FRIDAY, Jan. 4, 2008 (HealthDay News) -- Researchers have verified what many American drivers already knew: Drivers who talk on a cell phone clog traffic.
These highway conversationalists drive slower on the freeway, pass slower vehicles less often and take longer to complete their trip compared to the cell phone-free, reports a new study.
A fatal accident can cost up to $5 million in medical, property and loss-of-income costs, but these types of events occur much less often than everyday traffic delays, the researchers noted.
Traffic delays linked to cell phone use are estimated to cost about $13 per hour -- based on a measure of the value of a typical American traveler's time. Multiply $13 by the millions of drivers every day who talk, argue, yell and conduct meetings on the phone, and the figures add up, the researchers said.
Highway officials know that all too well.
"Safety on the roads is our number one priority," said Doug Hecox, a spokesman for the Federal Highway Administration, part of the Department of Transportation. "We cannot equivocally say that using a cell phone while driving is a distraction but we are doing everything we can to reduce distractions, which can include loud radios and kids in the back seat. When the driver is in charge of a vehicle, it is a serious operation."
The study was led by Joel Cooper, a doctoral student in psychology at the University of Utah, who will be presenting the findings Jan. 16 at the Transportation Research Board's annual meeting in Washington, D.C.
According to background information in the study, more than 240 million people now use wireless services in the United States, and an estimated 73 percent of them admit to using their phones while driving. One survey found that about 10 percent of drivers were using wireless phones at any daylight moment in 2005.
Previous studies have found that drivers talking on cell phones are up to four times as likely to be involved in an accident, the same risk as driving while drunk.
Fifty countries now have laws prohibiting the use of cell phones while driving, unless those phones are hands-free. Even then, the research isn't clear that hands-free devices help reduce driver distraction.
Earlier studies have found that cell phone users follow other cars at greater distances, are slower to hit the brakes and slower to regain speed after braking.
For this study, 36 University of Utah psychology undergraduate students used a PatrolSim driving simulator, built to mimic a Ford Crown Victoria sedan with automatic transmission. Different traffic scenarios appeared on three screens around the driver.
Each participant drove through six, 9.2-mile-long stretches of highway: two each in low-, medium- and high-density traffic with freeway speeds of 70 mph to 40 mph. One ride at each density level was done while talking on a cell phone and one while not using a cell phone.
"We found that when drivers were conversing on the cell phone, they drove those sections about two miles per hour slower when traffic density was medium or high," Cooper reported. "In all three scenarios, when people were talking on the cell phone, they made about 20 percent fewer lane changes."
Cell phone talkers took 15 seconds to 19 seconds longer to complete the distance assigned, and they also took 17 percent more time to recover half of their speed after braking. Motorists on cell phones also tended to trail other cars rather than overtake and pass them, potentially adding to traffic slowdowns.
All of this came from a simulation involving only one person talking on the phone.
"The next step is to take these, plug them into the microsimulator and try to make some more concrete generalizations about broad traffic flow," Cooper said.
There's more on driving and cell phones at the National Safety Council.