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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - September/October 2003

Fighting Fatigue

by John J. Sullivan IV

To improve the safety of the transportation system, multimodal partnerships within USDOT are addressing problems caused by sleep deprivation.

One person's lack of sleep can contribute to another's lack of safety on the Nation's roads. According to the National Highway Traffic Safety Administration's (NHTSA) Senior Research Psychologist Jesse Blatt, fatigue and sleep deprivation contribute to about 100,000 police-reported highway crashes, causing more than 1,500 deaths annually in the United States. And the National Transportation Safety Board also has linked operator fatigue with a number of costly public incidents, including the Exxon Valdez grounding and the collision of subway trains on the Williamsburg Bridge in New York City.

Long, straight roads like this one in a rural area are among the more common locations for drowsy driving crashes.

Sleep deprivation and operator fatigue are critical safety issues that cut across all modes in the transportation industry. Fatigue affects physical and mental alertness, decreasing an individual's ability to operate a vehicle safely and increasing the risk of human error that could lead to fatalities and injuries. As with drugs and alcohol, sleepiness slows reaction time, decreases awareness, and impairs judgment. Long hours at the wheel make truck drivers particularly prone to drowsy-driving crashes, but fatigue and sleep deprivation also affect other transportation operators such as railroad engineers, airline pilots, and ship captains.

"The incidence of fatigue is underestimated in virtually every transportation mode because it is so hard to quantify and measure," says Dr. Steve Popkin, leader of the Fatigue Monitoring and Countermeasures Research Team at Volpe National Transportation Systems Center in Cambridge, MA.

"Data on fatigue-related crashes is hard to come by," he adds, "because it is difficult to determine the degree to which fatigue plays a role in crashes. For example, if a motorist is unharmed in a crash, the increased arousal following the incident usually masks the impairment that could assist investigating officers in attributing the crash to sleepiness."

The modal administrations within the U.S. Department of Transportation (USDOT) are collaborating through partnerships, research and development, education and awareness campaigns, and policy changes to address fatigue-related crashes. In addition, the Federal Motor Carrier Safety Administration (FMCSA) and the Federal Railroad Administration (FRA) are partnering with an Australian researcher to explore how strategies from "down under" might prove valuable in the United States.

Fatigue and Highways

Sleepiness impairs driving performance, affecting reaction time, vigilance, attention, and information processing. In a poll conducted by the National Sleep Foundation in 1999, 62 percent of adult survey respondents reported driving a car or other vehicle while feeling drowsy in the previous year. Twenty-seven percent reported that they had dozed off while driving. Twenty-three percent stated that they knew someone who experienced a fall-asleep crash within the past year.

In 1998, the National Heart, Lung, and Blood Institute, the National Center on Sleep Disorders Research, and NHTSA published a report on drowsy driving. According to the report, Drowsy Driving and Automobile Crashes: Report and Recommendations, the typical sleep-related crash has the following characteristics: The crash occurs during late night, early morning, or mid-afternoon on a high-speed road; a single vehicle leaves the roadway; and the driver is alone in the vehicle and does not attempt to avoid the incident. Most at risk for sleep-related crashes are young people (ages 16 to 29, especially males) who tend to stay up late, sleep too little, and drive at night. Truck drivers, shift workers, frequent travelers, individuals using sedatives, and people with undiagnosed or untreated sleep disorders also are at risk.

Sleep 101: The Biology of Sleep

Darrel Drobnich from the National Sleep Foundation discusses sleep deprivation at the USDOT headquarters in Washington, DC, during National Sleep Awareness Week in April 2003.

"Good sleep promotes health, safety, productivity, and wellbeing," says Darrel Drobnich, senior director of government and transportation affairs at the National Sleep Foundation in Washington, DC.

The human body naturally follows a 24-hour period of wakefulness and sleepiness regulated by an internal circadian clock linked to nature's cycle of light and darkness. The circadian clock regulates cycles in body temperature, hormones, heart rate, and other body functions.

