An investigation of driver distraction near the tipping point of traffic flow stability.

This study explores the influence of a secondary task (using a cell phone) on unconstrained driving behavior in three levels of freely flowing traffic. In the study, participants drove in three simulated environments withdiffering traffic congestion while both using and not using a cell phone.Instructed only to obey the speed limit, participants were allowed to vary driving behaviors, such as those involving forward following distance, speed, and lane-changing frequency. Results showed that both driver distraction and traffic congestion significantly affected lane change frequency, mean speed, and the likelihood of remaining behind a slower-moving lead vehicle. These findings indicate that the behavioral profile of cell phone drivers may have unexpected consequences for traffic efficiency.