Caractérisation des tissus urbains à partir de l’analyse structurelle des réseaux viaires

Abstract

Street networks shape the urban layout that structures the city spaces and delineates homogeneous urban areas. We focus on the study of urban morphology from a structural analysis of the streets’ network. The work on a geographic model allows formalizing mathematically the street network by using graph theory. The structural analysis of street networks is very useful because it usually produces additional (hidden) semantic information and allows the enrichment of spatial data.The aim of this work is to perform some characterization of the urban fabrics using exclusively street networks as input data. Indeed, the structural properties of streets networks create several effects such as continuity, separation, centrality, proximity, connectivity, symmetry, and adjacency into the urban space.We work on an urban primal graph. On the basis of this real urban graph, we implement two additional artificial graphs. The first one is a “Delaunay triangulated network” and the second one is a “minimum spanning tree”. These graphs correspond to two extreme network morphologies delimiting a morphological continuum. The three graphs are then analyzed using shortest path algorithms. They all have been processed on both a topological and a geometric ways so as to extract some structural and multi-centrality indicators (closeness and betweenness centralities).The results produce some semantic information on the structure of urban fabric. They allow us to emphasize some specific morphological urban structures (organic zones, suburban tree structures) and some urban salient features (main roads and ring roads).

Keywords

• graph theory
• street network
• structural analysis (morphology)
• urban fabric
• Nantes