Permeability and interface catchment: measuring and mapping walkable access

The relationship between urban morphology and walkability is central to urban design theory and practice. In this paper, we develop new measures for pedestrian permeability and catchment areas, suggesting that their joint use can progress our understanding of the ways urban morphology mediates walkability. Existing measures of permeability do not account for heterogeneous morphologies. Likewise, measures of pedestrian catchment do not account for what it is that is caught. The proposed “area-weighted average perimeter” and “interface catchments” together integrate both street width and block size, measuring both walkable access and what one gets access to. What is at stake is not only correlations with health and transport, but also measures of walkable access that are geared to the social and economic productivity of the city.