"High-Speed Railways and the Geography of Inventors’ Collaboration : Evidence from France" (1980-2010)

Abstract : This paper studies the impact of transportation infrastructure on innovation collaboration between inventors, using the introduction of high-speed railways in France. To conduct our analysis, we use patent data of the European Patent Office from 1980 to 2010 on one hand, and on the other, we construct a novel dataset of city-to-city travel time by train in France. We conduct our analysis at the NUTS3 region level as well as at the region-pair level, using main cities as the reference point for train travel time between regions. First, we rely on a difference-in-difference model to estimate the effect for a region to be connected to the HSR network on its cross-regional patents as well as on its inward regional patents. Second, we estimate a gravity model with fixed effects to test whether the reduction in travel time, due to the expansion of HSR network, has a causal impact on the evolution of bilateral collaboration between inventors of different regions, as well as on the innovation border effect, which refers to asymmetries in collaboration patterns between versus within regions. Results show that after the introduction of HSR, connected regions count more cross-regional patents and less intra-regional co-patents. We also find that regions sharing a border to a treated region count fewer intra-regional co-patents as well, collaborate with more regions, and collaborate more with regions on the other end of the HSR. Finally, the regional border effect is found to decrease with a connection to the HSR network.