Approximations and Simulation of the Optimal Change Interval for Roundabout

As the increasing numbers of the traffic flow in the roundabout, non-traffic-light control, the traditional way of controlling, has been replaced since traffic congestion easily happens without red-green light. Therefore, the accuracy and quick design of the traffic light time is one of the hot spots in the traffic system. The optimal change interval design for the roundabout has been studied when the period of traffic signal has been given. We construct models to obtain an expression to approximate the optimal change interval in the south-north direction when ignoring the vehicles length and minimum gaps when outer cars enter the circle. Simulation has been made when considering the practical situation, in which vehicles length, gaps, judgments of drivers and other factors have been considered. Results show that the theoretical derivation is reasonable and the setting of traffic lights is imperative.