신칸센 신규 개통이 일본 국내선 항공 수요에 미친 영향에 관한 연구: 호쿠리쿠 신칸센 연장을 중심으로

Effect of New Shinkansen Openings on Domestic Air Demand in Japan: Evidence from the Hokuriku Shinkansen Extension

Purpose: This study examines the impact of the Hokuriku Shinkansen extension to Kanazawa on overall domestic air passenger demand at regional airports in Japan. While Japan possesses one of the world’s most extensive high-speed rail networks, empirical evidence on how new Shinkansen services affect regional airport demand remains limited. Research design, data, and methodology: A Difference-in-Differences(DiD) approach was employed using annual domestic passenger data from 15 Japanese airports between 2012 and 2019. Komatsu and Toyama airports were selected as the treatment group because their major Tokyo routes became directly competitive with the Hokuriku Shinkansen after its extension to Kanazawa in 2015. Thirteen airports located in regions without Shinkansen services were selected as the control group. Airport and year fixed effects were included, and several robustness checks, including event-study analysis, placebo tests, Driscoll–Kraay standard errors, Wild Cluster Bootstrap, and randomization inference, were conducted. Results: The results indicate that the Hokuriku Shinkansen extension reduced overall domestic passenger traffic at Komatsu and Toyama airports by approximately 43% relative to the control airports. Airport-specific estimates show that the relative decline was larger at Toyama Airport than at Komatsu Airport. Event-study results support the parallel trend assumption and reveal that the negative effect persisted and intensified after the opening of the Shinkansen extension. Robustness checks consistently confirm the main findings. Implications: The findings provide empirical evidence that high-speed rail can substantially substitute for regional air transport. The study offers policy implications for regional airport management and future transportation infrastructure planning in Japan.