Drivers increase their crash risk nearly tenfold when they get behind the wheel while visibly angry, sad, crying or emotionally agitated, according to new research from the Virginia Tech Transportation Institute.
Researchers also discovered that drivers more than double their crash risk when they engage in distracting activities that require them to take their eyes off the road, such as using a handheld cell phone, reading or writing, and using touchscreen menus on a vehicle instrument panel.
Drivers dialing a handheld cell phone increase their chance of crashing by 12 times, researchers found. Reading or writing, including on a tablet, increases crash risk by 10 times. Reaching for an object (other than a cell phone) bumps up the crash risk by nine times.
According to the institute’s research, drivers engage in some type of distracting activity about 52% of the time while operating a vehicle.
The research project’s findings were published in the Proceedings of the National Academy of Sciences. "Calculating a population-attributable risk for distraction overall shows that potentially 36% or 4 million of the nearly 11 million crashes occurring in the United States annually could be avoided if no distraction was present," the article stated.
“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. There were more than 3,500 participants across six data collection sites in the U.S.
The study represents the largest naturalistic crash database available to date, with more than 1,600 verified crash events. They range in severity from low (such as tire and curb strikes) to severe (including police-reportable crashes).
Previous naturalistic driving data analyses have required combining crash data with “surrogate” crashes — or near-crashes and minor collisions — to determine driver risk. But the magnitude of the Second Strategic Highway Research Program Naturalistic Driving Study facilitates the first crash-only analysis, resulting in the most conclusive findings of the biggest risks that drivers face today, the researchers said.
For the current research, transportation institute researchers considered 905 higher severity crashes involving injury or property damage. Researchers found that, overall, driver-related factors that include fatigue, error, impairment and distraction were present in nearly 90% 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, according to researchers.
Researchers also 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. That means they were minimally present or were not present at all in the crashes analyzed.
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.
“All of these findings are especially important as we work with policymakers, educators, drivers themselves, law enforcement officials, and vehicle designers to define and help mitigate driver risks,” Dingus said. “Our ultimate goal is to identify those risks and to help others create the necessary countermeasures to ensure the safety of ground transportation users.”
(To view an ABC News video report about the research, click on the photo or link below the headline.)
All factors analyzed in the published article were compared to episodes of model driving, or episodes in which the drivers were verified to be alert, attentive and sober.
The naturalistic driving study method pioneered at the Virginia Tech Transportation Institute involves equipping volunteer participants’ vehicles with unobtrusive instrumentation -- including a suite of cameras, sensors and radar. These instruments continuously collect real-world driver performance and behavior data.
Drivers in the Second Strategic Highway Research Program Naturalistic Driving Study participated between one and two years each, resulting in more than 35 million miles of continuous naturalistic driving data.