The start of the summer season means more than hot weather and BBQs — it's also the time of the year when car crashes involving teens typically increase.
And more than half of these crashes involve some form of distracted driving, according to a new study from the AAA Foundation for Traffic Safety.
In the study, the researchers looked at data gathered from teen drivers who were taking part in a safe driving program, and who had agreed to use a special camera attached to their windshield while driving. Whenever a crash, hard braking or acceleration occurred, the cameras recorded 12 seconds of audio, video and accelerometer data spanning the 8 seconds before the incident and 4 seconds afterward. [Understanding the 10 Most Destructive Human Behaviors]
Using this data, the researchers reviewed a total of 2,229 crashes that occurred between 2007 and 2015, specifically looking at the driver's behavior in the 6 seconds before the incident.
In about 59 percent of crashes, the driver was distracted immediately before the crash, the investigators found. This is more than four times than the government’s official statistics on crashes involving distracted driving, the researchers said. Those previous estimates were based on police reports, the researchers noted.
The most common cause of distraction was another passenger in the car: In 15 percent of the crashes, the driver was talking to or interacting with someone else in the car, according to the study.
Another 12 percent of the crashes involved cellphones, according to the study. While this percentage stayed relatively stable over the course of the study period, the researchers noted one important change over time: The percentage of crashes involving talking on the phone decreased, while the percentage of crashes involving looking at the phone increased.
"Many teens are texting or using social media behind the wheel, more often than in past, which is making an unsafe situation even worse," Jennifer Ryan, the AAA director of state relations, said in a statement.
Previous research has suggested that the percentage of drivers between ages 16 and 24 who use their cellphones while driving has increased from 1 percent in 2007 to nearly 5 percent in 2014, the researchers wrote. [10 Facts Every Parent Should Know About Their Teen's Brain]
The researchers found that cellphone use was more common in incidents in which the driver went off the road. In 28 percent of road-departure accidents, the driver was at looking at or using a cellphone. In addition, cellphones were being used during 19 percent of rear-end crashes, in which the driver hit the back of the car in front of him or her.
The third most common type of distracted driving was failing to focus on the road. Nearly 11 percent of the crashes involved the driver looking at or attending to something in the car, the study found. In the 6 seconds leading up to a crash, drivers spent an average of just 1.5 seconds with their eyes off the road ahead of them, according to the study.
The researchers also found that the percentage of rear-end crashes increased from 2007 to 2015. When the researchers looked at these types of accidents specifically, results showed that the average amount of time spent not looking at the road increased from 2 seconds in 2008 to 3 seconds in 2014.
Originally published on Live Science.