A Flow-based Vulnerability Measure for the Resilience of Urban Road Network

Since the beginning of the new millennium, various ideas and methods of measuring road network vulnerability have been proposed in the field of transportation and infrastructure engineering. However, most of the existing measures have been focusing on large road networks like highways between cities, even though urban networks are equally important. Also, the measures require full microscopic simulations for deriving the value of travel time increase, which is used for predicting network performance in case a disaster situation occurs. In order to overcome such issue, this study provides a new evaluation method for vulnerability of urban road network based on the concept of macroscopic fundamental diagram (MFD). We call such measure as MFD-based Vulnerability Index (MVI), which is derived by comparing the MFD behaviours in normal condition and event condition, in which one or more links of a road network are failed by a disaster. For testing the measure, a simulation study based on the road network of Gangnam district, Seoul, South Korea is provided. The results show that the measure can help us investigate the different patterns of network performance loss by different traffic states. This work provides a different perspective of investigating road network vulnerability.