[Federal Register: August 25, 2005 (Volume 70, Number 164)]
[Rules and Regulations]
[Page 49977-50073]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25au05-12]
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Part II
Department of Transportation
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Federal Motor Carrier Safety Administration
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49 CFR Parts 385, 390, and 395
Hours of Service of Drivers; Final Rule
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DEPARTMENT OF TRANSPORTATION
Federal Motor Carrier Safety Administration
49 CFR Parts 385, 390 and 395
[Docket No. FMCSA-2004-19608; formerly FMCSA-1997-2350]
RIN-2126-AA90
Hours of Service of Drivers
AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT.
ACTION: Final rule.
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SUMMARY: FMCSA is publishing today its final rule governing hours of
service for commercial motor vehicle drivers, following its Notice of
Proposed Rulemaking published January 24, 2005. The rule addresses
requirements for driving, duty, and off-duty time; a recovery period,
sleeper berth, and new requirements for short-haul drivers. The hours-
of-service regulations published on April 28, 2003, were vacated by the
U.S. Court of Appeals for the District of Columbia Circuit on July 16,
2004. Congress subsequently provided, through the Surface
Transportation Extension Act of 2004, that the 2003 regulations will
remain in effect until the effective date of a new final rule
addressing the issues raised by the court or September 30, 2005,
whichever occurs first. Today's rule meets that requirement.
DATES: This rule is effective October 1, 2005.
FOR FURTHER INFORMATION CONTACT: Tom Yager, Chief, Driver and Carrier
Operations Division, Office of Bus and Truck Standards and Operations
(MC-PSD), Federal Motor Carrier Safety Administration, 400 Seventh
Street. S.W., Washington, DC 20590. Phone 202-366-4009, E-mail
MCPSD@fmcsa.dot.gov.
SUPPLEMENTARY INFORMATION:
Table of Contents
A. Legal Basis for the Rulemaking
B. Background Information
C. Executive Summary
D. Research Review Process
E. Driver Health
F. Driver Fatigue
G. Current and Future FMCSA Research
H. Crash Data
I. Operational Data
J. Comments to Docket and FMCSA Responses
J.1. Sleep Loss
J.2. Exposure to Environmental Stressors
J.3. Workplace Injuries and Fatalities
J.4. Lifestyle Choices
J.5. Driving Time
J.6. Duty Tour
J.7. Off-Duty Time
J.8. The 34-Hour Restart and 60/70-Hour Rules
J.9. Sleeper-Berth Use
J.10. Regulation of Short-Haul Operations
J.11. Combined Effects
J.12. Effective and Implementation Dates
J.13. Electronic On-Board Recording Devices
J.14. Other Provisions
J.15. Legal Issues
K. Rulemaking Analyses and Notices
K.1. Executive Order 12866 (Regulatory Planning and Review) and
DOT Regulatory Policies and Procedures
K.2. Regulatory Flexibility Act
K.3. Unfunded Mandates Reform Act of 1995
K.4. National Environmental Policy Act
K.5. Paperwork Reduction Act
K.6. Executive Order 13211 (Energy Supply, Distribution, or Use)
K.7. Executive Order 12898 (Environmental Justice)
K.8. Executive Order 13045 (Protection of Children)
K.9. Executive Order 12988 (Civil Justice Reform)
K.10. Executive Order 12630 (Taking of Private Property)
K.11. Executive Order 13132 (Federalism)
K.12. Executive Order 12372 (Intergovernmental Review)
L. List of References
Table of Abbreviations
AHAS Advocates for Highway and Auto Safety
AMI Acute Myocardial Infarction
AMSA American Moving and Storage Association
ANPRM Advance Notice of Proposed Rulemaking
APA Administrative Procedure Act
ATA American Trucking Associations
BAC Blood Alcohol Content
BLS U.S. Bureau of Labor Statistics
BMI Body Mass Index
CATF Clean Air Task Force
CDL Commercial Drivers License
CEQ Council on Environmental Quality
CFR Code of Federal Regulations
CHP California Highway Patrol
CMV Commercial Motor Vehicle
CRASH Citizens for Reliable and Safe Highways
CRMCA Colorado Ready Mixed Concrete Association
CTC Corporate Transportation Coalition
CVD Cardiovascular Disease
CVSA Commercial Vehicle Safety Alliance
dBA Decibels Adjusted
DE Diesel Exhaust
DOT Department of Transportation
EA Environmental Assessment
ECMT European Conference of Ministers of Transport
EEI Edison Electric Institute
EOBR Electronic On-Board Recorder
EPA U.S. Environmental Protection Agency
FARS Fatality Analysis Reporting System
FHWA Federal Highway Administration
FMCSA Federal Motor Carrier Safety Administration
FMCSR Federal Motor Carrier Safety Regulations
FMP Fatigue Management Program
FONSI Finding of No Significant Impact
FR Federal Register
GVWR Gross Vehicle Weight Rating
HEI Health Effects Institute
HOS Hours of Service
IBT International Brotherhood of Teamsters
ICC Interstate Commerce Commission
ICCTA ICC Termination Act of 1995
IIHS Insurance Institute for Highway Safety
IRP International Registration Plan
ISO International Standards Organization
LBP Lower Back Pain
LH Long Haul
LR Long Regional
LTL Less-Than-Truckload
MCMIS Motor Carrier Management Information System
MCSAP Motor Carrier Safety Assistance Program
MFCA Motor Freight Carriers Association
MPH Miles per Hour
MTA Minnesota Trucking Association
NACA National Armored Car Association
NAICS North American Industrial Classification System
NEPA National Environmental Policy Act
NHTSA National Highway Traffic Safety Administration
NIH National Institutes of Health
NIOSH National Institute for Occupational Safety and Health
NITL National Industrial Transportation League
NPRM Notice of Proposed Rulemaking
NPTC National Private Truck Council
NRMCA National Ready Mixed Concrete Association
NSSGA National Stone, Sand, and Gravel Association
NTSB National Transportation Safety Board
OMB Office of Management and Budget
OOIDA Owner-Operator Independent Drivers Association
OOS Out-of -Service
OSHA U.S. Occupational Safety and Health Administration
OTR Over-the-Road
PATT Parents Against Tired Truckers
PM Particulate Matter
PMC PubMed Central
PRA Paperwork Reduction Act of 1995
PVT Psychomotor Vigilance Test
RIA Regulatory Impact Analysis
RMA Risk Management Association
R&T Research and Technology
RODS Records of Duty Status
SBA Small Business Administration
SH Short Haul
SR Short Regional
STAA Surface Transportation Assistance Act
TCA Truckload Carriers Association
TIFA Trucks Involved in Fatal Accidents
TL Truckload
TOT Time-on-Task
TRB Transportation Research Board
UMTRI University of Michigan Transportation Research Institute
UPS United Parcel Service
USV Utility Service Vehicle
VIUS Vehicle Inventory and Use Survey
VMT Vehicle Miles Traveled
VSL Value of a Statistical Life
VTTI Virginia Tech Transportation Institute
WBV Whole Body Vibration
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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 regulations adopted today deal directly with
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, FMCSA must also consider their
``costs and benefits'' [49 U.S.C. 31136(c)(2)(A) and 31502(d)]. Those
factors are also discussed later.
B. Background Information
B.1. History of the Hours-of-Service Rule
The Interstate Commerce Commission (ICC) promulgated the first
Federal hours-of-service regulations (HOS) in the late 1930s. The rules
were based on the Motor Carrier Act of 1935. The regulations remained
largely unchanged from 1940 until 2003, except for an important
amendment in 1962. Prior to 1962, driver hours-of-service regulations
were based on a 24-hour period from noon to noon or midnight to
midnight. A driver could be on duty no more than 15 hours in a 24-
consecutive-hour period. In 1962, among other rule changes, the 24-hour
cycle was removed and replaced by minimum off-duty periods. A driver
could ``restart'' the calculation of his or her driving and on-duty
limitations after any period of 8 or more hours off duty.
Section 408 of the ICC Termination Act of 1995 (ICCTA) (Pub. L.
104-88, 109 Stat. 803, at 958) required the Federal Highway
Administration (FHWA) to conduct rulemaking ``dealing with a variety of
fatigue-related issues pertaining to commercial motor vehicle safety.''
In response, FHWA published an advance notice of proposed rulemaking
(ANPRM) on November 5, 1996 (61 FR 57252). FMCSA was established as a
separate Agency on January 1, 2000. At that time, responsibility to
promulgate CMV regulations was transferred from FHWA to FMCSA, which
published an hours-of-service Notice of Proposed Rulemaking (NPRM) on
May 2, 2000 (65 FR 25540) and a final rule on April 28, 2003 (68 FR
22456). Technical amendments to the final rule were published on
September 30, 2003 (68 FR 56208). Motor carriers and drivers were
required to comply with the final rule on January 4, 2004.
FMCSA's 2003 rule did not change any hours-of-service requirements
for motor carriers and drivers operating passenger-carrying vehicles.
