There is a lot of reasons for us to visit France, aside from its French bread, bagels and churros. France is the country where the City of Love, Paris, can be found. France is furthermore famous for its Eiffel tower. But do you know that France also serves as a home to the world’s tallest vehicular bridge? Yes, none other than the Millau Viaduct.

Millau Viaduct
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The Millau Viaduct (French: le Viaduc de Millau, Occitan: lo Viaducte de Milhau) 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). 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 the day after and opened to traffic two days later. The bridge received the 2006 IABSE Outstanding Structure Award.

http://artofdesign.files.wordpress.com/2006/11/viaduct.jpgThe 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.

Construction Of Millau Viaduct
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Construction began on 10 October 2001 and was intended to take three years, but weather conditions put work on the bridge behind schedule. The enormous pylons were built first, together with intermediate temporary pylons which were in themselves a massive record-breaking construction project. The pylons range in height from 77 m (253 ft) to 246 m (807 ft), and taper in their longitudinal section from 24.5 m (80 ft) at the base to 11 m (36 ft) at the deck. Each pylon is composed of 16 framework sections, each weighing 2,230 tonnes (2,460 short tons). These sections were assembled on site from pieces of 60 tonnes (66 short tons), 4 m (13 ft) wide and 17 m (56 ft) long, made in factories in Lauterbourg and Fos-sur-Mer by Eiffage. The pylons each support 87 m (285 ft) tall masts.

http://artofdesign.files.wordpress.com/2006/11/millau-viaduct-construction02.jpgConstruction Timeline

Two weeks after the laying of the first stone on 14 December 2001, the workers started to dig the deep shafts. There were 4 per pylon; 15 m (49 ft) deep and 5 m (16 ft) in diameter, assuring the stability of the pylons. At the bottom of each pylon, a tread of 3–5 m (10–16 ft) in thickness was installed to reinforce the effect of the deep shafts. The 2,000 m3 (2,600 cu yd) of concrete necessary for the treads was poured at the same time.

Millau Viaduct

In March 2002, the pylons emerged from the ground. The speed of construction then rapidly increased. Every three days, each pylon increased in height by 4 m (13 ft). This performance was mainly due to sliding shuttering. Thanks to a system of shoe anchorages and fixed rails in the heart of the pylons, a new layer of concrete could be poured every 20 minutes.

http://artofdesign.files.wordpress.com/2006/11/millau-viaduct-construction03.jpgThe 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.

http://artofdesign.files.wordpress.com/2006/11/millau-viaduct-construction04.jpgBoth 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 upper wedge moves backward, placing it further back along the roadway, adjacent to the front tip of the lower wedge and ready to repeat the cycle and advance the roadway by another increment. It worked at 600mm per cycle (roughly 4mins long).

Millau Viaduct

The mast pieces were driven over the new deck lying down horizontally. The pieces were joined to form the one complete mast, still lying horizontally. The mast was then tilted upwards, as one piece, at one time in a tricky operation. In this way each mast was erected on top of the corresponding pylon. The stays connecting the masts and the deck were then installed, and the bridge was tensioned overall and weight tested. After this, the temporary pylons could be removed.

1. 16 October 2001: Work begins
2. 14 December 2001: Laying of the first stone
3. January 2002: Laying pier foundations
4. March 2002: Start of work on the pier support C8
5. June 2002: Support C8 completed, start of work on piers
6. July 2002: Start of work on the foundations of temporary, height adjustable roadway supports
7. August 2002: Start of work on pier support C0
8. September 2002: Assembly of roadway begins
9. November 2002: First piers complete
10. 25–26 February 2003: Laying of first pieces of roadway
11. Nov 2003: Completion of the last piers (Piers P2 at 245 m (804 ft) and P3 at 221 m (725 ft
12. 28 May 2004: The pieces of roadway apart, their juncture to be accomplished within two weeks
13. 2nd Quarter of 2004: Installation of the pylons and shrouds
14. 14 December 2004: Official inauguration
15. 16 December 2004: Opening of the viaduct, ahead of schedule
16. 10 January 2005: Initial planned opening date

http://www.mostlists.com/wp-content/uploads/2011/03/Millau_Viaduct_5.jpgCosts and Resources

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.

http://artofdesign.files.wordpress.com/2007/04/millau_fosterweb2.jpgThe 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.