Hours of Service of Drivers
Federal RegisterAug 25, 2005
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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.
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
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
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.
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
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
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.
].
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 [Brüske-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,
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)].
ER25AU05.000
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,
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/m
3
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
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
Study
(year)
Model year
(# of 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.
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 Injuries
Lack of Exercise
High Blood Pressure
Shift Work
Stress
Obesity
Short Sleep
Diabetes
Source: American Heart Association.
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
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 between long work hours and worker health, the NIOSH review concluded that “research questions remain about the ways overtime and extended work shifts influence health and safety. Few studies have examined how the number of hours worked per week, shift work, shift length, the degree of control over one's work schedule, compensation for overtime, and other characteristics of work schedules interact and relate to health and safety. Few studies have examined how long working hours influence health and safety outcomes in older workers, women, persons with pre-existing health problems, and workers with hazardous occupational exposures.”
The NIOSH review of the literature on long work hours documents a significant lack of data on general health effects. NIOSH reported that even when looking at fatigue and accidents, identifying “differences between 8-hour and 12-hour shifts [is] difficult because of the inconsistencies in the types of work schedules examined across studies. Work schedules differed by the time of day (
i.e.
, day, evening, night), fixed versus rotating schedules, speed of rotation, direction of rotation, number of hours worked per week, number of consecutive days worked, number of rest days, and number of weekends off” [Caruso, C.C.,
et al.
(2004), p. IV].
Additionally, van der Hulst conducted a review of 27 recent empirical studies of long work hours [van der Hulst, M. (2003), p. 171]. He showed that long work hours are associated with some adverse health outcomes as measured by several indicators (CVD, diabetes, disability retirement, subjectively reported physical health, subjective fatigue). He concluded, however, “that the evidence regarding long work hours and poor health is inconclusive because many of the studies reviewed did not control for potential confounders. Due to the gaps in the current evidence and the methodological shortcomings of the studies in the review, further research is needed.”
The driver health team found very little research to evaluate specifically the association between long work hours and CMV driver health. No research studies were found that permitted an examination of whether additional hours of driving or non-driving time would impact driver health. Research on other occupations is mixed and does not show conclusively that long hours alone adversely affect worker health. Also, FMCSA's 2005 survey of driver hours indicates that the 2003 rule has not increased the overall number of hours a driver actually works (see Section I.1). Overall, this rule improves driver health compared to the pre-2003 and 2003 rules through a combination of provisions (see discussion of Combined Effects, Section J.11). The Agency has adopted the non-extendable 14-hour driving window and the 10-hour off-duty requirement; these provisions shorten the driving window allowed before 2003 by one hour (or more, in some cases) and lengthen the off-duty period by two hours. In short, based on current knowledge and the limited research that is available, in the Agency's best judgment there is no evidence that the number of work hours allowed by the HOS regulation adopted today will have any negative impact on driver health.
E.7. Shift Work and Gastrointestinal Disorders
The term “shift work” covers a wide variety of work schedules and implies that shifts rotate or change according to a set schedule. These shifts can be either continuous, running 24 hours per day, 7 days per week, or semi-continuous, running 2 or 3 shifts per day with or without weekends. Workers take turns working on all shifts that are part of a particular system. Shift work is a reality for about 25 percent of U.S. workers. Similarly, 22 percent of CMV drivers work between the hours of 12 p.m. and 6 a.m. [Campbell, K.L., & Belzer, M.H. (2000), p. 115].
This final rule is intended to make work schedules more regular by adhering more closely to a 24-hour clock than the pre-2003 rule. It increases the number of consecutive off-duty hours to 10 and provides for a non-extendable daily driving window of 14 hours. The pre-2003 rule provided only 8 hours of consecutive off-duty time and prohibited driving after a cumulative total of 15 hours on duty per day. Under that rule, however, drivers could extend the 15-hour limit by taking off-duty time. Today's rule should provide some health benefits to CMV drivers, because, as previously shown, drivers are getting more consecutive hours of sleep and will generally adhere more closely to a 24-hour clock (14 hours on-duty and 10 hours off-duty = 24 hours).
By minimizing on-duty time and maximizing driving time, however, a driver could operate on a backward rotating 21-hour schedule (11 hours driving and 10 hours off duty = 21 hours). Although drivers might conceivably employ that schedule, data suggests drivers do so only rarely. Even when it does occur, this schedule is still beneficially closer to 24 hours than the pre-2003 rule, which allowed a backward rotating 18-hour work day (10 hours driving and 8 hours off duty = 18 hours).
The driver health team examined research on the health effects of disrupting the circadian rhythm. The circadian rhythm spans about a twenty-four-hour day, exemplified by the normal sleep-waking cycle. Circadian rhythms in humans originate from a clock circuit in the hypothalamus that is set by information from the optic nerve
about whether it is day or night. One of the earliest studies and most definitive works in the area of shift work by Taylor and Pocock showed no relationship between shift work and mortality [Taylor, P.J., & Pocock, S.J. (1972), p. 201]. Two recent studies used experimental conditions to evaluate the impact of an altered circadian rhythm on insulin secretion. The first [Morgan, L.,
et al.
(1998), p. 449] found a longer sleep-wake cycle, such as might occur in rotating shift work, to be associated with increased insulin resistance and glucose response. In the second study, 261 shift workers completed a Standard Shift Work survey in an investigation of health and well-being [Barton, J., & Folkard, S. (1993), p. 59]. Workers using a forward rotating schedule were more likely to complain of digestive and cardiovascular disorders than those on a backward rotating system. This finding is counterintuitive because most fatigue and shift work research suggests that a forward rotating schedule is better from a sleep and fatigue standpoint. The authors concluded that the combination of direction of rotation and length of break when changing from one shift to another may be a critical factor in the health and well-being of shift workers [
Id.,
p. 63].
In a thorough review of the literature on shift work and health up to 1999, Scott [Scott, A.J. (2000), p. 1057] concluded that gastrointestinal, CVD, and reproductive dysfunctions are more common in shift workers, and that these effects may be due to rotating or fixed shifts, number of nights worked consecutively, predictability of schedule, and length of shift and starting time. Exacerbation of medical conditions such as diabetes, epilepsy, and psychiatric disorders, as well as the diseases noted above, may occur due to sleep deprivation and circadian rhythm disruption. It should be noted, however, that individuals with these conditions would not generally be qualified to drive under FMCSA's medical standards.
In a more recent study, Ingre and A
kerstedt [Ingre, M., & A
kerstedt, T. (2004), p. 45] investigated the effects of lifetime accumulated night work based on monozygotic (from a single egg) twins. The authors studied 169 pairs of twins where one of the two twins worked night shifts while the other twin worked day shifts. The subjects were all over 65 years old and retired. The study found no significant difference between education, weight, body mass index (BMI), diurnal or circadian rhythm, habitual rise times, habitual bed times, and sleep times. The study found that the twin exposed to night work was significantly more likely than the twin exposed to day work to report lower ratings of subjective health (17.8% versus 10.7% who stated that their health was poor). The study did not look at objective measures of health. The most significant finding was how similar the twins remained and that shift work did not adversely affect important health measures (such as BMI, weight, sleep habits).
The general consensus in the shift work research community therefore is that while certain work schedules may result in health problems, there are few epidemiological studies of shift workers, and more empirical data is needed. Furthermore, no aspect of the 2003 rule or this final rule promotes the use of shift work within the transportation industry. FMCSA knows that some drivers will drive at night because of backward rotations of schedules or as a result of their preference to drive at night. The rule is “shift-neutral” with regard to driving during the daytime or nighttime. Therefore, in the Agency's best judgment, this final rule should pose no greater risk to driver health than the pre-2003 and 2003 rules with respect to shift work. By promoting 24-hour cycles, today's rule should, in point of fact, aid driver health in regard to shift work.