They were required to continue complying with the hours-of-service
rules existing before the 2003 rule (see 68 FR 22461-22462). Changes in
hours-of-service provisions in the new rule applied only to motor
carriers and drivers operating property-carrying vehicles. Compared to
the previous regulations, the 2003 rule: (1) Required drivers to take
10, instead of 8, consecutive hours off-duty (except when using sleeper
berths); (2) retained the prior prohibition on driving after 60 hours
on duty in 7 days or 70 hours in 8 days; (3) increased allowable
driving time from 10 to 11 hours in any one duty period; and (4)
replaced the so-called 15-hour rule (which prohibited drivers from
driving after being on duty more than 15 hours, not including
intervening off-duty time) with a 14-hour rule (which prohibited
driving after the 14th hour after the driver came on duty, with no
extensions for off-duty time). Note that the 15-hour limit had been
cumulative--so it could be interspersed with off-duty time--while the
non-extendable 14-hour limit was consecutive. Additionally, FMCSA
allowed drivers to ``restart'' the calculations for the 60- and 70-hour
limits by taking 34 consecutive hours off duty. Based on the data and
research available at the time, FMCSA was convinced that these new
rules constituted a significant improvement in the hours-of-service
regulations, compared to the rules they replaced, by providing drivers
with better opportunities to obtain off-duty time offering daily
restorative sleep, thereby reducing the incidence of crashes wholly or
partially attributable to drowsiness or fatigue.
On June 12, 2003, Public Citizen, Citizens for Reliable and Safe
Highways (CRASH) and Parents Against Tired Truckers (PATT) filed a
petition to review the new hours-of-service rule with the United States
Court of Appeals for the District of Columbia Circuit (D.C. Circuit).
On July 16, 2004, the D.C. Circuit issued an opinion holding that the
rule was arbitrary and capricious because the Agency failed to consider
the impact of the rules on the health of drivers, as required by 49
U.S.C. 31136(a)(4). Public Citizen et al. v. Federal Motor Carrier
Safety Administration, 374 F.3d 1209, at 1216. The D.C. Circuit noted,
however, that neither Public Citizen nor the court was ``suggest[ing]
that the statute requires the agency to protect driver health to the
exclusion of those other factors [i.e., the costs and benefits of the
rule], only that the agency must consider it.'' Id. at 1217 (emphasis
in original). Although FMCSA argued that the effect of driver health on
vehicle safety had permeated the entire rulemaking process, the court
said that driver health and vehicle safety were distinct factors that
must be considered separately.
In dicta the court also stated that: (1) FMCSA's justification for
increasing allowable driving time from 10 to 11 hours might be legally
inadequate because the Agency failed to show how additional off-duty
time compensated for more driving time, and especially
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because it failed to discuss the effects of the 34-hour recovery
provision; (2) splitting off-duty time in a sleeper berth into periods
of less than 10 hours was probably arbitrary and capricious, because
FMCSA itself asserted that drivers need 8 hours of uninterrupted sleep;
(3) failing to collect and analyze data on the costs and benefits of
requiring electronic on-board recording devices (EOBRs) probably
violated section 408 of the ICC Termination Act, which requires FMCSA
to ``deal with'' EOBRs; and (4) the Agency failed to address or justify
the additional on-duty and driving hours allowed by the 34-hour
recovery provision.
On September 1, 2004 (69 FR 53386), FMCSA published an ANPRM
requesting information about factors the Agency should consider in
developing performance specifications for EOBRs. As the Agency said in
the preamble to that document, ``FMCSA is attempting to evaluate the
suitability of EOBRs to demonstrate compliance with the enforcement of
the hours-of-service regulations, which in turn will have major
implications for the welfare of drivers and the safe operation of
commercial motor vehicles.'' The ANPRM asked for comments and
information, both on technical questions relating to EOBRs, and on the
potential costs and benefits of such devices. The EOBR rulemaking has
been and will remain separate from this hours-of-service rulemaking.
(For additional discussion of EOBRs, see Section J.13.)
On September 30, 2004, the President signed the Surface
Transportation Extension Act of 2004, Part V (Public Law 108-310, 118
Stat. 1144). Section 7(f) of the Act provides that ``[t]he hours-of-
service regulations applicable to property-carrying commercial drivers
contained in the Final Rule published on April 28, 2003 (68 FR 22456-
22517), as amended on September 30, 2003 (68 FR 56208-56212), and made
applicable to motor carriers and drivers on January 4, 2004, shall be
in effect until the earlier of--(1) the effective date of a new final
rule addressing the issues raised by the July 16, 2004, decision of the
United States Court of Appeals for the District of Columbia in Public
Citizen, et al. v. Federal Motor Carrier Safety Administration (No. 03-
1165); or (2) September 30, 2005.'' (118 Stat. at 1154).
B.2. Notice of Proposed Rulemaking (January 24, 2005)
FMCSA published an NPRM on January 24, 2005 (70 FR 3339) to
reconsider the 2003 rule and determine what changes might be necessary
to correct the deficiencies identified by the court. The Agency used
the 2003 rule as a proposal for the purpose of soliciting public
comments, but also announced that ``[t]his rulemaking is necessary to
develop hours-of-service regulations to replace those vacated by the
Court'' (70 FR 3342). The NPRM asked a series of questions on driver
health, sleep loss and deprivation, driving time, sleeper berths, and
other subjects; the answers are discussed later. While awaiting the
submission and review of docket comments, the Agency pursued a research
program to identify relevant studies on the same issues; the results of
that effort are also described in later sections of the preamble.
C. Executive Summary
Today's rule requires all drivers of property-carrying commercial
motor vehicles (CMVs) in interstate commerce to take at least 10
consecutive hours off duty before driving, limits driving time to 11
consecutive hours within a 14-hour, non-extendable window after coming
on duty, and prohibits driving after the driver has been on duty 60
hours in 7 consecutive days, or 70 hours in 8 consecutive days. Drivers
may restart the 60- or 70-hour ``clock'' by taking 34 consecutive hours
off duty.
These provisions are the same as those of FMCSA's 2003 final rule
that was vacated by the U.S. Court of Appeals for the D.C. Circuit and
then reinstated by Congress for the duration of fiscal year 2005. These
limits, however, are significantly different from the pre-2003 HOS
regulation, which required only 8 hours off duty before driving,
allowed 10 hours of driving time, and prohibited driving after having
been on duty for 15 hours (but allowed any off-duty time taken during
the work shift to be excluded from the calculation of the 15-hour
limit). The pre-2003 rule had no counterpart to today's 34-hour
recovery provision. The recovery role was played by the 60- and 70-hour
limits, the only element of the pre-2003 rule which has been adopted
without change for property-carrying vehicles in today's rule.
The 14-hour driving window and the 10-hour off-duty requirement of
today's rule combine to move most drivers toward a 24-hour cycle, which
allows the body to operate in accord with its normal circadian rhythm
and the driver to sleep on the same schedule each day. A driver may
remain on duty after the 14-hour window closes or go off duty after the
11th hour of driving, in each case returning to work after 10 hours off
duty on something other than a 24-hour cycle. Nonetheless, FMCSA
believes that most drivers, most of the time, will go off duty at or
before the end of the 14th hour, since their principal responsibility--
driving--is illegal after that point. The circadian friendliness of
today's rule is bolstered by the requirement for 10 consecutive hours
off duty. This is enough time to enable drivers to get the 7-8 hours of
sleep most people need to maintain alertness and prevent the onset of
cumulative fatigue.
The original restart provisions were the 60- and 70-hour limits.
Drivers could not drive after having been on duty for those periods
until they had been off duty long enough to reduce their 7- or 8-day
on-duty totals below the 60- or 70-hour threshold. These limits are
being adopted in today's rule, but the Agency is also adding a second
and more flexible recovery provision, as it did in 2003--the 34-hour
restart. A 34-hour period gives a large majority of drivers the
opportunity for two night sleep periods, and all drivers the
opportunity for two consecutive 8-hour sleep periods separated by a
full 18-hour day. Comments to the docket stated that the 34-hour
restart provides far more flexibility than the 60- and 70-hour limits
alone, enabling drivers to tailor their schedules to their business
requirements while still spending more time at home.
Today's rule also creates a new regulatory regime for drivers of
CMVs that do not require a CDL, provided they operate within a 150-mile
radius of their work-reporting location. These drivers are not required
to keep logbooks, though their employers must keep accurate time
records, and the driver may use a 16-hour driving window twice a week.
Driving time may not exceed the normal 11 hours, but the longer
operational window twice a week enables short-haul carriers to meet
unusual scheduling demands. Short-haul drivers rarely drive anything
close to 11 hours, and available statistics show that they are greatly
under-represented in fatigue-related accidents. On a per-mile basis,
long-haul trucks are almost 20 times more likely to be involved in a
fatigue-related crash. One study suggested that a contributing factor
to this statistical imbalance is the variety of work short-haul drivers
typically perform; variety seems to minimize fatigue.
The rule adopted today balances considerations of driver and public
safety, driver health, and costs and benefits to the motor carrier
industry--all factors the Agency is required to take into account. The
provisions are described separately in the preamble, but they
constitute an interconnected whole and cannot be adequately understood
in isolation.
