Millau Viaduct
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| Official name | Le Viaduc de Millau |
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| Carries | 4 lanes of the A75 autoroute |
| Crosses | valley of the River Tarn |
| Locale | Millau, France |
| Design | Cable-Stayed |
| Longest span | 342 metres (1,122 ft) |
| Total length | 2,460 metres (8,071 ft) |
| Width | 32 metres (105 ft) |
| Clearance below | 270 metres (886 ft) at maximum |
| Opening date | December 14, 2004 |
The 'Millau Viaduct' (French: le Viaduc de Millau) is a cable-stayed road-bridge that spans the valley of the River Tarn near Millau in southern France. Designed by French bridge engineer Michel Virlogeux in collaboration with British architect Norman Foster, it is the tallest vehicular bridge in the world, with one pier's summit at 343 metres (1,125 ft)—slightly taller than the Eiffel Tower and only 38 m (125 ft) shorter than the Empire State Building. It was formally opened on 14 December 2004 and opened to traffic two days later.
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[edit] Location
Millau Viaduct's coordinates are . 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 vacation season. The bridge now traverses the Tarn valley above its lowest point, linking the causse du Larzac to the causse rouge, and is inside the perimeter of the Grands Causses regional natural park.
The bridge forms the last link of the A75 autoroute, (la Méridienne) from Clermont-Ferrand to Pézenas (to be extended to Béziers by 2010). The A75, with the A10 and A71, provides a continuous high-speed route south from Paris through Clermont-Ferrand to the Languedoc region and through to Spain, considerably increasing the speed and reducing the cost of vehicle traffic travelling along this route. Many tourists heading to southern France and Spain follow this route because it is direct and without tolls for the 340 km between Clermont-Ferrand to Pézenas, except for the bridge itself.
The Eiffage group operates the viaduct as a toll bridge, with the toll currently (Nov 2006) set at €5.10 for light automobiles (€6.80 during the peak months of July and August). The bridge was constructed by the Eiffage group, which also built the Eiffel Tower, under a government contract which allows the company to collect tolls for up to 75 years.
[edit] Description
The Millau Viaduct consists of an eight-span steel roadway supported by seven concrete piers. The roadway weighs 36,000 tonnes and is 2,460 m long, measuring 32 m wide by 4.2 m deep. The six central spans each measure 342 m with the two outer spans measuring 204 m. The roadway has a slope of 3% descending from south to north, and curves in plan section on a 20 km radius to give drivers better visibility. It carries two lanes of traffic in each direction.
The piers range in height from 77–246 m, and taper in their longitudinal section from 24.5 m at the base to 11 m at the deck. Each pier is composed of 16 framework sections, each weighing 2,230 tonnes. These sections were assembled on site from pieces of 60 tonnes, 4 m wide and 17 m long, made in factories in Lauterbourg and Fos-sur-Mer by Eiffage. The piers each support 97 m tall pylons. The piers were assembled first, together with some temporary supports, before the decks were slid out across the piers by satellite-guided hydraulic rams that moved the deck 600 mm every 4 minutes.
The viaduct is the tallest vehicular bridge in the world, nearly twice as tall as the previous tallest vehicular bridge in Europe, the Europabrücke in Austria. (The proposed Strait of Messina Bridge in Italy, if constructed, would be taller.)
The Millau Viaduct is the second highest vehicular bridge measured from the roadway elevation. Its deck, at approximately 270 m above the Tarn, is slightly higher than the New River Gorge Bridge in West Virginia in the United States, which is 267 m above the New River. The Royal Gorge Bridge in Colorado, United States has a deck considerably higher than either, at 321 m above the Arkansas River.
[edit] Construction
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 officially 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 is depicted in a documentary of the Discovery Channel 'Megastructures' series.
[edit] Preliminary studies
In initial studies, four options were examined:
- bypass Millau to the east, requiring two large bridges over the Tarn and the Dourbie;
- bypass Millau to the west (12 km longer), requiring four bridges;
- follow the path of Route Nationale 9, providing good access to Millau but at the cost of technical difficulties and intrusion on the town; and
- traverse the middle of the valley.
The fourth option was selected by the government on 28 June 1989. It consisted of two possibilities: the high solution, and the low solution, requiring the construction of a 200 m bridge to cross the Tarn, then a viaduct of 2300 m extended by a tunnel on the Larzac side. After long construction studies, the low solution was abandoned because it would have intersected the water table, had negative effects on the town, cost more, and the driving distance would have been longer.
After the choice of the high viaduct's path, five teams of architects and researchers simultaneously worked on a technical solution. The original concept for the bridge was devised by French designer Michel Virlogeux. The architects of the bridge are the British firm Foster and Partners. They worked together with the Dutch engineering firm ARCADIS, responsible for the technical design of the bridge.
[edit] Implementation
The bridge deck was constructed on land at the ends of the viaduct and rolled lengthwise from one tower to the next, with eight temporary added towers also in place. The movement was accomplished by a computer-controlled system of pairs of wedges under the deck; the upper and lower wedges of each pair pointed in opposite directions. These were hydraulically operated, and moved repeatedly in the following sequence:
- 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 together, advancing the roadway a short distance.
- Lower wedge retracts from under the upper wedge, lowering the roadway and then allowing the upper wedge to drop away from the roadway.
