Scaling New Heights: A Quantitative Approach to Understanding the Effectiveness of Rockfall Mitigation

Rockfalls pose significant risks to infrastructure, leading to safety hazards, road closures, and substantial economic losses from detour delays and damages to transport. These risks are expected to intensify due to the increased frequency and severity of storms, adverse weather events driven by climate change, and seismic activity, all of which accelerate rock slope deterioration. Current rockfall mitigation approaches present notable challenges. Short-term methods, such as scaling and blasting, are both costly and hazardous, as they require personnel to work directly on unstable slopes. Meanwhile, longer-term solutions, such as rock bolting or nailing, are often financially prohibitive for widespread application. Compounding these challenges is the subjective, ad-hoc nature of rockfall mitigation assessments, which creates uncertainty around the actual effectiveness and longevity of slope improvements. In many cases, slopes may return to a similarly hazardous or even more precarious state after mitigation, leading to ongoing cleanup and maintenance costs. This highlights the need for quantitative, objective methods to enhance rockfall mitigation practices, optimize maintenance strategies, and improve overall asset management. In response to this need, this research investigates the use of the morphological classification system, specifically the Rockfall Activity Index, to assess the effectiveness of mitigation techniques. A controlled field site was established to monitor post scaling morphological changes of the slope over several years with terrestrial laser scanning. By examining changes in magnitude-frequency relationships, activity rates, block sizes, precarious overhangs, and potential energy associated with slope failures, this study aims to provide actionable insights into more effective and sustainable rockfall management practices.