Spatial–Temporal Effects and Driving Mechanisms of High-Speed Rail on County-Level Construction Land Expansion: A Case Study of the Beijing–Tianjin–Hebei Region

In the process of rapid urbanization, high-speed rail has become pivotal in shaping urban land-use patterns by facilitating factor mobility. This research examines the spatial–temporal dynamics of high-speed rail accessibility and urban construction land across 200 counties in the Beijing–Tianjin–Hebei region. Utilizing fixed panel models and geographical detectors, the study delineates the effects and the underlying drivers of high-speed rail on county-level construction land expansion. Key findings include (1) high-speed rail significantly enhances transportation accessibility between urban nodes across counties, evident in a strip-like expansion pattern along rail corridors. (2) Urban construction land initially increases and then decreases, displaying strong spatial clustering with expansion hotspots stretching southeast along the Beijing–Tianjin axis, increasingly concentrating and widening within Tianjin. Spatial variation in construction land expands, yet spatial correlations intensify, particularly in the southeast–northwest direction. (3) High-speed rail development correlates closely with the dynamics of county-level urban construction land, contributing to a 23.5% increase in such land, with pronounced effects in municipal districts and lesser in county-level cities and counties. A cubic relationship between high-speed rail factors and construction land area is identified, with population and gross domestic product interactions indicating a nonlinear amplification of effects. This study offers new insights into the interplay between railway transportation and land use, aiding in understanding the high-speed rail’s role in urban land expansion.