The Millau Viaduct
Gigantic and slim monument, the highest viaduct in the world attracts more than 700 000 visitors a year on the Brocuejouls and the Cazalous sites. Imposing, slim, elegant... the spectator will appreciate the human and technical feat as much as the architectural beauty. The perspective view offered during the trip with the Bateliers emphasizes even more the impression of height and the airy style of the work.
Well before the making of the Millau Viaduct, three routes were envisaged to link the motorway A75 from Clermont-Ferrand to Béziers :
More to the East, the visual and ecological impact of the crossing of the Causse Noir plateau would have been desastrous. On more than one ground. Montpellier le Vieux, site of rocks shaped like ruins, would have been endangered and the proximity of the town center meant that building a bridge over the Dourbie river would be ticklish.
More to the West, it was the Larzac farms that supply the Roquefort caves with milk which would have been threatened. The drawing would count an extra 18kms plus the equivalent of that amount in the petrol consumed by drivers.
Therefore, the direct route was chosen in the end. But considering the dimensions of the bridge which was going to overhang the Tarn river, it was first considered to go downhill in a gentle slope in order to cross the valley much further down, and then going into the Causse through a tunnel re-emerging a few kilometers away.
The limestone substratum and the gigantic caves and cavities which existed in it made the building of the bridge compulsory... underground!
This solution was envisaged and quickly abandonned for technical reasons. Having a motorway going onto a bridge inside an abyss would have been particularly extravagant !
A high-tech construction…
Conceived by the French engineer Michel Virlogeux and drawn by the English architect Sir Norman Foster, the Millau Viaduct is a bridge with many stays of 2640m in length with a steel deck overhanging the Tarn river 270m above. (360m at the top of the pylons).
The Eiffage company carried out the works in a record time of 23 months (excluding earthwork). The 7 pylons were erected over 16m deep foundations by the same number of autonomous teams. Pylon P2, the highest, is situated right on the Tarn right riverbank. The crane which enabled its erection was close to 300m high.
The steel deck of the Millau Viaduct was put together on each riverbank and then pushed from each side all the way to above the river.
80 000 cubic meter of high performance concrete, 20 000 tons of steel, tens of kilometers of stays, put together by a team of 600 people to carry out a technological challenge out of the common.