A tool for the management of alpine road networks in the wake of natural and man-made disasters

Road networks in mountainous areas are particularly vulnerable following natural and man-made incidents since they are sparse and have a limited number of links and nodes. This weakness, or vulnerability, complicates the management of traffic flows in the event of emergencies, thus leading to problems of congestion and accessibility. The case of the international corridors along Alpine Valleys is significant since they serve both tourist and commercial routes, and have a typical tree-like structure that accommodates few roads dedicated to long-distance mobility and to local access. To manage emergencies and support the decision making process, local administrations and Civil Protection Agencies should use tools able to evaluate the effects of localized or widespread network failures or incidents in real-time, and limit the effects of reduced accessibility and/or differentiated traffic demand. The authors have developed a dedicated tool, called PoliNET that implements the Network Analyst® extension of ArcGIS® to solve specific vehicle routing problems for mountainous road network. Essentially, PoliNET identifies the best (shortest and fastest) routes for different vehicle categories (cars and motorcycles, vans and small trucks, articulated lorry and tractor-trailers, exceptional load vehicles) when the network operates under specific constraints (road clearances) and/or experiencing failures (interruption). Some examples deriving from real events are presented and discussed in the paper.