You might think that roads today would be safer than ever before: Cars are smarter, sturdier, and better able to avoid crashes. Unfortunately, drivers are not. Scientists calculated the risks and prevalence of various distracting driver behaviors and found that we just can't put down our phones—and that this bad habit can really cost us.

The U.S. Congress funded the Second Strategic Highway Research Program Naturalistic Driving Study (SHRP 2 NDS) to identify the most common causes of highway crashes and traffic jams. It’s called “naturalistic” because the data was collected from real drivers in real cars on real roads. More than 3500 participants agreed to let the researchers install unobtrusive cameras, sensors, and radar units in their cars. Over the course of the study, participants were involved in more than 1600 incidents, ranging from a near miss or scraping a curb to a full-on collision.

Image Credit: Virginia Tech

For the report published last month in the Proceedings of the National Academy of Sciences, researchers from the Virginia Tech Transportation Institute looked at just the incidents that resulted in injury or property damage. They compiled data from the vehicles involved, analyzing speed as well as the drivers' sobriety, fatigue, and distraction. The results showed that distracted driving is indeed incredibly dangerous—almost as dangerous as driving drunk.

“Next to impairment, distraction is the greatest detriment to driver safety,” co-author Mindy Buchanan-King wrote in an email to mental_floss. “Based on six seconds of pre-crash video examined by trained data analysts, more than 68 percent of the 905 injurious and property-damage crashes analyzed in our study involved some type of observable distraction.”

Using the video footage, the researchers were also able to measure which distractions are the most common, and which are the most dangerous.

There were some surprises. They found that driving while crying, sad, angry, or agitated can increase crash risk by 980 percent. Other behaviors that seemed risky were less of a problem than expected, as the authors note in the paper:

An interesting finding in the SHRP 2 NDS crashes is the absence of factors previously thought to increase driver risk. For example, media sources often talk about putting on makeup as a distracting activity, but no crashes in the SHRP 2 NDS occurred when such an activity was performed, probably due to a very low prevalence. Similarly, previous research, the media, and parents often talk about distraction associated with interacting with children in the back seat as a dangerous activity. However, the results of this study show that interacting with children in the rear seat has a protective effect … This may be because parents generally drive more safely with children in the car.

But texting while driving is just as risky as you might think. “Distractions that take the driver’s eyes away from the roadway the longest, such as visual-manual tasks that include texting or dialing on a handheld cell phone, greatly increase a driver’s crash risk,” Buchanan-King told mental_floss.

The researchers were also surprised to find just how distracted we are. “Drivers are engaging in distracting activities more than 50 percent of the time while they are driving,” they note in the paper, “resulting in a crash risk that is 2.0 times higher than model driving." (By model driving, they mean driving safely while alert, attentive, and sober.)

"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," lead author Tom Dingus said in a press release. "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."