July 13, 2005

First evidence of crash risk when using a hand-held cell phone

Arlington, Virginia – The U.S. Insurance Institute for Highway Safety (IIHS) has reported on its study showing that the risk of a crash is four times higher when the driver is using a hand-held cell phone. The increased risk was estimated by comparing phone use within ten minutes before an actual crash occurred, with use by the same driver during the prior week. The subjects were drivers in Perth, Australia, treated in hospital emergency rooms for injuries suffered in crashes from April 2002 to July 2004.

The study, “Role of cellular phones in motor vehicles crashes resulting in hospital attendance” by S. McEvoy, et al, is published in the British Medical Journal and can be viewed at www.bmj.com.

Weather was not a factor in the crashes, almost 75 per cent of which occurred in clear conditions. More than half of the injured drivers reported that their crashes occurred within ten minutes of the start of the trip; 89 per cent involved other vehicles.

“The main finding of a fourfold increase in injury crash risk was consistent across groups of drivers,” says Anne McCartt, IIHS vice president for research and an author of the study. “Male and female drivers experienced about the same increase in risk from using a phone. So did drivers older and younger than 30 and drivers using hand-held and hands-free phones.”

The IIHS first tried to conduct similar research in the United States, but U.S. telephone companies were unwilling to make customer billing records available, even with permission from the drivers. Phone records could be obtained in Australia. It has been illegal in Western Australia to use hand-held phones while driving since July 2001, but one-third of the drivers said their calls had been placed on hand-held phones.

The results suggest that banning hand-held phone use will not necessarily enhance safety if drivers simply switch to hands-free phones. Injury crash risk did not differ between the two.

“This isn’t intuitive,” McCartt says. “You’d think using a hands-free phone would be less distracting, so it wouldn’t increase crash risk as much as using a hand-held phone. But we found that either phone type increased the risk. This could be because the so-called hands-free phones that are in common use today aren’t really hands-free. We didn’t have sufficient data to compare the different types of hands-free phones, such as those that are fully voice activated.”

The findings of this study are consistent with a 1997 Canadian study that showed phone use was associated with a fourfold increase in the risk of a property damage crash. The new study is the second to use phone records, and the first to estimate whether and how much phone use increases the risk of an injury crash.

Taken together, the two studies confirm that the distractions associated with phone use contribute significantly to crashes. Other studies have been published about cell phone use while driving, but most have been small-scale and have involved simulated or instrumented driving, not the actual experience of drivers on the road. When researchers have tried to assess the effects of phone use on real-world crashes, they usually have relied on police reports for information. But such reports are not always reliable because, without witnesses, police cannot determine whether a crash-involved driver was using a phone.

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