Resilience and Friability of Transportation Networks: Evaluation, Analysis and Optimization

To analyze the resilience of transportation networks, it is proposed to use a quantifiable resilience evaluation approach. First, we represent transportation networks by an undirected graph with the nodes as cities and edges as traffic roads. Because the survivability of transportation of a pair of cities depends on the number of passageways between them, the resilience of a city node can be evaluated by the weighted average number of reliable passageways with all other city nodes in the network. The network resilience can then be calculated by the weighted sum of the resilience of all nodes. To identify critical road lines or hub cities in networks, the concept of friability is proposed. This is defined as the reduction in total resilience upon removing an edge or hub city. Following the resilience and friability evaluation, a structure optimization model with a computational algorithm for transportation network design is recommended. Based on the recommended approaches, the resilience and friability of the railway network within the Chinese mainland is evaluated and analyzed. Several interesting conclusions are drawn from the computational results. The friability value of the railway lines in the Sichuan Basin which was damaged by the recent earthquake in China was also calculated.