Modeling And Simulation Of Urban Expressways Based On Cellular Transmission Model

With the development of urban expressway network construction, big cities have formeda modern urban traffic system. But the lack of research for expressways network makes itdifficult to form the effective management and control for urban traffic. Due to expresswaynetwork system is large and complex, and most traffic phenomenon are nonlinear dynamicprocess, we need computer simulation technology to find the basic rule of traffic flow. Thecell transmission model, as a new macro simulation model of traffic flow, provides aneffective method for the research of urban expressways network. In this paper, the celltransmission model is employed to build road network model for xi’an urban expresswaysnetwork. Moreover, we study the formation and dissipation process of traffic congestionthrough the simulation under bad traffic conditions. The main works of this dissertation canbe summarized as follows:(1) According to the traffic flow characteristics, the principles of cell transmission modeland the relations of the density and traffic flow, a simple road model and the ramp model isdesigned and established. On the basis of the above models, the traffic flow is simulated toshow the free flow status and congestion status, which verifies the reliability of the models.(2) Considering Xi’an expressways network’s layout, capacity, speed limits and otherfactors comprehensively, and using macro research methods, a cell transmission model isestablished to simulate and analyze the traffic flows, which describe the growth and dispersalprinciple of the traffic jam.(3) Based on the former expressways network model, introduce the concept of adversetraffic conditions, and discusse the influence on the urban expressways network trafficcapacity and safety operation under the conditions of rain and snow weather and holidays’highway for free. The formation of main road congestion and mechanism of congestiondissipation under the rain and snow weather are analyzed by the method of changing trafficparameters. As to the condition of holidays’ highway for free, we discuss the feasibility ofcontrol method through specific traffic simulation.