Sleepy drivers account for 20% of collisions: study

Findings from a study by the Virginia Tech Transportation Institute suggests that 20% of collisions are the result of driver fatigue, even among those that occurred during the day.

Results from the “100-car naturalistic study” go against other estimates based on surveys, simulator studies and test tracks that suggest fatigue is responsible for only 2% or 3% of crashes, the institute said in a statement on the study.

Drivers between 18 and 20 years old also account for more fatigue-related crashes than any other age group, researchers said.

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

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

Older drivers may have more experience coping with fatigue, which could explain more common collisions among younger drivers, the statement noted.

The study looked at driver behaviour just prior to a crash and in 20% of all crashes, the driver was showing fatigue, Klauer said.

“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,” she added. “This was not just yawning. The drivers were asleep.”

Researchers looked at 100 drivers who commuted into or out of the Northern Virginia/Washington, D.C. metropolitan area. Since other drivers may have used the same vehicles, data was collected from 132 additional drivers, the institute said.

The study also included 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 institute noted.

The data acquisition system used for the study was developed by engineers at the transportation institute and 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,” the institute added. .

“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,” the statement said.

Researchers also looked at 20,000 randomly selected six-second video segments, noting moderate to severe driver fatigue, “providing an estimate of the amount of time drivers were fatigued but were not involved in a crash or near-crash.”

“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,” Tom Dingus, director of the Virginia Tech Transportation Institute noted in the statement. “That suggests that about 12 percent of all crashes and near-crashes in the population are attributable to fatigue.”

The data set for the study was collected in 2003 and 2004 and has been mined several times since, the institute said, and databases from the 100-Car study are available for public use on the Virginia Tech Transportation Institute website.