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Fatigue and Health Research briefing to Motor Carrier Safety Advisory Committee

This research briefing provides an overview of driver fatigue and health research, including literature reviews, expert recommendations, and ongoing research studies. Topics covered include driving time, driver recovery, sleep and sleeper berth issues, and driver health.

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Fatigue and Health Research briefing to Motor Carrier Safety Advisory Committee

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  1. Fatigue and Health Research briefing toMotor Carrier Safety Advisory Committee December 7, 2009 Dr. Martin R. Walker, Chief, Research Division, FMCSA

  2. Driver Research Research Literature Review Process 1999 FMCSA Completed Literature Review 2005 TRB Conducted Literature Review FMCSA Team Reviewed & Summarized All Research Intermodal Team on Driver Fatigue & Health 2008 Additional Literature Review

  3. Fatigue Research - Driving Time VTTI Naturalistic Driving Results • Expert Panel Recommendation - No distinction should be made between on-duty and driving time. Cumulative hours on duty increase fatigue. Driving should not exceed 12 hours on duty. • Research Literature • Logistic Regression – using Driver Logs • Mackie and Miller (1978), Park et al. (2005) Kaneko and Jovanis, 1992; Lin, Jovanis, and Yang, (1993) Jovanis et al. (2005). • Naturalistic Driving Studies • Wylie et al., (1996), • Hanowski et al. (2005, 2006, 2007) • Forthcoming Research • Crash Risk and Driver Operating Schedules • Is examining fatigue-related crash risk by hours of driving and the effects of work breaks on crash risk. • Study will be completed in draft Aug 2010.

  4. Fatigue Research - Driver Recovery • Expert Panel Recommendation • Recovery time be at least two uninterrupted time periods between midnight and 6 am, at least once in every 7 days (Rosekind, Neri, and Dinges, 1997; Caldwell, Caldwell, and Colon, 1998; Johnson et al., 1998). • Research Literature Suggests • Recovery is required because of long work hours lead to fatigue. This fatigue is exacerbated by irregular shifts and night shifts, which reduce sleep length and quality (Jovanis and Kaneko, 1990; Linklater 1980, and Williamson et al., 1994). • Studies Finding Recovery in <34 hours • Two studies suggest that 24 hours is sufficient, however, in both (Alluisi, 1972) and (Feyer et al., 1997) the work period examined was short. • O’Neil et al., 1999, found drivers should be fit to resume duty after 36 hours. • Balkin et al., 2000 found that whether or not 24 hours was sufficient depended on the sensitivity of the measure used to assess recovery (lane tracking verses PVT measures).

  5. Fatigue Research - Driver Recovery • Studies Finding Recovery in >34 hours • Four studies that examined recovery concluded that 36 hours was not enough (Lille, 1967, Hildebrandt et al., 1975, Mallette, 1994 and Wylie et al., 1997). • Three of these studies involved rotating shift or night shift workers, and not day shift workers; one study included both day and night shift workers. • Wylie et al., (1997) extension of the U.S./Canada study suggests that 36 hours was not enough time for recovery, particularly for night drivers. • Forthcoming Research • Phase I - Preliminary Findings:The 34-hour restart was effective at mitigating sleep loss and consequent performance impairment for day-time drivers, but not effective for night-time drivers. • Phase 2 will begin in December 2009 and will be completed September 2010.

  6. Driver Fatigue - Sleep and Sleeper Berth • Research Literature Suggests • Fragmented sleep has little recuperative value and is similar to total sleep deprivation in its effects on performance. • Four hours of sleep in a noisy atmosphere is the same as not having slept at all in terms of recuperation. • Studies on the sleeper berth issue have generally found that sleeping in a sleeper berth, particularly when the vehicle is moving, is less restorative than sleeping in a bed (IIHS, 1988; Pilcher, 1996; Dingus, et al, 2002). • NTSB study of single-vehicle heavy truck accidents designed to examine the impact of fatigue (NTSB, 1996). • Split-shift sleeper berth use increased the risk of fatality over twofold. • Found the most important predictor of fatigue-related accidents is the duration of last sleep and that continuous sleep is important, they recommended elimination of split sleeper berth exception.

