An Optimization Method of Signal Control for a Four-Leg Roundabout Based on the Single Release Method

Abstract

A single release method for four-leg roundabouts is proposed. To completely use the time and space resources of roundabouts from the aspects of adjacent entrances and T-type storage spaces of the circulating lane, two types of optimized single release signal control models for a four-leg roundabout are presented. The coordination of signal phase design on the two types of optimized control models is presented, the phase coordination calculation is described in detail, and the original cycle length model is improved. By comparing the delays of the two optimized signal control models, the applicable conditions for optimized signal control models are discussed. Finally, considering the Tanxi Road/Changhong Road Roundabout in Xiangcheng, Xiangyang, as an example, the effectiveness of the presented optimized control models is evaluated. Simulated results show that the traffic flow at this roundabout is improved when the optimization methods are applied.