Interactive Effects of Relative Land Transport Infrastructure Improvements on Urbanization in China

Most studies link transport infrastructure to urbanization using mode-specific stocks or absolute scale, leaving the interactive effects of land transport infrastructure (LTI) and their stage-dependent effects underexplored. To fill this gap, this study examines the interactive effects of relative improvements in LTI on the relationship between urbanization and economic development. Using panel data covering 31 Chinese provinces (2000–2022) and the Gompertz function to model urbanization dynamics and the income elasticities. The modeled urbanization growth rate approaches zero near RMB 600,000 per capita, consistent with a saturation level of 12.2; the peak income elasticity is 1.39 at about RMB 90,000. Results by subsample reveal that high-accessibility roads support early urbanization, while rising incomes see conventional rail, high-mobility roads, and high-speed rail sequentially supporting more sustained urban growth. A mid MPA (balanced high-accessibility and high-mobility roads) fosters more advanced and sustained urbanization, whereas high MPA is detrimental to urbanization. Interaction analysis indicates that prioritizing high-accessibility roads and conventional rail best supports urbanization works at low income; conventional rail and high-mobility roads at mid income; and high-mobility roads and high-speed rail at high income; elasticity patterns mirror these stages. The estimates indicate that a configuration of low RPA and high HPM is linked to lower urbanization. These findings highlight the dynamic and stage-dependent impacts of LTI on urbanization, emphasizing that transport infrastructure strategies should be tailored to different stages of economic development to achieve faster and more sustainable urban growth.