Quantitative assessment of rockfall-induced risks to infrastructure: a framework for fragmentation, mitigation measures and socioeconomic consequences

Accurately predicting the consequences of geohazards remains a major challenge in quantitative risk assessment. Public and private stakeholders often face difficulties in defining risk management strategies, prioritising interventions, and allocating resources for mitigation, particularly in the case of rockfall hazards, where ensuring resilient infrastructure and safe communities is increasingly urgent. Building on a quantitative risk assessment framework previously developed by the authors, this study presents an enhanced methodology that integrates a new fragmentation model for propagation analysis. Understanding the size and energy of blocks potentially impacting elements at risk is crucial for the accurate design of protective systems and the estimation of their probability of failure, enabling a more realistic assessment of residual risk. Consequences are analysed across both social and economic dimensions. By capturing the interplay between hazard dynamics, infrastructure vulnerability, and the effectiveness of protective measures, the proposed framework supports the development of safer and more resilient transport networks in rockfall-prone areas, and it serves as a robust decision-support tool for policymakers and public authorities. The method is applied to viable infrastructure exposed to rockfall, such as high-traffic or mountainous roads that often serve as the sole access routes to remote areas.