Authors: David W. Eby
The automobile provides unprecedented personal mobility. The costs of this convenience, however, are traffic crashes and the deaths and injuries caused by these crashes. In the United States, for example, there were 6,394,000 police-reported traffic crashes, resulting in non-fatal injury to 3,189,000 people and fatal injury to 41,821 people, in the year 2000. In fact, motor vehicle crashes are the leading cause of death for people aged 4 to 33 years. For decades, traffic safety professionals have worked to reduce the frequency of motor vehicle crashes and the severity of resulting injury without compromising personal mobility. While this problem has been approached from several perspectives, such as designing safer roads and developing occupant crash protection devices for cars, perhaps the most important viewpoint comes from behavioral scientists. Regardless of the safety features present in cars or on the roads on which they travel, cars are operated by people whose behaviors are influenced by a multitude of psychological factors. Therefore, an important component of the traffic safety problem is understanding, predicting, and modifying the behaviors of drivers. Because of its clear influence on crashes, much research has focused on risky driving behavior. Estimates suggest that risky driving behavior causes or contributes to at least 40% of crashes. Risky driving behaviors are those actions that increase, above some threshold, the objective likelihood of a crash or the severity of injury should a crash occur. As such, a driver may not consider his or her action to be a risky one even though it increases his or her chances of being in a crash or becoming severely injured in a crash. This definition of risky driving behavior assumes a threshold from which to assess the increase in risk or crash severity. This objective threshold is set by societal standards. In the case of speeding, for example, the threshold may be the speed limit, the speed of traffic flow, or the speed that is safe for the current road or weather conditions. Thus, drunk driving, speeding, running red lights, talking on a mobile phone, and lack of safety belt use are all examples of risky driving behaviors.