(Redirected from
Millau bridge)
Millau Viaduct
[[Image:|250px|Millau Viaduct]]
|
| Official name |
Le Viaduc de Millau |
| Carries |
Motor vehicles |
| Crosses |
valley of the River Tarn |
| Locale |
Millau, France |
| Maintained by |
| ID number |
| Design |
Cable-Stayed |
| Longest span |
342 metres (1,122 ft) |
| Total length |
2,460 metres (8,071 ft) |
| Width |
32 metres (105 ft) |
| Vertical clearance |
| Clearance below |
270 metres (886 ft) at maximum |
| Average Daily Traffic |
| Opening date |
December 14, 2004 |
| Destruction date |
| Toll |
|
|
Panoramic view of Millau Viaduct from south-east side
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 341 metres (1,118 ft)—slightly higher than the Eiffel Tower and only 40 m (132 ft) shorter than the Empire State Building. It was formally opened on 14 December 2004 and opened to traffic on 16 December 2004.
Location
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 (la Méridienne) autoroute, providing a continuous high-speed route south from Paris through Clermont-Ferrand to Béziers. The purpose of the A75 is to increase the speed and reduce 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 Béziers, except for the bridge itself.
The Eiffage group operates the viaduct as a toll bridge, with the toll currently set at €4.90 for light automobiles (€6.50 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.
The nearly completed bridge in September 2004
Description
The Millau Viaduct consists of an eight-span steel roadway supported by seven concrete piers. The roadway weighs 36,000 metric tons and is 2,460 m (8,071 ft) long, measuring 32 m (105 ft) wide by 4.2 m (13.8 ft) deep. The six central spans each measure 342 m (1,122 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 plan section on a 20 km (12.4 mile) radius to give drivers better visibility. It carries two lanes of traffic in each direction.
The piers range in height from 77–246 m (253–807 ft), and taper in their longitudinal section from 24.5 m (81 ft) at the base to 11 m (36 ft) at the deck. Each pier is composed of 16 framework sections, each section weighing 2,230 metric tons. These sections were assembled on site from pieces of 60 metric tons, 4 m (13 ft) wide and 17 m (56 ft) long, made in factories in Lauterbourg and Fos-sur-Mer by Eiffage. The piers each support 97 m (319 ft) 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 (23.6 inches) 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 still and would also be the world's largest suspension bridge. Current plans call for towers 382.6 m high.
The Millau Viaduct is the second highest vehicular bridge measured from the roadway elevation. Its deck, at approximately 270 m (886 ft) above the Tarn, is apparently 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. The Royal Gorge Bridge in Colorado, United States has a deck considerably higher than either, at 321 m (1,053 ft) above the Arkansas River.
Panoramic view of the Millau Viaduct, as seen from the south. The four red temporary supports are still visible in this
June 29,
2004 photograph.
Construction
The viaduct under construction, seen from the south in early 2004.
Construction began on October 10, 2001 and was intended to take 3 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 December 14, 2004 to open for traffic on December 16, several weeks ahead of the revised schedule.
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 June 28, 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. He worked together with the Dutch engineering firm ARCADIS, responsible for the technical design of the bridge.
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.
Costs and resources
The bridge's construction costs amount 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 concrete for the cables and shrouds. The builder claims that the bridge's lifetime will be at least 120 years.
Single segment of the construction
on the small exhibition under viaduct
Statistics
- 2,460 metre: total length of the roadway
- 7: number of piers
- 77 m: height of Pier 7, the shortest
- 336 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 metric tons: total weight of the bridge
- 10,000–25,000 vehicles: estimated daily traffic
- €4.90–6.50: typical automobile toll, as of 2005
Project timeline
- June 28, 1989: governmental approval of the middle route
- October 19, 1991: selection of the high solution, with the viaduct at 2500 m
- January 10, 1995: declaration of utilité publique (public usefulness), as needed to apply eminent domain(U.S. term)
- July 9, 1996: choice of the cable-stayed bridge type
- 1998: decision to contract out both construction costs and future tolls to a private enterprise
- October 16, 2001: work begins
- December 14, 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
- February 25–February 26, 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.)
- May 28, 2004: the pieces of roadway are several centimeters 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
- December 14, 2004: official inauguration
- December 16, 2004: opening of the viaduct, ahead of schedule
- January 10, 2005: initial planned opening date
Trivia
See also
External links
