On the joint impact of high-speed rail and megalopolis policy on regional economic growth in China

This paper quantifies multifold effects of megalopolis (MP) and high-speed railway (HSR) inaugurations on regional economic growth, in the context of MP and HSR development in China during 1996-2017. Three types of policy interventions are examined, i.e., MP inauguration, HSR introduction, and the joint intervention of MP and HSR. The difference-in-differences (DID) method is adopted to quantify these effects among different groups of prefecture-level cities in China. Specifically, we firstly examine the effects of MP and HSR inaugurations on prefectural economic output, respectively. The simultaneous and joint impact of MP and HSR is then estimated by examining the effect of their interaction. We find that while both MP inauguration and HSR induction have stimulating effects on regional economic growth, the effect of MP inauguration is dominating. Moreover, the joint intervention of MP and HSR is significantly larger than either MP or HSR, and even larger than the sum of two individual effects. Comparing the effects of HSR among different city groups, we find that MP cities are likely to benefit more from HSR service than those not in an MP. Among various MPs, the joint intervention tends to be associated with larger economic growth in MPs with better economic development foundations. These observations imply that the strategical and transport policy interventions have reinforcing effects on one another. However, the simultaneous impact may contribute to regional development disparity since the most developed regions may benefit more from the joint intervention by siphoning resources from disadvantaged regions. Overall, the results shed lights on the interactive developments of transportation infrastructure and urban agglomerations.