The relationship between and option space and drivers’ indecision at signalized intersection approaches

A traffic signal is a substantially different traffic sign compared with other traffic devices. The uniqueness of traffic signals is manifested in their displaying an alternate message, not a constant one. The transition period from one message to another creates a decision problem for drivers. An inappropriate decision might create the risk of a rear-end collision. This article presents a disaggregate behavioral model of drivers’ decisions when the green light ends. It is demonstrated, and supported by field data, that a large option zone increases the indecision of drivers, which creates a greater risk of rear-end collisions. The influence on drivers’ decisions of distance from the intersection and of approach speed is examined through the model.