  7. Driver Fatigue - Forthcoming Research • Impact of Split-Sleep on Driver Alertness and Health • Emerging research seems to be finding that splitting sleep into two shorter periods results in equal levels of alertness, and that the time of day in which the sleep periods are taken is critically important.  • Is evaluating the effects of various split-sleep regimens on driver alertness and health. • Study began in July 2007 and will be completed in December 2010. • Driver Recovery and Napping • FMCSA and Transport Canada are working together to evaluate recovery periods and napping strategies for CMV drivers. • Study will 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. • Study began in July 2008 and will be completed in August 2010.

  8. Driver Health Research Driver Health Research • Cancer Risk • EPA has classified Diesel Exhaust (DE) (PM 2.5) as a likely carcinogenic because of the number of studies (>60) published. But, no definitive link has been determined. • Health impacts expected to be reduced based on EPA projections of lower DE. • FMCSA’s position is that additional hours should not adversely affect driver health. • Cardiovascular Disease (CVD) • Research suggests weak association between CVD and truck driving. • TRB panel found evidence that CVD is caused in part by truck driving. • FMCSA’s position is that other risk factors out weigh the additional hours and therefore HOS should not adversely affect driver health.

  9. Driver Health Research • Noise and Hearing Loss • OSHA workplace noise exposure standard for unprotected ears is 90 dBA limited to 8 hours per day. • Truck cab noise levels have decreased over the years. • Exposure to Whole Body Vibration (WBV) • No standard for WBV; medical community uses ISO 2631-1 WBV guidelines. • TRB Panel found that evidence regarding WBV and lower back problems is not very conclusive, mostly relying on self report data. Difficult to separate health effects due to vibration verses back strain due to loading, seat-back angle, etc. • Summary: Exposure to Noise and WBV was close, but not consistently exceeding, the health risk threshold. FMCSA’s position is that additional hours should not adversely affect driver health.

  10. Driver Health Research Driver Health Research • Latest Research • Truck Driver Mortality Study (NOISH, 2008).To characterize the mortality experience of owner-operator truck drivers. • Results: Overall and most cause-specific SMRs for the cohort were lower than expected. The only elevation was transportation crashes. The cohort had a deficit in mortality from ischemic heart disease. • CMV Driver Health and Fatigue Study (VTTI, 2008). This study showed a relationship between BMI and fatigued driving as well as BMI to safety-critical events. • Results: Obese drivers have a higher risk of fatigue than non-obese drivers.

  11. Driver Health Research Driver Health Research • Latest Research • Lung Cancer and Vehicle Exhaust in Trucking Industry Workers (Garshick et al.) Evaluated work records for unionized employees employed in 1985 (54,319 men and 4,007 women) from four large national companies. • Results: • Adjusting for age and a healthy-worker survivor effect, lung cancer hazard ratios were elevated in workers with jobs associated with regular exposure to vehicle exhaust. Smoking behavior did not explain variations in lung cancer risk. The authors stated “the increase in risk did not achieve conventional levels of statistical significance.” • Improving Truck Ergonomics Study (UT, 2009).Collected data on factors that may influence the health and performance of truck drivers. • Preliminary Results: • Noise Level: Noise levels were well below the OSHA standards. • Whole-body Vibration: Vibration were below the EU standards. • (3) Air Quality: In some instances, PM 2.5 exceeded EPA standards.

