Inter-city transport hubs and intra-city polycentric structure:Evidence from high-speed rail stations and airports in China

Transportation infrastructure plays a pivotal role in shaping urban spatial structure.Although numerous empirical studies have examined the impact of intra-city transport system on urban spatial structure,research on the impact of inter-city transportation infrastructure remains limited.This paper addresses this gap by accurately measuring the influence of inter-city transport hubs on urban spatial structure using calibrated nighttime light satellite images spanning from 2000 to 2020 in China.Through a series of time-varying difference-in-differences and event studies,we discover that the introduction of high-speed rail(HSR)stations and airports has a significant positive impact on polycentricity.However,the average effect masks great heterogeneity concerning the geographical location,transport accessibility,and local development level of these transport hubs.In cities experiencing population growth and a thriving service sector,HSR stations and airports situated far from the existing city center yet offering high accessibility play a crucial role in fostering urban polycentric development.These findings highlight the potential of inter-city transport hubs as effective policy tools for promoting urban polycentric development.