The design and optimization of overlapping phase combination for isolated intersection

To reduce the waste of green time as a result of unbalance of non-conflict streams, a method of overlapping phase was introduced. The design and optimization for overlapping phase combination is proposed in the paper. There are two steps of optimization in the process. Firstly to select a best group among the possible phase combination including overlapping phase by calculating the minimal cycle flow ratio of the group, secondly to use the object of minimum total delay based Particle Swarm Optimization approach to obtain optimal green time for each phase. The method is applied at the intersection of Xiuning Road and Hezuohua Road in Hefei, China. It shows that the waste of green time is diminished by overlapping phase. The total delay is reduced in large scale. The result was proved by simulation of Vissim and showed the method is effective in upgrading the traffic signal control program.