The average adult needs 7 to 9 hours of sleep every night. Losing one night's sleep can lead to extreme short-term sleepiness, while habitually restricting sleep by 1 or 2 hours a night can lead to chronic sleepiness. "Each hour of sleep lost gets added to an individual's sleep debt, which accumulates just like financial debt over time," Drobnich says. "Sleeping is the most effective way to reduce sleepiness." Repaying the sleep debt to restore normal waking function usually requires 2 nights of unrestricted sleep.

Among the factors that interfere with sleep are poor habits like smoking, drinking, or eating before bed; circadian factors; noise and light pollution; untreated sleep problems; and the stresses of living in a modern society.

"Americans are chronically sleep-deprived," says Drobnich, "as the Puritan work ethic meets the 24/7 technological society, with its cell phones, pagers, personal digital assistants, and the Internet. Sixty percent of us get less than 7 hours of sleep per night. Forty percent admit that fatigue interferes with daily activities, such as work, driving, and family interaction. The most important thing for a person to know is to maximize your sleep and minimize your risks."

For more information about sleep deprivation and the value of a good night's sleep, visit

Unlike the situation with alcohol-related crashes, investigators do not have measurable tests (blood or breath) to help them quantify levels of sleepiness. Also, because sleep deprivation increases the likelihood of attention lapses, drowsiness or fatigue may play a role in crashes attributed to other causes as well.

"When we're tired," says Popkin, "our ability to think and react swiftly is diminished. To compensate, we limit the amount of information we use for driving, for example, fixating on the road ahead instead of using the mirrors or glancing at the dashboard or traffic controls. An investigator may report that the driver ran a red light causing a crash, but in reality it happened because the driver wasn't appropriately vigilant due to his state of sleepiness and fatigue. We are working to come up with a way to determine the fatigue component, but we're not nearly there yet."

Installing shoulder and centerline rumble strips is one engineering method that the Federal Highway Administration (FHWA) supports and State departments of transportation use to reduce the likelihood of crashes. The combination of jarring motion and loud noise alerts drivers when they cross over a rumble strip, helping prevent drift-off-road crashes. (See "Rumbling Toward Safety," page 28.) In fact, according to NHTSA's Drowsy Driving report, rumble strips placed on high-speed, controlled-access rural roads can reduce run-off-the-road crashes by 30 to 50 percent.

New Hours-of-Service Ruling

FMCSA estimates that between 196 and 585 fatalities occur each year on the Nation's roads in crashes caused by drowsy or fatigued truck drivers. FMCSA's constituency, including the public, highway safety advocates, the trucking industry, and researchers, have identified driver fatigue as a priority safety issue for the commercial motor vehicle industry.

In 1995, Congress directed the FHWA Office of Motor Carriers to begin a rulemaking to increase driver alertness and reduce fatigue-related incidents. In response, scientific research was analyzed, expert panels were convened, hearings and roundtable discussions were held, and more than 53,000 individual comments were reviewed during the rulemaking process.

Finally, in April 2003, FMCSA issued the first significant revision to the hours-of-service regulations in more than 60 years. The new regulations—which allow truckers to drive up to 11 hours after 10 consecutive hours off duty—provide an increased opportunity for drivers to obtain rest and restorative sleep, and at the same time reflect operational realities of motor carrier transportation.

FMCSA estimates that the rule could save between 24 and 75 lives each year. .

According to FHSCA, large trucks like these drove 7 percent of all vehicle miles traveled in the United States in 2000.

Technologies to Monitor And Manage Fatigue

After Congress established FMCSA as a separate administration within USDOT on January 1, 2000, under the Motor Carrier Safety Improvement Act of 1999, the fatigue-related research conducted at FHWA migrated to the new agency. "Although FHWA doesn't interact with motorists and carriers, directly, like our sister DOT agencies," says Rudy Umbs, FHWA chief technical safety engineer, "we do advocate any roadway designs, treatments, and visibility countermeasures that will help make our Nation's highways safer."

