigue 
percentages. Another issue is that, by combining the data beyond the 
12th hour, the analysis leaves out some of the available information: 
for example, it does not consider the relative numbers of crashes at 
different TOT levels. The revised analysis, described below, addresses 
these shortcomings in the original approach and employs a superior 
statistical method for analyzing binary outcomes, i.e., whether the 
crash was fatigue-related crash or not. FMCSA specifically requests 
comment on this new modeling approach.
---------------------------------------------------------------------------

    \2\ In an analysis recently submitted to the Court by ATA, an 
expert statistician states that there is a ``reasonable basis in 
statistical theory and practice for FMCSA's approach.'' He has 
concluded that FMCSA's approach ``has a reasonable basis, in 
contrast with [Public Citizen's] illustrative example, which is 
virtually guaranteed to produce a biased result.'' The expert found 
that ``FMCSA's cubic regression curve matches the curves produced by 
more sophisticated methods quite closely over the relevant range of 
driving hours, in contrast to [Public Citizen's] illustrative 
alternative curve, which departs substantially from the curves 
produced by more sophisticated methods.'' Declaration of Dr. M. 
Laurentius Marais, Ph.D., at ] 6. See Tab F of the ATA Motion's 
Addendum to read Dr. Marais's declaration. It is in the docket 
referenced at the beginning of this notice.
---------------------------------------------------------------------------

    In response to the D.C. Circuit, FMCSA has re-estimated the 
function using a flexible logistic function, which lets predicted 
fatigue values range only from 0 to 100 percent. In this approach, 
every available crash data point was used, and several variants were 
tested to find the best-fitting logistic curve. See the RIA's Appendix 
V for details. The RIA is in the docket referenced at the beginning of 
this notice. In addition, because there are other determinants of 
fatigue-related crash risk besides the number of hours driving, FMCSA 
also explored taking other variables into account, including time of 
day, day of the week, and type of power unit (truck tractors or 
straight trucks). Again, this multivariate approach to predicting risk 
is a standard statistical technique. These extra factors did not change 
the simple relationship of TOT to fatigue crash risk; however, there 
are other interesting results relevant to the restart provision we will 
explain further below. This approach yielded a TOT fatigue crash risk 
function that was generally similar to the original cubic function for 
low TOT levels, but lay somewhat lower at the 11th hour as shown in 
Exhibit 2.

[[Page 71255]]

[GRAPHIC] [TIFF OMITTED] TR17DE07.008

    Division of the Fatigue Percentage by its Average. Dividing the 
predicted fatigue crash risk by an average value is a reasonable way to 
create a TOT adjustment factor that changes relative fatigue values 
within a set of data without changing the average value of that set. 
The fatigue model used in the original analysis yielded raw fatigue 
predictions for each simulated driving hour, but did not take TOT 
explicitly into account. Suppose these raw predictions happened to 
average 7 percent fatigue. To adjust these predictions to account for 
TOT effects, each simulated hour's fatigue percentage should be 
multiplied by an adjustment factor based on the TOT fatigue function: 
The raw predicted value for an 11th hour of driving, for example, 
should be multiplied by a larger value than for a 1st or 8th hour.
    FMCSA could have used the TOT fatigue function directly as an 
adjustment factor: Raw predicted values for the 11th hours could have 
been multiplied by 0.072, and those for the 1st hours by 0.014. On 
average, however, the resulting values would have been much smaller 
than the original values, because the average value of the TOT fatigue 
function across all hours is less than 0.03. To return the typical 
fatigue value to a more realistic level, the adjusted values would have 
had to be scaled up by close to two orders of magnitude. As an 
alternative, the TOT fatigue function can first be divided by its 
average. This step creates an adjustment factor that averages 1.0, with 
some values above 1 and some below. Using this adjustment factor will 
take the TOT effect into account while leaving the typical measured 
fatigue level relatively unchanged.
    Choice of the Divisor. In the original analysis, the TOT adjustment 
factor was created by dividing the TOT fatigue function by 2.92 
percent, which was the average relative fatigue-related crash risk 
level for the first 11 hours as seen in the underlying data. It was 
argued by Public Citizen that the average value of the function for the 
first 10 hours would have been more appropriate. Because of the details 
of the analysis, however, and the way the results were scaled, the 
choice of divisor has no effect on the results. As demonstrated in 
Appendix V of the RIA, when the fatigue adjustment factors are applied 
to both the baseline and policy options, the divisor cancels itself 
out, and has no effect on the estimate of the relative fatigue crash 
percentages with or without the 11th hour.
    Thus, FMCSA concluded both that there is a conceptual basis for 
dividing the predicted fatigue levels by TOT by the average fatigue 
level--to create an adjustment factor centered on 1.0--and also that 
the choice of an exact divisor is unimportant because that factor 
cancels out in the mathematical calculation.

