Study On The Reliability Of Mountain City Complex Transportation Network

This paper is a follow-up research based on an appoint project of Chongqing construction committee, called the Evaluation Indices research of urban traffic network system with cluster and multicenter.The imbalance between road resources supply and traffic demand is the root cause of the traffic congestion. The mountain city road network construction is limited a lot by terrain, and it is quite difficult to expand network of road. Therefore, the network optimization which is aimed at improving its performance becomes one of the main methods to alleviate the imbalance aforementioned. Meanwhile, the properties of mountain city traffic network includes complexity and uniqueness, so this makes numerous difficulties for people to understand it and many methods aimed at improving the network ability counterproductive. The emergence of complex network theory provides a very useful way to learn complex systems. In practice, plenty of networks nowadays can be described by complex networks. This paper tries to use it to study mountain urban traffic network, analyze the network reliability through the research of cascading failure phenomenon and the optimal network topology.First of all, this paper has analyzed the complex property and characters of mountain urban traffic network. Based on the two characters mentioned above, a model which can simulate the characters mentioned above is established. Comparing every kind of traffic load, the paper selected the user equilibrium model and studied the cascading failure phenomenon and optimal topology structure of mountain urban traffic network.The paper has done work below in the network modeling.(1) Analyzing the complex property and characters of mountain urban traffic network.(2) The simulated model of mountain urban traffic network topology is established. And this mode seize the three typical characteristics of Mountainous Urban traffic network—large pressure on main road and expressway, multi-center and cluster. By analyzing the model, we can finally come to a conclusion that the model is feasible. At last, the article realized the needed network by Matlab.While in the network cascading failure phenomenon and optimal topology study, this article made the following work.(1)Comparing with each traffic loading method, the paper selected the user equilibrium model for use and implemented it by Matlab.(2) Research of the phenomenon of cascading failures of network. The paper first analyzed the mountain urban traffic network cascading failure phenomena, and then established a model based on above analysis, ultimately put this model into simulation through Matlab. From the simulation results, we can resist the diffusion of cascading failures phenomenon through enhances the diffluence capacity of branch and sub-arterial road to main traffic road and connectivity between sub-arterial roads (or branch).(3) Research of optimal topological structure. The paper proposed a new concept of network capacity, named "effective network capacity". It can avoid the drawbacks that traditional network capacity became the largest when it paralyzed. And a model based on "effective network capacity" is established. We put it into simulation through Matlab and got the simulation results. The results show that we can improve the traffic network capacity by enhancing the diffluence capacity of branch and sub-arterial road to main traffic road and connectivity between sub-arterial roads (or branch).Finally, based on the model of optimal topological structure, the paper simulated the optimal way of connection between clusters. The results show that selection of join points in clusters should focus on the two balance bellows:capacity balance between cluster connection channels and ramps; balance between clusters ramps.