How does the location of high-speed railway stations affect the emission reduction effect of industrial structure upgrading?

The opening of high-speed railway (HSR) has accelerated the reorganization and reallocation of regional production elements, and constantly promoted the adjustment and upgrading of industrial structure. The cleaner production effect produced by industrial structure upgrading is of great significance to industrial pollution reduction. As a bridge connecting resources within the city and elements outside the city, the location of HSR stations has become an important factor affecting the structural emission reduction effect. Based on the data of 285 prefecture level and above cities in China from 2004 to 2018, this paper investigates the structural emission reduction effects of HSR opening and the impact of HSR station location on it by employing difference-in-differences (DID) model combined with mediation effect method. The results demonstrate that the opening of HSR has significant structural emission reduction effect, and the upgrading of inter-industry structure and the intra-industry structure are important mechanisms for HSR to achieve industrial emission reduction. The structural emission reduction effect of HSR opening is closely related to the location of HSR stations. With the increase of the distance between HSR station and city center, the industrial structure upgrading effect will continue to weaken, thus inhibiting the exertion of structural emission reduction effect, of which 10 km away from the city center is the optimal site strategy for the HSR service to give full play to the structural emission reduction effect, and exceeding 50 km will be significantly detrimental to its role in promoting industrial structure upgrading.