Kamis, 03 Januari 2008

Chatting While Driving Slows Traffic (NewsFactor)

According to a University of Utah study, motorists who talk on cell phones drive more slowly on the freeway, pass sluggish vehicles less frequently, and take longer to complete their trips. The study suggests drivers on cell phones congest traffic.

"At the end of the day, the average persons commute is longer because of that person who is on the cell phone right in front of them," says University of Utah psychology Professor Dave Strayer, leader of the research team.

Strayer and Joel Cooper, a doctoral student in psychology, conducted the study with Ivana Vladisavljevic, a doctoral student in civil and environmental engineering, and Peter Martin, an associate professor of civil and environmental engineering and director of the University of Utah Traffic Lab.

"If you talk on the phone while youre driving, its going to take you longer to get from point A to point B, and its going to slow down everybody else on the road," said Joel Cooper, a doctoral student in psychology. Martin said that, combined with Strayers previous research, the new study shows cell phones not only make driving dangerous, but also cause delays.


The study, which relied on a driving simulator to conduct the tests, involved 36 psychology students. Each student drove through six, 9.2-mile trip scenarios, two each in low, medium, and high-density traffic corresponding to freeway speeds of 40 mph to 70 mph. Each 9.2-mile drive included 3.9 miles with two lanes in each direction and 5.3 miles with three lanes each way. Traffic speed and flow were designed to mimic Interstate 15 in Salt Lake City.

Each student spoke on a hands-free cell phone during one drive at each level of traffic density, and did not use a cell phone during the other three drives. A volunteer on the other end of the phone was told to maintain a constant exchange of conversation. The drivers were told to obey the speed limit and use turn signals. That let participants decide their own speeds, following distances, and lane changes.

"We designed the study so that traffic would periodically slow in one lane and the other lane would periodically free up," Cooper said. "It created a situation where progress down the road was clearly impeded by slower-moving vehicles, and a driver would benefit by moving to the faster lane, whether it was right or left."


The Cellular Telecommunications and Internet Association claims there are 240 million U.S. subscribers in a nation of 303 million people. An insurance company survey estimated 73 percent of wireless users talk while driving. Another survey found that during any given daytime moment, 10 percent of U.S. drivers are using a cell phone.

"While the costs associated with accidents seem high, there are so very few of them, comparatively, they actually are dwarfed by the user costs associated with delay," Martin said. "If we compile the millions of drivers distracted by cell phones and their small delays, and convert them to dollars, the costs are likely to be dramatic. Cell phones cost us dearly."

Anne McCartt, senior vice president of the Insurance Institute for Highway Safety, said the study is in line with what her organization has discovered: Using a cell phone, even with a hands-free headset, is not safe while driving. The universitys findings that drivers talking on cell phones drive more slowly and are not as aware of driving behavior makes sense, she added, because the drivers focus is split between the talking and the road.

"This is a simulator study so you dont know for sure if the results would hold up for real drivers in their own cars on the road," McCartt noted. "In any case, we all agree that talking on a cell phone while driving increases the risk of having a crash."

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