Mobilities and the flexible boundaries of the neighbourhood: a test with crime data in Barcelona

This paper incorporates an explicit mobility dimension into the definition of the neighbourhood and explores its possible implications for the study of spatially distributed phenomena. We analysed the distribution of robbery and theft in Barcelona, Spain, as a testing application. Crime data were aggregated to nonoverlapping units (census tracts) and to a new measure of overlapping neighbourhoods, that we named 'walkhoods', accounting for the distance that can be covered in 5 min at a walking speed of 1 m/s, considering all possible physical barriers. The outcomes of regression models shed new light on the relationship between mobility and crime. When the walkhood scale is established, human mobility patterns have a stronger effect on the outcome variables than when census tracts are used. Results point to walkability constraints and social distances imposed by the massive presence of sporadic users in public spaces as strong predictors of crime occurrence, arguably due to their negative effects on neighbourhood social ties formation. Our findings suggest that more flexible definitions of the neighbourhood could address the social and spatial heterogeneity of urban spaces more properly than traditional approaches.