- Upper wedge moves backward, placing it into position farther (back) along the roadway, ready to repeat the cycle and advance the roadway again.
[edit] The builders
Four consortia were in competition for the building contract:
- One led by Dragados (Spanish), with Skanska (Swedish) and Bec (French);
- Société du viaduc de Millau, made up of ASF, Egis, GTM, Bouygues Travaux Publics, SGE, CDC Projets, Tofinso (all French) and Autostrade (Italian); and
- One led by Générale Routière, with Via GTI (French), and Cintra, Necso, Acciona, and Ferrovial Agroman (all Spanish).
- The successful bidders, lead by the Eiffage group, product of the Fougerolles-SEA fusion, the third largest French group in public works, and the sixth largest in Europe.
The work leader is the Compagnie Eiffage du Viaduc de Millau, owner of the government contract. The construction consortium is made up of the Eiffage TP company for the concrete part, the Eiffel company for the steel roadway (Gustave Eiffel built the Garabit viaduct in 1884, a train bridge in the neighboring Cantal département), and the Enerpac company for the roadway's hydraulic supports. The engineering group Setec has authority in the project, with SNCF engineering having partial control.
The formwork technology for the bridge piers came from PERI.
[edit] Costs and resources
The bridge's construction cost up to €394 million, with a toll plaza 6 km 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.
The project required about 127,000 m³ of concrete, 19,000 metric tons of steel for the reinforced concrete, and 5,000 metric tons of pre-stressed steel for the cables and shrouds. The builder claims that the bridge's lifetime will be at least 120 years.
[edit] Statistics
- 2,460 metre: total length of the roadway
- 7: number of piers
- 77 m: height of Pier 7, the shortest
- 343 m: height of Pier 2, the tallest (245 m at the roadway's level)
- 87 m: height of a pylon
- 154: number of shrouds
- 270 m: average height of the roadway
- 4.20 m: thickness of the roadway
- 32.05 m: width of the roadway
- 85,000 m³: total volume of concrete used
- 290,000 tonnes: total weight of the bridge
- 10,000–25,000 vehicles: estimated daily traffic
- €4.90–6.50: typical automobile toll, as of 2005
- 20 km: horizontal radius of curvature of the road deck
[edit] Project timeline
- 28 June 1989: governmental approval of the middle route
- 19 October 1991: selection of the high solution, with the viaduct at 2500 m
- 10 January 1995: declaration of utilité publique (public usefulness), as needed to apply eminent domain or compulsory purchase.
- 9 July 1996: choice of the cable-stayed bridge type
- 1998: decision to contract out both construction costs and future tolls to a private enterprise
- 16 October 2001: work begins
- 14 December 2001: laying of the first stone
- January 2002: laying pier foundations
- March 2002: start of work on the pier support C8
- June 2002: support C8 completed, start of work on piers
- July 2002: start of work on the foundations of temporary, height adjustable roadway supports
- August 2002: start of work on pier support C0
- September 2002: assembly of roadway begins
- November 2002: first piers complete
- 25 February–26 February 2003: laying of first pieces of roadway
- November 2003: completion of the last piers (Piers P2 at 221 m and P3 at 245 m are the highest piers in the world.)
- 28 May 2004: the pieces of roadway are several centimetres apart, their juncture to be accomplished within two weeks
- 2nd half of 2004: installation of the pylons and shrouds, removal of the temporary roadway supports
- 14 December 2004: official inauguration
- 16 December 2004: opening of the viaduct, ahead of schedule
- 10 January 2005: initial planned opening date
[edit] Gallery
 Single segment of the construction on the small exhibition under viaduct |
 Large numbers of people stop to observe the viaduct from the viewing area on the northern side |
[edit] See also
[edit] External links
- Viaduc de Millau
- Structurae: Millau Viaduct
- Millau Viaduct website
- France shows off tallest bridge (BBC report of official opening, 14 December 2004)
- Millau Viaduct - Worlds tallest bridge Stunning Panoramic Pictures
- In Pictures: The Millau Bridge (BBC images of the Millau Viaduct, including (page 2) a map showing the bridge's location)
- Project on Viaduc de Millau From Road Traffic Technology
- France opens world's tallest bridge (MSNBC article on the official opening, 14 December 2004)
- Eiffage group website
- Le Viaduc de Millau (in French)
- Technical popularisation conference on the Millau Viaduct by head engineer Michel Virlogeux (in French): RealAudio, Windows Media
- Google Maps Satellite photo (under construction)
- Millau, City and Bridge Map, photos, diagrams and text.
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| Antennas: | Alma-Ata Tower, Azeri TV Tower, Emley Moor, Europaturm, Gerbrandy Tower, Kiev TV Tower, Mumbai Television Tower, Saint Petersburg TV Tower, Sumida Tower (proposed), TV Tower Yerevan, WITI TV Tower, Zendstation Smilde |
| Bridges: | Millau Viaduct, Strait of Messina Bridge (proposed) |
| Dams: | Rogun Dam (construction), Nurek Dam, Jinping 1 Hydropower Station (construction) |
| Solar towers: | Solar Tower Buronga (proposed), Ciudad Real Torre Solar (proposed) |
| Electricity pylons: | Yangtze River Crossing |
| Oil platforms: | Petronius Platform, Baldpate Platform, Bullwinkle Platform, Troll Platform, Gullfaks C |
