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Auto and Road User Journal
Copyright © 1997 by TranSafety, Inc.
February 1, 1997
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TranSafety's free consumer journal for automobile and road users, three subscription journals on road maintenance, engineering, and injury litigation, and highway safety publications catalog. See our free consumer journal for automobile and road users, three subscription journals on road maintenance, engineering, and injury litigation, and a highway safety publications catalog.

Coping With Driver Fatigue

While Deborah M. Freund, author of "Coping with Driver Fatigue, Loss of Alertness, and Vigilance," expressed her opinion that drivers are seldom literally asleep when they have accidents, she also pointed out that statistics specify "operator error" as a cause in 70 to 90 percent of accidents. Moreover, 30 to 40 percent of commercial vehicle accident reports suggest operator fatigue as a component cause. Deborah Freund of the Federal Highway Administration's (FHWA's) Office of Motor Carrier Standards researched "information processing failures" resulting from fatigue and studied countermeasures to driver fatigue. On May 17, 1994 in Hershey, Pennsylvania, she presented her findings at the American Society of Civil Engineers' conference entitled "Innovations in Highway Safety--A Broad Perspective." This article summarizes information from Freund's report.

What Is Fatigue?
Deborah Freund began her discussion by attempting to define fatigue. While she found that a definition for fatigue is elusive, she offered a list of outcomes that characterize fatigue:

  • Decreased alertness,
  • Decreased vigilance/watchfulness,
  • Increased information-processing and decision-making time,
  • Increased reaction time,
  • More variable and less effective control responses,
  • Decreased motivation, and
  • Decreased psychophysiological arousal (measured by changes in body temperature, brain waves, heart action and nervous system activity).

Many factors contribute to fatigue, and drivers are often not aware of how fatigued they have become. According to Freund, stresses that add to fatigue include:

  • Many hours of driving, requiring a high alertness level,
  • Many hours on-duty (non-driving tasks),
  • Driving at low point in circadian cycle (24-hour body rhythm),
  • Irregular work schedules (circadian "jet-lag" effects),
  • Inadequate or poor quality sleep (timing, location, sleep disorders),
  • Boredom or monotony (external environment),
  • Pressure to meet delivery deadlines,
  • Restricted movement or seating discomfort,
  • Heat, noise, vibration, and poor air quality/air contaminants,
  • Mountain, desert, or adverse-weather driving, and
  • Heavy physical work.

Countermeasures to Fatigue
Freund referred to the work of Mackie and Wylie, who classified fatigue countermeasures as either "alarms" or "maintainers." Alarms come into play only after a driver's alertness level has dropped, whereas maintainers are ways to keep the alertness level from dropping.

Alarms: Freund described two ways to set off alarms that let drivers know they are becoming fatigued.

One type of alarm activates as a result of measuring an external indicator of fatigue--driving performance. Vehicle-mounted instruments monitor a driver's tracking skill within a lane, reaction time, steering adjustments, and changes in speed. Certain levels of variation set off the alarm; however, current experimental instruments produce many false alarms.

A second type of alarm depends on measuring physiological indicators of driver fatigue. Drivers wear leads that measure brain-wave data, or instruments mounted in the vehicle monitor eyelid movements and visual-field scanning. Existing designs tend to be expensive and intrusive.

Maintainers: Drivers sometimes benefit from measures that help maintain their alertness and avoid the problems that come with fatigue. Maintainers might be actions motorists initiate themselves, or drivers may follow regulations and restrictions imposed by outside agencies.

Freund suggested this list of self-initiated maintainers:

auditory stimulation--both passive (listening to a radio or cassette tape) and active (conversing on a CB radio)--mental games, control of cab heat and humidity, use of stimulants (caffeine, nicotine, and others), autoregulation (biofeedback), and brief stops for meals, vehicle checks, or naps.

Commercial drivers may avoid fatigue when they comply with external restrictions imposed by the company for which they work or by the government in its attempt to prevent practices that encourage overly fatigued drivers to stay on the road. According to Freund, such alertness maintainers involve: "government regulation of permissible driving and on-duty hours relative to driving, minimization of irregular day/night patterns, rest stops required by regulation or by motor carrier operational practice, and driver and company training."

Creating an additional group of countermeasures, engineers are experimenting with highway infrastructure designs that may serve as alarms or maintainers. These are measures such as flashing warning lights, raised pavement markers, pavement texturing, and rumble strips.

Research on Countermeasures
Freund referred to two studies on countermeasures to driver fatigue.

The "Driver Fatigue Alertness Study" is a cooperative research project of FHWA and several public and private agencies. The study hopes to:

Establish measurable relationships between driver activities and loss of alertness, Evaluate the effectiveness of various countermeasures to driver fatigue, Develop educational programs to inform drivers about fatigue and its countermeasures, and Gather scientifically sound information on fatigue to use in revising the "Hours-of-Service" section of the Federal Motor Carrier Safety Regulations.

To accomplish these ends, researchers are conducting field studies comparing the performance of commercial drivers who have baseline schedules of 10 hours of driving per day to two experimental groups: (1) those who rotate their schedules by starting earlier each day to conform to current regulations specifying 10 hours of driving and 8 hours off-duty and (2) those who drive 13 hours (longer than current regulations allow) and have 11 hours off-duty.

"Drowsy-Driver Studies" focus on vehicle-based countermeasures. With these studies, the National Highway Traffic Safety Administration's Office of Crash Avoidance Research is looking at ways to monitor driver alertness and performance. The goal is to create in-vehicle alarms that warn motorists when indicators of fatigue develop. Results of these studies hope to offer fatigue countermeasures for non-commercial drivers.

All motorists should avoid driving when they are too fatigued to be on the road, and drivers should be aware of and practice methods of keeping themselves alert. Engineers who design vehicles and roadways are helping motorists with these efforts. Driver awareness and continued research on driver fatigue and effective countermeasures could reduce the number of accidents, injuries, and deaths.

Copyright © 1997 by TranSafety, Inc.


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