Network Evaluation Based on Connectivity Vulnerability

Network reliability indices are generally expressed as a multiplier of the probability that the specific event may occur and the consequence of the event. It means that an inaccurate estimation of the probability of event occurrence may lead to different evaluation of the reliability. In contrast, the concept of “network vulnerability” has been proposed for evaluating the network component only by the consequence of the degradation. Though the concept of vulnerability may have avoided the uncertainty of the capacity degradation, it still requires an exact measurement of the traffic demand in the network which may not be accurate especially in the case of the disaster. We thus propose the method of critical link identification from the topological point of view, i.e., connectivity vulnerability. The concept of the k-edge-connectivity is applied in this study. The number of distinct paths with acceptable travel time between each origin-destination (OD) pair is used to measure the connectivity of that OD pair (similar to the concept of k-edge connectivity). A mathematical program for identifying acceptable distinct paths between each OD pair is formulated. The proposed method and indicator of connectivity vulnerability is then tested with the Kansai road network.