From Mass Movements to Mitigation Measures: A Statistical Evaluation of Landslides in the Austrian Federal Railway Network

Mass movements, especially landslides, pose a severe safety risk for critical infrastructure, such as railroads, and will very likely increase in the near future due to global warming. As part of the development of a network-wide natural hazard management strategy for the Austrian Federal Railways (ÖBB Infrastruktur AG), the landslide events of the last 20 years were recorded in an event register. The article provides a descriptive statistical evaluation of this landslide inventory, with the aim of deriving general conclusions for landslide hazard mitigation. About 91.9 % of all events were classified as shallow landslides (depth of the slip surface <2 m), which were mostly anthropogenically induced, and 49.0% of all events were attributed to the design and maintenance of roads and railways, thus being particularly related to fill slopes, cut slopes and drainage systems. Due to the frequent lack of geomorphological indicators, the ‘classic’ approach in landslide mitigation (i.e., geomorphological mapping, geological exploration, geotechnical monitoring and remediation) is only suitable to a very limited extent for small events. Quantitative landslide susceptibility assessment is therefore becoming increasingly important, even though the results are often questionable in heavily anthropogenically altered terrain, such as cut and fill slopes along traffic routes. In these areas, depending on the specific cause, additional measures (closer construction supervision, reinforced maintenance, risk communication, legal approaches) are required. As a consequence of the susceptibility analysis and the resulting designation of numerous landslide-prone areas, the need for the construction and planning of linear protective structures and monitoring systems is becoming increasingly apparent.