High-speed rail development and urban environmental efficiency in China: A city-level examination

High-speed rail (HSR) is among the most efficient and environmentally friendly transportation methods available today. Following a phase of rapid HSR development, China has built 35,000 km of operational rail network-the largest in the world. It is important to evaluate the role HSR has played in promoting the sustainable development of Chinese cities. In this study, a heterogeneous stochastic frontier model with undesirable outputs was implemented to measure the environmental efficiency of 273 cities in China from 2005 to 2017. Results showed that the average environmental efficiency increased by 48.7% during this period although there was differentiation between cities. Next, we introduced a difference-in-differences model employing an instrumental variable strategy for further analysis. Results revealed that the implementation of HSR significantly improved the environmental efficiency of the investigated cities. Considering that ordinary-speed rail (OSR) accounts for 74.8% of the total railway network area in China, this study also examined the interactive effect of HSR and OSR. The findings suggested that the positive environmental effects of HSR were lower in cities with an existing OSR system. Therefore, we suggest that the Chinese government consider the presence of existing railway networks when planning new HSR routes to maximize the efficiency of both railway systems. Moreover, we found the treatment effect of HSR on environmental efficiency to vary according to region, economic development, and population size. Specifically, we determined that cities in western China, with lower economic development or smaller population sizes, benefit more from HSR. These findings may suggest that policymakers could utilize HSR as a tool to promote balanced economic development.