Fatigue and Health Research Motor Carrier Safety Advisory Committee December 7, 2009

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Transcript Fatigue and Health Research Motor Carrier Safety Advisory Committee December 7, 2009

Federal Motor Carrier Safety Administration
Fatigue and Health Research
briefing to
Motor Carrier Safety Advisory Committee
December 7, 2009
Dr. Martin R. Walker,
Chief, Research Division, FMCSA
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
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), 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.
VTTI Naturalistic Driving Results
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.,
► 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).
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
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.
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.
Driver Health Research
Health Research
1. Cancer Risk
• 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.
2. Cardiovascular Disease (CVD)
• Research suggests weak association
between CVD and truck driving.
Carbon Monoxide
Nitrogen Oxide
Volatile Organic Compound
Particulate Matter (PM-2.5)
Particulate Matter (PM-10)
Sulfur Dioxide
• 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.
Heavy Duty Diesel Vehicles Emissions
1990 1995 2000 2005 2010 2015 2020 2025 2030
• 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.
Driver Health Research
3. 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.
4. Exposure to Whole Body Vibration (WBV)
• No standard for WBV; medical community uses ISO 2631-1 WBV
• 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.
Driver Health Research
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
Driver Health Research
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.
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:
(1) Noise Level: Noise levels were well below the OSHA standards.
(2) Whole-body Vibration: Vibration were below the EU standards.
(3) Air Quality: In some instances, PM 2.5 exceeded EPA standards.
Driver Health Research
Health Research
5. 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
Driver Health Research
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:
- Inflammation
- Depression
- High Blood Pressure
- Obesity
• 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.
- Stroke
- Diabetes
Effects of Duty Hours on Sleep
Hours of Sleep
- Drowsiness and Fatigue
Hours On-duty
Fatigue and Health Research
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
(202) 385-2364
[email protected]
Fatigue and Health Research
Backup Slides and Detail
Driver Health Research
 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.
Societal Cost Impacts
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.
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