A walker's paradise ain't a driver's hell: Evaluating the causal effect of temporary road pedestrianization on traffic conditions of surrounding roads

This study uses a natural experiment approach to evaluate the causal effect of three regular road pedestrianization schemes in Central Tokyo on traffic conditions in surrounding areas. Cross-sectional traffic volume data collected by the Metropolitan Police Department via traffic counters was used as the dependent variable and causal effect evaluation was done via a difference-in-differences (DID) approach, where the temporal pedestrianization of a street was used as the treatment of interest. We take advantage of (1) the variability in pedestrianization execution days and (2) the seasonal variability in pedestrianization time periods, to define the natural experiments. Furthermore, three different buffer areas of 500 m, 750 m and 1000 m were used to evaluate the sensitivity of effect estimates to the definition of the impact area. No evidence of severe increases in traffic volume in the surrounding areas of pedestrianized roads was found, suggesting that human-centric network design is not necessarily a zero-sum game between pedestrians and drivers. While small increases in traffic volume of around 5 % and slight increases in congestion near pedestrianized links can be expected, these changes are unlikely to translate into worsening traffic conditions and can be managed by the existing road network in Tokyo.