A method of traffic signal control for modern roundabout

Modern roundabouts have been used among many countries. But when the circulatory roadway of a roundabout has more than two lanes, the disorder of the traffic cause big problems. The weaving section where the vehicles enter or leave the roundabout appears to be the critical bottleneck. In this paper, a new method of traffic signal control for modern roundabout is put forward to solve the problem. Traffic signals are installed to control the traffic flow of entries and the left-turn traffic flow on circulatory roadway. Left-turn vehicles on circulatory roadway will stop before red signal to avoid weaving. The methodology including geometric design and traffic signal control of this new method is presented followed by the evaluation of the operational analysis with indexes of capacity and delay. This method has been successfully applied in Xiamen city to solve the very serious traffic congestion problem. By this method the green time of signal and the running lane of circulatory roadway are utilized optimally.