French architect and engineer Marc Mimram is realising his first inhabitable bridge, spanning the railway lines near Gare d’Austerlitz in Paris
Marc Mimram trained as an architect and then as an engineer, spending 15 years working for the likes of Renzo Piano and Rem Koolhaas, before returning to architecture and setting up his own practice with a mission to embrace both buildings and infrastructure as vital pieces of city-making that should enhance the experience of the city for its users. He has been championing the idea of inhabited infrastructure since as far back as 2008, when he gave a presentation at Columbia University in New York on ‘living bridges’. He suggests that bridges are one of the last, most vital, pieces of public space, places for socialising and communing at the heart of a city.
He is currently constructing his first habitable bridge - The Panorama - spanning 58m across a stretch of railway track, without intermediary support, in Paris, near the Gare d’Austerlitz.
What is the size of this inhabited bridge, and how many people will use it once completed?
The area of the inhabited bridge is 21,000 sq m, and we anticipate around 980 people will occupy it. The Panorama buildings will be occupied by an insurance company.
The Panorama buildings sit above the railway line, spanning it without intermediary support
How have you developed the structures, both of the bridge and the buildings on top of it?
The bridge itself spans 58m across the railway tracks. A series of box structures, like towers laid on their side, will sit on top of this. The horizontal core is a truss beam and the facades are Vierendeel beams without diagonals. The stress density is expressed in the series of punctuations in the facades.
The structure is mainly concentrated in the first two levels of the beam bridge boxes. This releases the rest of the building completely from structural constraints, frees up the plan and facades and gives the opportunity to develop new typologies for the offices through design interventions such as terraces and loggias.
What special structural techniques, materials and forms are you using to maximise the bridge’s strength, and moderate the buildings’ weight on top of the bridge?
We used very high-inertia beams for spanning the gap. The beams are developed on two or three levels [10m high]. They are made of high-stress steel limited to the vertical cores [elevations and stairs].
The bearings of the whole structure are dynamic dampers. These devices permit a reduction of the railway’s vibrations.
This section shows the railway lines running below
You have said that bridges should be celebrated as public space: how are you making sure this bridge is democratic, an asset to the community?
Through history, power has been represented by buildings, and usually large buildings — from castles and cathedrals to institutions and civic buildings. Not any more. Now the bridge is one of the key pieces of public space. We would like it to be a place for meeting and enjoying the city, a place of urban generosity. The ground floor here is used for commercial space as well as a garden. The building is private space. It is bordered by two bridges, one on each side.
What were the inspirations behind its form and concept?
Developing a project is about understanding and resolving a specific situation: a site, a landscape. Our projects are always specific and linked to the context of the local situation.
A bridge is never a generic structure nor a rational solution. It’s a device in dialogue with the unique situation it is spanning, specific to the place, unmovable, anchored in the sides and the abutments.
The landscape is the main condition of the bridge project: the landscape where it is embodied, the landscape it transforms. Then the static and rational development of the structure, the movement of its curves, the movement of the forces, give a coherent form to the bridge in its site.