Drivers increase their crash risk nearly tenfold when they get behind the wheel while observably angry, sad, crying, or emotionally agitated, according to Virginia Tech Transportation Institute researchers writing in Proceedings of the National Academy of Sciences.

The article also reported that drivers more than double their crash risk when they choose to engage in distracting activities that require them to take their eyes off the road, such as using a handheld cell phone, reading or writing, or using touchscreen menus on a vehicle instrument pane. And, according to the institute’s research, drivers engage in some type of distracting activity more than 50 percent of the time they are driving.

“These findings are important because we see a younger population of drivers, particularly teens, who are more prone to engaging in distracting activities while driving,” said Tom Dingus, lead author of the study and director of the Virginia Tech Transportation Institute. “Our analysis shows that, if we take no steps in the near future to limit the number of distracting activities in a vehicle, those who represent the next generation of drivers will only continue to be at greater risk of a crash.”

Virginia Tech Transportation Institute researchers used results from the Second Strategic Highway Research Program Naturalistic Driving Study, the largest light-vehicle naturalistic driving study ever conducted with more than 3,500 participants across six data collection sites in the United States.

The study represents the largest naturalistic crash database available to date, with more than 1,600 verified crash events ranging in severity from low, such as tire and curb strikes, to severe, including police-reportable crashes.

Transportation institute researchers considered 905 higher severity crashes involving injury or property damage in the data set and found that, overall, driver-related factors that include fatigue, error, impairment, and distraction were present in nearly 90 percent of the crashes.

“We have known for years that driver-related factors exist in a high percentage of crashes, but this is the first time we have been able to definitively determine – using high-severity, crash-only events that total more than 900 – the extent to which such factors do contribute to crashes,” Dingus said.

Traveling well above the speed limit creates about 13 times the risk, and driver performance errors such as sudden or improper braking or being unfamiliar with a vehicle or roadway have an impact on individual risk.