An integrated multi hazard risk framework for modelling transport system disruption from landslide and flood events

Transport systems cover vast areas across diverse terrains and climates. As an example of critical infrastructure, they are essential for economic and social connectivity worldwide. However, this extensive spatial reach also makes them highly vulnerable to a wide range of geohazards. Among these, landslides and flooding triggered by extreme precipitation or seismic activity pose serious risks to road networks, particularly when they occur as cascading or compound events. Road networks are highly interconnected and therefore susceptible to cascading failure; when a single link is disrupted, traffic redistributes across adjacent routes, generating congestion that propagates through the wider system and reduces overall network performance.

In response to these challenges, we present a modular multi hazard risk assessment framework that combines hazard simulation with transport network modelling to evaluate the effects of interacting geohazards on transport infrastructure. Landslide susceptibility is assessed using a slope stability analysis based on the infinite slope model and factor of safety under both precipitation driven and seismic loading conditions. The Synxflow modelling package is then applied to simulate shallow landslide runout and flood inundation. These outputs are then integrated within a GIS environment to produce composite hazard layers, which are translated into road passability classifications using depth and velocity thresholds tailored to different vehicle categories.

To assess how these hazards affect movement across the network, we apply a transport modelling framework, which enables the simulation of vehicle movement under conditions where road links are partially or entirely blocked by landslides or flooding. Our work offers a practical tool to capture delays, diversions, and loss of accessibility caused by multi-hazard events.