Bridges are often considered to belong to the engineer’s realm rather than the architect’s. But the architecture of infrastructure has a powerful impact on the environment. The Millau Viaduct, designed in collaboration with engineers, illustrates how the architect can play an integral role in bridge design.
Located in southern France, the bridge will connect the motorway from Paris to Barcelona at the point where it is interrupted by the River Tarn, which runs through a wide gorge between two plateaus. A reading of the topography suggested two possible approaches: to cross the river, the geological generator of the landscape; or there was the challenge of spanning the 2.5 kilometers from one plateau to the other in the most economical manner.
The structural solution follows from the latter philosophical standpoint. The bridge has the optimum span between cable-stayed columns. It is delicate, transparent, and uses the minimum material, which makes it less costly to construct. Each of its sections spans 350 meters and its columns range in height from 75 meters to 235 meters – higher than the Eiffel Tower – with the masts rising a further 90 meters above the road deck. To accommodate the expansion and contraction of the concrete deck, each column splits into two thinner, more flexible columns below the roadway, forming an A-frame above deck level. This structure creates a dramatic silhouette – and crucially it makes the minimum intervention in the landscape.