Scattered or polycentric? Untangling urban growth in three southern European metropolitan regions through exploratory spatial data analysis

The present study illustrates an exploratory spatial data analysis (ESDA) aimed at investigating changes in the distribution of built-up areas in three southern European metropolitan regions (Barcelona, Rome and Athens). An approach based on global Moran's indexes of spatial autocorrelations was proposed to assess similarities in the spatial organization of the three regions, based on land-use data for 1960 and 2010. Compact monocentric, scattered low-density and mixed polycentric structures were compared in the three regions using local Moran's indexes computed at two different scales, "urban" (5 km radius) and "regional" (20 km radius). The proposed approach identifies emerging trends in scattered monocentric or polycentric development. Our results outline the trend toward scattered urban expansion for the three cities, with signs of a modest shift toward polycentrism in Barcelona. ESDA provides basic information needed for policies promoting spatially balanced, sustainable development in originally compact and economically segmented regions.