Signal Timing Optimization Of Intersection With Left-turn Waiting Area Based On Genetic Algorithm

For the urban traffic network,the intersection node is the main bottleneck of the road traffic flow,and the key to alleviate its congestion is to take effective traffic organization methods.One of the important means to improve the efficiency of the nodes is organizing the left-turn traffic rationally.In recent years,the setting of left-turn waiting area has been widely used in urban intersections,then various studies on the waiting area,including researches on setting methods and conditions,characteristics of traffic flow parameters,and timing adjustments,are being made followly.Firstly,this paper studies the setting conditions of left-turn waiting area,including geometric channelization,traffic and safety distance conditions.The requirements for the geometrical dimensions of intersections and the threshold conditions for different types of left-turn lanes to set left-turn waiting area are given,and an improved design method of marking for left-turn waiting area is proposed in conjunction with the specifications.Secondly,by studying the changes of characteristics of the left-turn traffic flow after setting left-turn waiting area,the start-up lost time,capacity and delay calculation models of left-turn lane were proposed.Based on this,a nonlinear timing optimization model with minimizing the average delay of the intersection as the optimization goal is established.With MATLAB as the simulation environment,an implementation method based on genetic algorithm optimization is put forward.Finally,taking the example of an intersection in Changsha as an example.The characteristics of the headway of the left-turn traffic flow were further analyzed through the instance data,and based on which the lost time analysis model proposed previously was fitted,the relevant parameters showed that it matches well.Then getting better signal timing parameters through genetic algorithm tools by applying aforementioned optimization model based on the example data,which proved that the algorithm is effective.In addition,this paper proposed a method to realize the simulation model of the left-turning waiting area,and further validates the optimization effect of the timing program through the simulation model.Through the comparative analysis,it shows that the relevant calculation models are reasonable.The study of the left-turning area can provide guidence for the application of theleft-turning area in practice,and afford reference for developing the research and application of the comprehensive waiting area.