Impacts of vehicle restrictions on urban traffic speeds and transit ridership: an empirical analysis using high-frequency data

The impacts of vehicle restrictions in Santiago, Chile, on the average speeds of vehicle traffic and public buses as well as on transit card validations are quantified using novel high-frequency data, coming from millions of records from a ride-hailing service and the city’s public transport system. The restrictions were in force on weekdays during May through August between 7:30 am and 9 pm in urban districts, and applied on a given day to 20 % of the stock of vehicles registered before September 2011. The quality, frequency and spatial coverage of the data we use allow us to estimate not only classic methods like before-and-after and differences-in-differences, but also triple differences, which allows for a higher number of control variables. All these methods arrived at the conclusion that the restrictions produce small increases in speed vehicle traffic (between 3.3 % and 4.2 %) and bus speeds (between 1.8 % and 2.3 %); no increases in the use of public transport were detected. Three likely reasons for the size of the effects are the low percentage of vehicles subject to the restrictions on any given day (approximately 6.9 %), the tendency for frequent drivers to be from higher-income groups and thus to own newer vehicles, and widespread violation of the restrictions due to weak enforcement with low fines.