Study On The Layout Of Interchange Of City Ring Expressway Based On Reliability Theory

Along with the rapid development of expressways in china, the expressway network jointed by cities demand those cities are capable of holding and coordinating the traffic flow came from some other place, on the other hand, the expansion of the urban made more and more middle and long distance trips, the road network in the town centre trend to saturate, and the traffic demand asked for contract with some other cites is keeping expanding. In order to relieve the double pressure, the ring expressway has become one of the most important projects for future by lots of cities at home. But so far, Little research has been conducted in it. With the rapid increase of the traffic, many problems kept cropping out in some ring expressways in China for lacking overall plan for the development science. So, this paper makes a thorough study of the interchange which is the most important link for the ring expressway plan, analyze the relevant relation between the whole urban road network system and the interchange plan including the number design and the distance design. The paper is of important theoretical reference value and practical guiding significance to make the strategy and planning of ring expressway development, and to guide the work of increasing, building or expanding the interchange effectively, and to promote the development of the road network system, combined with the urban road as a axis, the ring expressway as a tie, and the highway between cities as extending, continuously, rapidly and healthy.This paper is based on the theories and methods relative to reliability, and has defined the inevitable inherent relationship between the interchanges planning and the reliability of urban road network, through system analysis of the traffic characteristics of the ring expressway. Take a typical virtual road network as an example, lots of calculation on travel time reliability of different interchange scheme has been taken, the relationships between the number of interchanges and the whole urban road network and all kinds of trip routes, and the relationships between the distance of interchanges and the whole and local urban road network, and routes were obtained successfully, and a method of defining the number and distance of interchange on ring expressway was proposed by contrast and analysis the trend line about reliability. This method is only based on the traffic distribution OD matrices and the road network structure map with a few physical parameters, while the whole calculative process was automatically achieved by Excel and TransCAD, so a syntax calculating program laid the groundwork for future extension of the method.