Mechanism And Empirical Analysis On The Evolution Of Urban Traffic Structure Based On System Dynamics

Traffic structure is a composition of different traffic modes in a specific region, which reflects the traffic demand characteristics, the function and position of every traffic mode. It directly affects the allocation of traffic resources and the possibility of providing optimal choice. The traffic structure has become the key determinant of traffic efficiency and the important research content in traffic development strategic planning.This paper analyzed the evolution mechanism of urban traffic structure in China and abroad, studied the effects of economic development level, urban development model, transport development policy and the trip characteristics on the evolution of traffic structure, built the evolution system dynamics model of public and private traffic structure, compared the development trend of traffic structure and policy effects in different scenarios, discussed the ideal aim and policy system.The main research contents and results of this paper are:(1) This paper discussed the transport development model and evolution mechanism of traffic structure, analyzed the formation reason and adaptability of traffic structure in different periods, and summarized the traffic structure adjusting policy and experiences in the process of management practice. Traffic structure is the long term result of traffic policy, directly determines the operation efficiency of urban traffic system. Big cities in China are in the process of rapid motorization, the traffic structure presents the coexistence of multi traffic modes. Facing the situations of the proportion decrease of non-motorized mode, the difficulty to keep the public proportion and the rapid development of private motorized mode, through the analyses on traffic structure and rational policies, the serious urban traffic situation can be avoided as possible.(2) This paper analyzed the traffic demand characteristics of specific time and region, studied the difference of traffic structure in different regions. To keep the absolute predominance of public transport in city center, especially in the commuting traffic mode, is the core to solve the traffic problems in the whole city. With the city development entering mature period, it's important to pay equal attention to planning and management in traffic development strategy. It's necessary to balance the public and private traffic share according to the resource level, guide and control the traffic structure in different regions, and make full use of traffic demand management to construct the integrated traffic treatment and traffic structure optimization plan. (3) This paper considered the promotion effects of economic development and urbanization process, analyzed the influencing factors of the number of vehicle and the development trend, and discussed the effects of vehicle development on the urban road network and traffic emission. The economic level is the main influencing factor of the number of vehicle, the economic growth makes the car transport fully developed which is promoted by consumption, the number of vehicle will keep the high speed in big cities of China. While the public transport under government investment is restricted both by demand and supply, and cannot adapt the traffic demand brought by economic development. The emphases of traffic investment policy should make a good change of the supply structure, keep the investment strength on public transport priority, and form the guide relationship from traffic investment to traffic demand.(4) This paper considered the interaction between city development and the evolution of traffic structure, discussed the causality relationship between various factors in the system from the aspects of social-economic development, traffic demand, traffic supply, traffic operation, traffic emission, traffic planning and policies, built the traffic structure development system dynamics model, and realized the scenario analysis, traffic emission analysis and effect test under different traffic policies.(5) This paper took Beijing as an empirical example, analyzed the evolution trend of traffic structure and the implementation effects of traffic policies, and discussed the rational aim and policy system of traffic structure. Under the comprehensive policy, the proportion of car trip is keep stable, the proportion of public transport is improved along with rail transit rapid development, the traffic emission is reduced, the urban road is great improved, and the traffic structure is optimized gradually. As the limitation of single traffic policy, the optimization should take the comprehensive policy, consideration to the technical feasibility, social equality and the public acceptability. It's necessary to pay attention to three policy aspects: traffic plan and investment, public transport attraction improvement and traffic demand management, and realize the traffic structure optimization aim, and then the urban traffic status and traffic structure will achieve a more coordinative effect.