The improvement and substitution effect of transportation infrastructure on air quality: An empirical evidence from China's rail transit construction

A large number of studies on road construction and rail transit have not taken the improvement effect and the substitution effect into account. Using the quarterly data from 2013 to 2016 of 28 cities with metro opened in China, this research firstly compares the improvement effect of road reconstruction with the substitution effect of rail transit construction on air quality. Empirical results show that urban rail construction exerts a greater marginal impact on improving air quality than urban road reconstruction. Then, we employ operation length of urban rail transit as a long-term proxy variable and the length of rail built in season as a short-term proxy variable of rail transit construction to make a further discussion. In general, rail transit has an air pollution reducing effect in the long run, while the construction of rail transit has a negative short-term effect on air quality. Based on above findings, governments should take measures to conduct convenient and efficient urban transportation network, and guide the construction of rail transit to multi-level development.