Research On Evaluating Of Urban Transportation Network's Performance

Urban transportation network is composed of all the roads of the city, is the basic skeleton of the city, is the carrier of urban socio-economic activities and the transportation of both travelers and goods. The existing urban transportation network performance evaluation system is not perfect, and its disadvantages mainly lie in the following two aspects:firstly, evaluation system of road network transportation lacks of study on anti-blockage indicators;secondly, connectivity indicator in evaluation system of road network infrastructure is static, in the absence of dynamic indicators.So, evaluation indicators need to be designed from the above two aspects to evaluate the performance of urban transportation network and expand the existing urban transportation network performance evaluation system.The main creative results of the research are as follows:1.For the existing urban transportation network performance evaluation system lack of study on anti-block capability, a concept, k-anti-blockage coefficient is presented to measure the anti-block capability on a transportation network. If once again the shortest path is chosed the current edge congestion occurs, then continue to choose, until you have selected one of the shortest path to the end. The coefficient gives the ratio of the distance of one of the shortest path to the end that is occurred after k-times blockages to shortest path..The characters of k-anti-blockage coefficient are analyzed for arbitrary couple of vertices, a road and a network. An algorithm is proposed and its complexity is given. An example of local transport network in Xi'an is shown for the validity of the algorithm.2.For the connectivity indicator in the existing evaluation system of road network infrastructure is static, in the absence of dynamic indicators. This research presented dynamic connectivity indicators from two angles.(1)As each road in the transportation network are whether blocked or not blocked, suppose each road of the transport network obey binomial distribution, the definition of dynamic connectivity is proposed, the characters of dynamic connectivity is analyzed, and an algorithm is given.(2)Assuming that the total number of the roads in the traffic network which was not blocked in time [0, t] is subject to random distribution, connectivity is studied. Assuming that the total number of the roads which was not blocked obey normal distribution and uniform distribution, respectively, the definition of dynamic connectivity is given, the characters of dynamic connectivity is analyzed. An example of local transport network in Xi'an is shown.