Exploring traffic evaporation : Findings from tactical urbanism interventions in Barcelona

Traffic evaporation - i.e. the opposite of induced traffic - is acknowledged as a well-established phenomenon which presents important implications for local urbanism and mobility policies, but there continue to be few academic studies which explore this issue in detail. This paper explores relative levels of traffic evaporation following the implementation of multiple tactical urbanism interventions on 11 streets in Barcelona in the context of the COVID-19 pandemic. Based on the analysis of publicly available traffic count data, the findings provide empirical support for the existence of significant levels of traffic evaporation following road space reduction. On average, traffic levels on streets with interventions diminished by −14.8 % relative to streets in the rest of the city. In the wider vicinity of intervention streets, traffic levels also decreased slightly on average (−0.9 %) compared to the rest of the city, except on immediately adjacent parallel streets to those affected by interventions, which reported a small relative traffic increase (+0.7 %). Overall, these findings provide further support for street redesign policies which entail the reduction of road space for motor vehicles, and suggest that fears of traffic congestion following such schemes may often be unfounded. From a methodological standpoint, this study also offers a transparent method of evaluating traffic evaporation which could be replicated in future studies