A Coordinated Green-wave Control Method on Arterial Roads Considering Critical Path Sequence

Traditional coordinated control method on arterial roads usually takes the maximum efficiency of the coordinated flows as the optimization objective. However, uncoordinated flows may be comparable to or even higher than the coordinated flows during certain periods, which can significantly deteriorate the overall efficiency of road operation in the actual fluctuated traffic flow environment on arterial roads. To solve this problem, a coordinated green-wave control method for arterial roads considering critical path sequence is proposed. The identification of the critical path sequence on the arterial road is calculated by the systematic clustering algorithm, and two indexes of traffic sharing rate of its path and travel time index are used as clustering parameters. On this basis, a coordinated green-wave control model for arterial roads considering critical path sequence is established. Firstly, the coordinated relationship among the signal phases of each critical path is considered, the signal phase matrix based on 0-1 variables is developed, and the constraints underlying the model are proposed. Secondly, the indicators for invalid bandwidth existence and the minimum importance are set, respectively, and a bandwidth allocation strategy for green wave considering the path importance is developed to ensure that the bandwidth of green wave is allocated to the critical path with a high importance in priority. Finally, the objective function of the model is established with the maximum weighted sum of green-wave-bandwidth of critical path sequences as the optimization objective. The simulation environment is developed using VISSIM simulation software where an arterial road section consisting of four intersections on Zhongshan Road in Wuhan City is used as a case study. The experimental results show that compared with the traditional coordination control methods for arterial green wave and arterial multi-path green wave, the proposed method results in a 12.1% and 4.8% reduction in the average arterial delay, 13.6% and 7.6% reduction in the average queue length, and 16.5% and 9.7% reduction in the average number of stops, respectively. Besides, the proposed method makes the average travel time of each critical path be strictly inverse proportional to its own importance, which avoids the waste of bandwidth of green wave.