Route Stability Index (RSI): an index for the assessment of rockfall-related hazards in rock slopes equipped for sport climbing

A multidisciplinary geomechanical method to evaluate and quantify rockfall hazards in rock slopes equipped for sport climbing is presented. This method exploits close-range survey data obtained from terrestrial laser scanner (TLS) and unmanned aerial vehicle-based digital photogrammetry (UAV-DP) and integrates them with traditional scanline survey data collected in the field. Based on the acquired information, a kinematic analysis is performed to predict the location of structurally controlled rock failure mechanisms. An index denoted as route stability index (RSI) is then proposed to quantify the associated hazard along sport climbing routes in the study area. In addition, hazard is also assessed at the overall slope scale. The method was successfully applied at an abandoned climbing site historically affected by rockfalls, 5 km north of Florence (Italy). RSI can be adopted as part of the planning and monitoring strategies for the management of risk related to outdoor climbing activities, which are becoming an important part of Italian and European geo-tourism.