Development and implementation of a quantitative multi-metrics methodology to characterize urban Permeability

This study aims at highlighting a morphological property of urban CAS (complex adaptive systems), Permeability, by introducing a set of quantitative metrics for its definition. It defines a strategy for the analysis of urban permeability, reproducible on any urban context. Our approach is multidisciplinary and moves from the idea that the urban structure can be seen as a porous medium where buildings represent solid elements and open spaces represent the pores. The selected metrics include concepts like tortuosity and constrictivity, which are routinely employed in fluid mechanics to characterize mass transport through porous domains. We showcase the proposed methodological framework on three different types of urban structure for three cities. The results highlights and quantify morphological differences between urban areas developed in different historical periods. Results are arranged in diagrams to provide a new objective perception of urban permeability as a synergetic emergence between constituent parts of the urban fabric.