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The rule addresses driver health issues in detail, and provides a
lengthy explanation and justification for the requirements adopted
today. FMCSA has examined a wide range of scientific evidence,
independently collected, summarized, and reviewed by a health panel
created at the Agency's request by the Transportation Research Board of
the National Academies of Science. FMCSA has concluded that the
operation of CMVs under this rule does not have a deleterious effect on
the physical condition of drivers. Because relatively little of the
available evidence was derived from motor carrier operations, the
Agency had to evaluate and weigh information from different fields and
adapt it to a trucking environment. We believe our conclusions
accurately reflect a preponderance of the scientific data. The
additional off-duty time provided by the rule, along with the 14-hour
driving window, should have a particularly beneficial effect on
drivers' sleep opportunities, and indirectly on their health as well.
In an indication of the fatigue-reducing benefits of the 2003 rule,
preliminary information on sleep habits under that rule shows drivers
are getting, on average, at least an additional hour of sleep compared
to the pre-2003 rule. There is no indication that drivers are averaging
more hours of work, as opponents of the 2003 rule had feared.
The Agency has examined all of the data on crash risk. Virtually
every study has weaknesses or limitations. The largest database on
fatal truck crashes (Trucks Involved in Fatal Crashes, or TIFA) records
accidents that occurred entirely under the pre-2003 HOS rule, when off-
duty time could have been as short as 8 hours. Furthermore, while the
crash risk reflected in TIFA data rises with the number of hours driven
before the crash, the risk in the 11th hour generally reflects illegal
driving, since the normal limit at the time was 10 hours. Also, despite
being the largest database available, the data contain relatively few
fatigue-related crashes after long hours of driving. All in all, we
thus must be careful in applying this data to the 2003 rule or today's
rule, where the minimum off-duty time is 25 percent greater.
On the other hand, we also examined recent data collected while the
2003 rule was in effect. Although this data suggests that fatigue-
related crashes have fallen since the 2003 rule became effective, this
newer data is mostly preliminary, self-reported without statistical
controls, and also reflects small sample sizes, all of which--once
again--sometimes leads to inconsistent findings.
The rule and the Regulatory Impact Analysis discuss the strengths
and weaknesses of each data source and balance the shortcomings of one
against the advantages of another. The TIFA data from 1991 to 2002 are
very comprehensive. In order to ensure that its safety analysis erred
on the side of caution, the Agency used TIFA data to estimate the risk
of additional driving hours, knowing that the risk is probably over-
stated given the better opportunities for restorative sleep available
under the 2003 rule and today's final rule. It is also clear that newer
CMVs, with their quieter and more comfortable cabs, are less fatiguing
to drive. That change may also affect the usefulness of the TIFA data,
though this factor is impossible to quantify.
Using the most conservative estimates of crash risk for a given
amount of driving time, FMCSA's analysis shows that the safety
differential between a 10-hour and an 11-hour driving limit is very
small while the economic cost differential is very large. The
operational and scheduling flexibility of an 11-hour limit, even when
it is not utilized fully, is both economically and socially valuable.
According to the drivers who commented to the docket, the 11-hour limit
in the 2003 rule enables them to get home more often, when the 10-hour
limit would leave them stranded at roadside, out of hours. It also
allows them to get home without pushing quite as hard as they might be
tempted to do under a 10-hour limit.
FMCSA examined a range of options and found that today's rule is
the only one that is cost-beneficial, with a net annual benefit
estimated at $270 million. Reducing driving time from 11 to 10 hours,
while leaving the rest of today's rule intact, would increase net costs
by $526 million per year. To confirm our findings, we conducted a
sensitivity analysis of the data and assumptions used. We changed these
parameters in a way that was unfavorable to today's rule in general and
to allowing 11 hours of driving in particular. No parameters tested,
either singly or in combination, produced a basis for either replacing
the 11-hour driving limit with a 10-hour limit, or suggested that
another option could be more cost-beneficial.
D. Research Review Process
In preparing this final rule, FMCSA thoroughly, systematically, and
extensively 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 this HOS rulemaking. This review included
research findings that discussed in a scientific, experimental,
qualitative, and quantitative way 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.
Dr. Peter Orris, M.D., Professor of Occupational Health at the
University of Illinois, led a team of six prominent medical doctors,
epidemiologists, and an ergonomist to identify relevant research on CMV
driver health. Dr. Alison Smiley, President of Human Factors North
Inc., Professor in the Department of Mechanical and Industrial
Engineering, University of Toronto, and the Department of Civil
Engineering, Ryerson University, led a team of three leading
transportation and fatigue experts to review relevant fatigue studies.
Each team conducted two literature reviews, a review of the literature
at the beginning of the project and a review of the literature that was
submitted by commenters to the 2005 NPRM. It was through this rigorous
process that FMCSA ensured that not only the latest research, but the
best available science was used to support this rulemaking. The final
reports are located in the docket and are entitled ``Literature Review
on Health and Fatigue Issues Associated with Commercial Motor Vehicle
Driver Hours of Work,'' Part I and Part II.
The driver health team used PubMed Central (PMC), which is the U.S.
National Institutes of Health (NIH) digital archive of biomedical and
life sciences journal literature. PMC includes MEDLINE, which is the
premier bibliographic database covering the fields of medicine,
nursing, dentistry, veterinary medicine, the health care system, and
the preclinical sciences. MEDLINE contains over 12 million
bibliographic citations dating back to the mid-1960s and author
abstracts from more than 4,800 biomedical journals published in the
United States and 70 other countries.
The initial driver health literature search from 1975 to present
resulted in
[[Page 49982]]
over a thousand research articles. The driver health team screened
these studies based on relevance to the topics of commercial vehicle
operator health and the health effects of work hours, shift work, and
sleep schedules. A total of 55 of the relevant studies were reviewed in
greater detail. Twenty-five were chosen and summarized by a primary
reviewer to be included in the Part I final report. The criteria for
inclusion were the validity of the methodology, the relevance of the
studied population to truck driving, and the quality of the statistical
analysis of health outcomes.
Similarly, the TRB driver fatigue team used the TRANSPORT database,
a bibliographic database of transportation research and economic
information produced by the 25-nation Organization for Economic Co-
operation and Development, together with the United States TRB, and the
31 nations of the European Conference of Ministers of Transport (ECMT).
TRANSPORT includes the Transportation Research Information Services,
International Road Research Documentation, and ECMT's TRANSDOC.
Collectively these sources contain over 530,000 citations from
publications, most with abstracts, of research information on all
surface transportation modes, air transport, and highway safety. The
driver fatigue team searched these studies for relevance concerning
hours of service, and CMV operator performance and fatigue. Because
FMCSA had previously docketed summaries of fatigue-related studies used
in preparing the 2003 rule, the scope of this literature review was
limited to studies published after 1995. Primary sources were selected
if they addressed truck driver performance (on road or simulated), and
included driving performance measures (vehicle control or critical
incidents). Only studies were selected which involved drivers on
typical work-rest schedules, involving extended hours of driving,
driving in a sleep-deprived state, and/or driving at night. After the
initial set of research reports was screened based on relevance, the
driver fatigue team reviewed a total of 26 relevant studies, and 13
were chosen to be summarized for the Part I report.
As a result of the questions posed in the 2005 NPRM, commenters
referenced over 200 studies. The driver health and fatigue teams
reviewed the titles and abstracts of studies referenced by commenters
using the identical criteria that were used for screening the initial
research discussed earlier. Articles considered most relevant were
those involving epidemiological studies, studies of CMV crash risk, or
field studies of performance of commercial drivers in relation to
fatigue issues such as daily and weekly hours, time of day, and short
sleep, or studies of non-CMV drivers showing the effects of sleep loss
and comparing sleep loss and alcohol impacts. The reasons for not
reviewing the remaining articles suggested by commenters included the
following: an article was not published as a report of a recognized
Agency or in a peer-reviewed journal; an article was very general in
nature (e.g. a discussion of circadian rhythm); or, an article was not
sufficiently relevant to the task of CMV driving. The driver health
team selected 11 of these studies to review and summarize for inclusion
in the Part II report, while the driver fatigue team selected 21
studies for the Part II report.
In addition to reviewing the studies mentioned above, FMCSA
internally reviewed, summarized, and evaluated research reports that
were previously cited in the 2003 rule, 2004 litigation, 2005 NPRM, and
driver fatigue and performance studies that were excluded from the TRB
literature review (i.e., published before 1996).
The Agency also assembled an intermodal team of experts on operator
fatigue and health to help FMCSA further identify and analyze relevant
research. The Federal agencies represented were the Federal Aviation
Administration, Federal Railroad Administration, U.S. Coast Guard, and
the National Institute for Occupational Safety and Health (NIOSH).
E. Driver Health
The D.C. Circuit held that FMCSA failed to consider the possibly
deleterious effect of the 2003 hours-of-service rule on the physical
condition of drivers, as required by 49 U.S.C. 31136(a)(4).
To assess driver health and better comprehend the impact of the
findings, one must understand the differences in the types of relevant
medical research. Epidemiology is the study of diseases in populations
of humans or animals, specifically how, when, and where they occur.