E.8. Efforts to Improve CMV Driver Health
Recognizing the important role that driver health and wellness play in driver safety, performance, job satisfaction, and industry productivity, FMCSA began a research project in May 1997 to design, develop, and evaluate a model truck and bus wellness program. The results of the research led to the creation of the “Gettin” in Gear” program to create heightened awareness of and interest in driver health and wellness. Materials from this program were distributed within the truck and bus industry and provided basic health, nutrition, and fitness information to CMV drivers. The “Gettin” in Gear” program was found to have a positive health impact on drivers who participated in the program, both initially and when the Agency followed-up with participants [Roberts, S., & York, J. (1999), pp. 15-28]. This was shown in both lifestyle habits (
e.g.
, exercising, resting, eating balanced meals) and physical data (
e.g.
, body mass index; pulse; diastolic blood pressure; aerobic, strength, and fitness levels).
In addition, FMCSA has assessed the prevalence of sleep apnea among CMV drivers and the safety impacts of this condition. FMCSA is currently working with the National Sleep Foundation to develop an education and outreach program to inform the motor carrier industry of the problem of sleep apnea and how it can be effectively addressed.
E.9. Driver Health Summary
Today's rule provides for 10 hours of consecutive off-duty time, giving drivers the opportunity to obtain 7 to 8 hours of restorative sleep per day. Research on the implementation of the 2003 rule shows that drivers are sleeping 6.28 hours of verified sleep and this is within normal ranges consistent with a healthy lifestyle. Actually, the data shows that, compared to pre-2003, drivers are on average sleeping more than an hour longer per day.
On the issue of exposure, FMCSA has not found any evidence that drivers are working significantly longer hours as a result of implementation of the 2003 HOS rule, although it would be permissive. While exposure to diesel exhaust may pose a cancer risk, no definitive link has been yet established. Without a definitive link it is impossible to determine the actual risk or estimate the societal costs of DE to CMV drivers' health. However, based on EPA estimates of lower emissions (starting in 1990 and continuing until 2030), and the fact that drivers do not appear to be working longer hours, the Agency believes that any potential health risk to CMV drivers already has been reduced and will be reduced more in the coming years.
The noise levels documented in the research have not been shown to exceed OSHA or FMCSA standards. Therefore, the noise levels in CMVs should not result in a significant risk of hearing loss. The studies that tested vibration in CMVs found that on average vibration was close to the ISO health risk threshold, but it did not consistently exceed the threshold. Changes in CMV cabs, diesel fuel, and engine designs appear to have greatly reduced any potential health risks associated with CMV driving. These changes have reduced drivers' exposure to diesel exhaust, vibration, and noise. The research has shown that exposure to these stressors do not to pose a significant health risk to CMV drivers.
The research suggests the presence of only a weak association between CVD and truck driving. No research studies were found that permitted an examination of whether additional hours of driving a CMV impacts driver health as measured by increased cardiovascular disease or myocardial infarction. 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.
The research on long hours and driver health is very limited. Research on other occupations is mixed and does not show conclusively that long hours alone adversely affect worker health. Also, FMCSA has not found any evidence that drivers are working significantly longer hours as a result of the 2003 rule. Therefore, the Agency has concluded that there is no clear evidence that the number of work hours allowed by the HOS regulation will have any impact on driver health.
While it is generally believed that shift work may result in health problems, there are few epidemiological studies conducted on shift workers. The most definitive research of shift work and health showed no relationship between shift work and worker mortality. A recent study of twins suggests that shift work does not alter important health measures (such as BMI, weight, and sleep). Regardless, today's rule is “shift-neutral” with regard to driving during the daytime or nighttime. Therefore, as previously stated, in the Agency's best judgment this final rule should pose no greater risk to driver health with respect to shift work.
F. Driver Fatigue
Over the past decade FMCSA has been conducting research and reviewing the literature on driver fatigue in support of its effort to revise the Agency's HOS regulations. In preparing this final rule, FMCSA internally reviewed and evaluated numerous research reports that were published prior to 1995. The TRB driver fatigue team already mentioned conducted a literature review to identify studies concerning hours of service and CMV driver performance and fatigue published after 1995. Additionally, the driver fatigue team reviewed additional studies that were referenced in the comments to the 2005 NPRM. The pertinent information from all these reviews was used in guiding the development of this rule and is discussed in context under the relevant provisions in Section J of this preamble. This section provides a discussion of driver fatigue research relevant to the various provisions finalized in today's rule. The following subsections will discuss research on: (1) Issues related to driver fatigue (2) Circadian influences (3) Driving, duty, and off-duty times, (4) Split-sleep, (5) Recovery, and (6) Short haul. In addition, the Agency's current and future fatigue research activities are discussed in Section G of this preamble.
F.1. Issues Related To Driver Fatigue
This regulation addresses the phenomenon of driver fatigue,
i.e.
, the partial and at times total loss of alertness resulting from insufficient quantity or quality of sleep. Sleep plays a critical role in restoring mental and physical function, as well as in maintaining general health. For most healthy adults, 7 to 8 hours of sleep per 24 hour period appears to be sufficient to avoid detrimental effects on waking functions. Young adults, for example, report sleeping an average of 7.5 hours per night during the week and 8.5 during the weekend [Carskadon, M.A., & Dement, W.C. (2005), p. 18]. In a laboratory study that compared the performance of two groups of subjects that spent 7 and 9 hours in bed, respectively, performance improved throughout the study. With 7 hours in bed, impaired performance was only found on the more sensitive tasks [Balkin, T.,
et al.
(2000), p. ES-8]. Time in bed does not necessarily equate to time asleep; and time asleep does not always equate to quality sleep. For example, eight hours in bed is not likely to yield the same restorative benefit for someone with a sleep disorder or someone sleeping in a noisy, hot/cold, or otherwise uncomfortable environment, as it does for a “normal” sleeper. Studies of shiftworkers show that a given number of hours of sleep obtained during the late morning (waking hours) does not yield the equivalent amount of restorative sleep as the same number of hours obtained during the late night/early morning (sleeping) hours [Monk, T. H. (2005), p. 676].
F.2. Circadian Influences
Humans “are biologically wired to be active during the day and sleepy at night” [Monk, T. (2005), p. 674]. We have a homeostatic drive to sleep that interacts with the circadian cycle [Van Dongen, H.P.A., & Dinges, D.F. (2005), p. 440]. It has been well established that mental alertness and physical energy rise and fall at specific times during the circadian cycle, reaching lowest levels between midnight and 6 a.m., with, for some people, a lesser but still pronounced dip in energy and alertness between noon and 6 p.m. [Van Dongen, H.P.A., & Dinges, D.F. (2005), p. 439]. To stay alert throughout one's waking period, especially during these circadian troughs, most adults require 7 to 8 hours of quality sleep per day. Sleep obtained during the daylight hours of the circadian cycle is generally of poorer quality than sleep obtained during the nighttime/early morning “sleeping hours.” Working/driving during the “third shift” (midnight to 6 a.m.) has the combined effect of affording poorer quality daytime sleep, while requiring the driver to work/drive during times when the physiological drive for sleep is strongest. Changes of two or more hours in sleep/wake times cause one to become out of phase with the circadian cycle. This disrupts the synchronization of behavioral and biological processes (
e.g.
, cognitive performance, sleep, digestion, and body temperature), often resulting in increased fatigue and performance decrements. Circadian de-synchronization results from irregular or rotating shifts, especially those that are not anchored to a 24-hour day (
i.e.