For almost a decade, fatigue-related research—conducted in laboratories, simulators, and more recently in actual operational environments—has helped define causes of driver fatigue and countermeasures. FMCSA is performing pilot tests to demonstrate the use of various technologies to manage fatigue within the current hours-of-service rules. In one project, a joint effort between USDOT and Transport Canada, FMCSA researchers are investigating the recovery period required for commercial vehicle drivers with cumulative fatigue. The purposes are to determine the minimum duration of off-duty periods that would enable drivers to recover from cumulative fatigue and to investigate the individual differences in drivers recovering from fatigue. With the literature review recently completed, the study team is in the process of developing the experimental protocol for the project.

A second initiative looks at using artificial neural networks to detect drowsy drivers. Unlike earlier research directed at identifying and measuring physiological correlates of fatigue, The George Washington University Center for Intelligent Systems Research is using driver performance measures (such as steering) to develop an algorithm to determine when a driver becomes fatigued. Ultimately this neural network-based algorithm could help researchers better understand how roadway and psychological factors interact and affect driver behavior. The research could lead to the development of monitoring and warning systems for drowsy drivers.

Motorists like those driving at dusk are among the most at-risk for drowsy driving crashes.

In cooperation with Transport Canada and the American Transportation Research Institute of the American Trucking Associations, FMCSA is conducting a naturalistic study of a suite of technologies for managing fatigue. The study tests the potential benefits of combining monitoring technologies with training on fatigue management. In September 2002, Transport Canada completed data collection on three in-vehicle technologies and one driver-worn device. Data collection on the same technologies began in the United States in May 2003, and study results should be available by early spring 2004.

The first in-vehicle technology is a dashboard-mounted device that monitors the length of time the driver's eyelids are closed 80 percent or more over a given time interval (an FMCSA/NHTSA-validated measure of fatigue). Another is a lane-tracking device that uses a sophisticated camera that reads the white line on the highway—even when the pavement is dirty or wet—and monitors how many times the driver leaves the lane. Mounted in the dashboard, this device emits a beep to alert drivers when they cross the center lane without activating the turning signal. The third in-vehicle device is a steering system that dampens vibrations from the road, ultimately reducing the physical fatigue of fighting road feedback and crosswinds to keep the vehicle on course without the driver having to make steering adjustments. A fourth technology, worn on the driver's wrist, is a sleep monitor (also known as an actigraph or sleep watch) that measures a driver's wrist movement. Software built into the device monitors driver wakefulness and measures the sleep debt incurred over several days (see "Sleep 101: The Biology of Sleep").

According to Bob Carroll, manager of FMCSA's fatigue and alertness program, the purpose of the Canada-U.S. study is to determine the most promising technologies and countermeasures to field-test later in controlled environments or in trucking operations. "This is an exploratory study to assess how drivers use these devices, in combination with fatigue management training," Carroll says. "We want to evaluate drivers' reactions to these different technologies. This will help us decide which technologies we should pursue further."

Fatigue Detection System

NHTSA and FMCSA recently initiated a field operational test of another technology, a fatigue detection system, to determine the safety benefits of using the device to measure the alertness of commercial truck drivers. Developed in collaboration with the National Robotics Engineering Consortium at Carnegie Mellon University, the University of Pennsylvania, Virginia Tech Transportation Institute, and Volpe, the 3-year field test will evaluate the technology on heavy vehicles such as 18-wheelers.

The fatigue detection system sits on the dashboard of a truck and provides a continuous real-time measurement of eye position and eyelid closure. Specifically, the device calculates percent eye closure, which is defined as the proportion of time the eyes are closed over a specified time interval. The device has a visual gauge that represents the driver's drowsiness level and emits an audible warning when the driver reaches a preset drowsiness threshold.

According to Dr. Paul Rau, manager for the Drowsy Driver Technology Program at NHTSA, the purpose of the fatigue detection system is to help drivers realign their estimation of their own alertness. "In previous sleep lab and truck simulator studies, we found that you can't do a whole lot to wake up a driver," Rau says. "But you can provide the driver with objective feedback about his state of alertness. Most drivers, as they become drowsy, underestimate their level of drowsiness and the passage of time. The fatigue detection system refocuses the drivers' estimation of alertness, so they can take appropriate defensive actions to prevent a crash due to drowsiness."

