Millau Viaduct

Year:2004

Duration:3 years

Cost:€394m (about £351m)

Country: Millau, France

What did this project achieve?

Construct a vehicle bridge across a massive valley in southern France

The French Ministry of Public Works (MPW) needed a solution to serious traffic congestion in the town of Millau on the river Tarn in southern France.

The Tarn valley is wide and the only way to cross the gorge was by using the main road. This wound its way slowly down each side of the valley to a narrow bridge over the river in Millau town centre.

The MPW initially considered a low level bridge but this didn’t deal with the long and winding descents on each side.

After several studies they decided on a high level viaduct with a maximum deck height of 200m. The bridge also had to fit into a sensitive natural location.

A competition to design and build the structure was won by an engineering and architectural group headed up by French engineer Michel Virlogeux and British architect Sir Norman Foster.

Difference the viaduct has made

Millau viaduct relieved a severe bottleneck that slowed down thousands of tourists driving from northern France to the Mediterranean coast. Before, motorists could take up to 4 hours to cross the valley when traffic was heavy. Now, they can cross in minutes.

The bridge has also become a tourist attraction – the approaching motorway was modified so drivers coming from the north get an impressive view of the bridge and valley before they arrive.

How the work was done

The bridge is 2.5km long and 343m tall at its highest point – the top of one of the masts.

It rests on 7 concrete piers. These support an 11m deep continuous hollow steel deck suspended from 7 steel pylons. The pylons are 87m above deck level and support 11 cable stays on each side.

The 7 piers are rooted in 4 reinforced concrete shafts. Project engineers sunk these deep into the valley bedrock and covered them with more reinforced concrete.

The hollow steel deck was prefabricated in box sections at the Eiffel factory at Alsace in eastern France. Barges then floated them down the Rhine to the Mediterranean and on to the French coast. From there they went by road to the construction site. They were then joined together and painted to make the continuous deck.

The 87m high steel pylons were moved out from each bank on hydraulic transporters and erected on the deck at each concrete pier.

Construction challenges included extreme weather such as strong winds and low cloud.

"​‌

The mother of all bridges.

John Lichfield

Journalist , writing on the bridge opening for the Independent newspaper

Fascinating facts

Millau Viaduct has been consistently ranked as one of the great engineering achievements of all time. It received the 2006 Outstanding Structure Award from the International Association for Bridge and Structural Engineering.

The 2-lane motorway deck is 200m above the valley floor on average. When it opened in 2004 it was the highest road crossing in the world.

The bridge is sometimes used for extreme sports such as base jumping.

People who made it happen

  • Architect: Sir Norman Foster
  • Designer: Michel Virlogeux
  • Main contractor: Eiffage

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