Impact of the transit metropolis pilot policy on traffic congestion: Evidence from China

The Chinese government considers the development of public transit a crucial strategy for mitigating urban traffic congestion and reducing carbon emissions. Using monthly congestion delay index data from 62 cities for the period October 2015 to December 2022, this study employs a difference-in-differences methodology to empirically examine the effect of China's Transit Metropolis Pilot (TMP) policy on urban traffic congestion. Our difference-in-differences estimation demonstrates that the TMP policy significantly mitigated urban traffic congestion. Further analysis revealed that the TMP policy significantly increased the number of public transit vehicles and ridership while significantly reducing the ownership of private vehicles and civil vehicles, which provides indicative evidence of the underlying mechanisms behind the observed effects. Finally, our heterogeneity analysis shows that the congestion alleviation effect of the TMP policy was more pronounced in cities with higher congestion levels and lower per capita GDP and that this effect was not influenced by the presence or absence of a rail transit system. This study offers valuable insights for policymakers into how to effectively mitigate urban traffic congestion and build a sustainable urban transportation system.