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 ‘3 D’s’ (Cervero & Kockelman 1997): Density, Design and Diversity. Individual data allow us to identify the effects of urban form and the spatial sorting of households on emissions. We also use instrumental variables to control for other endogeneity issues. Our results suggest that doubling residential Density would result in an annual saving of approximately two tanks per household, that is approximately 10% of the average yearly fuel consumption of a household in France. Larger gains would result from better urban Design (job-housing centralization, improved rail/bus routes to central business districts, reduced pressure on road construction and a less fragmented built environment in urban areas) while improved Diversity (the concentration of various local amenities such as shops and public facilities) can further help lower fuel consumption. Another important finding is that the relationship between the metropolitan population and car emissions per household is bell-shaped in France, contrary to the United States, suggesting that small cities do compensate for their lack of Density or Diversity by environmentally-friendly Design.

Outreach on this research

« Une ville fractale pour consommer moins de carburant » , 2017, A City Maker Blog

« Spatial planning as a response to the climate crisis? Urban forms and sizes, and the carbon ‘carprint’ of households in France » , october 2019, PSE Economics for Everyone

We study the welfare implications of public good agglomeration externalities in an economic geography framework. We first present new empirical evidence on scale economies in the consumption of local public goods using administrative panel data on French cities. We estimate strong agglomeration gains with an elasticity between 0.46 and 0.56. We then characterize the optimal spatial transfers achieving efficient population distribution in a spatial equilibrium model with endogenous public goods where workers have unobserved location preferences. In standard applications of our framework, we show that the government can improve upon the laissez-faire only when preference heterogeneity is weak enough. When heterogeneity is strong enough, place-based transfers unambiguously create winners and losers. Finally, we argue that the interplay between agglomeration forces and location preferences may justify place-specific transfers on horizontal or categorical equity grounds. We empirically investigate the relevance of these equity concerns in France by investigating the structure of the welfare weights rationalizing observed situations.  Ceteris paribus, the underlying social welfare function compensates low-density places.

By integrating social equity concerns and deviating from a traditionally more utilitarian designof transport networks, can cities reduce spatial inequalities ? This paper relies on an extensivemulti-city Light Rail Transit (LRT) building program of the last two decades in France as well as anovel geocoded individual unemployed database to assess the effects of opening of a new transportoption on individual unemployment trajectories and local social mixity. We find no evidence of anyimprovement in individual unemployment trajectories of the residents of the treated neighborhoodsaround the arrival of LRT. In the medium term we find effects on the housing market consistent withcapitalization of accessibility gains as well as a change in income composition of renters althoughgentrification is limited by the large share of social housings


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