PRIORITIZING RAILWAY STRETCHES REQUIRING RISK MITIGATION MEASURES BASED ON THE INTEGRATED USE OF AIRBORNE LIDAR AND MOBILE MAPPING DATA: CASE STUDIES IN CENTRAL ITALY

Landslides originating in hilly and mountainous natural slopes can directly affect the railway corridors, in turn causing – often severe – indirect consequences to travelling persons (in terms of injuries and loss of life) and economic activities. This is the case of existing landslides, slowly moving on buried sliding surfaces, which may dislocate the railway platforms so isolating urbanized areas. First-time landslides, rapidly moving on channelized or open slopes, may generate detrimental effects too. Owing to the importance of the problem, activities must be carried out to properly predict the landslide occurrence and (eventually) prevent the related direct and indirect consequences to the exposed railway stretches. In this regard, qualitative risk-based approaches can be adopted to profitably tackle the problem under consideration at large scale (1:5,000 to 1:25,000), when many slopes are dealing with. These approaches includes the use of ranking matrices, as operated in the official practice in Italy within the so-called Hydro-geological Setting Plans - HSPs (Law 365/2000). In compliance with governmental requirements, four risk levels had to be considered by Authorities at that time in charge of the landslide risk analysis and zoning (i.e., River Basin Authorities and Regions). Independently of the adopted approach, all the produced risk zoning maps are unsuitable for: i) the prioritization of equally-classified at-risk areas/linear facilities requiring either non-structural or structural interventions and the related earmarking of financial resources, and ii) the selection of the most appropriate risk reduction strategy (including type, location and size of structural interventions, in the cases where they are required).