Research: Cell-phones plus driving equals traffic

You might just think you’re an excellent driver, even while chatting on your cell phone. In truth, however, even if you’ve got both hands on the wheel thanks to a handy hands-free phone, you’re likely contributing to aggravating, dangerous, fuel-wasting traffic.

According to a bit of research from the University of Utah, cell-phone users drive more slowly than their non-cell using counterparts, Some of you might react to this news that way I did: Rolling your eyes and saying or thinking, “No kidding.” (You might have employed a naughtier word than kidding, but that’s beside the point.)

Thirty-six students participated in the testing aspect of the study. Each student drove through six, 9.2-mile-long freeway scenarios, two each in low-, medium- and high-density traffic, corresponding to freeway speeds of 70 mph to 40 mph. Traffic speed and flow mimicked Interstate 15 in Salt Lake City, according to the researchers.

Each student spoke on a hands-free cell phone during one drive at each level of traffic density. The maintained conversations throughout those trips. They also did the same three drives sans phones.

The research ultimately found that “when drivers conversed on a cell phone, they made fewer lane changes, had a lower overall mean speed and a significant increase in travel time in the medium and high density driving conditions,” the researchers wrote.

Specifically, in medium- and high-density traffic, drivers talking on cell phones were 21 percent and 19 percent, respectively, less likely to change lanes (roughly six lane changes per 9.2-mile drive versus seven or eight lane changes by drivers not on cell phones).

Further, “in low-, medium-, and high-traffic density, cell phone users spent 31 percent, 16 percent and 12 percent, respectively, more time following within 200 feet of a slow lead vehicle than undistracted drivers. That meant they spent 25 to 50 more seconds following another vehicle during the 9.2-mile drive.”

The researchers acknowledge that, at first blush, these findings might seem pretty minor. But it scales when numerous drivers are yakking on phones as they putter about in their vechicles. “If you get two or three people gumming up the system, it starts to cascade and slows everybody’s commute,” says University of Utah psychology Professor Dave Strayer, leader of the research team, in a written statement.

The researchers have started to plug the data into computer simulations of multiple vehicles. She studied repeated simulations with the proportion of drivers on cell phones ranging from none to 25 percent.

“We saw an increase in delays for all cars in a system, and the delays increased as the percentage of drivers on cell phones increased,” says Ivana Vladisavljevic, a doctoral student in civil and environmental engineering who also participated in the research.

Strayer stresses the importance of studying how cell phone uses affects traffic. “When people have tried to do cost-benefit analyses to decide whether we should regulate cell phones, they often don’t factor in the cost to society associated with increased commute times, excess fuel used by stop-and-go traffic and increased air pollution, as well as hazards associated with drivers distracted by cell phone conversations.”

Notably, Stayer has performed additional research on how cell-phone use affects driving. His findings include:

— hands-free cell phones are no less dangerous while driving than hand-held cell phones because the conversation itself is the major distraction.

— When young adults talk on cell phones while driving, their reaction times become as slow as reaction times for senior citizens.

— Drivers talking on cell phones are as impaired as drivers with the 0.08 percent blood-alcohol level that defines drunken driving in most states.

For more information about the Univeristy of Utah’s study, go here.

Ted Samson is a senior analyst at InfoWorld and author of the Sustainable IT blog. Subscribe to his free weekly Green Tech newsletter.