The Carbon `Carprint' of Suburbanization: New Evidence from French Cities

This paper investigates the impact of urban form on households' fuel consumption and car emissions in France. We analyze more particularly three features of cities commonly referred to as the `three D's' (Cervero and Kockelman, 1997): Density, Design and an innovative measure of Diversity. Individual data allow us to circumvent selection issues, as some households may live in a location consonant to their socioeconomic characteristics or travel predispositions, while instrumental variables help control for other endogeneity issues. The results suggest that, by choosing to live at the fringe of a metropolitan area instead of its city-center, our mean-sample household would bear an extra-consumption of approximatively six fuel tanks per year. More generally, doubling residential Density would result in an annual saving of approximatively two tanks per household, a gain that would be much larger if compaction were coupled with better Design (stronger jobs centralization, improved rail-routes or buses transiting to job centers and reduced pressure for road construction), and more Diversity (continuous morphology of the built-up environment). Another important finding is that the relationship between metropolitan population and car emissions is not linear but bell-shaped in France, contrary to the US, which suggests that small cities do compensate lack of Density by either a better Design or more Diversity.