(*2005 Millau Viaduct: “Between the Earth and the Sky”)
Normally, a slogan for a bridge is the sort of the marketing and awareness gimmick that I ignore, not least so that they don’t wind me up and cause a blood pressure incident. But, in this case, I feel it is justified, for what is surely one of the most dramatic and graceful viaducts or bridges of this or any era.
The Millau Viaduct (Viaduc de Millau in French) is on the A75 autoroute running south from Paris and Clermont-Ferrand to Beziers and Montpellier on the Mediterranean coast, before splitting to the west for Languedoc and Spain, and to the east for the French Riviera, Marseilles and Italy. It is the tallest bridge in the world, reaching 1125ft above ground level to the top of the tallest mast; the road deck is 890ft above the ground at its maximum, which is the highest in Europe. The piers are taller than the Eiffel Tower, and the second pier, known as P2, is the tallest structure in France.
The viaduct (this is much, much more than a bridge) crosses the River Tarn and its Gorge close to the town of Millau, taking the A75 away from the town and eliminating a notorious bottleneck in the town itself. As always and everywhere, the period from first idea to the start of building was longer than you might think necessary – in this case from 1987 to 2001.
Various routes were considered – as well as the selected high level route, there were alternative routes further from Millau and a low level solution at Millau proposed, with the autoroute descending into the valley, crossing the river on a bridge and then running through a tunnel. The high solution was selected, and this is when this great viaduct started to take shape. This route crosses the Tarn Gorge up to 890 ft above the floor of the gorge, directly between two large limestone causses, or plateaux, and is within the Parc Regional des Grands Causses national park.
Five competing ideas were selected for detailed assessment by the French government, and aesthetically the chosen design was a clear winner. The design was by Norman Foster, probably Britain’s greatest practising architect and one of the world’s greatest architects of the last 50 years, and the structural design by Frenchman Michel Virlogeux and the Dutch company Arcadis. Final details, including wind tunnel testing (up to 140 mph), were completed in 1998 and the design officially selected late that year.
The statistics of the viaduct are worth noting – the length is 8070 ft long, with six central spans each measuring 1122 ft and the outer spans at 699 ft each. The road deck is up to 890 ft above the river, at the time the world’s highest. 166,000 cu yd of concrete were used in the construction with 21,000 tons of steel reinforcing it and around 5500 tons of steel cables holding it all together. The pylon masts (the pier and the mast above the road deck) are the tallest in the world, reaching up to 803 ft and the highest pylon in the world at 1125 ft. Perhaps surprisingly, to non civil engineers at least, the piers are located in shafts only 49 ft deep.
The construction used some innovative techniques also; The bridge deck was constructed on land at the ends of the viaduct and rolled lengthwise from one pylon to the next; eight temporary towers provided additional support, accomplished using a system of pairs of wedges under the deck, with the upper and lower wedges of each pair pointing in opposite directions. The temporary towers were also used to erect the masts on top of the piers, the cables pensioned and the temporary towers removed. The construction was led by the Eiffage Group, and the steel work for the roadway was completed by Eiffel Company, the builder of many viaducts and famous towers in France for 130 years.
Building work commenced in October 2001, the piers completed by November 2003 and roadway in place in June 2004. The bridge opened by French President Jacques Chirac (seen above left, with Norman Foster) in December 2004, actually a month ahead of schedule. Construction cost €400 million (around $475 million) and the current road toll is €7 each way. The toll plaza is at the north end.
One of the concerns about the viaduct, raised during the assessment period, was that it would negatively affect the economy of Millau, by taking the traffic away from the town, or alternatively that the traffic would not accept the toll and continue to use the old route.
Not for the first time, it has been proved that great architecture and infrastructure can increase economic activity, and not adversely effect traditional economies either. Well, these sheep are herded down a village street every evening just a few miles away and not only are the visitor and information centres always busy these people are coming to the town and the surrounding area whereas previously they either passed by or just didn’t go there. It has also been used for marathon races and the Tour de France.
But, sometimes, you just to have to look at it.