The Study On Factors Of Establishment At The Exit And Entrance Of Urban Expressway

It's important for the construction of urban expressway network to improve the service level and mitigate the press of the city transportation. The exit and entrance of urban expressway, as the important part of the urban expressway, not only is the connection between the urban expressway network and other networks, but also is to achieve the transition of every grades of road. The reasonable layout of the exit and entrance will directly influence the use of urban expressway network. But in fact, the status of traffic reflect, many exits and entrances are the points which cause traffic jams, and furthermore cause the relative roads and networks around into traffic jams,and at last cause traffic networks inefficient.This paper takes the exit and entrance connecting the main line and auxiliary road of urban expressway as the object of study. It introduces the three basic characteristics involved in layout of the exit and entrance, the quantity, the combination type, the spatial position. It describes the traffic characteristic about the exit and entrance of urban expressway. It systematically analyzes and summarizes the four factors which take effect on the layout of the exit and entrance of urban expressway: effects taken by basic layout factors, effects taken by traffic demand from city transportation networks, effects taken by public service facility provision, effects taken by the methods of traffic management and control.According to the investigation data of traffic characteristics about the third - ring expressway in Beijing, establishes the models based on traffic simulation. Selected the number of passing vehicles , the traffic travel time, the delay time, the length of the queue as the evaluation indexes. Takethe DEA / AHP two stage integrated model to calculate the evaluation value of the whole program for further comparative analysis.This paper makes use of the quantitative analysis and the qualitative analysis to give simulation studies on the effects taken by the layout of lane on the main line and auxiliary road of urban expressway, the lengths of distances between the entrance and the road intersection, the lengths of distance between the exit and entrance of every types, relationship about expectation speed of the main line and auxiliary road, the size of traffic volume of the main line and auxiliary road, the ratio of traffic volume between the main line and auxiliary road. Through analyzing the data from by the number of passing vehicles, the traffic travel time, the delay time and the length of the queue four evaluation by simulation output, using DEA / AHP two stage integrated model to calculated evaluation value of various program ,gives comparison study on the program under different factors, summarizes how the six basic factors take effect on the layout of the exit and entrance of urban expressway.