Built Environment Effects on Passenger Flow Distribution in Overlapping Catchment Areas of Adjacent Rail Transit Stations

With the continuous integration of rail transit and urban development, station-centered high-density construction often expands outward and forms a point-axis development pattern. As a result, the influence areas of adjacent stations increasingly overlap, and passenger flow distribution within these shared catchment areas is jointly associated with walking time costs and built-environment differences. Taking Xiamen rail transit as a case, this study constructs a framework for delineating adjacent-station overlapping catchment areas, measuring passenger flow contribution, interpreting built-environment associations, and deriving planning strategies. Isochrone analysis and population heat data are used to identify overlapping areas and estimate passenger flow differences, while ordinary least squares (OLS) regression and XGBoost models are used to estimate distance–ring contribution weights and interpret nonlinear built-environment associations. The results show that distance decay, development intensity, land-use mix, road-network accessibility, public-service facilities, and interface conditions are jointly associated with passenger flow allocation between adjacent stations. The study shifts station–area research from single-station catchments to multi-station overlapping spaces, provides a method for measuring passenger flow differences at a fine-grained spatial level, and offers planning support for coordinated station–city integration, differentiated pedestrian and feeder-facility allocation, and passenger flow guidance in high-density urban areas.