A sound empirical and quantitative analysis on the relationship between different patterns of urban expansion and the environmental or social costs of mobility is rare, and the few studies available provide at best a qualitative discussion of these issues. Some recent tentative studies on the metropolitan area of Milan have empirically explored whether different patterns of urban expansion generate different levels of land use and heterogeneous impacts of urban mobility. The results confirmed the expectation that a higher environmental impact of mobility may result from more extensive and sprawling urban development, from recent urbanisation processes and from residential specialisation. The present paper extends the previous empirical analysis to seven major Italian metropolitan areas (namely, Bari, Florence, Naples, Padua, Perugia, Potenza and Turin) in order to corroborate the previous tentative results for the Italian context. The novelty of the present paper is threefold. First, we are interested in exploring the changes that have occurred due to the increased intensity of mobility across a ten-year period, from 1981 to 1991, which corresponds to the Italian economic boom years. Secondly, using an econometric analysis of cross-section data, we consider several metropolitan areas simultaneously, and are therefore able to explore whether there are significant differences in the way the model explains variations in the mobility impact across various Italian urban areas. And finally, we offer a structural interpretation of the causal chain in the explanation of the mobility impact intensity by using Causal Path Analysis as a statistical test framework.
Chiara M. Travisi, Roberto Camagni and Peter Nijkamp
Tinbergen Institute, The Netherlands