High-speed rail, urban form, and regional innovation: a time-varying difference-in-differences approach

Abstract

China's high-speed rail (HSR) construction provides an ideal ‘quasi-natural experiment’ in which regional issues are investigated. This study explores how HSR affects innovation efficiency and explores the mediating effect of urban form. Based on panel data comprising 280 cities in China from 2006 to 2016, this study uses a time-varying difference-in-differences method to analyze whether HSR affects regional innovation, and it explores the mediating effect of urban form. The results show the following. (1) HSR significantly promotes regional innovation. The parallel trend test shows that the treatment group and the control group have the same trend before HSR construction. (2) Knowledge spillovers are important manifestations through which HSR promotes regional innovation. HSR can significantly improve the level of total factor productivity and human capital. (3) Urban form mediates the impact of HSR on regional innovation significantly, which varies across the different indexes of different urban forms.