Study On The Capacity Of Motor Vehicles At Urban Road Intersections Under Combined Traffic Flow

Urban intersections are not only important nodes of urban traffic network,but also the concentrated points in urban traffic safety,efficiency and environment.The study on capacity of motor vehicles at urban mixed-release intersections can provide effective value in improving the operational efficiency of intersections and traffic congestion,and can also provide theoretical value in for the calculation model of capacity of motor vehicles at mixed-release intersections.This paper takes the vehicle capacity calculation method of mixed release intersection as the main research objective,and discusses from the aspects of basic theoretical analysis,simulation experiment,model construction,model optimization and verification.Firstly,the basic theory of vehicle capacity and characteristics at intersections is analyzed and expounded.Based on the analysis of traffic flow characteristics,influencing factors of capacity at intersection,calculation methods of capacity at intersection and evaluation of intersection service level,the operational characteristics of intersections are combined for expounding the necessity of studying the capacity at mixed-release intersections with traffic conflicts.The main research contents are proposed.Analyzed from the aspects of the spatial layout of intersection,the statistics and parameters vehicle traffic flow,the control characteristics of intersection,the traffic conflicts of intersection and the influencing factors of capacity.Secondly,the mixed intersection is classified and discussed,and the simulation experiment is carried out with investigation.Divide the six types of common conflict at the intersection are classified.The mixed-release intersections are selected to collect information such as intersections,parameters of signal control and data of traffic flow from Jinan,Zibo and other cities.And the simulation and analysis is carried out with the help of VISSIM traffic simulation platform.Thirdly,the capacity model of intersection is constructed by using the method of analogy analysis and the existing capacity calculation method.Based on the control classification of urban intersections,starting with the calculation methods of non-signalized intersections and signalized intersections,and combined with the conflict characteristics of intersections,it is determined that the intersection controlled by mixed-release is the intermediate state between non-signalized intersections and signalized intersections.If the two intersecting roads are signal controlled and the mixed-release is non-signal controlled to opposite access,the traffic priority characteristics of turning left and going straight in the opposite direction for mixed-release intersections are analogous to the main road priority characteristics of non-signal control.And calculation model of capacity is constructed for mixed-release intersections.Finally,the model is optimized and validated by combining the measured data with the simulation data.The model is optimized according to the data obtained from the simulation model,which including the complexity of the intersection,he proportion of turning traffic flow,the geometric characteristics of the intersection and the influence of bicycle-pedestrian crossing the street.Finally,the intersection of Xinluo Street and Yingxiu Road in Jinan was selected as the case.Detailed data were brought into the model to calculate,and the results were compared with the capacity calculated by the measured saturation flow rate.