, that start and end at different times each day), resulting in poor quality sleep and leading to accumulated fatigue. Backward rotating shifts that start an hour or more earlier each day also cause one to become out of sync with the circadian cycle, restricting sleep and leading to cumulative fatigue. “Forward rotating shifts—starting at a later time each day— are not as good as a non-rotating shift, but are more compatible with the properties of the circadian system than are backward-rotating shifts.” [Czeisler, C.A.,
et al.
(1982), p. 462]. The importance of maintaining a 24-hour day was highlighted in the 1998 HOS expert panel report [Belenky, G.,
et al.
(1998), p. 5].
The effects of the circadian cycle on driver alertness are addressed in this final rule in the 14-hour maximum on-duty and 10-hour minimum off-duty provisions (see Sections J.6 and J.7), which move drivers closer to a 24-hour day, while allowing some scheduling flexibility. This rule is far better than the pre-2003 HOS rule which allowed a backward-rotating schedule of 18 hours per day. Being more closely aligned to a 24-hour circadian cycle will allow drivers to obtain better rest, mitigate driver fatigue, and improve CMV safety.
F.3. Driving, Duty, and Off-Duty Times
A review of the past and current research provides support for adopting a maximum 14-hour driving window, which, when combined with the 10 hours off-duty provision, helps maintain a 24-hour clock (circadian cycle) and provides enough time for most drivers to obtain adequate sleep before returning to work.
Two studies that assess the length of driving time have been conducted since the 2003 rule went into effect.
One is an analysis of data from an on-road field test of a drowsy driver-monitoring device. The study monitored, among other things, driver
sleep quantity and the number of critical incidents (
e.g.
, crashes, near-crashes, and evasive actions) in which the driver became involved, and assessed driver fatigue and performance during critical incidents. Analysis of the study data, which were collected from May 2004 to May 2005, found that drivers included in the study were sleeping an average of 6.28 hours under the 2003 rule, which requires at least 10 hours off duty. For drivers who drove in both the 10th and 11th hour, no significant difference was found between the 10th and 11th hours of driving with respect to either alertness or involvement in critical events [Hanowski, R.J.,
et al.
(2005), p. 9]. A similar but pre-2003 on-road study [Wylie, C.D.,
et al.
(1996), p. ES-9] with 80 long-haul drivers who drove either 10 (U.S. rule) or 13 hours (Canadian rule) found that drivers were averaging 5.18 hours sleep per night. Both the Canadian and U.S. HOS rules that were in effect at the time required a minimum 8 hours off duty. Thus, comparing these two studies, drivers working under the 10-hour minimum off-duty rule are averaging over 1 hour more sleep per night. In the Wylie,
et al.
[Id.] study, there was no difference in the amount of drowsiness observed in video records (for comparable daytime segments) between the 10-hour and the 13-hour driving times. Self-rating of fatigue increased with driving duration even though there were no strong performance changes, leading the authors to conclude, “Time on task was not a strong or consistent predictor of observed fatigue” [Wylie, C.D.,
et al.
(1996), page ES-9].
Another study under the pre-2003 rule, “Trucks Involved in Fatal Accidents” (TIFA) [Campbell, K.L. (2005)], found an increase in crash/fatality risk with increasing driving time. This study included only data on crashes that occurred from 1991 to 2002, prior to the 2003 HOS rule change. Additionally, among the 50,000 trucks involved in fatal crashes that occurred over the 12-year period, only nine crashes involving drivers who drove in the 11th hour of driving were fatigue-related. Note that these drivers were probably driving illegally, since the pre-2003 rule had a 10-hour driving limit.
A recent study [Jovanis, P.P.,
et al.
, (2005)] used time-based logistic regression models to develop crash risk estimates by hours of driving. While all drivers drive during the first hour of the trip, relatively few drive through the 11th hour. Therefore, the sample sizes in the 11th hour of driving are typically so small that the resulting model has a large standard error, particularly at the upper limits of the driving time. As a result, the model's 95 percent confidence intervals in the crash risk estimates for the 11th hour of driving show that the crash risk could be significantly higher than driving in the first hour, or it could be just slightly elevated above the first hour of driving. The most likely cause for this inconclusive result is small sample size.
2
2
Statistical estimates based on small sample sizes tend to have large sampling variations, meaning that detecting statistically significant differences between two estimates may not be possible.
Sleepiness, performance decrements and crash risk follow the circadian cycle, that is, they peak in the late afternoon at one of the circadian low points [Wylie, C.D.,
et al.
(1996), pp. 1-3; A
kerstedt, T. (1997), p. 106]. This fact emphasizes the value of moving toward a 24-hour work/rest day. The 14-hour maximum driving window, combined with the 10-consecutive-hour minimum off-duty time provided in today's rule, moves toward stabilizing the 24-hour clock by helping to avoid driver shift rotation, and providing enough time to obtain 7-8 hours of sleep for most drivers. Rotating shifts that advance or delay the starting time for each subsequent shift can cause drivers to become out of phase with their circadian rhythm, depending on the extent of the change in their starting time. The 14-hour driving window and 10-hour off-duty time provisions of this final rule provide an opportunity to maintain a 24-hour work/rest day that will allow drivers to maintain circadian rhythm. FMCSA analysis indicates that approximately 22 percent of CMV drivers drive during the early morning hours (midnight to 6 a.m.). These drivers will benefit from the 10-hour minimum off-duty provision in order to maximize their sleep time.
Longer daytime work hours combined with good quality and quantity of sleep (7-8 hours) per day do not appear to pose a safety or health problem to CMV drivers. In a driving simulator study, the schedule of 14 hours on duty/10 hours off duty for a 5-day week did not appear to produce significant cumulative fatigue over the three-week study period [O'Neill, T.R.,
et al.
(1999), p. 2].
In Wylie,
et al.
[
Id.
] and other studies, the authors point out that many of the drivers showed signs of, or reported, fatigue early in the workweek after their “weekend” off-duty period [Morrow, P.C., & Crum, M.R. (2004), p. 14; Hanowski, R.J.,
et al.
(2000), p.17; Wylie, C.D.,
et al.
(1996), p. ES-9], implying that sleep habits on non-work days are likely a significant contributor to driver fatigue. FMCSA regulations can provide an opportunity for sleep, but drivers need to maintain responsible sleeping habits.
Lin and his colleagues formulated an elapsed time-dependent logistic regression model to assess the safety of motor carrier operations [Lin, T.D.,
et al.
(1993), p. 2]. Using crash data, this model provides estimates of the probability of CMVs having a crash. The estimates indicate that increased driving time had the strongest direct effect on crash risk. All of the data for these estimates were obtained from a single-less-than-truckload motor carrier. This study has many of the same problems associated with the time-based logistic regression models mentioned earlier;
i.e.
, small sample size in the later hours of driving. The authors concluded that crash risks “are particularly disturbing at 8th hour of driving. Unfortunately this is when mathematical structure of the model becomes less certain * * * it weakens our conviction to recommend reducing driver hours regulations” [Lin, T.D.,
et al.
(1993), p. 10]. Understanding the limitations of their models, these authors did not recommend reducing driving time. They did, however, recommend increasing the minimum off-duty time from 8 hours to 10 hours.
