The impacts of aviation and high-speed rail on urban innovation capacity in China

Transportation is the physical carrier of knowledge and technology spatial flows such as talent and capital flows in innovation networks, and its impacts on urban innovation capacity have become a cross-cutting frontier in economic geography. Based on the city-scale data of China from 2007 to 2018 and taking air and high-speed rail transportation as examples, this study constructed a theoretical framework for the effect of transportation on urban innovation capacity, adopted the two-way fixed-effects panel regression model to empirically test the multiple heterogeneity mechanisms of aviation and high-speed rail on urban innovation capacity, and explored the mediation effects of knowledge dissemination, capital accumulation, and industrial upgrading between transportation and innovation capacity. The results are as follows: 1) Both aviation and high-speed rail development have significant positive impacts on urban innovation capacity, and the spillover effect of high-speed rail on urban innovation is about three times that of aviation. 2) The innovation spillover effects of aviation and high-speed rail on different types of cities are significantly different. In terms of urban grade heterogeneity, the positive impact of aviation and high-speed rail on the innovation capacity of central cities is higher than that of other cities. In terms of population size heterogeneity, aviation has a significant positive impact on the innovation capacity of large and medium-sized cities and an inhibitory effect on small cities, while high-speed rail transportation has a positive impact on urban innovation capacity of cities of different population sizes, showing the trend of large cities > medium-sized cities > small cities. In terms of regional heterogeneity, aviation and high-speed rail have improved the innovation capacity of the eastern, central, western, and northeastern cities of China in varying degrees with a significant Matthew effect, and eastern China has a prominent dominant position. 3) Both aviation and high-speed rail can indirectly promote urban innovation capacity by stimulating technology transfer, venture capital allocation, and foreign capital allocation. Aviation can also indirectly promote urban innovation capacity by stimulating industrial upgrading.