National-scale assessment of railways exposure to rapid flow-like landslides

In landslide-prone regions, railway networks are vulnerable to rapid flow-like landslides, which can cause extensive damage, even at significant distances from the landslide's point of origin. The prioritization of protective measures on a national scale depends on the accurate assessment of each railway segment's exposure to landslides. This study introduces a methodology for evaluating the exposure of transportation infrastructure, with a specific focus on flow-like landslides. The application of this methodology is demonstrated on Italy's national railway network. The methodology involves a multi-phase approach, including a training phase using DEM data and landslide inventories, a modeling phase for landslide source areas and runout, and a final phase for infrastructure exposure assessment. Key outputs of this approach include the creation of a landslide susceptibility map and, critically, the generation of an exposure map that quantifies the risk to transportation infrastructure posed by flow-like landslides. Validation using an independent landslide dataset demonstrated satisfactory results, especially in regions with area under the ROC curve values ranging from 0.7 to 0.95. The resulting exposure map shows that approximately 13.4% (2376 km) of the entire national railway network is exposed to a medium-high level of risk from flow-like landslides. This methodology highlights its effectiveness in nationwide exposure analysis of transportation infrastructure, providing valuable insights for risk mitigation and resource allocation, while relying solely on existing landslide inventories and digital elevation models.