The Millau Viaduct is a large cable-stayed road-bridge that spans the valley of the river Tarn near Millau in southern France. Designed by the structural engineer Michel Virlogeux and British architect Norman Foster, it is the tallest vehicular bridge in the world, with one mast's summit at 1,125 ft — slightly taller than the Eiffel Tower and only 125 ft shorter than the Empire State Building. The viaduct is part of the A75-A71 autoroute axis from Paris to Béziers. It was formally dedicated on 14 December 2004, inaugurated the day after and opened to traffic two days later. The bridge won the 2006 IABSE Outstanding Structure Award.
The Millau Viaduct consists of an eight-span steel roadway supported by seven concrete pylons. The roadway weighs 36,000 tonnes and is 2,460 m (8,100 ft) long, measuring 32 m (100 ft) wide by 4.2 m (14 ft) deep, making it the world's longest cable-stayed deck. The six central spans each measure 342 m 1,120 ft with the two outer spans measuring 204 m 670 ft. The roadway has a slope of 3% descending from south to north, and curves in a plane section with a 20 km 12 mi radius to give drivers better visibility. The pylons range in height from 250 ft to 810 ft, and taper in their longitudinal section from 24.5 m 80 ft at the base to 36 ft at the deck. Each pylon is composed of 16 framework sections, each weighing 2,230 tons. These sections were assembled on site from pieces of 60 tons, 4 m 13 ft wide and 56 ft long, made in factories in Lauterbourg and Fos-sur-Mer by Eiffage. The pylons each support 97 m 320 ft tall masts.
The pylons were assembled first, together with some intermediate temporary pylons, before the decks were slid out across the piers by satellite-guided hydraulic rams that moved the deck 600 mm every 4 minutes. Then the masts were driven over the new deck, erected on top of the pylons, connected to the deck and the temporary pylons removed.
Construction began on 10 October 2001 and was intended to take three years, but weather conditions put work on the bridge behind schedule. A revised schedule aimed for the bridge to be opened in January 2005. The viaduct was inaugurated by President Chirac on 14 December 2004 to open for traffic on 16 December, several weeks ahead of the revised schedule.
The construction of the bridge was depicted in an episode of the National Geographic Channel MegaStructures series, as well as Discovery Channel's Extreme Engineering
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