With a three-stage alarm, the device provides real-time, immediate feedback to the driver. The earlier stages are the most forgiving, displaying a bar graph that indicates the longest lapse of time passed with the driver's eyes closed. It also shows how much roadway has gone by during the longest lapse. "That's usually a shocker because the length of a football field could go by in a matter of seconds at highway speeds," Rau adds.

"Fatigue has been one of the top concerns at trucking summits," Rau says, "This technology addresses an important niche in public health. The challenge for regulatory agencies will be to determine how the technology can be used with hours-of-service rules."

The fatigue detection systems, shown here on the vehicle's dashboard, monitors eyelid closure. The device emits a beep alerting a driver who has closed her eyes longer than a threshold amount of time that she should take actions to maintain alertness.

A Continent-Wide Program

In partnership with Transport Canada, FMCSA is developing a comprehensive fatigue management program for motor carriers. Transport Canada already pilot-tested the program in two provinces, and a U.S. pilot project with a carrier in Texas is nearing completion. Tests involve screening drivers for sleep disorders and treating those who test positive, and conducting training sessions targeting shippers, drivers, and their families on proper sleep hygiene and fatigue countermeasures. In the next phase, FMCSA will implement the revised program with a motor carrier for a 21-month evaluation to determine the safety benefits.

If the program proves to be cost-effective in terms of benefits to motor carriers and increased public safety, FMCSA plans to partner with Canada and possibly Mexico to develop a North American Fatigue Management Program. The program will be made available to all commercial motor carriers.

Insights from Australia

Recent developments in Australian policies for managing fatigue piqued the interest of officials at USDOT. Both FRA and FMCSA are working with Drew Dawson, director of the Center for Sleep Research at the University of South Australia in Adelaide, Australia, to write strategic plans for managing fatigue in the rail and motor carrier industries in the United States.

In recent years, fatigue management in Australia shifted from prescribing the number of hours a person can work to regulating the amount of sleep employees get prior to starting work. "In our view," Dawson says, "good fatigue management is about regulating, measuring, and managing the opportunity to obtain sufficient sleep rather than prescribing the hours that an individual works."

Australian Sleep Model

The Australian approach is based on creating a model for shared responsibility. The employer is responsible for providing staff with a shift system that permits sufficient opportunity to rest. When determining the shift system, the employer has to take into account the nonwork activities and responsibilities of employees. The employees are responsible for using their allocated time off to obtain sufficient sleep to work safely. If for some reason an employee does not get enough sleep, then he or she must notify the employer.

Dawson points to the Obtained Sleep Model as a simple and objective method for determining an employee's readiness for work. The model involves counting the number of hours of sleep the employee has had in the last 24 and last 48 hours. Specifically, to begin work (the start rule), the employee must have obtained 5 hours of sleep in the prior 24 hours and 12 hours of sleep in the 48 hours prior to commencing work. And the period from waking up to the end of shift (the finish rule) should not exceed the amount of sleep obtained in the 48 hours prior to beginning the shift. If either rule is broken, fatigue is a potential problem and the company should take steps to reduce the risk.

"If you want to know if your people are tired, you want to know how much they're sleeping, not how many hours they're working," Dawson says. "That way, you're not affecting operational flexibility or people's capacity to earn money. What you're saying is, 'Provided you get enough sleep, we don't care how much you work.' If an employee chooses to cannibalize his social and family life in pursuit of the holy dollar, so be it. But if he chooses to earn money by shorting himself on sleep, thereby putting himself and the community at risk, then we have a problem with that."

Three Core Elements

According to Dawson, regulators should require transportation companies to develop fatigue management plans that include three core elements. First, each plan should outline a policy for how the organization is going to manage fatigue. Second, the company should establish a training and education program to inform employees about the risks and how to manage fatigue on personal and organizational levels. Third, transportation firms should have an auditable system for ensuring that people are getting sufficient sleep.

A test subject drives a locomotive simulator at the USDOT Volpe Center while experimental devices monitor his alertness.

