Study On Urban Road Traffic Network Vulnerability Identification Method

Vulnerability in road transportation system describes the sensitivity for degradingserviceability of road network in disasters. Vulnerability identification on road networkis premise to prevent and mitigate disaster in road network, which will support thedecision such as resources allocation of road maintaining and timing priority oftransport network reconstruction. First, after introducing road network robustness index,static network traffic flow model with link queuing capacity constraint and capacityconstraint is proposed, which is solved by transforming constraint problem intounconstraint problem according to Lagrange dual algorithm. Numerical exampleprovides the rank of critical roads, and show that the identification methodology basedon network robustness index can accurately recognize the bottlenecks of the roadnetwork from a global perspective while overcoming the defect of methodology basedon saturation. In addition, the identification model whether considered road queuingcapacity constraint and capacity constraints concern the reliability of identificationresults of traffic network vulnerability Second, after putting forward the vulnerabilityindex of dynamic transportation network, it also sets up a link-based reactive dynamicmodel meeting the dynamic user optimal principle. In order to simplify the operationsprocess, it will transform the dynamic model to static one by using the expansion oftime-space network on the basis of equivalent optimal control model, then F-Walgorithm and diagonal algorithm can be used to solve the static problem. By simulatingthe breakdown of different links at different time intervals we can get the order ofvulnerable links, as well as the transformation of the vehicles’ number, inflow, outflowof the links and traffic distribution of the road network.