Investigating the spatial heterogeneity in distance decay of rail passenger transportation: empirical evidence in Guangdong Province, China

• We examine heterogeneity in distance decay of interregional rail with ticketing data. • Modeling decay rate and onset time of decay reveals three distance decay patterns. • Decay patterns reflect joint effects of supply, demand, and spatial context. • We link decay pattern to regional industrial role to assess rail-industry alignment. Distance decay, a fundamental concept in understanding spatial interactions within human movement, is consistently discussed across various disciplines. While considerable research has examined distance decay in urban transport systems, interregional passenger rail has received less attention. This study addresses this gap by analyzing railway passenger flow data from Guangdong Province, China, to estimate how distance decay differs across space and identify its main drivers. The results reveal that (1) the log-normal decay function best fits the distance decay in interregional rail; (2) differences in decay rate and when the decay begins lead to three distinct distance decay patterns (DDPs); (3) these patterns reflect the combined effects of rail transport supply, travel demand, geographic location and network centrality, showing the need to match transportation services with both travel demand and regional spatial structure; (4) peripheral counties divide into two categories—those oriented toward provincial cores and those acting as gateways, with different rail planning and operation needs. By linking DDPs with regional industrial functions, the alignment between rail planning and industrial spatial development is assessed. The approach in this study can also be applied to other regions and national contexts to map disadvantaged rail areas and to measure inequality in passenger rail, supporting decisions on infrastructure investment and service allocation. Overall, this study advances the understanding of rail distance decay and provides insights for advancing equitable, efficient, and spatially adaptive rail systems.