The Effects of Cellular Phone Usage on Driver Decisions at Signalized Intersections

The term “dilemma zone” is generally used to describe the dilemma where approaching drivers must determine whether to stop or proceed through an intersection when a traffic signal changes from green to yellow (Gates et al., 2010). The zone is defined in either time or space, and deterministic design values are used initially; however, both the length and the location of a dilemma zone may vary with the speed of the approaching vehicle, driver reaction time, and vehicle acceleration and deceleration rates (Liu et al., 2006). Both types of driver error in the dilemma zone pose significant safety risks. In the first case, a rearend crashes may result if a driver decides to stop when he or she should have proceeded. The other error where a driver decides to proceed when he or she should have stopped will result in a red light violation and possible right-angle crash. These safety concerns make the study of dilemma zones critical.