Abstract. Rockfall presents an ongoing challenge to the safe operation of transportation infrastructure, creating hazardous conditions which can result in damage to roads and railways, as well as loss of life. Rockfall risk assessment frameworks often involve the determination of rockfall runout in an attempt to understand the likelihood that rockfall debris will reach an element at risk. Rockfall modelling programs which simulate the trajectory of rockfall material are one method commonly used to assess potential runout. This study aims to demonstrate the effectiveness of a rockfall simulation prototype which uses the Unity3D game engine. The technique is capable of simulating rockfall events comprised of many mobile fragments, a common limitation of available rockfall modelling programs. Five fragmental rockfalls were simulated using the technique, with slope and rockfall geometries constructed from high-resolution terrestrial laser scans. Simulated change detection was produced for each of the events and compared to the actual change detection results for each rockfall as a basis for testing model performance. In each case the simulated change detection results aligned well with the actual observed change in terms of location and magnitude. An example of how the technique could be used to support the design of rockfall catchment ditches is shown. Suggestions are made for future development of the simulation technique with a focus on better informing simulated rockfall fragment size and the timing of fragmentation.

Remote sensing techniques can be used to gain a more detailed understanding of hazardous rock slopes along railway corridors 10 that would otherwise be inaccessible. Multiple datasets can be used to identify changes over time and create an inventory of rockfall events including frequency-magnitude relationships for rockfalls sourced on the slope. This study presents a method for using the remotely sensed data to develop inputs to rockfall simulations, which can be used to determine the likelihood of a rockfall impacting the railway tracks given it's source zone location and volume. The results of the simulations can be related to the rockfall inventory to develop modified frequency-magnitude curves presenting a more realistic estimate of the hazard. 15These methods were developed using the RockyFor3D software and LiDAR and photogrammetry data collected over several years at the White Canyon, British Columbia, Canada, where the CN Rail main line runs along the base of the slope. Rockfalls sourced closer to the tracks were more likely to be deposited on the track or in the ditch, and of these, rockfalls between 0.1 and 10 m 3 were the most likely to be deposited. Smaller blocks did not travel far enough to reach the bottom of the slope and larger blocks were deposited past the tracks. Applying the results of the simulations to a database of over 2000 rockfall events, 20 a modified frequency-magnitude can be created, allowing the frequency of rock falls deposited on the railway tracks or in ditches to be determined. Suggestions are made for future development of the methods including refinement of input parameters and extension to other modelling packages.