Static Traffic Assignment On Road Network With Spatial Queuing And Spillback

With the increase in population and income of urban residents,the number of private cars increase,resulting in an imbalance between supply and demand on the road network and frequent traffic congestion.To alleviate traffic congestion,demand forecasting should be done at the stage of macro planning and design,so that the supply capacity of the road network can match the actual traffic demand to reduce the occurrence of congestion.The impact of traffic congestion in the demand forecast model is reflected in the traffic assignment stage,so the research on congestion traffic assignment is crucial to alleviating traffic congestion.Existing research on congestion traffic assignment focuses on describing the impact of capacity constraints and link impedance of bottleneck links,but does not consider the impact of congestion spread effects on other non-bottleneck road sections,resulting in underestimation of the impact range of congestion and poor reasonableness of assignment results,etc.The spatial queues spillback process can describe the impact of congestion spread.Therefore,this paper proposes a static traffic assignment question with spatial queues and spillback,and establishes a solution algorithm to calculate the assignment results considering the impact of congestion spread.At the same time,predict the the impact range of congestion.The research results provide theoretical reference traffic planning and design and macro-traffic organization.The main research contents of the paper are as follows:(1)Research on the problem of traffic assignment.In order to describe the impact of congestion spread on traffic assignment,a question of traffic assignment with spatial queues and spillback was proposed.And macroscopic phenomena such as queuing spillback,congestion interference,congestion bottleneck(physical bottleneck and secondary bottleneck)and congestion penetration were introduced to characterize the queuing spillback effect,and the quantitative calculation method of queuing spillback effect was studied.Next,put forward concepts to depict the influence of congestion spread which included "multi-state link","segmented assignment flow",etc.After that,a calculation method of the segmented link impedance was created.(2)Research on construction of solving algorithms.An incremental assignment solution algorithm that introduced backtracking in congestion space was established to solve the assignment question.The algorithm consisted of the main incremental assignment algorithm,physical bottleneck identification and spatial queuing backtracking sub-algorithms.Two sub-algorithms described the backtracking process of congestion space,which could convert the demand traffic volume of links into assignment traffic volume by considering the queuing spillback effect,and predicted bottleneck links and congested areas in the road network.(3)Comparative analysis and theoretical application research.Using the assignment method established in this paper,the Jiugongge road network was calculated and analyzed to verify the feasibility of the model and the algorithm.The assignment calculation was carried out on the traditional assignment model and the congestion assignment model with point queues,and the results of the three model were compared with the results of the spatial queues and spillback model established in this paper,which characterized the superiority.In the end,applied the model and algorithm to the road network upgrade,and provided a reference for the formulation of the upgrade plan.Hereafter,predicted the network status after the upgrade,and evaluated and analyzed the effect of the upgrade,reflecting the practicability of this research.