Some developments in rock slope hazard assessments for road and rail

The paper considers developments in the systematic appraisal through to the ongoing management of rock slopes affecting significant infrastructure. The Rock Hazard Index (RHI) system was originally developed for rapid appraisal of rock slopes affecting Scottish Roads. It has been developed further in connection with slopes appraisal under the Quarry Regulations and for rock slopes affecting rail, other infrastructure and property. A notable feature is the differences in targets/receptors and the owners' perceptions of these. It is particularly important to engage with the various interested parties in this. This has led to development of the STAR (Stability Appraisal and Risk) system, following a source-pathway-receptor approach analogous to approaches used for contaminated land. This considerably assists communication and risk management planning, for instance distinguishing slopes with high hazard but for very little receptors at risk from those that may have low hazard but major receptors at risk. Remedial measures can be systematically studied in the light of this. Options can be readily assessed and costed ranging from improving the source (e.g. scaling, bolting), breaking the pathway, e.g. rock trap, catch fences, vegetation barrier, through to modifying the receptors (e.g. controlling development).