The historic Renault factory, the driving force and the symbol of French industry for much of this century, is to make way for this new, "green" urbanisation. The factory was often thought of as an indicator of the health of French industry, "When Billancourt comes down with a cold, all France coughs" the saying went. As the largest factory close to central Paris, its employees played a pivotal role in the May 1968 uprisings. Jean-Paul Sartre even addressed a meeting at the factory gates.
The land is an architect's dream in terms of location, size and opportunity. It covers 70 hectares (approximately the size of the le de la Cite in central Paris) and all its existing buildings, once the cutting edge of the European car industry, are due to be demolished.
Bruno Fortier, 48, is the architect who won the three-horse race to redesign the new island, and areas of land on the river banks on either side, at Meudon and Boulogne-Billancourt. The factory, closed since 1992, now looks forlorn, "a huge empty carcass" in Fortier's words. It will be knocked down to make way for small clusters of offices and residential buildings among green parks.
Fortier, whose other projects include developing Nantes town centre and the area around the TGV train station in Marseilles, was the preferred candidate of Jean-Pierre Fourcade, mayor of Boulogne-Billancourt, and when the three plans were put to a local referendum his came top of the poll with 57 per cent of the votes.
Talking to The Independent, Fortier explained the appeal of his design. "I have tried not to devote everything to buildings and construction, but, on the contrary, to create a breathing-space by freeing the banks from traffic and creating numerous green spaces."
"The presence of cars along the banks of the Seine in the centre of Paris is hellish. What I wanted to do was to divert the traffic into the built- up areas and liberate the banks, as the Boulevard St Germain does in the sixth arrondissement." So on the Boulogne-Billancourt bank Fortier has ensured that traffic passes through the centre of the town, and has created a pedestrian walkway alongside the river.
On the island itself, the architect has "kept vehicles to a minimum". The north side has a small road at ground level but on the south side traffic goes underground. All car parks will be situated beneath the buildings. The outer periphery is a green trail reserved for pedestrians and cyclists.
Fortier concedes that "it will take great determination to ensure that these plans are executed. The features that have attracted people, are the very ones that frighten them. They like the idea of having tranquil footpaths alongside the river but they worry about the traffic and the noise from the diverted roads through the town".
The residents of Boulogne-Billancourt will have a new park by way of compensation. In this respect Fortier's project is original, in that the park runs parallel to the Seine. "There is a habit in Paris to build parks perpendicular to the Seine, such as the Champs de Mars near the Eiffel Tower, but I decided to opt for a parallel park that mirrors the magnificent Parc de Saint-Cloud on the opposite hill".
The Communist contingent of the local council are dismayed that environmental considerations are outweighing industrial ones. The Communist vice-president of the regional council for urban development, Jocelyne Riou, explained: "Fortier's project puts too much emphasis on the environment and the standard of living, without realising that the latter is dependent on jobs."
Fortier counters this by saying that it has not yet been decided what will go into the new buildings, so the number of jobs to be created is unknown.
There has been talk of the island being used as the Olympic village, if France wins its bid for 2008. Another suggestion is a science research centre - a proposal perhaps fitting to the birthplace of the car.
Whatever their eventual use, the buildings Fortier has designed are in harmony with the island. The clusters are not in a straight line, but curve as the island curves. None of the dwellings is more than six storeys high, in keeping with a government directive.
Fortier, however, is a little critical of this constraint. "It stems from the catastrophe of the Sixties when too many sky-rises were built. But there can be an adverse tendency to build dense blocks of three-storey buildings that look just as crap. Personally I think different heights provide interest."
The four "gardens" between the buildings are further proof that Fortier's project has been put together with the pedestrian in mind. "I would like those who walk around the le Seguin in 2015 to appreciate it... and hope that the area becomes truly memorable".
However, there are still obstacles to be overcome: the old factory site must be cleaned, a new bridge is to be built, and Fortier must battle to retain what he regards as the key features of his proposal.
And money. At a time when the state is trying to redress the imbalance within Paris, it will be difficult for a site located in the already rich west to procure funds, when projects in the poorer northern and eastern areas of the city are a priority.