Study On Optimized Control Methods Of Asymmetrical Traffic Flow At Signalized Intersections

The research on traffic management and control of intersections are getting more and more attention,with the traffic problems of urban road network occuring frequently in recent years.When the signal control scheme at the intersection doesn't coordinate with the traffic flow characteristics,it will cause the imbalanced traffic load of each approach and the low efficiency of the space-time resource utilization at the intersection,thus affecting the overall traffic operation benefit of the intersection.In this paper,an adaptive signal control method is proposed combined with the space design of the intersection,based on the asymmetrical arrival rate of the traffic flow from opposite approach at the signalized intersection.Firstly,the arangement methods of the space-time resource at several typical urban signalized intersections are surveyed,and the adaptability problems of the signal control schemes at intersections are analyzed and diagnosed.Based on the data obtained from the traffic investigation,the vehicle delay is used as the evaluation index to analyze the influence of the change of the asymmetrical extent of the traffic flow on the signal control scheme effect of the intersection with the help of VISSIM simulation,definiting the optimal threshold of the asymmetrical traffic flow under the symmetrical signalized scheme.Then,the operating characteristics of the asymmetric traffic flow at the signalized intersections are analyzed in depth.The paper summarizes the existing traffic organization methods of asymmetric traffic flow,and points out the unresolved problems on this aspect.Then,considering the operating characteristics of the asymmetrical traffic flow at signalized intersections,we use the left-turn waiting area and straight waiting area at each approach in order to take maximum use of the space resource at the intersection.Based on this space design,the paper puts forward dynamic phase design and an adaptive signal control method with real-time optimization.Finally,from the perspective of the utilization of space-time resource and the operating efficiency of the intersection,the paper uses the analytic hierarchy process to construct the evaluation system of the general operation benefit of the intersection,with the utilization of space-time resource,the saturation,the vechicle delay,the average queue length and the parking rate as the evaluation indexes.Taking the Red Flag Street-Huaihe Road intersection in Harbin as an example,the paper compares the current arrangement method of the space-time resource at the intersection with the optimalized design scheme proposed in this paper with the VISSIM simulation.It is found that the general operation benefit is improved after optimization,together with different degree of improvement of other indexes,which verifies the validity of the proposed method.