The Effects of Subway Expansion on Traffic Conditions: Evidence from Beijing

Does public transportation reduce vehicle congestion? Using a regression-discontinuity framework, we examine the effect of six subway openings on short-run congestion in Beijing between 2009 and 2015. We find that vehicle congestion drops sharply immediately after new subway openings. In our central specification, each of the subway openings decreased delay times by an average of 15% in the short run over the city of Beijing.