A performance-based approach puts the onus on the company to prove that it is doing the right thing. "From a regulatory perspective, we want proof that employees are actually getting sufficient sleep," Dawson says. "If the operator is not consistent with its plan, then it needs to revise the plan to come into compliance. What typically happens in Australia is that non­compliant operators get put on a very short leash, so they are inspected monthly or on a more regular basis. On the other hand, for companies in compliance with their fatigue management plans, a year might pass between inspections. So there's a tendency to reward companies that do the right thing and punish companies that don't."

Paradigm Shift

Convincing the Australian government and industry representatives of the seriousness of fatigue as a safety problem, and ultimately motivating a paradigm shift in managing fatigue, took about 5 years. Research conducted by Dawson and his colleagues showing that the effects of fatigue are similar to those of alcohol in terms of how it impairs reaction time helped focus community awareness on the relative risks of fatigue.

"That research got a whole lot of publicity in Australia and focused people's attention," Dawson says. "The argument has been that if the effects of fatigue on performance are the same as alcohol, and it's considered unacceptable for people to operate machinery in the workplace under the influence of alcohol, then the same level of impairment from fatigue surely should be unacceptable as well. The logic was inexorable: We won't let you in the workplace with that level of impairment; whether due to alcohol, drugs, or fatigue, it really doesn't matter."

The other factor contributing to the new paradigm is a shift from viewing fatigue within an hours-of-service, labor relations, and regulatory framework to framing it as an occupation health and safety hazard.

"People are finally starting to realize that fatigue is one of the last major causes of crashes and injuries in the transport sector," he says. "We've fixed nearly everything else, and in a sense there's a lot of low-hanging fruit with fatigue. You don't have to do very much to get quite significant improvements."

The Human Factor

In addition to research on fatigue-related technologies and policies, the USDOT modal agencies are cooperating on education and outreach. Under the auspices of the USDOT Human Factors Coordinating Committee, the modal administrations launched a partnership to deliver practical solutions for ensuring driver endurance and reducing the risks of fatigue. Overseen by the Research and Special Programs Administration (RSPA) at USDOT, the Operator Fatigue Management initiative pulls together the expertise of government, industry, and labor to create tools to meet the immediate and future needs of drivers.

"The USDOT fatigue management program," says K. Thirumalai, manager of the Operator Fatigue Management initiative at RSPA, "identifies best practices, pools knowledge from all the administrations, and builds on the work already in progress by various modal administrations within the Department. The program is helping translate scientific results into practical strategies to reduce fatigue-related risks for commercial entities."

Drew Dawson, director of a sleep research center in Australia, says, "Increasingly, governments are recognizing that they can't afford to inspectors running around trying to catch people doing the wrong things. What we need is an approach that works with industry to help them manage fatigue internally."

In August 2000, RSPA cosponsored a conference—Partnering for Transportation Safety, Human-Centered Systems: Operator Fatigue Management—that spurred the development of public-private partnerships. Based on recommendations gleaned from the conference, RSPA issued an agency announcement seeking research on four projects: (1) a software tool to assist managers in evaluating and designing work schedules that promote on-duty alertness; (2) a procedure for validating tools that managers, schedulers, crash investigators, and operators can use to model fatigue and predict employee alertness and performance levels based on work schedules; (3) a handbook of best practices that helps managers and schedulers identify, evaluate, and implement approaches; and (4) a tool that organizes current information on operator fatigue management and provides a blueprint for evaluating and implementing additional interventions.

Under a discussion of countermeasures, NHTSA's Drowsy Driver report concludes that rumble strips and other technology-based approaches can help reduce the risk of fatigue-related incidents, but they do not reduce the number of sleepy drivers. Transportation companies and drivers, alike, need to understand the risks and be able to make the right choices about their performance and readiness levels. Falling asleep on the job isn't an option.

Workers serving all transportation modes, including those employed on ships like this one, need to understand how to manage fatigue.


John J. Sullivan IV is a contract writer for FHWA and assistant editor for PUBLIC ROADS magazine.

For more information about USDOT initiatives on fatigue management, contact K. Thirumalai at 202-366-0375 or e-mail