Performance Analysis of Signalized Roundabouts for Four-leg Intersections

摘要

Implementing signal control is considered as one of the most effective ways to improve the capacity and safety performance of intersections. However, the operational performance of roundabouts with full signalization has not been studied in depth, and suitable traffic conditions for selecting signalized roundabouts instead of signalized intersections are still unclear. This paper aims to make a comparison among signalized conventional intersection, signalized conventional multilane roundabout and signalized turbo roundabout based on their operational performance, including capacity and delay of vehicles, as well as delay of pedestrians. With the same traffic demand, the same common used signal phasing is applied to three types of layouts respectively. Furthermore, for turbo roundabout, 2-phase signal phasing control and approach based control are investigated. The optimal radius of central island is found to maximize the capacity of signalized turbo roundabout under 2-phase control. The result shows that signalized roundabouts can operate better than signalized intersections when demand of right-turn vehicles is heavy.