Epidemiology attempts to determine what factors are associated with
diseases (risk factors). Epidemiological studies can never prove
causation; that is, they cannot prove that a specific risk factor
actually causes the disease being studied. Epidemiological evidence can
only show that a risk factor is associated (correlated) with a higher
incidence of disease in the population exposed to that risk factor. The
higher the correlation the more certain the association, but it cannot
prove the causation.
Another type of study is a dose-response study. A dose-response
study is based on the principle that there is a relationship between a
toxic reaction (the response) and the amount of substance received (the
dose). Knowing the dose-response relationship is a necessary part of
understanding the cause and effect relationship between chemical
exposure and illness.
A third type of study is a case-control study, which investigates
the prior exposure of individuals with a particular health condition
and those without it to infer why certain subjects, the ``cases,''
become ill and others, the ``controls,'' do not. The main advantage of
the case-control study is that it enables the study of rare health
outcomes without having to track thousands of people. One primary
disadvantage of a case-control study is a greater potential for bias.
Because the health status is known before the exposure is determined,
the study does not allow for broader-based health assessment.
These are important distinctions for the following discussion of
the research on driver health, specifically regarding exposure to
environmental stressors such as exhaust, chemicals, noise, and
vibration. FMCSA has reviewed and evaluated the available and pertinent
information concerning driver health, with emphasis on chronic
conditions potentially associated with changes from the pre-2003 and
2003 rules, to this final rule. The research on CMV driver health falls
into several broad categories: (1) Sleep loss/restriction, (2) exposure
to exhaust, (3) exposure to noise, (4) exposure to vibration, (5)
cardiovascular disease, (6) long work hours, and (7) shift work and
gastrointestinal disorders.
E.1. Sleep Loss/Restriction
The lack of adequate sleep has been shown to have detrimental
impacts on the overall health of humans. Research suggests that sleep
deprivation adversely affects human metabolism as well as the endocrine
and immune systems [Spiegel, K., et al. (1999), p. 1438]. Chronic
partial sleep loss is associated with decreased glucose tolerance,
decreased leptin levels, increases in evening cortisol levels, and
adverse cardiovascular effects [Spiegel, K., et al. (2004), p. 5770].
Consistent with these studies, epidemiologic research demonstrates that
short sleep duration is modestly associated with symptomatic diabetes
[Ayas, N. T. et al. (2003), p. 383], cardiovascular disease, and
mortality [Alvarez, G.G., & Ayas, N. T. (2004), p. 59]. Other studies
have shown that short sleepers (less than 6
[[Page 49983]]
hours) have hormone and metabolic changes which result in weight gain
[Hasler, G., et al. (2004), p. 661; Morikawa, Y., et al. (2003), p.
136; Taheri, S., et al. (2004), p. 210; Vioque, J., et al. (2000), p.
1683]. Interleukin 6 (IL-6) is a marker of systemic inflammation that
may lead to insulin resistance, cardiovascular disease, and
osteoporosis. Sleep loss of as little as two hours per night increases
daytime IL-6 and causes drowsiness and fatigue during the next day,
whereas post-deprivation decreases nighttime IL-6 and is associated
with deeper sleep [Vgontzas, A. N., et al. (2004), p. 2125].
As to the amount of sleep necessary, the National Sleep Foundation
recommends 8 hours per day. This standard comes primarily from studies
by the National Institutes of Health (NIH), which notes that this was
the mean time period that healthy young adults gravitated to when
external influences were removed. Not all sleep researchers agree with
this conclusion, particularly with regard to individual health and
well-being. Two large-scale studies have found no relationship between
longer sleep and better health [Kripke, D. F., et al. (2002), p. 131;
Patel, S. R., et al. (2004), p. 440]. The epidemiological research on
sleep duration suggests that mortality may even begin to rise with
sleep durations greater than 8 hours. Likewise, mortality risk
increases for short sleep durations less than 6 hours per day [Id.].
The research identified that prior to the 2003 HOS rule, CMV
drivers were not getting enough sleep (i.e., 7-8 hours per day) as
needed to maintain individual health. In four major research studies,
where sleep was verified using either an actigraph watch (wrist-worn
monitoring device) or electroencephalogram, CMV drivers averaged from
3.8 to 5.25 hours of sleep per day [Dinges, D. F., et al. (2005), p.
38; Balkin, T., et al. (2000), p. 4-48; Mitler, M. M., et al. (1997),
p. 755; Wylie, C. D., et al. (1996), p. ES-10]. These averages are
below the 6 to 8 hours of sleep that are associated with lower
mortality or a healthy lifestyle.
Preliminary data from the following sources suggest that, on
average, CMV drivers are obtaining more sleep than before under the
2003 rule, which requires at least 10 consecutive hours of off-duty
time. First, an ongoing joint National Highway Traffic Safety
Administration (NHTSA) and FMCSA study conducted in 2005 found that
drivers were averaging 6.28 hours of sleep per day, a figure that was
verified with an actigraph watch [Hanowski, R.J., et al. (2005), p.1].
Second, in a survey of its membership, the Owner-Operator Independent
Drivers Association (OOIDA) found that of the 1,264 drivers responding,
355 or 30 percent of drivers stated that they were getting more rest as
a result of the 2003 HOS rule with 10 consecutive hours of off-duty
time. The other 70 percent of the drivers responded that they were
getting either the same amount of rest or no additional rest was needed
as a result of the 2003 rule.
Comparing study findings before and after the 2003 HOS rule change
suggests that drivers are getting more than an hour of additional sleep
per night than they previously were able to obtain. While the Agency
would like to see drivers obtain a sleep period between 7 to 8 hours
per day to maximize driver alertness, the finding of 6.28 hours of
sleep per night is within normal ranges consistent with a healthy
lifestyle and is a vast improvement over previous sleep findings. Based
on the research that led to the 2003 final HOS rule, FMCSA knew that
short sleep (less than 6 hours) among drivers was a concern from both a
safety and health standpoint. As a result, FMCSA increased off-duty
time to 10 consecutive hours thereby increasing driver sleep by up to
an additional two hours per day. This final rule adopts the requirement
for the 10 consecutive hours of off-duty time.
E.2. Exposure to Diesel Exhaust
The Environmental Protection Agency's (EPA) Health Assessment
Document for Diesel Engine Exhaust (2002) concluded that ``long-term
(i.e., chronic) inhalation exposure is likely to pose a lung cancer
hazard to humans, as well as damage the lung in other ways depending on
exposure'' [EPA (2002), p. ii].
Diesel exhaust (DE) is not a single ``thing'' but a mixture of
hundreds of gases and particles, which differ with the type of engine
generating them, operating conditions, and fuel formulations. Some of
the components of DE are known carcinogens (e.g., benzene) and others
are mutagenic or toxic. Particulates from diesel engines, which
constitute about 6 percent of the total ambient particulate matter (PM)
with an aerodynamic diameter of 2.5 micrometers or less (PM-2.5), are
highly respirable and able to reach the deep lung. Yet EPA has not
formally declared DE to be a carcinogen. There are several reasons for
this ambiguity.
A dose/response curve is the classic means of measuring the effect
of exposure. A curve is typically established in a laboratory. Very
high doses are given over a relatively short period, and the
physiological response is measured. A dose/response curve is assumed to
be a straight line, which can be extended downward to the lower
exposures typical of ambient conditions outside the laboratory. If the
dose/response curve is not a straight line (because the physiological
response decreases disproportionately when exposure is reduced), the
curve will overstate the effect of ambient exposure by some unknown
amount. In that case, long-term population studies might be an
alternative, provided long-term exposure can be established.
Attempts to establish a dose/response curve for DE have not
produced clear-cut results. In animal studies, rats develop lung tumors
after lifetime inhalation of DE at exposures vastly higher than any
ambient condition; but these cancers appear to be at least partially
the result of particle overload, which prevents lung clearance and
causes chronic inflammation and subsequent lung disease. Chronic
inhalation studies in mice show equivocal results, and hamsters do not
develop cancer [Bunn, W.B., et al. (2002), p. S126; EPA (2002), p. 7-
139]. EPA therefore concluded that ``the rat lung tumor response is not
considered relevant to an evaluation of the potential for a human
environmental exposure-related hazard'' [Id.]. EPA further noted that
``[t]he gaseous phase of DE (filtered exhaust without particulate
fraction) was found not to be carcinogenic in rats, mice, or hamsters''
[Id.].
Although EPA has declared DE to be a ``probable human carcinogen,''
based in part on a review of 22 epidemiologic studies of workers
exposed to DE in various occupations, it also noted that the
``Increased lung cancer relative risks generally range from 1.2
to 1.5, though a few studies show relative risks as high as 2.6.
Statistically significant increases in pooled relative risk
estimates (1.33 to 1.47) from two independent meta-analyses further
support a positive relationship between DE exposure and lung cancer
in a variety of DE-exposed occupations. The generally small increase
in lung cancer relative risk (less than 2) observed in the
epidemiologic studies and meta-analyses tends to weaken the evidence
of causality. When a relative risk is less than 2, if confounding
factors (e.g., smoking, asbestos exposure) are having an effect on
the observed risk increases, they could be enough to account for the
increased risk'' [EPA (2002), pp. 7-138 and 7-139].
