How to assess urban quality: A spatial multicriteria decision analysis approach

From the early 1990s the quality of public space is at the centre of the Agenda of major European cities. Today, more than before, the health emergency due to the Covid-19 pandemy has pointed out the importance of the relationship among public space, quality of life and health. Public and semi-private spaces, especially in high-dense cities and in the most affected areas by Covid-19, represent a strong driver both for restarting and for helping cities to face the new normal age. Despite the advancement of research during the past two decades and empirical evidence about the relationship among quality of open spaces, quality of life and urban sustainability, there is still a lack of studies on how to measure the quality of open spaces. Among the several research lines, the Urban Design approach across its evolution has always focused on it, starting from aesthetic as well as technical issues and increasingly including the social and economic ones. The current paper proposes an integrated approach supported by Geographic Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) able to provide a comprehensive evaluation of the quality of open spaces under the Urban Design perspective. In detail, the issue of urban quality has been divided into 5 criteria and 12 sub-criteria which consider both the characteristics of the built environment and its organization and the perception of users. The evaluation process has been structured according to the traditional steps – Intelligence, Design and Choice – and it has been applied to three different areas in the city of Milan, in order to achieve a broad measurement of urban quality with respect to various urban locations. What’s new in this research is the spatialization of the urban quality scores and their assessment based on specific value functions, that shows potentials for future implementations in the sphere of urban planning, where the proposed evaluation approach could be applied with different purposes: an evaluation model for supporting public and private planning agreements by the use of value maps; a companion guide with operational recommendations for open spaces design; a model to estimate the marginal price of the urban quality through hedonic price analyses.