Study On Connectivity Reliability Of Expressway Network Based On Decision Diagram

By connecting different cities, a functional expressway system play a direct role in the development of cities’ economy as well as their function. The expressway network reliability, as a key part of the express transportation system reliability, is an important indicator to measure its ability to working in traffic accidents, natural disasters and other emergencies. As a complex system, it has theoretical value and practical significance to study the expressway networks reliability.Network reliability analysis based on the decision diagram usually uses the connectivity to measure the network. The network is considered to be operational, as long as there exists a connected path between two given nodes without considering the attribute of network elements and the demand of consumers. It will overestimate the reliability of the network. In this thesis, with the decision diagram theory, we investigate the expressway networks reliability respectively by considering of the path choice and node importance. The main work is as follow.(1) In consideration of the emergencies and difference between travelers’ path selection standards, we evaluate the express network connectivity and reliability based on the path selection. By constructing a formal model of road network under the restrictive condition of travel, we establish an ADD algorithm based on the path selection for network reliability and set the Zhejiang highway network as an example. Our research results can be used to provide an option for different travelers when they travel and are accord with actual path selection behavior, which has certain practical significance and applicative value.(2) From the practical significance of the nodes, we propose a method to evaluate the expressway network connectivity and reliability based on node importance. We developed some useful index and used the gravity models to analyze the importance degree of road network nodes. According to the BDD method for the connectivity reliability of OD pair in the road network, we get the connectivity reliability of the whole network. Then we compared connectivity reliability of road network under normal and damaged condition, calculate the correlation of nodes importance and connectivity reliability. By using Zhejiang highway network as an example network, we evaluate the connectivity and reliability of road network. it is shown that our method can effectively evaluate the node importance of whole network, and the node importance based on the network topology is effective.