A novel fuzzy model for the traffic signal control of modern roundabouts

Traffic signal control is a challenging task for traffic systems. As fuzzy logic is proved to be well suited to control some complex systems with uncertainties and human perception, it has been widely used to control the traffic signal in recent years. This paper proposes a novel fuzzy logic controller for signalizing modern roundabouts. Different from existing fuzzy traffic-signal controllers, the proposed controller consists of two fuzzy layers each of which has its own duty. According to the current traffic condition, one layer of the controller controls the phase sequence while the other layer determines the signal timing. By the cooperation of the two layers, the proposed controller is capable of immediately responding to the current traffic condition so as to reduce the vehicle delay or the queue length of waiting vehicles, as well as smoothing the traffic flows in order to reduce the risk of traffic jams. Simulation results prove the effectiveness of the proposed controller, for it can improve the traffic efficiency of the roundabout when compared with several existing controllers.