Rockfall Hazard Assessment in Pennsylvania through Coupled Monitoring and Modeling

Rockfall hazards present safety and usability issues in highway transportation. Damages and instabilities associated with rockfall have been reported from exposed steep rock surfaces next to roads in Southeastern Pennsylvania, offering study sites to evaluate mechanisms and drivers of rockfall in the region through continuous monitoring. New monitoring equipment and software have been shown to successfully predict rockfall hazards. Predicting the timing and trajectory of rockfalls remains challenging; therefore, use of case study sites for monitoring, evaluation, and modeling to unlock parameters that lead to rockfall is important. This study investigates the morphological characteristics of high-risk rockfall locations and delineates associated hazards using high-resolution Light Detection and Ranging (LiDAR) techniques. Multiple LiDAR scans were conducted at a rock-slope site over a one-year period to capture changes in surface morphology. To evaluate these features, the Rockfall Activity Index (RAI) classification and scoring methodology—an approach for assessing rockfall hazards based on rock surface morphology—was applied. An actual rockfall event occurring between scan intervals enabled calculation of the rockfall volume and assessment of resulting morphological changes.