Overall, the evidence is not sufficient for DE to be considered a
proven human carcinogen because of exposure uncertainties (lack of
historical exposure data for workers exposed to DE) and an inability to
reach a full and direct accounting for all possible confounders [Id.].
[[Page 49984]]
The actual cancer risk involved in operating a diesel-engine truck
depends on the degree and duration of exposure to DE, and especially to
smaller particulate matter (PM-2.5). Information on the real-world DE
exposure of truck drivers is limited by many uncertainties. Because
trucks spend a great deal of time in motion, the exposure levels of
different highway, municipal, and regional environments have to be
collected and combined. Idling time at terminals, in traffic jams, or
while using a sleeper berth presumably generates higher exposure than
does highway driving, but estimating the possible combinations of
conditions for a large population of drivers is difficult. Furthermore,
because of the long latency period of most cancers, the extent of the
risk to truck drivers depends on the length of their exposure. This in
turn is influenced by the factors that existed several decades ago:
engine design, formulation of diesel fuel, prevalence of smoking among
driver populations, total particulate levels from all sources, etc. In
most cases, this information is less well known than comparable data on
these factors today. Nor can one project previous (assumed) conditions
forward or current conditions backward; virtually everything about DE
has been changing in the last few decades and will continue to change
as EPA tightens the regulations that govern diesel engine design and
diesel fuel. Also, given EPA initiatives to reduce truck idling, and
Federal financing available for idle-reduction programs, FMCSA expects
additional reductions in exposure of CMV drivers to DE.
Before discussing the studies reviewed by the driver health team,
it is useful to analyze a potential exposure effect of a feature of the
2003 rule, which is adopted in this final rule--the availability of
additional driving and on-duty hours through the use of the 34-hour
recovery provision. If utilized to the extreme, this would allow
another 17 hours of driving time and 24 hours of on-duty time in a 7-
day work week, compared to the limit of 60 hours of driving time
without the recovery provision. To examine the effect of the 2003 rule
on driver work hours, FMCSA compared an earlier survey of drivers
operating under the pre-2003 rule with a recently completed survey. In
a 7-day work week, the 451 drivers who responded to the earlier survey
worked, on average (driving and other on-duty time), 64.3 hours per
week [Campbell, K.L., & Belzer, M.H. (2000), p. 104]. In 2005, FMCSA
evaluated a sample of driver logs and determined that the 489 drivers
included, with a total of 5,397 7-day periods, worked an average of
61.4 hours (driving and other on-duty time) per week [FMCSA Field
Survey Report (2005), p. 4].
At the annual meeting of the TRB in Washington, D.C. in January
2005, Schneider National, a large motor carrier, provided a
distribution of the weekly (8-day period) on-duty hours for its drivers
(available in the docket for this rule). The data shows that
Schneider's employee drivers averaged 62 hours on duty per 8-day period
and its leased drivers averaged 65 hours on duty per 8-day period. In
addition, J.B. Hunt, another large motor carrier, in comments to the
NPRM, reviewed the work records of 80 randomly selected over-the-road
drivers for a 30-day period. J.B. Hunt found that 74 percent of its
drivers used the 34-hour restart at least once during the 30-day
period. On average, J.B. Hunt's drivers accumulated 62.25 hours on duty
per eight-day period.
This data provides some indication of the hours worked as a result
of the 2003 rule. Given the data from surveys and comments regarding
work hours from motor carriers, it does not appear that CMV drivers are
working on average significantly more hours as a result of the 2003
rule as compared to the pre-2003 regulation. Consequently, based on
review of the data, the average exposure of drivers to DE has remained
essentially unchanged.
The driver health team identified and reviewed four studies that
address the issue of hours of work and duration of DE exposure in
transportation workers. A large case-control study in Germany found
significant associations between lung cancer and employment as a
professional driver. The risk reached statistical significance for
exposures longer than 30 years [Br[uuml]ske-Hohlfeld, I., et al.
(1999), p. 405]. An exposure response analysis and risk assessment of
lung cancer and DE found a 1 to 2 percent lifetime increased risk of
lung cancer above a background risk of 5 percent among workers in the
trucking industry, based on historical extrapolation of elemental
carbon levels [Steenland, K., et al. (1998), p. 220]. A large case-
control study of bus and tramway drivers in Copenhagen found a negative
association between lung cancer and increased years of employment
[Soll-Johanning, H., et al. (2003), p. 25]. Finally, a meta-analysis of
29 studies addressing occupational exposure to DE and lung cancer
showed that 21 of the 23 studies meeting the inclusion criteria,
observed relative risk estimates greater than one (probability of a CMV
driver developing lung cancer divided by the probability of the control
group developing lung cancer). A positive duration response was noted
in all studies that quantified exposure [Bhatia, R., et al. (1998), p.
84].
Several studies have shown an association between truck driving and
bladder cancer. The driver health team reviewed three studies that
addressed the association between duration of exposure to DE and
bladder cancer. A population-based case-control study in New Hampshire
found a positive association between bladder cancer and tractor-trailer
driving, as well as a positive trend with duration of employment [Colt,
J.S., et al. (2004), p. 759]. A large study in Finland found increased
standard incidence ratios for six types of cancer in truck drivers.
Cumulative exposure to DE was negatively associated with all cancers
except ovarian cancer in women with high cumulative exposure [Guo, J.,
et al. 2004, p. 286]. A meta-analysis of 29 studies on bladder cancer
and truck driving found an overall significant association between
``high'' exposure to DE and bladder cancer as well as a dose-response
trend. The authors concluded that DE exposure may result in bladder
cancer, but the effects of misclassification, publication bias, and
confounding variables could not be fully taken into account [Boffetta,
P., & Silverman, D.T. (2001), p. 125].
As a result of the number of studies showing an association, DE is
considered to be a ``probable'' carcinogen by the World Health
Organization and the U.S. Department of Health and Human Services'
National Toxicology Program. Because of the complexity of proving a
definitive link between DE and cancer, no organization, other than the
California EPA, has classified DE as a known carcinogen [Garshick, E.,
et al. (2003), p. 17]. Studies have a great degree of uncertainty due
to study design and exposure assumptions, measurement issues, and
synergistic effects of various pollutants, among other variables.
[Bailey, C.R., et al. (2003), p. 478]. Excluding rats, animal studies
are overall negative with regard to lung tumor formation following DE
exposure. In rats, lung tumors are produced by lifetime inhalation
exposure to many different particle types. These exposures are
characterized as ``lung overload;'' however, numerous analyses point to
a lack of relevance of data from lung-overloaded rats to human risk
calculations, particularly at environmental or ambient levels [Bunn,
W.B., et al. (2002), p. S122]. As noted earlier, EPA's risk assessment
on DE, based on long-term (chronic) exposure,
[[Page 49985]]
concludes that DE is ``likely to be carcinogenic to humans by
inhalation.'' Studies show a causal relationship between exposure to DE
and lung cancer, but EPA has not concluded that DE is a human
carcinogen and cannot develop a quantitative dose-response cancer risk.
The rat inhalation studies underpinning these findings resulted from
overloading DE and are unrealistic exposure scenarios for humans [Ris,
C. (2003), p. 35].
The acute (short-term) effects of DE, which would allow us to
determine safe exposure levels, are not currently known [Id.]. Also,
there are not enough human test data to make a definitive risk
assessment on the chronic long-term respiratory effects of DE. Tests on
animals, however, suggest chronic respiratory problems exist [Id.].
Cleaner burning diesel fuel standards (2006) combined with cleaner
diesel engine technologies from more stringent emission standards
(2007) will generate a net reduction in pollutant emissions, despite
growth in diesel use [Sawyer, R.F. (2003), p. 39].
EPA models project on a national basis the amount of emissions or
pollutants expected annually from all mobile sources. These are based
on estimates of vehicle miles traveled and new vehicles entering and
old vehicles leaving the inventory, and they reflect changes in vehicle
emissions standards. The models project emissions for the following
pollutants: Carbon Monoxide, Oxides of Nitrogen, Volatile Organic
Compounds, Particulate Matter (PM-2.5), Particulate Matter (PM-10), and
Sulfur Dioxide. EPA estimates show that vehicle emissions from all
mobile sources have declined significantly from 1990 to 2005 (average
35 percent reduction in emissions) and are projected to decline further
until 2030 (average 55 percent reduction in emissions). DE from heavy
vehicles represents about 23 percent of all emissions from mobile
sources. DE from heavy vehicles has also declined from 1990 to 2005
(average 55 percent reduction in emissions) and is projected to decline
further until 2030 (average 88 percent reduction in emissions). The
following chart shows the projections of heavy vehicle DE from the on-
the-road fleet by type of emission from 1990 to 2030. The chart is
based on U.S. EPA's ``National Annual Air Emissions Inventory for
Mobile Sources,'' which was conducted for a variety of pollutants
emitted by on-road vehicles. [EPA (January 2005)]. Mobile source
emission inventories were directly modeled for 2001, 2007, 2010, 2015,
2020, and 2030. Other years were obtained by linear interpolation.
EPA's Air Inventory was developed using the National Mobile Inventory
Model [EPA (March 2005)].
