Research On The Method Of Urban Expressway Network Layout Planning And Evaluation

Along with the increasing traffic demand and pressure on the urban traffic network, the urban expressway was planed and constructed in many cities in order to separate the traffic with middle and long distance from short distance, protecting the centre region in cities. It is the key issues of layout planning and evaluation in road network that how to determine the size of the urban expressway, how to take on layout, how to ensure the smoothness in join point of urban expressway with roads and how to select the optimum scheme from many planning schemes. There would be integration and development on methods of layout planning and evaluation form this paper.Using the methods of regression analysis, AHP, fuzzy synthetic evaluation, and so on, the reckoning of rational scale of urban expressway network and the evaluation of urban expressway network are studied in this paper. Based on the theory of Wardrop, the method of fixing on the least radius of inboard loop is researched.The accounting method of equivalent length of urban expressway is expatiated in this paper, and it is took as the index of the scale of urban expressway network. Based on the analyzing the merits and demerits of the existed reckoning methods of rational scale and the scales of urban expressway in China, the rational scale of urban expressway is researched. It is discussed that different layout planning forms of urban expressway to fit urban morphology, and the layout method. It is discussed that the setting principle, the method to fix on the shortest distance and the location for exit and entrance of urban expressway. Then from the perspective of traffic design, the optimized designs are made to connect the traffic between passageway and other roads. The paper summarizes the common types of urban expressway interchange, analyzes their advantages and disadvantages, then bring up the improvements. The measures to resolve the connection problem are analyzed between urban expressway and local road network, important traffic accumulating and dispersing nodes, arterial road network. The synthetic evaluating index system of urban expressway network layout is established. The fuzzy model is put forwards to evaluate urban expressway network layout.By the research of this paper, the empirical formula of urban expressway rational scale is set up that considers the factors of economic, population, area and the amount of vehicles. Based on traffic unit dividing, it is improved on that the layout planning methods of urban expressway with the theory of traffic location. Suggested value for the least radius of inboard loop and the method to fix it are put forward. The method of going to the entrance and exit, and the optimized designs are made. It is set up that the synthetic evaluating index system of urban expressway network and the synthesize evaluation method.