The Millau Viaduct ( French: le Viaduc de Millau, [vjadyk də mijo] ) is a cable-stayed road-bridge that spans the valley of the river Tarn near Millau in southern France. Designed by the French structural engineer Michel Virlogeux and British architect Norman Foster, it is the tallest bridge in the world with one mast's summit at 343.0 metres (1,125 ft) above the base of the structure. It is the 12th highest bridge in the world, at 270 metres (890 ft) high below the road deck.
The viaduct is part of the A75-A71 autoroute axis from Paris to Montpellier. Construction cost was approximately €400 million. It was formally dedicated on 14 December 2004, inaugurated on the 15th, and opened to traffic on the 16th. The bridge received the 2006 IABSE Outstanding Structure Award. Problems with traffic on the route from Paris to Spain along the stretch passing through the valley near the town of Millau, especially during the summer when the roads became jammed with holiday traffic, necessitated the building of a bridge across the valley.
The first plans were discussed in 1987 by CETE, and by October 1991 the decision was made to build a high crossing of the Tarn River by a structure of around 2,500 m (8,200 ft). During 1993–1994 there were separate consultations with seven architects and eight structural engineers; and during 1995–1996 there was a second definition study with five associated architect groups and structural engineers. In January 1995 there was a declaration of public interest; and in July 1996 the jury decided in favour of a cable-stayed design with multiple spans, as proposed by the Sogelerg consortium (Michel Virlogeux and Norman Foster). The decision to proceed by grant of contract was made in May 1998; then in June 2000 the contest for the construction contract was launched, open to four consortia.
The bridge's construction cost up to €394 million, with a toll plaza 6 km (3.7 mi) north of the viaduct costing an additional €20 million. The builders, Eiffage, financed the construction in return for a concession to collect the tolls for 75 years, until 2080. However, if the concession is very profitable, the French government can assume control of the bridge in 2044. The project required about 127,000 cubic metres (166,000 cu yd) of concrete, 19,000 tonnes (21,000 short tons) of steel for the reinforced concrete and 5,000 tonnes (5,500 short tons) of pre-stressed steel for the cables and shrouds. The builder claims that the lifetime of the bridge will be at least 120 years.
Numerous organizations opposed the project, including the WWF, France Nature Environnement, the national federation of motorway users, and Environmental Action. Opponents put forward several arguments. The bridge now traverses the Tarn valley above its lowest point, linking two limestone plateaus, the Causse du Larzac and the Causse Rouge, and is inside the perimeter of the Grands Causses regional natural park.
The toll plaza is protected by a canopy in the shape of a leaf (formed from tendrilled concrete, using the ceracem process). Consisting of 53 elements ( voussoirs ), the canopy is 100 m (330 ft) long and 28 m (92 ft) wide. It weighs around 2,500 tonnes (2,500 long tons; 2,800 short tons ). The toll plaza can accommodate sixteen lanes of traffic, eight in each direction. At times of low traffic volume, the central booth is capable of servicing vehicles in both directions. A car park and viewing station, equipped with public toilets, is situated each side of the toll plaza. The total cost was € 20 million. Unusual for a bridge closed to pedestrians, a run took place in 2004 and another on 13 May 2007.