Functionality assessment method for road transportation systems under the joint impact of earthquakes and coseismic landslides

This study addresses the joint impact of earthquakes and coseismic landslides and develops an assessment framework for the post-earthquake functionality of road transportation systems. The damage probabilities and functionality levels of vulnerable transportation components (bridges and tunnels) are determined using seismic fragility analysis. Coseismic landslide hazard is assessed with the Newmark model and a landslide-impact-zone-based method is proposed to estimate the probability that functionality of road segments is affected by landslides. The functionality metric, comprehensive emergency connectivity efficiency, is introduced to quantify the functional performance of road transportation systems during the post-earthquake emergency phase. A case study of a Chinese city’s road transportation system indicates that, for an M_w 7.0 scenario earthquake, the probability of the road transportation system’s functional loss exceeding 30% under the joint impact of earthquakes and coseismic landslides is double that of considering the earthquake impact alone. In the study area, where coseismic landslide hazard is localised and spatially clustered, coseismic landslides significantly increase the risk of large functional losses in the road transportation system, and this risk is positively related to earthquake intensity.