[GRAPHIC] [TIFF OMITTED] TR25AU05.000
If diesel or all engine emissions are in fact carcinogenic (not yet
proven), then the risk of developing cancer is a function of both the
amount of DE being inhaled and cumulative exposure (time). Based on EPA
emission projections of lower emissions from on-the-road heavy
vehicles, continued reduction in health impacts can be expected over
time.
It appears that chronic (long-term) exposure to DE may cause
cancer. The exposure/dose required, however, is currently unknown due
to the extreme difficulty in measuring and modeling exposure. EPA has
noted that there is great
``uncertainty regarding whether the health hazards identified from
previous studies using emissions from older engines can be applied
to present-day environmental emissions and related exposures, as
some physical and chemical characteristics of the emissions from
certain sources have changed over time. Available data are not
sufficient to provide definitive answers to this question because
changes in DE composition over time cannot be confidently
quantified, and the relationship between the DE components and the
mode(s) of action for DE toxicity is unclear'' [Ris, C. (2003), p.
35].
Some of those flaws might be addressed by Garshick's effort to
quantify lung cancer risk in the trucking industry through an
epidemiological study using up to 72,000 subjects [Garshick, E., et al.
(2002), p. 115]. At this time, however, according to EPA,
[[Page 49986]]
NIOSH, the Centers for Disease Control and Prevention, and NIH, there
is not enough evidence to declare DE a carcinogen. Nonetheless, EPA's
finding that DE is a probable carcinogen is a cause for concern. EPA
has therefore adopted new diesel engine performance requirements and
will by 2007 require refiners to produce low-sulphur fuel [66 FR 5002].
EPA's previous and forthcoming regulatory changes lead to a projection
of dramatically lower DE through 2030, which will greatly reduce any
health effects of DE exposure.
Still, the question remains whether today's rule, regarding
exposure to DE, ensures that ``the operation of commercial motor
vehicles does not have a deleterious effect on the physical condition''
of CMV drivers [49 U.S.C. 31136(a)(4)]. After reviewing all the studies
mentioned, there is no evidence that today's rule has a deleterious
effect. This is not to deny the possibility that DE may have some
impact on truck drivers. The Agency, however, cannot attempt to address
a problem without data on its extent and severity. The data on exposure
to DE is notoriously deficient. As Garshick and his colleagues noted,
``The ideal marker of DE exposure would be a single marker that
would be inexpensive, easy to measure, and clearly linked to the
source of diesel emissions. However, the reality is that DE is a
complex mixture, and in many real-life scenarios it may not be the
only important source of exposure to the individual particles and
gases that constitute DE. In addition, the mechanism of the health
effects and specific causal agents are uncertain. The best diesel
exposure marker is likely to be more complex and involve the
measurements of molecular organic tracers and elemental carbon. The
nature of the exposure assessment and marker chosen may also depend
on mechanism of health effect postulated, and may include
measurement of exhaust gases (such as ozone and nitrogen oxide) in
the setting of nonmalignant respiratory diseases. Although current
literature identifies DE as a health hazard, insight into a dose-
response relationship is limited by factors related to both cohort
selection and exposure assessment. The development of an exposure
model in the existing DE epidemiologic literature is hindered by a
lack of exposure measurements upon which an exposure model can be
developed, uncertainty regarding the best measurement or marker(s)
indicative of exposure, and uncertainty regarding historical
exposures'' [Garschick, E., et al. (2003), p. 21].
One of the best works to date on DE, lung cancer, and truck driving
is a series of studies by Steenland and his colleagues published
between 1990 and 1998. The abstract of the 1998 study concludes that,
``[r]egardless of assumptions about past exposure, all analyses
resulted in significant positive trends in lung cancer risk with
increasing cumulative exposure. A male truck driver exposed to 5
micrograms/m3 of elemental carbon (a typical exposure in
1990, approximately five times urban background levels) would have a
lifetime excess risk of lung cancer of 1-2 percent above a background
risk of 5 percent.'' The difference between 1 percent and 2 percent is
obviously quite large, but the absence of a dose/response curve for DE
and uncertainties in the exposure data make greater precision
impossible.
In 1999, however, the Health Effects Institute (HEI), a non-profit
corporation chartered in 1980 to assess the health effects of
pollutants generated by motor vehicles and other sources, and supported
jointly by EPA and industry, found significant flaws even in the 1998
Steenland study. As summarized by Bunn et al. [Bunn, W.B., et al.
(2002), p. S127], the HEI found that the Steenland study ``quite likely
suffers from an inadequate latency period, making it completely
unsuitable for reaching any qualitative or quantitative conclusions
about the link between DE exposure and lung cancer.'' Furthermore, the
workers in the study were exposed to an inseparable mix of gasoline and
diesel fumes. ``Indeed, during the 1960s (the critical years of the
Steenland study from a latency perspective), diesel fuel represented
only 4-7 percent of the total fuel sales (cars and trucks). Moreover,
in the 1960s, gasoline-fueled vehicles had no after-treatment, so that
emissions from gasoline-fueled vehicles likely would have been
comparable to those from diesel vehicles'' [Id.].
Given the uncertain effects of exposure to DE, FMCSA could not
include this factor in any cost/benefit analysis for any regulatory
change it wished to consider. Some changes are beyond FMCSA's
authority. EPA has exclusive authority to set emission standards for
new trucks, and NHTSA has comparable jurisdiction over equipment
standards for new vehicles. FMCSA retains a degree of authority to
order the retrofitting of safety equipment to vehicles already in
service [see 49 CFR 1.73(g)], but it is unclear what CMV equipment, if
any, could be installed on the current fleet to reduce the driver's
exposure to DE. A driver's ability to open one or both side windows
could defeat any air-cleaning technology that might be added to the
tractor, and all drivers spend time outside the vehicle at terminals,
truck stops, and other locations where exposure to DE is unavoidable.
Another possible means of reducing drivers' DE exposure would be to
curtail driving and on-duty time, or even to limit a driver's career to
a certain number of years, all in the interest of improved health. As
indicated above, however, there is no dose/response curve for DE and
the Agency could not be sure that a given reduction in hours or years
of service would produce a clear benefit. Forced retirement after a
certain number of years on the job is especially problematical. There
is nothing in the legislative history of 49 U.S.C. 31136(a)(4) to
indicate that Congress wanted FMCSA to protect the health of drivers by
limiting their livelihood. A limit on driving or on-duty hours for the
specific purpose of reducing DE exposure seems unnecessary, because the
available evidence shows that drivers have not increased their driving
or on-duty time in response to the 2003 rule.
One of the benefits of the 2003 HOS rule has been that it limits
driver duty periods to 14 consecutive hours per day with no extensions
for intervening off-duty periods. Under the pre-2003 rule, drivers were
allowed a 15-cumulative-hour duty period but could extend their maximum
duty period indefinitely by taking off-duty time during their workday.
This perpetuated the problem of excessive waiting time for pick up and
delivery of freight at shippers and receivers, because the drivers were
expected to place themselves in off-duty status while waiting. A 1999
study of dry freight truckload carriers by the Truckload Carriers
Association (TCA) revealed that drivers spent nearly seven hours
waiting for each freight shipment that they picked up and delivered.
The non-extendable 14-hour provision of the 2003 rule has given
motor carriers greater leverage to insist that shippers and receivers
reduce waiting time. At the 2005 Annual Meeting of the Transportation
Research Board (TRB) in January 2005, in Washington, DC, several large
carriers stated that as a result of the 14-hour rule, they are
increasingly charging detention fees when shippers and receivers cause
delays. As a result of the 14-hour provision, shippers and receivers
have had to improve the efficiency and productivity of loading docks.
Many drivers have commented that waiting time has been significantly
reduced. Reduced waiting time has a positive impact on drivers. First,
it reduces the total duty period for the driver, and reduces
unproductive and often uncompensated time. Second, loading docks were
cited by Garshick [Garshick, E. et al. (2003), pp. 24-25] as having
high levels of DE particulate
[[Page 49987]]
matter. Thus, reduced waiting time reduces driver exposure to DE and
could have beneficial impacts on driver health.
Diesel emissions have been falling steadily since the early 1990s
and will continue to decline for many years to come. To whatever
unknown extent DE may cause lung cancer, EPA's long-range regulatory
program is expected to reduce that risk. Three recent developments may
accelerate that downward trend. The first is the cost of diesel fuel,
which makes idling more expensive. The second is the spread of local
regulations that limit CMV engine idling time. The third is the
proliferation of truck-stop services available to drivers that
eliminate idling by providing hot or cold air for the sleeper berth,
cable TV, and internet access through an attachment to the side window
of the tractor. The expected reduction in engine idling in the next few
years should amplify the health and environmental benefits of EPA's
regulations. FMCSA has thus concluded that, while DE probably entails
some risk to drivers, after a thorough review of the data available, it
is the Agency's best judgment that, compared to the pre-2003 rule,
today's rule neither causes nor exacerbates that risk.
