Talking on the cellphone while driving isn’t just a safety risk. It also slows down traffic.
Motorists talking on the phone drive about two miles per hour more slowly than people who aren’t on the phone, according to a new study
by researchers at the University of Utah. And while hands-free devices often are touted as safer alternatives, the scientists found that people using them also putter along, which suggests that it’s the talking, not the cellphone, that distracts the brain.
While a few miles per hour may not sound like much, as many as one in 10 drivers on the road is talking on the phone, says University of Utah psychology professor David Strayer, who coauthored the research. Slower cellphone drivers may be increasing overall commuting times by 5 percent to 10 percent, he calculates, and talking on the phone may increase each daily commuter’s travel time by 20 hours a year.
“The distracted driver tends to drive slower and have delayed reactions,” Dr. Strayer told the Associated Press. “People kind of get stuck behind that person, and it makes everyone pay the price of that distracted driver.”
The researchers, who will present their findings later this month to the Transportation Research Board of The National Academies, tested three dozen students in simulators. The participants “drove” six 9.2-mile stretches with low, medium and high amounts of traffic. They were only instructed to obey the speed limit and to signal when changing lanes; they were also allowed to talk on a hands-free cellphone.
When the subjects were talking on phones, they made fewer lane changes, traveled at lower speeds and drove 2 percent to 3 percent more slowly in medium and highly congested traffic. Cellphone drivers were also more likely to trail slow-moving vehicles than drivers not on the phone. On a positive note, cellphone users were as likely as non-talkers to maintain a safe driving distance.
While more commuting time is usually just an inconvenience, the data show how distracting even a hands-free cellphone can be. While their slower speeds and safe driving distances might suggest cellphone users are more careful, other studies have shown that delayed reaction time related to cellphone use is a safety hazard. Talking drivers are four times more likely to be involved in crashes that cause serious injury, the British Medical Journal reported