Vulnerability of road networks along transalpine corridors

Natural and man-made extreme events have a great impact on the social cohesion and economic development of territories. The road network plays a key role in the aftermath of any such events by assuring accessibility to land and populated areas, and by facilitating the management of emergencies. Nevertheless, this role is limited in mountainous and valley areas where the road network density and capacity are low and hence more vulnerable. In the paper, the authors evaluated the vulnerability of such road networks in terms of reduced accessibility, an approach that the authors considered more pertinent than others available in literature. The two most important Italian North-Western transalpine corridors located along the Susa and Aosta valleys were selected as case studies, thus allowing for the investigation of cases that differ in terms of territorial structure and network layout. For the purpose of this study, the authors developed a dedicated GIS code based on the graph theory. The results obtained enabled the identification of those road sections which are extremely vulnerable, and where future investment should be directed in order to limit the effects of possible network failures in the event of emergencies