Is the High-Speed Rail Opening Environmentally Friendly? Taking the Difference-in-Differences Test in Jiangsu, China

In view of rapid development of high-speed rail, the relationship between high-speed rail and air pollution needs to be tested and determined. Most research studies focused on the impact of high-speed rail on environmental pollution and just viewed high-speed rail as a control variable, which lacked a direct study on this relationship. Also, these rarely involved regional research, which is short of pertinence and insufficient understanding of regional issues. Therefore, based on the difference-in-differences (DID) model which is a natural experiment evaluation method, this study examined the impact of high-speed rail opening on air pollution by using the panel data of Jiangsu province, China, from the year of 2000 to 2017. The empirical results showed that the opening of Jiangsu high-speed rail, which increases cities’ good day significantly by 21.5%, has inhibitory effect on air pollution. Among control variables, there is no inverted “ U ” relationship between the economic development level and air pollution. Personal income and urbanization significantly improve air pollution, whereas foreign direct investment exacerbates it. And the results are still valid after robustness tests, including trend test and counterfactual test. Moreover, this study explores the relationship between the degree of reducing pollution caused by high-speed rail and the location of cities, which found that the opening of high-speed rail can greatly improve air pollution of areas in central city circle. Finally, it is found that when high-speed rail and other possible pollution items coexist, the improved effect of high-speed rail on air pollution is still obvious. Therefore, in order to exert the mitigating effect of high-speed rail on air pollution, it is necessary to rationally plan high-speed railway lines and develop the high-speed railways in cities closer to Shanghai.