MILLAU VIADUCT

      The Millau Bridge, usually called Millau Viaduct / Le Viaduc de Millau (French) in southern France is the tallest bridge in the world and it is a cable-stayed bridge that passing through the Tarn valley near the town of Millau.

       It is located on the territory of the communes of Millau and Creissels, France, in the département of Aveyron. Before the bridge was constructed, traffic had to descend into the Tarn River valley and pass along the route nationale N9 near the town of Millau, causing heavy congestion at the beginning and end of the July and August holiday season. 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.

          Inaugurated on 14^th December 2004, and opened to traffic on 16^th December 2004, the constructions cost €.394,000,000.00. It was designed by Norman Foster (a British Architect) and Michel Virlogeux (a French Structural Engineer) from Sogelerg Consortium. The bridge has been consistently ranked as one of the great engineering achievements of all time. The bridge received the 2006 International Association for Bridge and Structural Engineering Outstanding Structure Award.

       The bridge deck was constructed on land at the ends of the viaduct and rolled lengthwise from one pylon to the next, with eight temporary towers providing additional support. The movement was accomplished by a computer-controlled system of pairs of wedges under the deck; the upper and lower wedges of each pair pointing in opposite directions. These were hydraulically operated, and moved repeatedly in the following sequence: 

         The lower wedge slides under the upper wedge, raising it to the roadway above and then forcing the upper wedge still higher to lift the roadway. Both wedges move forward together, advancing the roadway a short distance. The lower wedge retracts from under the upper wedge, lowering the roadway and allowing the upper wedge to drop away from the roadway; the lower wedge then moves back all the way to its starting position. There is now a linear distance between the two wedges equal to the distance forward the roadway has just moved. 

The bridge’s construction broke several records:

-             The highest pylons in the world: pylons P2 and P3, 244.96 metres (803 ft 8 in) and 221.05 metres (725 ft 3 in) in height respectively, broke the French record previously held by the Tulle and Verrières viaducts (141 m or 463 ft), and the world record previously held by the Kochertal Viaduct (Germany), which is 181 metres (594 ft) at its highest;

-             The highest bridge tower in the world: the mast atop pylon P2 peaks at 343 metres (1,125 ft).

-              The highest road bridge deck in Europe, 270 m (890 ft) above the Tarn River at its highest point. It is nearly twice as tall as the previous tallest vehicular bridges in Europe, the Europabrücke in Austria and the Italia Viaduct in Italy. It is slightly higher than the New River Gorge Bridge in West Virginia in the United States, which is 267 m (876 ft) above the New River.