Updates to the Analysis

    FMCSA concluded that two issues newly identified by the D.C. 
Circuit needed to be addressed in revising the estimated benefits of 
eliminating the 11th hour. First, the function used by the Agency was 
not ideal. As discussed above, although we continue to believe our 
original approach is reasonable, we have developed a more sophisticated 
model. Second, the approach laid out above was implemented incorrectly. 
Although all TOT hours should have been adjusted, in the 2005 analysis, 
only hour 8 or more were given adjustment factors. The Agency has 
calculated how these two issues would have affected the estimated 
benefits of eliminating the 11th hour by estimating the change in the 
average fatigue crash risk twice: once with the original approach, and 
once with an updated approach. For each approach, this was accomplished 
by
     Estimating the fraction of driving that was done in each 
TOT hour,

[[Page 71256]]

assuming that driving 11 hours was legal;
     Multiplying the fraction for each TOT hour by a TOT 
fatigue adjustment factor;
     Summing the results of this multiplication;
     Repeating these calculations for a case that allowed only 
10 hours of driving; and
     Finding the percentage change in the fatigue percentages 
between the 11 and 10 hour cases.
The details of these calculations are shown in Appendix V of the RIA. 
Under the original analysis, the fatigue crash risk appeared to fall by 
almost 3.6 percent if the 11th driving hour were restricted. Under the 
revised analysis, the fatigue crash risk fell by 5.1 percent. Thus, 
correcting the TOT approach is expected to increase the projected TOT 
safety benefits by a factor of about 5.1 percent/3.6 percent, or about 
1.42 times. Thus, if the analysis had been done correctly, the true 
benefits would be about 1.42 times the original estimate of $60 
million, or about $85 million per year.

Comparisons of Revised Benefits to Estimated Costs

    The increase of $25 million in benefits per year still leaves the 
projected benefits of restricting the 11th hour of driving of $85 
million per year far short of the projected costs. The costs of 
prohibiting the 11th hour were estimated by finding the average 
reduction in driver productivity in shifting between a case that 
assumed driving time is capped at 11 hours and a variant that capped 
driving time at 10 hours. As described in Appendix V of the RIA, the 
change in productivity of almost 2 percent, valued at almost $300 
million per percentage point, led to an estimated cost of $586 million 
per year for eliminating the 11th hour. In the original analysis, 
subtracting the benefits of $60 million left estimated net costs of 
$526 million; with the revised TOT analysis, the net costs are now 
estimated to be $501 million. This reduction in net costs from $526 
million to $501 million amounts to less than 5 percent of total net 
costs. Thus, the revisions to the TOT analysis have very little effect 
on the estimated cost-effectiveness of eliminating the 11th hour.
    The RIA did present a sensitivity analysis that showed, under a 
variety of unique circumstances, the net costs could fall from $526 
million to about $240 million. As such, the conclusion reached in the 
RIA accompanying this rule was that, regardless of the assumptions 
made, whether they were related to the percent of all large truck 
crashes that are fatigue-related, the relative risk associated with 
fatigue-related large truck crashes in the 11th hour, or the value of a 
statistical life, there would still be a minimum annual net cost of 
approximately $160 million to eliminate the 11th hour of driving.
    The 34-hour restart provision.
    The 34-hour restart provision gives drivers, particularly long-haul 
drivers, operational flexibility in planning their trips that 
previously was not available with the 7- and 8-day limits. FMCSA set 
the limit at 34 hours because that would provide drivers with an 
opportunity to obtain two 8-hour sleep periods while keeping them on a 
24-hour cycle. The Agency adopted the 34-hour restart after reviewing 
studies considering the time periods necessary for overcoming 
cumulative fatigue caused by sleep debt. [Dinges, D.F., et al. (1997), 
p. 267; Balkin, T., et al. (2000), p. ES-8; Belenky, G., et al. (2003), 
p. 11; Van Dongen, H.P.A., et al. (2003), p. 125. The research studies 
cited in this interim rule are included in the List of References in 
the 2005 final rule (70 FR 49978, at 50067). Copies or abstracts are in 
the docket referenced at the beginning of this notice.] As the Agency 
explained in 2005, fatigue resulting from sleep loss is usually 
characterized as acute, resulting from a single insufficient sleep 
period; or cumulative, resulting from two or more insufficient sleep 
periods [Rosekind, M.R., et al. (1997), p. 7.2]. Rosekind describes 
three types of sleep loss (i.e., total sleep loss, partial sleep loss, 
and sleep debt): ``Sleep loss can occur either totally or as a partial 
loss. Total sleep loss involves a completely missed sleep opportunity 
and continuous wakefulness for about 24 hours or longer. Partial sleep 
loss occurs when sleep is obtained within a 24-hour period but in an 
amount that is reduced from the physiologically required amount or 
habitual total. Sleep loss also can accumulate over time into what is 
often referred to as 'sleep debt.' Sleep loss, whether total or 
partial, acute or cumulative, results in significantly degraded 
performance, alertness and mood'' [Id.].
    Public Citizen's challenge to the 2005 rule argued that the restart 
provision allows drivers to work more hours each week, leading to 
cumulative fatigue that is different from sleep debt. In its opinion 
invalidating the 34-hour restart the Court agreed, explaining that it 
was interested in a ``different kind'' of cumulative fatigue, the 
cumulative fatigue ``associated with the increased driving and working 
hours that [the 34-hour restart] would permit,'' and not ``the `sleep 
deficit' that `accumulates with successive sleep-deprived days.' '' The 
Court concluded that FMCSA had not adequately considered this 
``cumulative fatigue.''
    This interim rule responds to this finding by the Court in two 
parts. First, the Agency found in 2005 that few studies address the 
effect of recovery periods between work periods spanning multiple days, 
such as a workweek [O'Neill, T.R., et al. (1999), p. 2; Wylie, C.D., et 
al. (1997), p. 27; Smiley, A., & Heslegrave, R. (1997), p. 14]. After 
reviewing the studies relevant to the 34-hour recovery period, as cited 
in the 2003 rule and those submitted by commenters to the 2005 NPRM, 
the Agency determined that current scientific evidence is limited with 
respect to the type of cumulative fatigue raised by Public Citizen and 
the Court. Studies of time-on-task frequently measure ``fatigue'' as a 
function of drowsiness. For example, Wylie, C.D., et al.'s 1996 
operational study of 80 long-haul drivers engaged in revenue-generating 
runs in the U.S. (under the 10-hour driving limit) and Canada (under 
that country's 13-hour driving limit), reported that time-on-task was 
not a strong or consistent predictor of observed fatigue, measured as 
drowsiness, as observed in video records of comparable daytime segments 
of driving. In Wylie's study, no difference in drowsiness was found 
between 10 and 13 hours of driving. Some measures of performance, such 
as lane tracking and individual cognitive performance, as well as self-
rating of fatigue, were better at 10 hours of driving time than at 13 
(lane tracking was confounded by difference in driving routes and road 
conditions in the two countries). Conversely, reaction time was better 
at 13 hours of driving than at 10. The authors noted that the lack of 
variance in drowsiness between driving periods may be attributable to 
the fact that the study measured only daytime drowsiness. Other 
research suggests the body's circadian rhythm limits the negative 
effects of more hours of work during daytime operations. [Wylie, C.D., 
et al. (1996) pp. 5.13-5.14].
    A 1999 study evaluated the effects on fatigue and performance 
during a daytime schedule of 14 hours on duty and 10 hours off duty, 
with drivers performing simulated driving and loading/unloading tasks. 
The authors found mild cumulative effects on subjective measurements of 
sleepiness; a slight but statistically significant deterioration in 
duty-day subjective sleepiness, reaction time response, and measures of 
driving performance over the course of a week; but no cumulative 
deterioration of driver response in