The research findings associated with driving time are conflicting. The research on the effects of fatigue in operational (on-road) and simulated/laboratory settings generally have found no statistically significant difference in driver drowsiness or performance between the 10th and 11th hours of driving. The research analyzing crash data by time of day are typically conducted with small sample sizes, particularly in the 10th and 11th hours of driving, and the driver samples are arguably not representative of the whole industry. These studies generally find increasing risk with longer driving hours. On-road/simulator studies, however, have found no increase in fatigue or critical incidents while driving as many as 11 or as many as 13 hours per day. The Agency regards the research on driving time as inconclusive. FMCSA is adopting an 11-hour driving limit for the reasons given in sections H and J.5. The data on off-duty time is less problematical. Drivers appear to be obtaining more sleep as a result of the 10-consecutive-hour off-duty provision in the 2003 rule. The Agency has therefore decided to adopt a 10-hour off-duty requirement for CMV drivers, coupled with a 14-hour driving window. This will move CMV drivers toward a more-stable 24-hour clock. Because there is a good deal of evidence that hours of continuous wakefulness
are a better predictor of fatigue than driving time, a 14-hour non-extendable driving window will help to reduce driver fatigue, compared to the extendable 15-hour window included in the pre-2003 rule. See Sections H.6 and J.5 through J.7 for a more detailed discussion of the Agency's findings and decisions regarding driving, duty, and off-duty times.
F.4. Split Sleep
In the 2003 rule, drivers using trucks equipped with sleeper berths were allowed to split their 10-hour off-duty/sleep time into two periods of varying length as long as the shorter of the two periods was a minimum of two hours. This exception to the 10-consecutive-hours off-duty rule had, in many instances, resulted in drivers splitting their sleep into two periods. Drivers could, for example, divide their sleep over two 5-hour periods. The National Transportation Safety Board (NTSB) has been critical of the split sleep provision in the past, noting that, “* * * sleep accumulated in short time blocks is less refreshing than sleep accumulated in one long time period” [NTSB (1996), p. 46)].
Sleep becomes fragmented when drivers elect to take their sleep in two shorter periods, rather than one 7 to 8 hour period. Fragmented sleep has less recuperative value and has been shown to be similar to partial sleep deprivation in its effects on performance [Belenky, G.,
et al.
(1994), p. 129]. Studies of truck crash fatalities indicate that split sleep taken by drivers has an adverse effect on CMV safety. In a study of heavy truck crashes and accidents, NTSB cited police accident reports that show decrements in performance occurring earlier for drivers using sleeper berths. NTSB also found that “drivers using sleeper berths had a higher crash risk than drivers obtaining sleep in a bed.” NTSB reported that “split-shift sleeper berth use increases the risk of fatality more than two-fold;” and “[s]plit-sleep patterns are among the top three predictors of fatigue-related accidents” [NTSB (1996), p. 46]. In summary, NTSB concluded that accumulating 8 hours of rest in two sleeper-berth shifts increases the risk of fatality to tractor-trailer drivers who are involved in crashes.
An earlier study by the Insurance Institute for Highway Safety (IIHS) examined the association between sleeper berth use in two periods and tractor-trailer driver fatalities [Hertz, R.P. (1988)]. The findings from this study were similar to those reported by the NTSB. The IIHS found that, “* * * split-shift sleeper berth use (driving without an eight-hour consecutive rest period), increased the risk of fatality over twofold;” and that, “* * * split-shift sleeper berth use increased the risk of fatality in all analyses except those limited to urban crashes and local pick-up and delivery crashes” [
Id.,
p. 7]. The results of this analysis also found that accumulating 8 hours of rest over two sleeper berth periods increases the risk of fatality to tractor-trailer drivers who are involved in crashes. IIHS further concludes “[t]he fact that risk remained the same regardless of team status suggests that increased risk of fatality is associated with nonconsecutive sleep rather than disturbance from the motion of the truck while sleeping” [
Id.,
p. 11].
Today's rule is based on the research cited and addresses the concerns about driver fatigue resulting from sleep fragmentation by requiring a consecutive 8-hour sleeper berth period to allow drivers to obtain one primary period of sleep and a second 2-hour off-duty or sleeper berth period to be used at the driver's discretion for breaks, naps, meals, and other personal matters. The new sleeper berth provision is fully described in Section J.9 of this preamble.
F.5. Recovery
Sleep restriction over several days leads to a degradation in alertness and driving performance. When sleep is restricted by extended duty periods or night work, cumulative fatigue occurs and an extended off-duty period is needed to recover. Past studies have indicated that a large percentage of drivers (commercial and noncommercial) get less than the commonly recommended 7 to 8 hours 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]. Many drivers who obtain less than their daily requirement of sleep over time incur a sleep debt; the resulting cumulative fatigue leads to an increased crash risk [Hanowski, R.J.,
et al.
(2000), pp. 11-12]. Recovery time is required to restore the mind and body to normal function and health, as well as to erase the deleterious effects that sleep loss has on alertness and performance.
The TRB fatigue team found five studies that provided information regarding the recovery time needed for CMV drivers after working a long week. Four of these studies provide support for recovery periods of 34 hours or less while only one of these studies supports a recovery period longer than 34 hours.
Two studies suggest that a single 24-hour period is sufficient time for a driver to recover from any cumulative fatigue. Alluisi's research [Alluisi, E.A. (1972), p. 199] involved subjects who worked 8 hours a day for 3 days, followed by a 4 hours on/4 hours off schedule (similar to driving with a sleeper berth) over a 2-day period. He found that the average performance of drivers dropped to 67 percent of baseline toward the end of this period. A 24-hour rest period was sufficient to permit recovery back to baseline. A simulator study examined daytime driving of 14 hours on/10 hours off over a 15-day period [O'Neill, T.R.,
et al.
(1999), p. 36]. These authors found that 24 hours was an adequate amount of time for recovery. A third study [Feyer, A.M.,
et al.
(1997), p. 541] found a dramatic recovery with respect to fatigue in team drivers who stopped overnight in the middle of a 4 to 5 day trip. Thus, with less than 24 hours off, a single night of sleep was very helpful for recovery. A fourth study [Balkin, T.,
et al.
(2000), p. 1-2] found that whether or not 24 hours was sufficient depended on the sensitivity of the performance measure used to assess recovery. Subjects who carried out performance tasks during the day and were restricted to 3, 5, or 7 hours in bed at night were fully recovered after 1 day of recovery sleep of 8 hours in bed, if the performance measure was lane tracking or simulator driving crashes. If the measure was performance on the psychomotor vigilance test (PVT), a more sensitive test of fatigue, then recovery required more than 24 hours. The group who had 9 hours in bed during the work period, but were then restricted to 8 hours in bed during the recovery period, did not perform well on lane-tracking as well as during the work period, clearly illustrating how sensitive and essential one's performance is to even one additional hour of sleep.
The TRB driver fatigue team found two recovery studies that were conducted with CMV drivers in a field environment. The Wylie [Wylie, C.D.,
et al.
(1997)] study was a small demonstration study of a methodology that could be used to evaluate drivers' recovery periods. Twenty-five drivers were assigned into small groups (four to five drivers) and were used to evaluate different recovery (12-, 36-, and 48-hour) periods and driving time. None of the recovery periods examined were found to be of sufficient length for driver recovery. However, the study concluded that the small subject sample limited the ability to make reliable estimates of observed effects [Wylie, C.D.,
et al.
(1997), p. 27].
The methodology and sample size nullifies Wylie study findings, and the
Agency has not relied on this study in determining the appropriate recovery period for CMV drivers. Balkin [Balkin, T.,
et al.
(2000), p. 5-1] as discussed in the previous section, found that after 7 days of daytime work, when sleep had been restricted to 5 or 7 hours in bed, a recovery period of more than 24 hours was required to return to baseline levels of the most sensitive performance task. For extreme sleep restriction of 3 hours in bed, 72 hours recovery was insufficient to bring performance of the PVT task back to baseline.
While the research on driver recovery appears limited to five studies that particularly focus on CMV driver recovery, two simulator studies suggest that 24 hours is sufficient for recovery after 70 hours of daytime driving [O'Neill, T.R.,
et al.
