Distracting behaviors are common at red lights, less so at roundabouts

March 31, 2015

Drivers engage in distracting behaviors in all types of traffic situations, but the most demanding activities are more likely to be seen at red lights than during more challenging driving, a new IIHS study shows.

Researchers observed nearly 17,000 drivers on four roads in Northern Virginia during 2013-14. On each road, observations were made at different times of day on a straightaway, in a roundabout and at a signalized intersection. The locations on a given road were in close proximity to one another, allowing the researchers to observe a similar group of drivers in varying traffic situations.

Nearly a quarter of all the drivers were observed doing something in addition to driving. The most common secondary behavior, seen among 5 percent of drivers, was holding, but not using, a cellphone. The next-most common behavior, at 4 percent, was talking on a hand-held phone.

When it comes to specific roadway situations, the rates of any secondary behavior were 30 percent among drivers stopped at traffic lights, 24 percent on straightaways, 23 percent of drivers in moving vehicles at intersections and 21 percent in roundabouts. Eating or drinking was the most commonly observed activity among drivers waiting for the light to change, with nearly 6 percent seen doing it. That compares with about 3 percent of drivers on straightaways, in roundabouts or moving through an intersection. The next-most common behavior among stopped drivers was talking or singing with a passenger.

Percentage of drivers engaged in secondary behaviors in different traffic situations

  Straightaway Roundabout Moving at intersection Stopped at intersection
Any secondary behavior 24.1 21.2 23.3 30.0
Holding cellphone 6.0 4.2 6.3 2.2
Talking on hand-held cellphone 4.4 4.2 4.0 3.6
Eating or drinking 3.3 2.6 2.7 5.5
Talking or singing with passenger 2.0 3.4 2.1 4.3
Manipulating cellphone 2.8 1.2 2.7 3.8
Talking or singing without passenger present 1.8 2.5 1.7 3.3
Smoking 1.4 1.6 1.7 2.6
Wearing headphones or earbuds 1.2 1.6 1.2 1.3
Other 1.3 0.7 1.2 3.8
Wearing Bluetooth device 0.5 0.6 0.5 0.8
Manipulating in-vehicle system 0.5 0.2 0.5 0.9
Grooming 0.5 0.1 0.2 1.3
Manipulating or holding device other than cellphone < 0.1 < 0.1 < 0.1 < 0.1
Note: Multiple secondary behaviors could be coded for each driver.

After controlling for driver age and gender, community and time of day, the researchers found that the likelihood of a driver engaging in any secondary behavior was 41-66 percent higher when drivers were stopped at a red light than in any other situation. The likelihood was lowest when drivers were traveling through roundabouts.

Drivers stopped at red lights were more likely to be talking or singing with passengers, eating or drinking, or manipulating a cellphone than drivers in the other situations. They were less likely to be simply holding a cellphone, but this may be because they were doing more complex tasks instead. Drivers navigating roundabouts were less likely to be engaged in any secondary behavior than drivers in other situations. In particular, they were 40-73 percent less likely to be manipulating a cellphone. Talking on a handheld phone didn't vary by situation.

"It makes sense that drivers would be more likely to give their full attention to the road when the driving is more complicated, as in a roundabout," says David Kidd, an IIHS senior research scientist and the study's lead author. "It seems that some drivers are saving the most demanding tasks like eating, dialing a phone or texting for when they're stopped at a light."

Drivers' apparent intuition about which secondary behaviors are more demanding is borne out in other research, at least when it comes to cellphone use. A 2014 report by IIHS and the Virginia Tech Transportation Institute looked at cellphone use and other secondary behaviors by 105 drivers whose daily driving was recorded in a naturalistic driving study for a year. Researchers found that the risk of a crash or near crash tripled when a driver was reaching for, answering or dialing a cellphone. In contrast, talking on a cellphone wasn't associated with an increased rate of crashes or near crashes (see "Searching for answers to the problem of distracted driving," Oct. 24, 2014).

In a similar finding to the current observational study, drivers in the naturalistic study were much more likely to be reaching for, answering or dialing a phone when they were stopped than when they were moving, while the likelihood that a driver was talking on the phone didn't vary much.

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