Millau Viaduct (2004) France
The Millau Viaduct is a multi span cable stayed bridge linking the A75 motorway across the Tarn river valley in Southern France. Arguably one of the most spectacular bridges ever built it is the tallest bridge in the world at 343 metres (1125 ft) from base to the top of its highest mast. It is also the 12th highest bridge in the world, with a 270 meters (886 ft) drop from the bridge platform to the valley below.
The design was a collaboration between French structural engineer Michel Virlogeux and British architect Norman Foster and the bridge opened in 2004 after a construction period of just over 3 years. This followed 14 years of delays due to discussion and disagreement over the best route, design, financing and two lengthy inquiries. Planning permission was granted in 1998 and finally construction began in December 2001.
The bridge is 2,460 metres (8,070 ft) long and consists of eight spans; 2 end spans of 204 metres (669 ft) and 6 central spans of 342 metres (1122 ft). An interesting feature of its design is that the bridge is not straight. It was felt that a straight road could induce a sensation of floating for drivers and a slight curve which would remedy the problem was incorporated into the design. The road also has a slight incline of 3% which improves visibility and gives drivers a very good view of the structure.
The construction project required about 127,000 cubic meters of concrete, 19,000 tonnes of steel for the reinforced concrete and 5,000 tonnes of pre-stressed steel for the cables and shrouds. The total cost of the project was almost €400 million.