Virginia Tech research focuses on fatigue as the leading cause of distracted driving crashes

Researchers at Virginia Tech say fatigue plays a larger role in distracted driving than previous research suggested. A study from the Virginia Tech Transportation Institute indicates that fatigue is the leading form of distracted driving that results in crashes and near crashes.

Charlie Klauer is a research scientist with the Virginia Tech Transportation institute Center for Automotive Safety Research. "We've always suspected drowsiness is a contributing factor in a lot of heavy vehicle truck crashes," Klauer told us in an interview Tuesday, "but not so much for light vehicle crashes. Turns out it's a very large contributing factor."

Researchers found fatigue played in role in 20 percent of crashes, instead of the 2 to 3 percent that earlier studies estimated.

The study also revealed that fatigue is not limited to late night driving.   "We associate drowsy driving with nighttime driving, but that is not what we found," she said. "We found many of the crashes and the near crashes we observed with this extreme drowsiness were both on morning and afternoon commutes."

Klauer hopes the research will bring more public awareness of the problem. And she says it could lead to smart car systems that would warn drivers when fatigue begins to affect their performance behind the wheel.

Following is the text of the news release from the Virginia Tech Transportation Institute:

Virginia Tech researchers show fatigue is the leading form of distracted driving resulting in crashes, near crashes

BLACKSBURG, Va., April 15, 2013 – Get more sleep. Have another cup of coffee before you drive to school or work. It could save your life.

A 100-car naturalistic driving study conducted by the Virginia Tech Transportation Institute has shown that fatigue is a cause of 20 percent of crashes, rather than the 2 or 3 percent previously estimated based on surveys, simulator studies, and test tracks.

And 18- to 20-year-olds account for significantly more fatigue-related crashes than any other age group. Adolescents’ sleep patterns shift to later hours; however, the school day still tends to start early, resulting in daytime sleepiness. Older drivers can face similar issues with late nights and early work times, but have more experience coping with moderate fatigue – although, not always.

“One of the most important results from the 100-car naturalistic driving study was the degree to which fatigue is a cause of accidents,” said Charlie <> Klaue (, group leader for teen risk and injury prevention at the transportation institute’s Center for Vulnerable Road User Safety<> (

“A finding that surprised people is the prevalence of fatigue during the day. We found significantly more crashes/near crashes due to fatigue during the day than at night,” she said.

“The study allowed us, for the first time, to observe driver behavior just prior to a crash. In 20 percent of all crashes and 16 percent of all near crashes, the driver was showing fatigue. We saw eye-lid closure, head bobbing, severe loss of facial musculature, micro sleep – which is when your eyes drift shut and then pop up,” said Klauer. “This was not just yawning. The drivers were asleep.”

One-hundred drivers who commuted into or out of the Northern Virginia/Washington, D.C., metropolitan area were initially recruited as primary drivers to have their vehicles instrumented or receive a leased vehicle instrumented for the study. Since other family members and friends would occasionally drive the instrumented vehicles, data were collected on 132 additional drivers.

Researchers selected a larger sample of drivers below the age of 25, compared to the total population of drivers, and a sample that drove more than the average number of miles.
The data acquisition system used for the 100-Car Study was developed by engineers at the Virginia Tech Transportation Institute. Sensors included five video channels, forward and rearward Vorad radar units, accelerometers, lane tracking software, and an in-vehicle network sensor. The cameras were mounted unobtrusively in order to facilitate naturalistic driving behavior.

Researchers viewed more than 110,000 events in order to validate 10,548 events – specifically, 82 crashes, including 13 where the data was incomplete; 761 near crashes; 8,295 incidents, such as braking hard for slowing or stopped traffic; and 1,423 non-conflict events, such as running a stop light with no traffic present.

In addition, 20,000 randomly selected 6-second segments of video were viewed. Incidents of moderate to severe driver fatigue were noted, providing an estimate of the amount of time drivers were fatigued but were not involved in a crash or near-crash.

The total number of subjects who were involved in fatigue-related crashes and near-crashes was 38, with 11 drivers accounting for 58 percent of all the fatigue-related crashes and near-crashes.

“Applying the findings to the population at-large, these results suggest that drivers are at a four times greater risk of a crash or near-crash if they choose to drive while fatigued,” said Tom Dingus, director of the Virginia Tech Transportation Institute. “That suggests that about 12 percent of all crashes and near-crashes in the population are attributable to fatigue.”
Analyses with the 100-car study database will continue, plus data from a new U.S. study, the Strategic Highway Research Program, with 2,000 cars, will provide greater statistical power.
In addition, new naturalistic driving studies focused on 16- to 18-year-old drivers are now under way. A Naturalistic Teenage Driving Study, sponsored by the National Institute of Child Health and Human Development, seeks to determine the effects of experience on driving performance, and the extent of variability in driving performance under specific driving conditions, such as at night. The National Highway Traffic Safety Administration provided additional funds to analyze the data from the teen driving study to help determine which driving performance parameters and situations should be used to provide feedback about unsafe driving performance to newly licensed teens.

The 100-Car Naturalistic Driving data set was collected in 2003 and 2004 and has been mined numerous times since. Databases from the 100-Car study are available for public use on the Virginia Tech Transportation Institute website. Several publications<> ( resulting from analysis of the data are reported by the National Highway Traffic Safety Administration.

The Virginia Tech Transportation Institute<> ( is an international leader in the transportation research dedicated to conducting applied research to solve significant transportation challenges. Employing an elite team of multi-disciplinary researchers, engineers, statisticians, technicians, support staff, and students, the institute conducts applied research to address transportation challenges from various perspectives: vehicle, driver, infrastructure, and environment. As the National Surface Transportation Safety Center for Excellence, the Virginia Tech Transportation Institute develops and tests advanced transportation safety devices, techniques, and innovative applications.