The Millau Viaduct consists of an eight-span steel roadway supported by seven concrete pylons. The roadway weighs 36,000 tonnes (40,000 short tons) and is 2,460 m (8,070 ft) long, measuring 32 m (105 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 (1,122 ft) with the two outer spans measuring 204 m (669 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 enormous pylons were built first, together with intermediate temporary pylons which were in themselves a massive record-breaking construction project.
Remarkably, the entire length of deck surface (that is to say, the bridge itself, the actual kilometres of roadway) was slid out, into the valley, across the pylons from both sides.
This feat was achieved using hydraulic rams that moved the deck about 600 mm every 4 minutes, over the course of many days.
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.