Study On Traffic Carrying Capacity Of Urban Road System

In recent years urban car ownership keeps growing at a rapid speed with the development of economy and the support of government policy. Meanwhile, so many cars have brought us high living standard, speeded up urbanization and motorization, as well as congestion which causes air pollution, time-consuming and so on. With the fact that urban road system is the foundation and environment of traffic and dicides the maximum traffic flow in it, car ownership shows a continuously growing trend while the city structure is fixed and extra land used for road construction is limited. This paper systematically and dynamically studies on urban road system's carrying capacity of car traffic.First of all, this paper makes clear on the issue and aim; analysises research on road capacity of both home and abroad, gives a brief introduction about the applicability of system dynamics method and its advantages, and then proposes new concept and measurement of road carrying capacity.After respectively discusses the influence factor of road system from the point of supply and of car traffic from demand, the paper decides on traffic load as the index to discuss the equivalence of supply and damand and network mean speed to evaluate traffic conditions.Based on systems engineering method, system dynamics theory, the paper establishes a system dynamics model, studying the interactive relationship between road carrying capacity, car traffic and related variables with the help of Vensim (PLE edition) software, following the process of determining system boundary, relevant variables, causal chain, feedback loops and flow diagram at the end.Finally, do simulation. Comparing the predictive results with the actual statistical data from annual report demonstrates that the model is valid. Then the paper stimulates the ideal traffic conditions of network after repeated policy trials, and brings forward corresponding policy to ensure implementation.