The “Franges franciliennes” are a ring of an average width of 50 km between the Ile-de-France region (in which is Paris) and the five around it. There live more than 3,5 million people, a population growing faster than in neighboring areas.
On this space there are logics at play that are similar to those at play between the provinces of Madrid and Toledo, or at other limits between coterminous jurisdictions with diverging legal or planning status. As there were differences during the XIXth century between the central cities with their planned extensions and the slums in neighboring towns in which the lack of an equivalent control favored more loose development, a regulatory border can always provide fringe issues.
There is a network of mid-sized cities (Meaux, Beauvais, Chartres, Melun…) with roles including administration, tourism (Fontainebleau, Chantilly) and retail. The land is quite fertile, being one of the main agrarian areas in the country. The relation with the metropolitan core is complex, but overall of dependence. In urban planning terms, the conjunction of a growth pressure through metropolitan dynamics and of the very French municipal micro divisions can certainly favor sprawl: municipalities with small populations and scarce technical services, in which a local politician can be easily seduced by a real estate project which would be small in a large city, but which here can represent a large percentage of the existing urban tissue (and the possibility, through the increase in population, to get more public services). Despite the evolution of the French law favoring regional planning, some dynamics are complex.
At a given moment the Ile-de-France regional planning scheme even considered that the urban growth limits were not to be applied to the small municipalities in these areas, as development would occur in more central areas; in a crisis situation, it was precisely on these fringes that an part of the growth occurred, as it was simpler… and as always, on cheaper land…
According to SDRIF 2012, the priority must be to limit the use of agrarian, wooded and natural spaces, so encouraging urban development through densification of already urbanized spaces. The surface and continuity of the impervious spaces must be limited, and the per capita share of impervious area must not be increased. In municipalities with less than 10% of their area with farmland, woods, natural spaces or urban green spaces, there should be an increase in ecological potential areas.
The new growth capacities must be defined taking into account the needs up until 2030, with in an imperative for continuity with preexisting urban tissue. But the “non cartographic extension capacity” is offered to the “moderate extension of towns, villages and hamlets”. Under this chapter, by 2030 an increase of the urbanized space of around 5% is allowed; the reference calculation must be based on the urbanized space at the date in which the SDRIF is enacted, excluding farmland, woods, natural spaces and water, the spaces of non-built character of supra municipal condition (energy systems, airports…) and the urban open spaces (parks, campings, large stadiums…). It is possible to redistribute this capacity among a pool of municipalities through regional planning.