Assessing Public Transport Vulnerability to Urban Flooding: A GIS Approach Incorporating Network Risk and Population Exposure

Urban flooding increasingly disrupts public transportation, critical for vulnerable populations including elderly and low-income groups. Most research on flood resilience in transportation focuses on private vehicles, overlooking vulnerable users’ reliance on public transport. This study addresses that gap by assessing flood-related disruption across the surface public-transport network of a large municipality in Athens, Greece. Using a two-dimensional coupled hydrological–hydraulic model, we simulate a 100-year flood and estimate water depths across the road network. Public transport and road infrastructure data are integrated in a Geographical Information System to identify segments where depths exceed 0.3 m, an operational safety threshold used for conservative detour screening. Critical links, affected bus stops and disrupted routes are systematically mapped, while the affected population is estimated through isochrone curves that delineate 15- and 30-minute accessibility. This approach pinpoints vulnerable areas, nodes and corridors in the network, supporting disaster preparedness and operational planning. The findings facilitate flood-risk maps tailored to public transport, enabling transit operators and municipal authorities to pre-emptively design alternative service plans.