US researchers have found that drivers increase their crash risk when they get behind the wheel when emotional.
When drivers are observably angry, sad, crying, or emotionally agitated, their chance of crashing increases nearly tenfold, according to Virginia Tech Transportation Institute researchers.
Writing in Proceedings of the National Academy of Sciences, the researchers also found that drivers more than doubled their crash risk when they chose to engage in distracting activities that required them to take their eyes off the road, such as using a handheld mobile phone, reading or writing, or using touchscreen menus on a vehicle instrument panel.
And, according to the institute’s research, drivers engage in some type of distracting activity more than 50% of the time they are driving.
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.
Researchers found several factors previously thought to increase driver risk, including applying makeup or following a vehicle too closely, actually had a lower prevalence in the naturalistic driving study, meaning they were minimally present or were not present at all in the crashes analysed.
Factors such as interacting with a child in the rear seat of a vehicle were found to have a protective effect, or had a risk lower than the base risk value.
"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.
"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 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.