(1999), p. 2; Alluisi, E.A. (1972), p. 199]. One on-the-road study found that drivers achieve adequate recovery after 24 hours off duty. Another on-road study suggests that 36 hours is not quite sufficient with regard to PVT measures, but is adequate for driving parameters, including lane-tracking performance during daytime driving.
In balance, most of the research with CMV drivers supports the assessment that a recovery period of 34 consecutive hours is sufficient for recovery from moderate cumulative fatigue. The importance of two night (10 p.m.-6 a.m.) recovery periods was highlighted by the 1998 HOS expert panel report [Belenky, G.,
et al.
(1998), p. 13]. The majority of drivers (approximately 80 percent) are daytime drivers, and would likely start their recovery period between 6 p.m. and midnight. All of these drivers would have the opportunity for two full nights prior to the start of the next work week. For a more detailed discussion regarding the recovery period provision of this rule, see Section J.8 of this preamble.
F.6. Short-Haul
Motor carrier operations that are conducted solely within a 150 air-mile radius from their terminals and require drivers to return to their work-reporting location every night are generally considered short-haul operations. A review of the research literature revealed only a few studies on short-haul operations. The first study reviewed was the Massie study [Massie, D.L.,
et al.
(1997)] which found that short-haul drivers have significantly fewer fatigue related crashes as compared to drivers for longer trips (0.4 percent for short-haul trucks compared to 3.0 percent for other trucks). Another important finding was that “class 7-8 trucks [26,001 pounds gross vehicle weight rating (GVWR) and up] have a fatigue-related fatal involvement rate 8 times higher than class 3-6 trucks [10,001-26,000 pounds GVWR]; over-the-road trucks have a rate 18 times higher than local service trucks; and the rate for tractors exceeds the rate for single-unit straight trucks by a factor of 11” [Massie, D.L.,
et al.
(1997), p. 35].
A second study evaluated the stress that short-haul drivers face daily. Researchers that administered a cross-sectional questionnaire to 317 CMV drivers found that short-haul drivers have significantly higher stress-related symptoms than the general adult population [Orris, P.,
et al.
(1997), p. 208]. These drivers perceived their daily events to be more stressful than the norm because of heavy workloads and inflexible schedules.
Hanowski,
et al.
(1998; 2000) conducted two studies on short-haul drivers—a focus group and a field study. The first study provided a better definition of what constituted a short-haul driver and the varied tasks and demands they encounter [Hanowski, R.J.,
et al.
(1998), p. 1]. The focus groups concluded that driving was not their primary task, accounting for about 40 percent (less than 5 hours) of their work time, scattered throughout the day. The two safety problems most often mentioned by short-haul drivers were dealing with poor driving by operators of cars, pickups, SUVs, etc., and “stress due to time pressure.” Additionally, Hanowski,
et al.
[Hanowski, R.J.,
et al.
(2000), pp. 1-162] conducted a field study of short-haul drivers with instrumented vehicles to gain a better understanding of critical incidents that occur within short-haul operations. A critical incident was defined as a near crash event,
i.e.
, an event that without evasive action by the driver would likely have resulted in a crash. Of the 249 critical incidents found in the study, 137 were attributed to “other” (
i.e.
, non-CMV) drivers, 77 to the short-haul drivers, and 35 were attributed to incidents outside the control of the driver, such as an animal in the road. Fatigue played a role in only 6 percent of those incidents, and no fatigue crashes were reported [
Id.
].
In determining whether to allow short-haul drivers additional time to complete their deliveries, the Agency relied on both laboratory and field research studies which confirm the ability of drivers to work a 16-hour shift without significant degradation of performance. A laboratory study of 48 healthy adults found the critical wake period beyond which performance began to lapse was statistically estimated to be about 16 hours [Van Dongen, H.P.A.,
et al.
(2003), p. 125]. A study of New Zealand drivers found that drivers could maintain their performance until about the 17th hour of wakefulness; beyond the 17th hour, performance capacity was sufficiently impaired to be of concern for safety [Williamson, A.M.,
et al.
(2000), p. 3].
Some short-haul drivers do accrue fatigue, however, and in a field study of CMV drivers, it was found that short-haul drivers take short naps of 1- to 2-hours duration in order to reduce any fatigue accrued during the course of a normal work day. This study showed that these drivers take naps within the work shift while they are waiting for their vehicle to be loaded or unloaded or during normal breaks for meals [Balkin, T.,
et al.
(2000), p. 4-63]. Short-haul drivers are unique in that they do not drive for long periods of time. As mentioned, Hanowski [Hanowski, R.J.,
et al.
(2000), p. 17] found that only 40 percent of their time is actually spent driving, and that time was scattered throughout the day. Therefore, traditional performance models (time-on-task) do not apply because periods of driving are interrupted during their work day. Based on this evidence, FMCSA has concluded that because of the uniqueness of short-haul operations, and because short-haul drivers are involved in fewer crashes than long-haul drivers, they will be able to maintain alertness and vigilance for an additional 2 hours for 2 days per week.
The short-haul provision in this final rule takes into account the available research on short-haul drivers and addresses one of the key problems confronted by short-haul drivers—the stress of tight schedules. To set the context, the research discussed in Section F, “Driver Fatigue,” and elsewhere in this preamble suggests that driver fatigue is much less of an issue with short-haul drivers than with long-haul truckers, primarily because they return home nightly. Many also have fixed work schedules. Short-haul drivers typically operate during the daytime hours and are able to sleep at night, which is generally preferable to sleeping during the day. Short-haul drivers do not drive for long periods each day, either cumulatively or in a single session, and driving is usually followed by the physical activity of unloading throughout the day, which improves alertness. Short-haul drivers are less likely to fall asleep at the wheel due to driving monotony. In addition, short-haul driving generally occurs in urban settings requiring high levels of alertness, but also providing more stimuli to drivers. Short-haul crashes, when they happen, are more likely to
involve property damage than severe injuries or fatalities. Because the short-haul regime adopted by this final rule increases the work window available to short-haul drivers, it should relieve them, at little risk to CMV safety, from the stress and need to hurry caused by inflexible schedules and limited work hours. The new regulatory regime for short-haul drivers is described in more detail in Section J.10.
G. Current and Future FMCSA Research
In the 2005 NPRM, the Agency requested information on hours-of-service research issues, including data gaps and processes, and methodologies to facilitate data collection and analysis [70 FR 3350]. The Agency received no specific responses to this request. However, FMCSA continues to proactively research health and safety issues relevant to HOS.
The FMCSA Research and Technology (R&T) 5-Year Strategic Plan outlines a vision for delivering an appropriately targeted research and technology program that will assist in fulfilling FMCSA's primary mission to reduce crashes, injuries and fatalities involving large trucks and motorcoaches. One of the challenges identified in the R&T 5-Year Strategic Plan is to curtail driver fatigue and lack of alertness. Fatigue and the lack of alertness are factors in CMV crashes, but more research is needed to better understand the causes of fatigue and methods of improving alertness. Hours-of-service rules and driver-oriented programs will need to be continually evaluated and improved. R&T will investigate, by means of simulator and field studies, the factors affecting fatigue and the recovery times. Other initiatives identified in the R&T 5-Year Strategic Plan will also result in the research and evaluation of driver health issues. Moreover, in an effort to address the complex HOS health issues confronting CMV drivers, FMCSA anticipates working with NIOSH on areas of mutual concern and interest.
FMCSA is identifying, through the use of surveys, the best practices employed by experienced CMV drivers to manage their fatigue. This study will be published later this year. In addition, FMCSA has the following fatigue-related studies that are under way in 2005 and will continue for the next several years.
