Vulnerability patterns of road network to extreme floods based on accessibility measures

Accessibility is a key measure of the vulnerability of road networks to disruptions such as floods. However, studies comparing the contribution of parameters to the accuracy of accessibility-based vulnerability assessment are lacking. We propose modifying two accessibility measures to include flood-affected populations, opportunities, and average shortest travel time. We also applied three methods including the divergent ranking method to identify the direct impact of extreme floods on road networks. The shortest travel time pathway calculation was enhanced with the inclusion of spatially distributed settlements as an input. The results indicate a strong relationship between parameter weights and the accessibility measures, irrespective of the evaluated approaches. The results of the study highlight that measures of overall vulnerability, with respect to inter comparisons of flood scenarios alone, do not fully capture the local vulnerability of some traffic zones. This is particularly evident with the flooding of highly connected roads that serve these zones.