| Throughout the city can be found that the rapid development of urban transportation network is increasingly complicated,traffic also will increase,but generated by the stimulus of residents quantity is greater than the speed of urban road construction,eventually led to the supply and demand traffic contradictions increasingly prominent,therefore,planning limited road resources,solve the problem of traffic congestion is imminent.Phase difference is an important parameter of coordinated control of trunk lines.Firstly,it is necessary to make clear that phase difference has different effects on coordinated control of trunk lines under different traffic conditions.Secondly,phase difference optimization is a necessary means to adjust traffic pressure of urban road network in coordinated control of trunk lines.Therefore,this paper focuses on the optimization method of phase difference of trunk coordination control under different traffic conditions.The main research work completed is summarized as follows:Firstly,the division basis and index selection of different traffic states are proposed,and the supersaturated and unsaturated states are divided by the inequality relationship between the arrival rate of the initial queuing,stranded queuing vehicles and the saturated flow rate,and the two states are qualitatively analyzed to determine the supersaturated state.The delay and the number of stops are selected as the optimization objectives,and the green wave bandwidth and the number of stops are selected as the optimization objectives in the unsaturated state,which provides a theoretical basis for building the model.Secondly,taking the coordinated intersection as the cut-in,the main line delay model and the stop number model under the supersaturated state are proposed,and the delay model focuses on introducing the time parameters from the time when the red light is on and the first vehicle of the convoy to the stop line and the impact of pedestrians crossing the street.The vehicle start-up time parameter is used to introduce different vehicle arrival rates into the parking times model.Based on the graphical method,a comprehensive model of green wave bandwidth and parking times is constructed combined with the timedistance diagram,and the changes of the bandwidth model in different time periods are emphasized.At the same time,the bidirectional bandwidth proportional coefficient ΞΆ and the parking threshold Y are introduced to improve the efficiency of the coordinated control of the trunk line.Finally,taking the minimum dual comprehensive index value,the minimum number of parking times and the maximum green wave bandwidth as the optimization goals,a phase difference optimization method in the two-way traffic control scenario is proposed,and the improvement of the internal and external loops,the step distance and the starting point of the climbing are alternately changed.The hill-climbing method is used to solve the problem,which greatly reduces the probability of falling into a local optimum.Finally,taking Wenhua East Road,Lixia District,Jinan City as a research case,the model is analyzed,and the results before and after optimization are compared and evaluated,which effectively verifies the scientific rationality of the optimization model. |
