Research On Urban Expressway Network Planning

The construction of urban expressway system, whose investment is tremendous and effect is far-reaching, is taken seriously by the government and traffic planning circles. On the basis of the Four Phases Method and the theory of urban spatial structure, the research focuses on the theory and the method of urban expressway network planning. I hope this research could promote the development of the theory and method of expressway system planning.It' s fundamental to understand and grasp the essential characteristics of the expressway system before carrying on the network planning. The characteristics functions and components of the expressway system are summarized, and the integrate procedure of the expressway planning is analyzed in the paper. The traffic zone split is studied deeply. The research regards the critical distance of medium-long distance trip as the centroid distance between the two adjoining traffic zones, and uses this critical distance as the equivalent diameter to estimate the area of the traffic zone. Gearing to the traffic characteristic of the expressway system, which serves the intracity medium-long distance vehicle traffic and the outbound vehicle traffic, the opinion and method how to forecast the traffic demand are raised. It' s one emphasis of the paper.The research about the method of network planning is another emphasis of the paper. The influence factors and the planning principles are analyzed and summarized. The urban spatial structure is considered to the most important influence factor. Two calculation methods are raised to estimate the expressway network scale. A new planning method-analysis of factors of point line and area and control points optimization, which is based on the analysis of urban spatial structure, is tried to put forward. Analyzing the important functional clusters in the spatial layout of the urban, theintracity medium-long distance vehicle traffic major directional desire line how the urban to link up with the highway network and the whole structure of expressway system, the skeleton of the expressway network can be obtained. Using the degree of importance method Analytic Hierarchy Process(AHP), one or several intersections can be selected. These intersections can be regarded as control points to optimize the expressway line route. The paper raises the evaluation criterion system. Analytic Hierarchy Process(AHP) is applied in the integrated evaluation, and a calculation example applying Analytic Hierarchy Process(AHP) is given in the end of the paper.