This research and survey of best practices may contribute to educational initiatives, to technological aids, to the rulemaking process on EOBRs, and to other aspects of CMV operation and regulation.
G.1. Fatigue Management Program
The FMCSA Fatigue Management Program (FMP), under development in partnership with Transport Canada, provides managers and drivers with a framework for managing driver fatigue through, among other items, awareness and education on screening for sleep disorders, biocompatible scheduling practices, and an understanding of the need and implications of good sleep habits. The program has been developed, pilot tested in the U.S. and Canada, and is currently in an evaluation phase where its cost and safety effectiveness will be assessed in an operational environment. Pending a positive result from the evaluation, the FMP materials will be revised and finalized, implementation guidelines will be developed, and comprehensive program materials and guidelines will be made available to motor carriers and individuals who wish to implement them.
G.2. Shift Changes and Driver Fatigue Recovery
The FMCSA Shift Changes and Driver Fatigue Recovery Study currently under way has two primary goals:
• Investigate and make recommendations regarding the minimum duration of off-duty periods required for CMV drivers to recover from the effects of cumulative fatigue resulting from various work shift conditions.
• Complete a study and publish a report with conclusions and recommendations from the Shift Changes and Driver Fatigue Recovery Study.
Hours-of-service initiatives in both the United States and Canada have highlighted scheduling issues closely related to shift changes, in particular, the issue of “weekend” recovery from cumulative fatigue. Although CMV drivers may take their “weekends” on any day of the week, the issue of concern is the recovery process that occurs during these days off. If some degree of sleep deprivation occurs during the workweek for drivers (especially when that week has involved night driving and/or shift changes), it is critical that drivers have sufficient time off during their “weekend” to recover full alertness and physical vitality. This continuing research is focusing on the recovery process in the context of various schedules including day driving, night driving, and rotating shifts. After conducting a review of the relevant literature (Phase I), a research plan was developed that includes recommended hypotheses to be examined and empirical research methodologies to be employed (Phase II). In 2005, a contract was awarded to conduct the empirical studies (Phase III). A final report stating study conclusions and recommendations (Phase IV) will be completed by the end of 2007.
G.3. Advanced Driver Fatigue Alerting Technology
The objective of FMCSA's Advanced Driver Fatigue Alerting Technology research initiative is to increase driver alertness through a fatigue-alertness monitor. This will be done by establishing a low cost, reliable, comfortable, rugged, and user-friendly driver fatigue and alertness technology. Driver fatigue-alerting technology is intended to monitor driver drowsiness, provide continual alertness level feedback to the driver, and provide alerts and warnings when the driver's alertness level falls below a specified threshold.
Currently, FMCSA in partnership with NHTSA is conducting a proof-of-concept test of a drowsy-driver detection system based on the PERCLOS (percent of time the eyelids are closed 80% or more over a given time period) concept. PERCLOS has been demonstrated to be the most valid measure of driver fatigue. The current infrared-based technology to measure PERCLOS appears to work well at night, but has the limitation of not working in daylight, limiting the system's utility to night driving. FMCSA plans to explore new technologies and combinations of technologies or measures, such as steering, lane tracking, etc. that may overcome these limitations, and investigate development of a more robust system. The objective is to identify and develop a relatively low-cost device to be used primarily to reinforce driver fatigue training and promote behavioral change to assure drivers are well rested.
G.4. Effects of Vehicle Ergonomics on Driver Fatigue
The FMCSA Effects of Vehicle Ergonomics on Driver Fatigue initiative plans to identify design alternatives to assess the effects of vehicle ergonomics on driver fatigue. There have been many human factor studies designed to determine the effects associated with driving a CMV. However, there are no current studies to determine the effects of ergonomics on driver fatigue and CMV safety. Therefore, it is difficult for FMCSA to provide guidance or support to ergonomic-related rules that could improve safety. This study will review the project objective, conceive design
alternatives, examine methods, evaluate feasibility, and develop a final design incorporating a pilot study capable of demonstrating the approach's viability.
H. Crash Data
FMCSA compiled and reviewed recent large truck crash data throughout the industry to assess the impacts of the 2003 rule on crash rates, and to determine if there are ways to improve the 2003 rule to better address fatigue and fatigue-related crashes. This review consisted of examining the following studies and data sources: (1) Trucks Involved in Fatal Accidents (TIFA), (2) Virginia Tech Transportation Institute (VTTI) (preliminary), (3) Penn State University (preliminary), (4) data submitted in comments to the NPRM, and (5) Fatality Analysis Reporting System (FARS).
H.1. Trucks Involved in Fatal Accidents (TIFA) Data
The Trucks Involved in Fatal Accidents (TIFA) file combines data from the FARS with additional data on the truck and carrier collected by the University of Michigan Transportation Research Institute (UMTRI) in a telephone survey with the truck driver, carrier, or investigating officer after the fatal crash. TIFA records six variables: fatigue, time of day, power unit type, carrier type, intended trip distance, and hours driving since the last 8-hour off-duty period.
The report used by the Agency [Campbell, K.L. (2005)] reviewed TIFA data for the years 1991 through 2002 (the most recent year available). The sample size of this file represents over 50,000 medium/heavy trucks involved in fatal crashes in the U.S., roughly 1,000 of which were fatigue related. The objective of this report was to identify the operating conditions where the most fatigue-related crashes occur and to determine the association of fatigue risk factors with fatal crashes.
Over the period reviewed, the report found a gradual decline in the percent of trucks involved in all fatal crashes where truck driver fatigue was present at the time of the crash, with fluctuations around the downward trend. Campbell also noted that “[b]oth prevalence and risk point to long-haul tractor drivers as the appropriate focus of efforts to reduce the incidence of fatigue.”
When examining the prevalence of fatigue-related fatal crashes by the number of hours driven at the time of the crash, the data reveal that the majority of such crashes occur in the early hours of the trip. This is largely attributable to exposure, since each trip necessarily begins with the first hour, which must be the most frequently driven. However, when examining the relative risk of a fatigue-related crash by hours of driving, or the number of trucks involved in fatigue-related fatal crashes in a given driving hour as a percent of all large trucks involved in fatal crashes in the same hour, the results trend differently. The likelihood a truck driver was fatigued at the time of a fatal crash generally increases with the number of hours driven. TIFA data show that the relative risk of a large truck being involved in a fatigue-related crash in the 11th hour of driving or later is notably higher than in the 10th hour of driving.
Despite its scope and complexity, however, TIFA data must be treated with caution. The number of fatigue-related crashes that occurred in the 11th hour of driving or later is extremely small. Of the roughly 1,000 trucks involved in fatigue-related fatal crashes between 1991 and 2002, only nine were operating in the 11th hour of driving time.
The HOS rule in effect when the TIFA data were collected allowed only 10 hours of driving, required a minimum off-duty period of only 8 hours, and allowed driving within a 15-hour window that could be extended by the amount of off-duty time taken during that period. The 2003 rule, which allows up to 11 hours of daily driving but requires 10 hours off duty, may have reduced the risk of driver fatigue and thus the percent of large truck fatal crashes involving fatigue. The applicability of TIFA data under the regulatory environment created by the 2003 rule is no longer clear.
FARS, the source of the crash data for the TIFA study, does not contain information on driving hours at the time of the crash. TIFA researchers therefore contact the driver (or the employing carrier) after the fatal crash to collect such information. However, a good deal of time can elapse (more than a year in some cases) between the date of the crash and the date the TIFA researcher first contacts the driver (or the employing carrier). This delay raises the question whether the driver can accurately recall his/her driving time so long after the incident.
