Impacts of high-speed railway on carbon emission: A comparative study between China and Japan during 21st century

This study investigates the carbon impacts and mechanisms of high-speed railway (HSR) expansions in China and Japan during the 21st century. HSR is often considered a sustainable transport option due to its energy efficiency compared to road transport. However, its influence on urbanization and industrial agglomeration creates dynamics that can either mitigate or exacerbate CO₂ emissions. Using Difference-in-Differences (DID) and Market Access (MA) frameworks, this research examines both local, station-specific effects and broader, network-wide impacts. The findings highlight that while HSR increases carbon emissions in both nations, the underlying drivers differ. In China, rapid urbanization amplifies emissions through the growth of energy and construction sectors around HSR stations. In Japan, station openings have no detectable local effect; emissions rise through network-wide market access, with an elasticity statistically indistinguishable from China's, as secondary industry activities concentrate in cities farther from stations. These results underline HSR's dual role in economic development and environmental challenges, offering valuable insights for sustainable railway planning and policy design.