Subcenters, mode choice and transport policies: evidence form Nantes[Nouvelles centralités, choix modal et politiques de déplacements : le cas nantais]

In this paper based on empirical microeconomic choices of households, we use the hedonic pricing method to define the urban form of Nantes Métropole. The number of Central Business Districts (CBDs) should guide the second generation of transport policies in agglomerations subject to the LAURE law (law on air and the rational use of energy). Thus, if improved accessibility is capitalized into residential property values close to public transport, then strengthening the current incentive policy in favor of public transport networks and active modes seems appropriate to continue to limit the negative externalities generated by car trips in urban areas. Conversely, if improved accessibility is capitalized close to major roads, then a more coercive policy can take over in the form of an urban toll: this will generate revenue to subsequently improving the public transport network. In fact, the Spatial Durbin Model (SDM) reveals that Nantes situation matches neither the one nor the other of these patterns. In line with the theoretical background, acting on travel costs would nevertheless lead to a higher demand for centrality by house purchasers. So the major component of the local environmental policy could be a prior land-use policy involving a better control of space consumption at any point of the city, coupled with the potential implementation of an urban toll.