H.2. Virginia Tech Transportation Institute Study
FMCSA contracted with the Virginia Tech Transportation Institute (VTTI) to collect and analyze data on crash risk during the 10th and 11th hour of driving as part of an on-the-road driving study VTTI was conducting under an FMCSA/NHTSA joint initiative. This study offered an opportunity to analyze empirical, real-world data obtained under the 2003 HOS rule. The primary goal was to determine the effect of the 11th hour of driving on driver performance and drowsiness.
Data collection for the study, “A Field Operational Test of a Drowsy Driver Warning System,” began in May 2004. All data collected through May 1, 2005 were used in this analysis. The researchers have found no statistically significant difference in the number of “critical” incidents in the 10th and 11th hours of driving [Hanowski, R. J.,
et al.
(2005), p. 9]. The study defines critical incidents as crashes, near crashes (where a rapid evasive maneuver is needed to avoid a crash) and crash-relevant conflicts (which require a crash-avoidance maneuver less severe than a near-crash, but more severe than normal driving). When the occurrence of critical incidents is used as a surrogate for driver performance decrements, there is no statistical difference between the 10th and 11th hour of driving. The study has also determined that drivers are not measurably drowsier in the 11th than the 10th hour of driving. These results may be related to another finding, that drivers appear to be getting more sleep under the 2003 rules than they did when the minimum off-duty period was only 8 hours. Compared to four sleep studies conducted under the pre-2003 rules (see section E.1), the Hanowski study found that drivers operating under the 2003 rule are obtaining over 1 hour of additional sleep per day [
Id.,
p. 8]
It should be noted, however, that the study is not yet complete. The study involves 82 drivers working for three trucking companies who had driven a total of 1.69 million miles as of May 1, 2005, under the 2003 HOS rule. A copy of this VTTI analysis is in the docket.
H.3. Crash Risk and Hours Driving: Interim Report II
In January 2003, the Pennsylvania Transportation Institute at Pennsylvania State University began work for FMCSA to model the effects of various commercial driving operational measures (hours driving, hours of rest, multi-day driving patterns) on crashes [Jovanis, P.P.,
et al.
(2005)]. This study collected records of duty status (RODS) for 7-day periods prior to crashes, as well as for a non-crash control group. The RODS were collected between January 2004 and December 2004. Through time-dependent logistic regression modeling, the study found a pattern of increased crash risk associated with hours of driving,
particularly in the 9th, 10th and 11th hours, and multi-day driving. The study also suggests a higher crash risk associated with sleeper-berth operations. For all operations, the study found that the 11th hour of driving has a crash risk of more than three times that of the first hour.
Like the VTTI study, this study is incomplete. All RODS were collected from 3 for-hire motor carriers. The researchers obtained RODS for 231 7-day periods with one or more crashes and 462 7-day control periods with no crashes. Driving in the 11th hour occurred only 34 times.
H.4. Comments on Crash Risk and Data
Many companies and associations submitted data on crash and injury rates. Figure 4 shows changes in DOT recordable accidents, preventable accidents, and injuries under the 2003 rule, as reported in several comments. In general, the data show that crash and injury rates were lower in the year since the 2003 rule went into effect in January 2004.
Figure 4.—Changes in Accident and Injury Rates From 2003 to 2004
[Per million miles]
Commenter
Fleet size
Crash or injury type
2003
2004
Percent change
Maverick Transportation
1100 power units
DOT recordable accidents
0.63
0.60
−4.8
Preventable accidents
0.32
0.24
−25
Crash-related injuries
−30
Roehl Transport
1600 power units
DOT accidents involving injuries
0.08765
0.06554
−25
ABF Freight System
1635 road tractors
Over-the-road accidents
*1.49
1.42
−4.6
Preventable road accidents
*0.715
0.586
−15
Injuries for over-the-road drivers
−41
CR England
2550 power units
Collision-related injuries
−1.9
Overnite Transportation
6000 power units
DOT recordable accidents
0.84
0.80
−4.8
DOT preventable accidents
0.31
0.31
0
Collision-related injuries
−8.6
Werner Enterprises
8700 tractors
DOT recordable accidents
0.6898
0.7092
+2.8
Chargeable accidents
0.3311
0.3238
−2.2
J.B. Hunt
11,000 tractors
DOT recordable accidents
−10
DOT preventable accidents
−16
Driver injuries as a result of motor vehicle accidents
−19
Schneider National
13,340 tractors
Preventable major (over $100,000 in cost accidents
−36
Fatigue-related major accidents
−50
Worker's compensation claims from vehicle accidents
−10
ATA survey
77,000 to 79,000 trucks
DOT recordable accidents
0.60
0.57
−5.0
DOT preventable accidents
0.24
0.24
0
Injuries
0.81
0.75
−7.4
FedEx
71,000 motorized vehicles
At FedEx Express, fatigue-related accidents
−3.8
At FedEx Ground, DOT recordable accident rate
−9
At FedEx Freight, driver injury rate
−4
National Private Truck Council
63 questionnaires
DOT recordable accidents
0.4921
0.4248
−13.7
Minnesota Trucking Association survey
85 questionnaires (61% long-haul carriers)
Preventable/recordable crashes
61% of members reported no change. 33% reported a decrease.
* Five-year average. Blank cells indicate data not reported.
In addition to the information provided in Figure 4, eighteen other companies and associations reported a decrease in crash rates, but did not provide data to support their claims, and 8 others found little change in crash rates between 2003 and 2004. The Commercial Vehicle Safety Alliance (CVSA) cautioned that additional data over a longer period of time are needed to determine to what extent the 2003 rule has impacted large truck safety.
ATA reported data showing that carriers had statistically significant lower average crash rates in 2004, causing ATA to believe that the 2003 rule is superior to the pre-2003 rule from the perspective of overall safety. Two State government agencies, however, pointed out that the FMCSA Motor Carrier Management Information System (MCMIS) data show an increase in CMV crashes. FMCSA considered the use of MCMIS data to examine changes in truck-related crashes between 2003 and 2004. However, the Agency decided to utilize FARS data for this analysis (see below), in lieu of available MCMIS data, for two reasons. First, the MCMIS crash data do not provide researchers the ability to isolate fatigue-related crashes, which are critical for this rulemaking. FARS data do provide this ability. Second, FMCSA crash data experts believe that, for a variety of reasons, MCMIS currently fails to capture roughly 20 percent of the fatal crashes that are reported in FARS. Because of these MCMIS limitations, FMCSA chose to use FARS data for its analysis.
The information provided by commenters is not available from any other source, but there is undoubtedly some variability in the methods and accuracy with which the data were collected. Equally important, the crash and injury reductions reported by
commenters cannot be definitively attributed to the effects of the 2003 rule, though some commenters noted that the rule is the only major variable that changed from 2003 to 2004.
H.5. Fatality Analysis Reporting System (FARS)
FARS is a national census of fatal crashes involving motor vehicles, including large trucks. FARS data are reported annually by the States, maintained by NHTSA, and are generally recognized as the most reliable national motor vehicle crash data available.
FMCSA began by analyzing the 2003 FARS Annual Report File. Because the 2004 Annual Report File had not yet been released at the time the analysis for this rulemaking was conducted, FMCSA examined its predecessor, the “Early Assessment File,” which typically contains most of the fatal crashes that eventually appear in both the Annual Report and Final FARS data sets. For example, a NHTSA comparison of calendar years 2002 and 2003 indicates that the Early Assessment File captured at least 75 percent of the total crashes and fatalities later included in the Annual Report Files for those years. Since the earlier months of the calendar year are reported more completely in the Early Assessment File, FMCSA restricted its analysis to the first 9 months of 2003 and 2004.
