A resilience assessment framework for urban transportation systems

Unexpected disruptions in an urban transportation system may severely damage its structure and functionality. The resilience of urban transportation networks, i.e. the ability to recover from destroyed conditions, is thus significant for the mobility of passengers and freight in cities. However, its definition and measurement have been confused with robustness. This research advances a trackable assessment framework for the resilience of two typical urban transportation modes, i.e. road system and metro system, considering the characteristics of their structure and functionality. Individual vertex-based and edge-based failure models are established for the two transportation systems based on their network models. The proposed measurement approach is applied to an inner-city road freight system and the metro system in Hangzhou, China, to analyse their resilience, considering different combinations of vertex-based and edge-based failures. The proposed approach is compared with an efficiency-based resilience measurement method and outperforms in two parts. First, it has a broader application than previous related methods because it can describe disruptions occurring on one directed vertex or edge using a directed network model. Second, the new method outputs more reliable results due to considering more structural and functional characteristics of urban transportation systems than previous methods.