Spatial and functional evolution of urban rail transit station areas in mountainous cities: a case study of Daping Station, Chongqing

Background Transit-Oriented Development (TOD) has been widely adopted to promote compact and integrated urban growth. However, in mountainous cities, the spatial transformation of urban rail transit station areas (URTSAs) is constrained by steep topography, limited developable land, and fragmented vertical urban forms, which challenge the effective implementation of TOD principles. This study investigates the spatiotemporal functional evolution of the Daping Station area in Chongqing, China, over a decade (2014–2024), with a specific focus on the spatial coordination between transit infrastructure and adjacent land use. Methods A mixed-method approach was employed, combining space syntax analysis, Points of Interest (POI)-based kernel density estimation, and spatial information entropy modeling to uncover structural transformation patterns and underlying spatial mechanisms. Results Three key challenges are identified: (1) persistent misalignment between station facilities and urban functions, characterized by linear commercial corridors with inadequate clustering; (2) a vertically dense but spatially fragmented urban core lacking coherence; (3) enhanced network connectivity and limited pedestrian integration and vitality. Conclusion Drawing on these findings, a three-dimensional intensification strategy is proposed, encompassing the optimization of vertical circulation systems, reorganization of mixed-use zones, and integration of fragmented public spaces. The study provides practical insights for adapting TOD strategies to complex urban terrains and contributes to policy-oriented planning in mountainous cities.