Driving restrictions, traffic speeds and carbon emissions: Evidence from high-frequency data

We investigate the effect of driving restrictions on traffic speeds and calculate the implied reduction in carbon emissions using empirical evidence from the city of Xi'an in China. We obtain high-frequency road-section-level transportation data from the Didi Chuxing Technology Company and use a regression discontinuity design (RDD) to identify the causal effect of driving restrictions on vehicle cruising speeds by exploiting a policy variation in 2018. We find that the driving restrictions led to an increase in vehicle cruising speeds of up to 15–20% during peak hours, which consequently dramatically reduced carbon emissions. Based on our back-of-the-envelope calculations, carbon emissions from private vehicles could be reduced by 2.2–5.8% thanks to increased fuel efficiency due to less traffic congestion.