Utility analysis of zipper-merging for improvement of traffic jam by CA simulation

When slow vehicles go at the merging point of roads from a branch road to a main road, a traffic jam occurs there. Some researchers pointed out that the zipper merging of the vehicles is effective for reducing the traffic jam near the merging point of roads. The aim of this study is to discuss the effectiveness of the zipper merging by using cellular automata simulation. The vehicle behavior is modeled according to the single and multiple vehicles following models. While, in the single vehicle following model, the acceleration rate depends ou the velocity difference with the nearest vehicle ahead alone, the multiple vehicles following model controls the acceleration rate according to the velocity differences with three vehicles ahead. The results show that, in the case of the single vehicle following model, the maximum speed reduction is about 40% in case of no-zipper merging and 20% in case of zipper merging. In addition to that, the multiple vehicle following model can recover the velocity sooner than the single vehicle following model. Therefore, we can conclude that the combinational use of the zipper merging and the multiple vehicles following model can reduce successfully the traffic jam near the merging point of roads.