FMCSA examined all fatal crashes involving large trucks from January through September of 2003 and 2004, as well as those where the truck driver was coded as fatigued at the time of the crash. Results from this year-to-year comparison are presented in Figure 5.
Figure 5.—Fatal Crashes Involving Large Trucks
[Calendar years 2003 and 2004 (first 9 months of each year)]
Calendar year
Total crashes
Number
Fatigue-related (truck driver) crashes
Percent
2003
3,120
54
1.7
2004
2,954
43
1.5
Year-to-Year Difference (Number)
−166
−11
−0.2
Year to-Year % Difference
−5.3
−20.4
−11.8
Source(s): 2003 Fatality Analysis Reporting System (FARS) Annual File; 2004 FARS Early Assessment File, National Highway Traffic Safety Administration.
Figure 5 shows that the total number of fatal crashes involving large trucks decreased by 166, from 3,120 in 2003 to 2,954 in 2004. This represents a 5.3 percent reduction. The number of large truck crashes where the driver was coded as fatigued dropped by 11 crashes, or 20.4 percent. More importantly, however, fatigue-related fatal crashes are down from 1.7 percent of all crashes in 2003 to 1.5 percent in 2004, an 11.8 percent reduction.
These reductions in fatigue-related fatal crashes are very small, and are not enough to allow final conclusions about the long-term impact of the 2003 rule on highway safety. However, the available information may suggest that fatigue-related crashes overall are trending in the right direction.
H.6. Conclusion
Available information on the effect of allowing 11 hours of driving time is inconclusive. TIFA is a large data set based on crashes that occurred across the nation over a relatively extended period. While the statistical risk increases rather sharply in the 11th hour of driving, in all the years from 1991 to 2002 TIFA classified only 9 fatal crashes that occurred in the 11th hour of driving as fatigue-related. Furthermore, TIFA data were collected at a time when Federal HOS regulations required only 8 hours off duty, and allowed driving within an extendable 15-hour window, both of which may have ensured that drivers operating in the 11th hour were more fatigued than would be the case under the 2003 rule. Finally, the pre-2003 rule allowed only 10 hours of driving, which means that drivers operating in the 11th hour were out of compliance with the rules at the time, and therefore may not be representative of drivers legally operating in the 11th hour after adoption of the 2003 rule.
The on-going studies by the Virginia Tech Transportation Institute and the Pennsylvania Transportation Institute are being conducted under the 2003 HOS rule and therefore avoid one of the problems associated with TIFA data. One finds that the 11th hour of driving poses an increased crash risk while the other finds no statistical difference between the 10th and 11th hours of driving. Because of the relatively short time since the 2003 rule was adopted, both studies acknowledge a considerable amount of uncertainty which may be resolved once the datasets increase.
Nearly all of the motor carriers and trucking organizations that submitted comments to the docket reported lower crash and injury rates in 2004, when the 2003 HOS rule was first enforced, than in 2003. This downward trend reveals nothing specific to the 11th hour of driving time, nor can it be attributed directly to the 2003 rule, but it does suggest that the net effect of the various provisions of the 2003 rule has not been harmful. However, the data summarized in Figure 4 were undoubtedly collected and reported with differing degrees of statistical sophistication. Still, the number of drivers employed by the carriers that provided information is very large and the downward trend in accidents and injuries is unmistakable.
Preliminary FARS data show that there were fewer fatigue-related fatal CMV crashes in the first nine months of 2004, when drivers and carriers were subject to the 2003 rule, than in the same months of 2003, when they were subject to the previous rule. Fatigue-related fatal crashes as a percentage of all CMV fatal crashes were also down in 2004. This result is similar to the information provided in motor carrier comments to the NPRM. The downward trend is clear, but the data do not allow a calculation of crash risk for each additional hour of driving.
In short, the available crash data do not clearly indicate whether the 11th hour of driving, combined with the other provisions of the 2003 rule, poses a significant risk. Because the data are not clear, for the purposes of this rulemaking's RIA, FMCSA conservatively assumed that the increased fatigue crash risk of driving in the 11th hour could be explained by the TIFA data as summarized in Campbell 2005, and FMCSA tests the robustness of the conclusions of this analysis
through a sensitivity analysis that assumes an even higher relative fatigue crash risk of driving in the 11th hour.
FMCSA carried out a cost/benefit analysis of a 10- and 11-hour driving limit and other aspects of this final rule. The results are described fully in section K.1 and in the Regulatory Impact Analysis (RIA) filed separately in the docket. Motor carrier operations were modeled very elaborately. As discussed above, the Agency used a time-on-task multiplier based on the TIFA data. The model assumed that the risk of the 11th versus the 10th hour of driving increased, as based on the TIFA data. FMCSA estimated that a 10-hour driving limit would save no more than 9.3 lives per year compared to an 11-hour limit, but at an annualized net cost of $526 million ($586 million in gross costs minus $60 million in safety benefits), relative to an 11-hour limit. In other words, a 10-hour driving limit would cost more than $63 million per life saved.
FMCSA conducted a number of sensitivity analyses regarding the relationship between fatigue-related crash risk and driving in the 11th hour to test the sensitivity of the RIA results to the assumptions built into the model. The sensitivity analyses are contained in Chapter 6, Section 8, of the RIA.
While the Agency did not explicitly estimate the marginal costs and benefits of limiting daily driving to 8 or 9 hours, FMCSA believes that such a change would not be any more cost beneficial than a 10-hour limit. This is due to the fact that, while the increase in the relative risk of a fatigue-related crash generally rises after the 8th hour of driving (according to the TIFA data), the increase is more notable in the 10th hour and later. Therefore, since the Agency's economic evaluation shows that a 10-hour driving limit results in considerably higher costs than benefits, compared to an 11-hour limit (holding all other HOS regulations constant), it logically follows that limiting driving time to 8 or 9 hours would yield the same result. Additionally, limiting daily driving to 8 hours, for instance, could increase the impact of a backward rotating schedule for some drivers (8 hours of driving + 10 hours off duty = 18 hours) relative to the 2003 rule (11 hours of driving + 10 hours off duty = 21 hours). Such a change has the potential to increase fatigue-related crash risks due to the disruption of driver circadian rhythms.
Although FMCSA's mission is improved CMV and highway safety, the Agency is required by statute to consider the costs and benefits of requirements it may impose [49 U.S.C. 31136(c)(2)(A) and 31502(d)]. Such consideration is clearly expected to influence the Agency's rulemaking decisions. The Department of Transportation currently uses $3 million as the “value of a statistical life” (VSL) for rulemaking purposes. A 10-hour driving limit would essentially have a VSL more than 21 times the current DOT standard. This cost per life saved is substantially higher than the maximum $10 million per statistical life cited by the Office of Management and Budget (OMB) in its guidance to Federal agencies on conducting regulatory impact analyses [OMB Circular A-4, p. 30]. Setting the maximum driving time at 10 hours would impose upon the motor carrier industry, an important sector of the American economy, regulatory costs entirely disproportionate to regulatory benefits. Most of the studies and analyses that report an increased crash risk in the 11th hour of driving are based on data collected while the driving limit was 10 hours and the minimum off-duty period 8 hours. The agency expected the new 10-hour off-duty period required by the 2003 rule to reduce driver fatigue and improve safety, despite allowing 11 hours of driving time instead of 10 hours. Comprehensive data to test that assumption are not yet available, but many motor carriers have reported lower crash and injury rates under the 2003 rule, and preliminary FARS data indicates that fatigue-related fatal truck crashes have declined, both in number and as a percentage of all fatal CMV crashes. This suggests that the pre-2003 studies and data connecting the 11th hour of driving with a higher crash risk may no longer be relevant because the 2003 rule has crea
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