The Evaluation of Road Network Vulnerability in Mountainous Areas: A Case Study

This paper deals with the issue of road network vulnerability, with special reference to a mountainous area case. It describes the implementation of a methodology that ranks links of a network according to their importance in maintaining a proper connectivity between all origin-destination pairs. Such a ranking can be particularly helpful in prioritising maintenance investments to be planned along the links of a road network. Following a conceptual approach observed in transport literature, we consider vulnerability to be connected to importance, i.e. a measure of the consequences of the collapse of a network element. In the present study we introduce a new definition of importance - with respect to a given link - that simultaneously includes two aspects: its level of usage, i.e. how many people typically use the link when travelling in a given time window, and the impact that the closure of that link could have on the general functionality of the network as a whole. The methodology proposed was implemented in order to obtain a ranking of importance for the links of a real-scale network, i.e. the road network of the Province of Bolzano, a highly mountainous area located in the Italian Alps.