E.3. Exposure to Noise
The Occupational Safety and Health Administration (OSHA) noise
exposure standard for the workplace for unprotected ears is 90 decibels
adjusted (dBA) limited to 8 hours per day (29 CFR 1910.95). FMCSA also
has adopted a 90 dBA noise standard (49 CFR 393.94). Twenty-five
percent of the work force in the United States is regularly exposed to
potentially damaging noise [Suter, A.H., & von Gierke, H.E. (1987), p.
188]. In 1995, the FHWA Office of Motor Carriers conducted a study of
noise in CMVs. The study showed that noise levels in CMV cabs as
reported over the previous 25 years (1970-1995) had decreased
[Robinson, G.S., et al. (1997), p. 36]. The following table summarizes
noise findings from several studies:
Figure 2.--CMV Cab Noise Levels Documented From Several Studies
----------------------------------------------------------------------------------------------------------------
Model year (# of
Study (year) trucks) dBA
----------------------------------------------------------------------------------------------------------------
Enone (1970)............................ 1960s era (4)................... >100 dBA.
Morrison & Clark (1972)................. 1960s era (16).................. 85-90 dBA.
Hessel (1982)........................... 1972-1977 (8)................... 74-87 dBA.
Reif & Moore (1983)..................... 1968-1978 (58).................. 85-90 dBA.
Morrison (1993)......................... 1993 (4)........................ < 80 dBA.
Micheal (1995).......................... 1995 (6)........................ < 80 dBA.
Van den Heever (1996)................... 1995 (16)....................... 83 dBA.
Robinson (1997) \1\..................... 1990-95 (9)..................... 89 dBA.
Seshagiri (1998) \1\.................... 400 measurements................ 83+ dBA.
----------------------------------------------------------------------------------------------------------------
Note 1: Study findings added to the table reported by Robinson (1997).
The truck-cab noise levels for nine trucks Robinson et al.
evaluated were found to be 89.1 dBA for eight conditions of highway
driving. This was very close to the FMCSA permissible exposure limit of
90 dBA. A sound dosimeter \1\ was used to determine the noise doses
experienced by 10 truck drivers during normal commercial runs of 8 to
18 hours. The noise doses were measured with rest breaks, meal breaks,
and refueling breaks included, so they represented realistic
projections of actual truck trip noise doses experienced by drivers.
Robinson et al. also conducted pre- and post-workday audiograms for a
group of 10 drivers. Those results indicated that CMV drivers suffered
no temporary hearing loss after a normal driving shift.
---------------------------------------------------------------------------
\1\ A sound dosimeter is an instrument used to measure exposure
to sound.
---------------------------------------------------------------------------
In a more recent study of tractors of different models, makes, and
ages operating on routes that covered different types of Canadian
terrain, noise exposure was measured (over 400 measurements) under
several conditions. The noise level recorded ranged from 78 to 89 dBA,
with a mean of 82.7 dBA. The noise levels increased by 2.8 dBA with the
radio on, 1.3 dBA with the driver's side window open, 3.9 dBA with both
the window open and radio on, and 1.6 dBA for operations on four-lane
highways. Cab-over-engine vehicles appeared to be quieter than
conventional tractors by about 2.6 dBA. Long-haul (city to city)
operations on hilly terrain appeared to be quieter than on flat terrain
by about 2.2 dBA, probably indicating the strong effect of speed (tire,
wind, and engine noise). These researchers found conditions where CMVs
exceeded the Canadian noise limit of 85 dBA, mainly when the radio was
on and the driver's side window open [Seshagiri, B. (1998), p. 205].
In its comments to the docket, the American Trucking Associations
(ATA) reported that modern tractors usually have dBA levels ``in the
low 70's'' and that a ``typical Class 8 sleeper tractor cruising at 60
mph on level ground pulling a load will have a sound pressure level of
about 69-73 dBA.''
The research discussed earlier suggests cab noise levels are well
within FMCSA's 90-dBA noise standard. The noise levels documented have
not been shown to exceed OSHA or FMCSA standards. Therefore, the noise
levels in CMVs should not result in significant hearing loss over a
lifetime of on-the-job exposure, even if drivers drove the maximum
hours allowed by this final rule.
E.4. Exposure to Vibration
Exposure to whole body vibration (WBV) is believed to cause
fatigue, insomnia, headache, and ``shakiness'' shortly after or during
exposure. After daily exposure over a number of years, WBV can affect
the entire body and may result in a number of health disorders.
Occupational exposure to WBV may contribute to circulatory, bowel,
respiratory, muscular, and back disorders. The combined effects of body
posture, postural fatigue, dietary habits, long hours, and loading and
unloading are the possible other causes for these disorders.
Vibration in CMVs is a function of the age and maintenance of the
vehicle, speed, type of roadway, and driving behavior and performance;
and the most important variable is the condition of the roadway. There
are no vehicle manufacturing or operational standards for the control
of WBV, either in this country or abroad. The medical and research
communities use the 1997 International Standards Organization (ISO)
2631-1 guidelines for evaluating WBV.
[[Page 49988]]
Teschke conducted a thorough review of the research on WBV and back
disorders (including over 99 studies). This research found a number of
potential risk factors associated with lower back pain (LBP). Besides
WBV, the study identified a number of other confounding variables that
are associated with lower back pain. The following risk factors have
been found identified in the review of research in this area: (1)
Driver's age, (2) working postures, (3) repeated lifting and heavy
lifting, (4) smoking, (5) previous back pain, (6) falls or other
injury-causing events, (7) stress-related factors including job
satisfaction and control, and (8) body condition and morphology
including weight, height, physical condition, and body type [Teschke,
K., et al. (1999), p. 7]. The number of potential risk factors and
confounding variables makes it difficult to isolate the effects of WBV,
or even to conclude that WBV is the cause of lower back pain.
A recent study of volunteer drivers at a large transport company in
Canada found that operators were not on average at increased risk of
health effects from daily exposure when compared to the ISO guidelines.
The study did, however, find several instances where drivers in a 10-
hour shift were exposed to WBV levels established in an earlier ISO
standard. These instances were highly correlated to road conditions
[Cann, A.P., et al. (2004), p. 1432]. One of the criticisms of this
study was that vibration was measured at the floor or base of the
driver's seat, and measurements did not take into account the
attenuation of vibration by the driver's seat. Most seats in CMVs today
are air suspended to better isolate the driver from vibration.
Much of the WBV research is based on self-reporting through surveys
and questionnaires to identify factors that are associated with lower
back pain and back problems. For instance, a questionnaire study of bus
and truck drivers in Vermont and one in Sweden found a significant
association between long-term vibration dose and low back pain
[Magnusson, M.L., et al. (1996), p. 710]. Another questionnaire survey
in the Netherlands found significant associations between vibration and
low back pain as well as a significant dose-response [Boshuizen, H.C.,
et al. (1990), p. 109]. A recent review of the health literature on WBV
and lower back pain (LBP) concluded that, while ``there is probably an
association between WBV and LBP,'' there was no evidence of dose-
response [Lings, S. & Leboeuf-Yde, C. (2000), p. 290].
Studies addressing musculoskeletal disorders in truck drivers by
and large evaluate the effects of WBV. A questionnaire survey of
Japanese truck drivers found short resting time and irregular duty time
to be significant risk factors for lower back pain. It also found
positive but insignificant associations with long driving time per day
and week, but the hours classified as long were not specified
[Miyamoto, M., et al. (2000), p. 186]. A study of knee pain in taxi
drivers found a significantly increased risk of knee pain in workers
with more than 10 hours of daily driving. A significant dose-response
trend was also seen [Chen, J.C., et al. (2004), p. 575].
Our review of the literature on WBV and its potential health
effects, such as low back syndrome, is inconclusive because the studies
rely primarily on self-reporting and application of risks derived from
other environments. The literature related to commercial driving and
other musculoskeletal disorders suffers from the same limitations. A
causative relationship can only be viewed as suggestive within this
context.
The studies that tested vibration in CMVs found that vibration was
close to the ISO health risk threshold, but it did not consistently
exceed the threshold. The introduction of new trucks, which reduce the
driver's exposure to WBV, would be expected to mitigate any potential
effects of vibration. ATA submitted comments to the docket that modern
truck cabs are much quieter, are well ventilated, and have well
designed, efficient heating and air conditioning units. Physical stress
on drivers, including road vibration, is reduced by power steering.
Many trucks are also equipped with automatic transmissions, further
reducing stress. Improved suspension gives the driver a better ride,
and provides better handling. ATA maintained that the comfort and
safety improvements in truck tractors improve the driver's conditions,
leading to a reduction in stress and fatigue. Two carriers also
commented that modern trucks have greatly reduced noise and vibration.
Much of the research on whole body vibration within a CMV and its
effects on lower back pain or musculoskeletal disorders was based on
subjective measures and only weak associations have been found. Given
all the other confounding factors that have been shown to be associated
with these conditions (age, postures, lifting, smoking, falls, job
satisfaction, and body condition, including weight) it is highly
unlikely that vibration is the cause of LBP or musculoskeletal
disorders. The few studies of more objective measures of vibration have
not shown vibration to be, on average, above the health risk level
(with ISO standard).
When comparing the 2003 HOS rule to today's rule, it is the
Agency's best judgment that, based on the studies reviewed and comments
received, WBV does not pose a significant health risk to CMV drivers.
