Banning cellphones while driving does not decrease accidents, researchers find

July 18, 2014 // By Jean-Pierre Joosting
It is conventional wisdom that mobile phones cause accidents when used while driving. Considering that people drive under a lot of distractions such as screaming children, eating, smoking, changing radio channels, setting GPS routes, and so on, how significant is mobile phone use in the big picture.

A recent study goes against this conventional wisdom A researcher at the University of Colorado Boulder found no evidence that a California ban on using hand-held cellphones while driving decreased the number of traffic accidents in the state in the first six months following the ban.

The findings, published in the journal Transportation Research Part A: Policy and Practice, are surprising given prior research that suggests driving while using a cellphone is risky. For example, past laboratory studies have shown that people who talk on a cellphone while using driving simulators are as impaired as people who are intoxicated.

"If it's really that dangerous, and if even just a fraction of people stop using their phones, we would expect to find some decrease in accidents," said Daniel Kaffine, an associate professor of economics at CU-Boulder and an author of the study. "But we didn't find any statistical evidence of a reduction."

California enacted its ban on hand-held cellphones on July 1, 2008. For the new study, Kaffine and his co-authors—Nicholas Burger of the RAND Corporation and Bob Yu of the Colorado School of Mines—looked at the number of daily accidents in the six months leading up to the law's enactment and compared that to the number of accidents in the six months following the ban.

They chose to look a relatively narrow window of time to reduce the number of other variables that might have an impact on accident rates, including the possible introduction of safer cars into the market, an economic recession that leads to a drop in overall driving, or other changes to state traffic laws.

The researchers also corrected their data to account for precipitation, which can cause more accidents; gas prices, which can affect how many vehicles are on the road; and other unobservable factors that may have influenced accidents.

The study was not designed to determine why accidents did not decrease, but there are several