Urban Network Based On Variable Cell Transmission Model Traffic Flow Simulation

With the continuous acceleration of urbanization and motorization in China,the ownership of private cars in China is growing rapidly,"difficult to travel" has become a hot and difficult issue of general concern.As the main participant of urban traffic system,how to truly describe the internal operation law of urban road network traffic flow has important practical significance for traffic congestion management and traffic system optimization.In this paper,the variable cell transport model(VCTM)is used as a tool.Taking siouxfalls network as the road network simulation environment,the urban network traffic flow simulation model is established,and the Java language is used to carry out simulation iteration.The characteristics of road network traffic flow operation under the demand,key nodes of road network,road sections and travelers’ path selection behavior are discussed respectively.It mainly includes the following work:(1)First,the spatial-temporal distribution characteristics of the road network traffic flow when the demand level is fixed are analyzed from the overall perspective,and then the overall and local spatial-temporal distribution characteristics of the road network traffic flow are analyzed when the demand changes.(2)The influence of the location of the road section,the source of the traffic flow carried,and the direction of the traffic flow on the average travel speed of the road section are discussed.It is found that this influence depends on the local structural characteristics of nodes and road sections.(3)A network key node mining model based on node tightness centrality and edge weighting PageRank algorithm is proposed;a road network key section recognition model based on edge median centrality is proposed.And identify the key nodes and road sections in the test network.The simulation test shows that the model has high rationality.(4)The characteristics of spatio-temporal distribution of network traffic flow under dynamic path selection based on the degree of road congestion are discussed.Iterative simulation of road network traffic flow under fixed demand and changing demand is carried out.(5)From the perspective of user optimization and system optimization,the relationship between the path selection mechanism that only considers the degree of road congestion and the dynamic path selection mechanism and the traffic flow of the road network under the dual factors of considering the degree of congestion and attraction of the road section are discussed.relationship.(6)Analyze the influence of single intersection signal timing on traffic flow,establish a single-point dual-target dynamic signal timing optimization model,propose three-dimensionalspatial double neighbor cell genetic algorithm,and use an improved cell genetic algorithm To solve.