E.5. Cardiovascular Disease
Cardiovascular disease (CVD), principally heart disease and stroke,
is the nation's leading killer for both men and women among all racial
and ethnic groups. Almost one million Americans die of CVD each year--
42 percent of all deaths. CVD does not kill just the elderly--it is
also the leading cause of death for all Americans age 35 and older.
More than 16 percent of the deaths due to CVD are individuals 35 to 64
years old. The causes of CVD are complex. The following table
identifies some of the known risk factors:
Figure 3.--Risk Factors for Cardiovascular Disease
----------------------------------------------------------------------------------------------------------------
Individual factors Occupational factors Lifestyle factors
----------------------------------------------------------------------------------------------------------------
Genes
Age Sedentary Work Smoking
Gender Working Long Hours Alcohol/Drug Use
High Cholesterol Work Stress Sedentary Lifestyle
Amino Acid--Homocysteine Exposure to Physical Stressors and Lack of Exercise
Injuries
High Blood Pressure Shift Work Stress
Obesity .................................... Short Sleep
Diabetes
----------------------------------------------------------------------------------------------------------------
Source: American Heart Association.
[[Page 49989]]
The NIOSH representative to FMCSA's health group reviewed the
literature regarding CMV driving and the risk of developing CVD. Since
1992, a number of population research studies from Sweden and Denmark
have presented data suggesting an association between driving and CVD.
In contrast to occupational studies undertaken in the United States,
these research studies did not attempt to quantify ``hours of service
driving a truck'' or ``occupational chemical and particulate
exposures.'' Thus, these studies provide no data that could be used to
correlate individual or group ``exposures'' and CVD outcomes. No
studies conducted in the United States were found that permitted
examination of long hours of driving among truck drivers and the
possible association with CVD.
Swedish and Danish population studies provide support for the
hypothesis that driving occupations have elevated risks for
cardiovascular disease. Among drivers, Swedish population studies
indicate the greatest risk elevations occur among bus drivers, with
relative risks ranging from 50 percent to 114 percent in excess of
comparison populations [Bigert, C., et al. (2003), p. 333]. The
greatest risk ratio reported for truck drivers (a relative risk of
1.66), was reduced to 1.10 following statistical adjustment for
competing health and disease risk factors. A recent study suggests that
truck drivers experience no more than a 14 percent elevated risk
[Bigert, C., et al. (2004), p. 987].
Most epidemiologists take a fairly rigorous view of relative risk
values. In observational studies, results are not normally accepted as
significant if a relative risk ratio is less than 3 and is never
accepted if the relative risk ratio is less than 2 [Brignell, J.
(2005)]. In epidemiologic research, increases in risk of less than 100
percent are considered small and are usually difficult to interpret.
Such increases may be due to chance, statistical bias, or the effects
of confounding factors that are sometimes not evident.
A number of Japanese hospital record studies have examined the
association between long hours of work (not hours of driving) and acute
myocardial infarction (AMI). The most recent study suggests that weekly
work time in excess of 60 hours is related to increased risk of AMI
[Liu, Y., & Tanaka, H. (2002), p. 447]. This research suggests a two-
fold increased risk for overtime work (crude risk of 2.1, reduced to
1.81 after statistical adjustment for competing health and disease risk
factors). The authors conclude that overtime work and insufficient
sleep may be related to the risk of AMI.
Research is under way at NIOSH to evaluate mortality risk of
independent truck drivers in the United States. However, this study is
not designed to collect data on hours of service and other CVD risk
factors.
FMCSA's NIOSH representative concluded that current research
suggests the presence of only a weak association between CVD and truck
driving. Additionally, CVD is associated with many other occupational
types. No research studies were found that permitted an examination of
whether additional hours of driving a CMV impacts driver health as
measured by increased CVD or AMI. After thoroughly reviewing the
collective data, in the Agency's best judgment, based on the research
available, nothing implicates today's HOS rule in a heightened risk of
CVD or AMI.
Any increased risk of CVD or AMI may be mitigated by the increased
off-duty time (10 hours off duty) as well as the increase in
stabilization from the pre-2003 rule to the 2003 and today's rule of
the drivers' schedules (circadian rhythm). Changes implemented in truck
cab design, reducing exposure to exhaust, whole body vibration, and
noise may also mitigate the risk of CVD and AMI as well.
E.6. Long Work Hours
The average number of hours worked in the United States annually
has increased over the past several decades and currently surpasses
most countries in Western Europe and Japan [Caruso, C.C., et al.
(2004), p. 1]. Worker health and safety is a growing area of concern,
and thus more attention is being placed on whether there should be
limits on hours of work--similar to the hours of service regulations
for CMV drivers. The primary question being asked is whether there are
more adverse health consequences as a result of longer hours of work.
Beyond the previous study mentioned regarding CVD and long hours
[Liu, Y., & Tanaka, H. (2002), p. 447], the driver health team was able
to find only one other study that met their selection criteria and was
directly related to CMV drivers and long work hours [Jansen, N.W.H., et
al. (2003), p. 664]. This study focused on employees from 45 companies
in the Netherlands. Self-administered questionnaire data from 12,095
employees of the Maastricht Cohort Study on Fatigue at Work were used.
The researchers concluded that employees needed greater recovery
because their recovery scores (subjective measure of the self-perceived
need for rest) were significantly elevated in those working 9 to 10
hours per day, more than 40 hours per week, and frequent overtime
[Id.].
The lack of research literature on driver work hours required the
driver health team to expand its literature review into occupations
other than transportation workers. Particularly useful was a study
published by NIOSH in April 2004 entitled ``Overtime and Extended Work
Shifts: Recent Findings on Illnesses, Injuries, and Health Behaviors''
[Caruso, C.C., et al. (2004)]. The NIOSH report documents published
research on long work hours (greater than 8 hours work per day) and an
extended work week (greater than 40 hours per week).
The NIOSH review generally concluded that long work hours appear to
be associated with poorer health, increased injury rates, more
illnesses, or increased mortality. NIOSH found that individuals working
long hours generally have greater risk of unhealthy weight gain,
increased alcohol use, increased smoking, increased health complaints,
increased injuries while working, poorer neuropsychological
performance, reduced vigilance on task measures, reduced cognitive
function, reduced overall job performance, slower work, and decreased
alertness and increased fatigue, particularly in the 9th to 12th hours
of work. The adequacy of these study findings is addressed later in
this section of the preamble.
The NIOSH review examined the relationship between hypertension (a
risk factor for CVD) and long hours. It concluded that the research
findings regarding hypertension were inconsistent. Park [Park, J., et
al. (2001), p. 244] found no correlation between the hours worked by
Korean engineers, whose work hours during the previous month ranged
from an average of 52 hours to a high of 89 hours per week, and
increased hypertension. This study is relevant because the work-hour
limits are reasonably close to the limits a CMV driver could work under
this final rule.
CMV drivers, on average, work slightly more than 60 hours per week,
but FMCSA operational data show they rarely reach the maximum of 84
work hours per week. This number of work hours is beyond the typical
number of work hours examined by the research in the NIOSH review. The
NIOSH review did, however, examine three studies that identified the
relationship between very long shifts and immune function or
performance. Nakano [Nakano, Y., et al. (1998), p. 32] reported better
immune function in taxi drivers who were allowed to work overtime as
compared with drivers having work-hour
[[Page 49990]]
restrictions. This study examined taxi drivers working 48-hour or
longer shifts in 1992 and again in 1993. Leonard [Leonard, C., et al.
(1998), p. 22] reported declines in two tests of alertness and
concentration in medical residents who had worked 32-hour on-call
shifts. They reported no significant declines in a test of psychomotor
performance or a test of memory. A survey of anesthesiologists linked
long working hours to self-reported clinical errors [Gander, P.H., et
al. (2000), p. 178].
Two studies in the NIOSH review identified the relationship between
long hours and compensation. Siu and Donald [Siu, O.L., & Donald, I.
(1995), p. 30] and van der Hulst and Geurts [van der Hulst, M., &
Geurts, S. (2001), p. 227] suggested that compensation may reduce
adverse effects of long work hours. Siu and Donald [Siu, O.L., &
Donald, I. (1995), p. 31] reported a relationship between perceived
health status and overtime pay. Men from Hong Kong who received no
payment for overtime reported more health complaints when compared with
men who received payment. In addition, van der Hulst and Geurts
examined the relationship between reward and long working hours in
Dutch postal workers. Rewards included salary, job security, and career
opportunities. They reported that high pressure to work overtime in
combination with low rewards was associated with a three-fold increase
in the odds for somatic complaints as compared with a reference
category of low overtime pressure in combination with high rewards.
Alternatively, high pressure in combination with high rewards did not
differ from the reference category. [van der Hulst, M., & Geurts, S.
(2001), p. 227] This research suggests that if workers are adequately
compensated for their time, they are less likely to have health
complaints. This is an important variable that can play a significant
factor in conducting subjective types of research on the effects of
long work hours and health. It also raises concerns regarding most
subjective data regarding the health consequences of long hours that do
not look at compensation as a factor.
With regard to the relationship betwe |
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