New study: Drivers who use cell phones slow down traffic

Drivers talking on cell phones are probablymaking your commute even longer, concludes a new study.

Motorists yakking away, even with handsfree devices, crawl about2 mph slower on commuter-clogged roads than people not on thephone, and they just don’t keep up with the flow of traffic, saidstudy author David Strayer, a psychology professor at theUniversity of Utah.

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

“The distracted driver tends to drive slower and have delayedreactions,” said Strayer, whose study will be presented later thismonth to the Transportation Research Board of the National Academyof Sciences. “People kind of get stuck behind that person and itmakes everyone pay the price of that distracted driver.”

Strayer’s study, based on three dozen students driving insimulators, found that drivers on cell phones are far more likelyto stick behind a slow car in front of them and change lanes about20 percent less often than drivers not on the phone.

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

Combine those factors and Strayer figures distracted drivers areadding an extra 5 to 10 percent of time to your commute.

It’s simply a matter of brain overload. Your frontal cortex canhandle only so many tasks at one time, so you slow down, Strayersaid.

Generally the study makes sense, but what happens to students ina simulator may not translate to real world conditions, said AnneMcCartt, senior vice president of the Insurance Institute forHighway Safety. Further, she said the study itself points out howdistracted drivers are slower, but is short on calculations on justhow it affects other drivers.

Wireless phone companies encourage people not to talk on thephone in bad traffic, said Joe Farren, a spokesman for the cellularphone industry’s trade association. But he said he couldn’t commenton the study because he had not had a chance to go over it.