Urban Polycentricity and the Costs of Commuting: Evidence from Italian Metropolitan Areas

Polycentricity at the metropolitan scale is perhaps the model of spatial organisation that needs to be investigated more thoroughly as regards its effects on travel. The aim of this paper is to test the role of polycentricity-as well as other spatial characteristics, such as compactness, functional diversification and size-in the costs of commuting, taking into account an external cost component (per-capita CO2 emissions) and a private cost component (time spent on travelling). The degree of urban polycentricity has been measured by adopting a dynamic approach based on commuting flows and on social network analysis tools. The analysis is carried out using a database of 82 Italian metropolitan areas (MAs). Results show that MAs with a higher degree of polycentricity are more virtuous both in terms of private and external costs of mobility, while the degree of compactness is associated with lower environmental costs but with higher private costs. Size is associated with both higher external and private costs, while the role of functional diversification turns out to be statistically insignificant. Socio-demographics also play a role.