  12. Driver Health Research Driver Health Research • Health Risks Associated with Long Work Hours • NIOSH completed a review of research on long work hours (>8 hrs work per day and 40 hrs per week). • NIOSH generally concluded that long work hours are associated with poor general health, increased injury rates, more illnesses, or increased mortality in 16 of 22 studies. • Individuals working long hours were found to have greater risk of: • Unhealthy weight gain - Poorer neuropsychological performance • Increased alcohol use - Decline in vigilance on task measures • Increased smoking - Reduced cognitive function • Injuries while working - Increase in health complaints • Deterioration in performance - Slower Work • Decreased alertness and increased fatigue at the 9th to 12th hours of work

  13. Driver Health Research Driver Health Research 6. Sleep - How much sleep is needed? • Research on sleep duration shows that mortality rates increase with sleep durations greater than 8 hours or less than 6 hours. • Health Effects: Sleep deprivation affects the metabolic, hormone, and immune systems. It is associated with increased risk of: • - Drowsiness and Fatigue - Depression - Obesity - Stroke • - Inflammation - High Blood Pressure - CVD - Diabetes • Average Sleep times Under the Old Rule. CMV drivers were getting significantly less sleep than needed to maintain health lifestyle. Documented in 4 major studies where sleep was verified, ranging from 3.8-5.5 hours per night. • This was reason drivers were given additional 2 hours or 10 consecutive hours off duty time, which should improve driver health. • VTTI 2005 Naturalistic Driving study showed drivers were averaging 6.31 hours.

  14. Fatigue and Health Research Summary FMCSA’s Research Division is working on complementary research to provide support for HOS rulemaking: • A better understanding the causes of fatigue, • Provide data-driven foundation for this Federal Rule, and • Reduced driver fatigue via driver/carrier education, • Supporting driver health research to determine impacts of changes in work hours. Contact info: Martin R. Walker Martin.r.walker@dot.gov (202) 385-2364

  15. Fatigue and Health Research Backup Slides and Detail

  16. Driver Health Research Association Dose-Response Societal Cost Impacts • TRB Panel. Dr. Peter Orris led a panel of 5 prominent Medical Doctors to identify CMV driver health research. • Literature Search. Over 1,850 studies were found (1975-2004), after screening for methodology, relevance and quality of statistical analysis, 55 were reviewed; 25 were chosen to include in final TRB report. • Study Types. • Epidemiological Studies. Determine what factors are associated with diseases (risk factors). They can never prove causation. • Dose-Response Studies. A change in the amount, intensity, or duration of exposure is associated with an increase or decrease in risk of a specified health outcome.

  17. Fatigue Research - Driving Time • Expert Panel Recommendation - No distinction should be made between on-duty and driving time. Cumulative hours on duty increase fatigue. Driving should not exceed 12 hours on duty. • Research Literature • Logistic Regression – using Driver Logs • Mackie and Miller (1978) studied relationship between HOS and truck crash risk. They found a strong increase in crash risk as continuous hours of driving increased, evidence of reduced driving performance as the number of consecutive shifts increased, and a circadian effect (i.e., time-of-day) with the highest crash risk occurring between the hours of 2-6 AM. • Jovanis and colleagues found that crash risk increased as hours of driving increased, most notably after the 4th hour of driving (Park et al. (2005) Kaneko and Jovanis, 1992; Lin, Jovanis, and Yang, 1993). • Jovanis et al. (2005) analyzed relative crash risk of the 11th hour of driving, finding that crash risk increases about 20% between 8-10th hours of driving while it increased 113% in the 11th hour.

  18. Fatigue Research - Driving Time • Research Literature (continued) • Naturalistic Driving Studies • Driver Fatigue and Alertness Study casts doubt on whether hours driving has any effect on increased crash risk (Wylie et al., 1996). On-road study with instrumented vehicles day/night-time driving with 80 US and Canadian drivers. • Findings: “…simple time on task is not a uniformly effective determiner of performance. Factors such as time-of-day (and its relation to circadian cycle) and rest break schedule are so influential that other factors customarily associated with performance deterioration over time are dwarfed. That the strongest and most consistent factor influencing driver fatigue and alertness in this study was time-of-day.” • Hanowski et al. (2005, 2006, 2007) using instrumented vehicles collected naturalistic day/night-time driving with 102 drivers (2.3 million miles). • Findings: “…analysis on critical incident relative frequency, used as a surrogate for driver performance decrement, showed no statistical difference between the 2nd through 11th hour of driving” VTTI Naturalistic Driving Results

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