The Parisian peripheral boulevard, inaugurated by Prime Minister Pierre Messmer on April 25, 1973, is only celebrating its half-century, but, for many, it already embodies urban prehistory. Monument of nuisances whose benefits have been exhausted, it concentrates everything that we no longer want in the cities of the 21st century: congestion, noise, urban heat islands, CO2 and fine particle emissions, thermal mobility individual, but also social separatism. While it had to connect, connect, accelerate, it has become a double enclosure that freezes the little Paris and locks motorists in their own pollution.

Last January, during a morning organized by the Ville hybrid club, Emmanuel Grégoire, first deputy to the Paris City Hall responsible, in particular, for urban planning, architecture and Greater Paris, declared that destroying the device was “a fantasy”.

Sure, but how do you rebuild it? Noise-reducing coatings, revegetation, lane reserved for collective use, covering of certain portions, passage from four to three lanes: there is no shortage of projects to update the ring road and are at the heart of the work of the Parisian Urban Planning Workshop.

If a consultation has just been opened on the “modalities of the lane project dedicated to carpooling and public transport”, these are all possible ways of the future of the ring road that should be opened up to the project. The concepts forged by welfare economics could serve as a compass here.

The first question is what is meant by “infrastructure”. For Karl Marx, it is a foundation made up of productive forces and relations of production on which rests a superstructure, itself on two levels: institutions and ideologies.

Very recently, this issue of definition was raised, across the Atlantic, around the investment plan wanted by US Democratic President Joe Biden. In November 2021, Congress adopted only one of the three pillars of the initial plan, that entitled “infrastructure”, understood in the narrowly material sense of the term: 1,200 billion dollars were committed over ten years to maintain bridges, roads and enable the deployment of a high-speed Internet connection anywhere in the United States.

It will be necessary to wait until August 2022 to snatch from the Republicans a plan on climate and health, to the tune of 370 billion dollars, very far from the approximately 1,750 billion hoped for by the progressives: capital measures for the energy transition, the care or access to university, have been withdrawn.

In the United States, therefore, superstructures continue to undermine social and ecological infrastructure. How, in Île-de-France, do better and think about urban social-ecological infrastructures from the economy of well-being? What face would the ring road have in the post-growth city?

The first face of the post-growing city is the shrinking city, an object still largely unthought of in academic literature. We can distinguish three urban declines in descending order – as long as possible – of importance.

The first decrease, undoubtedly the least explicit and yet the most essential, is the disartificialization of the soil, in the wake of the climate and resilience law of August 22, 2021 and the principles of land sobriety and urban densification. This could well turn out to be, quietly, the first French degrowth policy.

The third degrowth, finally, is urban deceleration, which aims to reduce not only the volumes of material flows consumed by cities – urban metabolism – but the speed of human flows in cities. The “quarter-hour city” is the paradoxical watchword, partly masking the issue of digital deceleration.

The second face of the post-growth city has already been experienced in Brussels and Amsterdam. This is the City of Donuts, a model inspired by the work of British economist Kate Raworth. It aims to find, for each place, a social floor and an ecological ceiling between which to situate activities: a minimum of resource consumption is necessary to satisfy basic needs, but there are also dangerous thresholds to cross.

Kate Raworth is trying, with her team, to implement her theoretical intuitions in a Donut Economics Action Lab (DEAL), which inspired the Brussels Donut project. In particular, it proposes to answer in an empirical, coherent and integrated way the following four questions: “what would it mean for the inhabitants of the territory to live a fulfilling life? “What would it mean for the land to thrive in its natural habitat?” “What would it mean for the territory to respect the well-being of all people around the world?” “What would it mean for the territory to respect the health of the planet?” “.

The third and last face of the post-growth city is the city of well-being, which would put social cooperation and full health – both physiological and psychological, individual and collective, human and ecological – at the heart of territorial policies. This city of well-being is not a city of attractiveness: its priority is the well-being of the people who live on its territory rather than that of the people who do not live there but would like to make their capital live there.

Three recent initiatives allow us to better consider this. The first, initiated in Grenoble, consists of proposing to pilot the city with health-environment indicators to deduce public policies aimed at co-benefits and environmental justice. Indicators recently produced for the metropolis of Lyon make it possible to imagine this type of management.

At the heart of this city of well-being lies cooperation rather than collaboration. One could think of these terms as synonymous, but collaboration is exercised by means of work alone, for a determined duration and purpose, while cooperation calls on all human capacities, over a long horizon, in a free process. mutual discoveries.

As we can see, the worlds of post-growth emerge and evolve in the urban universe, in France as elsewhere, as far from their caricatures as they are close to the realities and challenges of their time. As these approaches flourish and converge across Europe, can the great transformation of the Parisian ring road come down to leveling up with the American highways of 50 years ago? The first lane for collective use, bus and carpooling, was indeed opened in Washington in 1973, the year of the inauguration of the ring road.

The transformation projects of the gates in place, such as those in progress at Porte Maillot or under debate at Porte de Montreuil, nevertheless draw new horizons: to stitch together Paris with the neighboring municipalities and to promote cooperation between territories and between inhabitants. Interchange spaces, designed with a view to streamlining and optimizing car traffic, would be intended to become living spaces.

The Parisian executive is also looking for spaces to set up urban forests and could want to make the ring road a green belt, that is to say also a belt of freshness to face the heat waves. The benefits in terms of health and justice would be considerable.

The need to build an infrastructure for full health corresponds to the need to design it as a just transition, in which the inhabitants would be fully associated. It is certainly ambitious, but the idea was at the heart of the Routes of the Future of Greater Paris and it could put human well-being, social justice and democratic participation, now peripheral, back at the center of Ile-de-France policies.

* Éloi Laurent teaches at Sciences Po and Stanford University, senior economist at the French Observatory of Economic Conditions.