Drivers using cellphones cause traffic to slow

A University of Utah study finds "the distracted driver tends to drive slower and have delayed reactions," said David Strayer, whose report will be presented this month to the Transportation Research Board of the National Academy of Sciences. (Daniel Hulshizer/Associated Press)

WASHINGTON - Drivers talking on cellphones are probably making your commute even longer, concludes a new study.

Motorists yakking away crawl about 2 miles per hour slower on commuter-clogged roads than people not on the phone, and they just don't keep up with the flow of traffic, said study author David Strayer, a psychology professor at the University of Utah.

If you commute by car an hour a day, it could all add around 20 hours a year to your commute, Strayer said.

"The distracted driver tends to drive slower and have delayed reactions," said Strayer, whose study will be presented this month to the Transportation Research Board of the National Academy of Sciences. "People kind of get stuck behind that person and it makes everyone pay the price."

Strayer's study, based on three dozen students driving in simulators, found that drivers talking on cellphones are far more likely to stick behind a slow car and change lanes about 20 percent less often than drivers not on the phone.

Overall, drivers on cellphones took about 3 percent longer to drive the same highly traffic-clogged route (and about 2 percent longer to drive a medium-congested route) than people not on the phone. About one in 10 drivers is on the phone so it really adds up, said Strayer, whose earlier studies have found slower reaction times from drivers on phones and compared those reaction times to people legally drunk.