Research On Signal Timing Optimization Method For Intersection Groups Based On Critical Path Identification

With the continuous advancement of urbanization in China,the scale of cities is expanding and the number of automobiles is increasing rapidly.A series of problems,such as traffic congestion,traffic pollution and traffic accidents,also come along.The intersection is the bottleneck of the entire urban road traffic network,so it is extremely urgent to improve the operation status of intersections.Due to the strong correlation between intersections in the intersection group,the adjustment of the traffic signals for one single intersection often affects the traffic operation status of several intersections adjacent to it.Therefore,a method of signal timing optimization for intersections is urgently needed from the overall strategic perspective of intersection group.Based on the National Natural Science Foundation of China(51878166)and the current situation of urban transportation development and engineering requirements in China,this paper firstly takes Chongqing as an example.Based on the Chongqing Basic Transportation Network Database built on the “TranStar” software platform,quantitative analysis of the traffic characteristics within intersection group and the short-term traffic flow prediction are carried out accordingly.Secondly,starting from the key intersection with high traffic load,the breadthfirst search algorithm is used to determine the access order of nodes.The range of the intersection group is determined according to the adjacency relationship and the strength of the correlation degree.Then,the similarity between traffic flow sequences is measured by DTW distance,and the depth-first search algorithm is used to determine the selection range of the critical path.The critical path of intersection group is selected from the set so that the coordinated control problem of intersection groups is simplified to the coordinated control problem of different critical paths.Finally,the classical single-point timing design and trunk coordinated control method are improved to make them suitable for the coordinated control of intersection groups.The software implementation of the algorithm is carried out by means of the “TranStar” software platform to promote the engineering application of research results.The method of signal timing optimization for intersection group based on critical path identification can reduce the urban traffic delay,improve the service level of traffic network,alleviate urban traffic congestion,reduce traffic pollution,and save energy consumption.It is of great significance to establish the safe,smooth,low-carbon and economic urban transportation systems.