[[Page 71257]]

crash-likely situations. The authors reported that a schedule of 14 
hours on duty (with 12 hours of driving) and 10 hours off duty for 5 
consecutive day periods did not appear to produce significant 
cumulative fatigue over the 2-week testing period [O'Neill, T.R., et 
al. (1999), p. 48].
    Additionally, as its second part of its response to the Court's 
finding, FMCSA sought recent (i.e., post-2005) scientific studies 
addressing cumulative fatigue of the type focused upon by the Court. 
Although some popular literature discusses ``burnout,'' the Agency does 
not consider these anecdotal narratives to be evidence that cumulative 
fatigue is a significant concern under normal driving conditions. While 
the Agency concluded based on a reasonable review of the literature 
that cumulative fatigue associated with increased weekly truck driving 
activity under the conditions similar to that studied in the literature 
was not a substantial problem, the critics of the 2005 rule did not 
provide any scientific literature supporting their claims of cumulative 
fatigue specific to truck driving. It is therefore not surprising that 
FMCSA has been unable at this time to identify an available model that 
it could use to evaluate the effects of cumulative fatigue as a factor 
separate from fatigue caused by sleep deficits in a motor carrier 
context. FMCSA seeks existing studies or models that could be used to 
further analyze and validate the veracity of these claims regarding 
cumulative fatigue, specifically studies or models analyzing or focused 
on truck driving.
    Furthermore, Public Citizen discussed a scenario by which the new 
rulemaking would allow for a substantially higher number of hours than 
would be found under the more normal driving conditions similar to 
those studied in the literature. This would be accomplished by driving 
11 hours, immediately going off duty for 10 hours, and repeating this 
pattern.
    First, although such a pattern could develop in certain operations 
for certain periods, nothing like this was observed in FMCSA's 2005 and 
2007 Field Surveys. Additionally, non-standard driving patterns were 
allowed under the pre-2003 rule that had the potential to result in 
significantly more sleep-associated fatigue than the driving patterns 
that would be allowed even under Public Cit