Prior research has estimated that crash risk is four times higher when talking on a cellphone versus not talking. The objectives of this study were to estimate the extent to which drivers talk on cellphones while driving and to compute the annual number of crashes attributable to cellphone use as implied by the use rate and relative crash risk A national survey of approximately 1,200 US drivers was conducted. Respondents were asked to approximate the amount of time spent driving during a given day, number of cellphone calls made or received, and amount of driving time spent talking on a cellphone. Population attributable risk (PAR) was computed for each combination of driver gender, driver age, day of week, and time of day. These were multiplied by the corresponding crash counts to estimate the number of crashes attributable to talking on a cellphone. On average, drivers were talking on cellphones approximately 7 percent of the time while driving. Rates were higher on weekdays (8 percent), in the afternoon and evening (8 percent), and for drivers younger than 30 (16 percent). Based on these use rates, talking on cellphones while driving accounted for an estimated 22 percent (i.e., 1.3 million) of the crashes in 2008. Although increased rates of cellphone use while driving should be leading to increased crash rates, crash rates have been declining. Reasons for this paradox are unclear. One possibility is that the increase in cellphone use and crash risk due to cellphone use have been overestimated. Another possibility is that cellphone use has supplanted other driving distractions that were similarly hazardous. (Author/publisher)
Abstract