|Name in local language:||Viaduc de Millau|
|Beginning of works:||16 October 2001|
|Completion:||14 December 2004|
|Duration of works:||38 months|
Multiple-span cable-stayed bridge
Cable-stayed bridge with semi-fan system
|Function / usage:||
Motorway bridge / freeway bridge
Longitudinal launching with temporary cable-stays
Millau, Aveyron (12), Occitanie, France
Creissels, Aveyron (12), Occitanie, France
Centre d'information du viaduc de Millau
Millau Viaduct Toll Gate (2004)
|Coordinates:||44° 5' 6.00" N 3° 1' 18.00" E|
|total length||2 460 m|
|span lengths||204 m - 6 x 342 m - 204 m|
|span lengths||204 m - 6 x 342 m - 204 m|
|horizontal radius of curvature||20 000 m|
|deck||deck depth||4.20 m|
|height above valley floor or water||270 m|
|total width||32.050 m|
|longitudinal slope||3.025 %|
|pier P1||height||94.50 m|
|pier P2||height||244.96 m|
|pier P3||height||221.05 m|
|pier P4||height||144.21 m|
|pier P5||height||136.42 m|
|pier P6||height||111.94 m|
|pier P7||height||77.56 m|
|pylons||pylon height (above deck)||88.92 m|
|pylon height (above ground)||max. 343 m|
|volume of earthworks||350 000 m³|
|deck||structural steel||S355: 23 500 t
S460: 12 500 t
|foundation slabs||concrete volume||13 000 m³|
|reinforcing steel||1 300 t|
|foundations||reinforcing steel||13 450 t|
|piers||concrete volume||53 000 m³|
|prestressing steel||200 t|
|reinforcing steel||10 000 t|
|piles||concrete volume||6 000 m³|
|reinforcing steel||1 200 t|
|pylons||structural steel||S355: 3 200 t
S460: 1 400 t
|stay cables||steel for cable-stays||1 500 t|
|temporary works||structural steel||S 355: 3 200 t
S 460: 3 200 t
|concrete volume||7 500 m³|
|reinforcing steel||400 t|
|cost of construction||Euro 300 000 000|
CETE (Aix-en-Provence) establishes the first possible alignments for the A75 at Millau.
Decision by the ministry to cross the Tarn valley by a 2500-meter long bridge.
Seven architectural offices and eight engineering offices are consulted separately for proposals.
Second design phase with five groups each associating an architecture and engineering office.
The jury retains the solution proposed by Lord Norman Foster in association with Sogelerg.
The decision is made to operate the Millau Viaduct under a concession agreement.
Competition is launched for the concession/construction tender.
Eiffage is awarded the first prize of the competition and declared concessionaire.
The construction contract is signed.
The concession is awarded to Eiffage.
|16 October 2001||
Pier P2 (to be the highest) reaches 100 meters in height.
|26 February 2003||
Launching of the deck commences.
|28 May 2003||
Pier P2 surpasses the height of 180 m and thus becomes the highest pier in the world, a record previously held by the Kochertal Viaduct. The record will be broken again when the highest pier reaches 245 meters.
25 August 2003
- 26 August 2003
Launching phase L4.
Completion of piers.
|26 March 2004||
Launching phase L10 from the south end. The deck reaches Pier P3.
Night of 4 April 2004
- 5 April 2004
The metal deck is launched onto P2, the highest pier in the world. The launching operation is slowed down by wind and mist which perturb the laser guidance system. A this phase, 1 947 m of deck have been launched.
|20 April 2004||
End of launching of the deck from the north side. The end of the canitlever reaching out beyond pier P2 is at midspan over the Tarn. Two launch phases remain from the south side.
|28 May 2004||
The deck is completed.
|End of July 2004||
Completion of the construction of the pylons.
Expected completion of the dismantling of the temporary piers.
|17 November 2004||
Load testing begins with a total load of 920 tons.
|14 December 2004||
Inauguration by President Jacques Chirac.
|16 December 2004, 09:00||
Opened to traffic.
Outstanding Structure Award 2006 (IABSE)
About the Millau Viaduct
The Millau Bridge and the Rion-Antirion Bridge are the most modern and most important examples for series of cable-stayed bridges. They answer the main questions for series individually: – How can the inner towers be stabilized to avoid too large beam deflections due to spanwise live loads? – How can the changes in beam lengths of these long bridges, e. g. due to temperature, be taken into account, together with longitudinal forces, e.g due to breaking, together with the forces from an earthquake?
In 2004 the large viaduct of Millau was opened for traffic, thereby closing the last gap in the second north–south highway A 75. The bridge has earned its title „Record Bridge“ not only because it is the highest in the world, crossing the Tarn River at a height of 270 m, but also the construction period of only 38 months and the costs of about € 400 million are outstanding. For the second north–south highway the main obstacle was the wide valley of the Tarn River near the city of Millau, well-known for its seemingly endless queues during the summer. It was decided to cross the valley by a 2 460 m long viaduct. In 1996 a series of cable-stayed bridges with two side spans of 204 m, and six main spans of 342 m was selected. For the financial success of the concession company, it was important to keep the construction period to a minimum in order to receive tolls as early as possible. For this reason, the French contractor Eiffel Construction Métallique proposed an alternate with a steel beam and steel towers above deck against the tender design of a post-tensioned concrete bridge. This alternate was selected in March 2001 and construction started in October 2001. The advantages of the steel design against the original concrete design are:
- light-weight and slenderness of the beam (36 t against 120 t)
- reduction of the depth of the beam to 4.2 m, meaning smaller wind loads
- improved safety: less work at great height due to pre-assembly on ground and incremental launching construction
- minimizing the number of stay cables and the size of foundations
- reduction in total costs – the over-riding advantage.
Within two and a half years nearly 43 t of steel were fabricated for the beam, the towers and the auxiliary piers. For the complete design phase Michel Virlogeux was the engineer- in-charge for the French Highway Authority SETRA, and during the construction phase he was an important advisor.
The Millau Bridge has a total length of 2 460 m and comprises eight spans: two side spans with 204 m and six inner spans with 342 m. The cross-section consists of a steel box with orthotropic deck, two vertical inner webs and two inclined outer plates. The vertical webs are required for construction by incremental launching, and the triangular outside boxes create a streamlined cross-section which reduces the wind load on the bridge. On the outside of the beam, wind shields are installed which prevent the overturning of high-sided vehicles. The rounded edges on both outsides improve the aerodynamic behavior and the appearance. Due to the great height above the valley a central girder, with one cable plane only, was the most effective design for avoiding twin piers. The required torsional stiffness is provided by the box girder. Governing the design of the bridge was the condition that the up to 230 m high piers are stiff enough to carry unsymmetrical loads in the longitudinal direction. Also they have to be flexible enough to follow the beam’s longitudinal changes due to temperature. The solution is a strong concrete box girder for the piers with a vertical slot underneath the beam. This bisectioning of the box provides for the required flexibility. The 87 m high towers above deck form stiff A-frames in the longitudinal direction. The spread legs of the towers meet at the beam the spread upper pier halves. In this way, an overall system from pier and tower is created which converts the moment from loads acting at the tower tips into a couple of tension and compression and thus restrains the tower head. The 90 m long pier shafts are vertically post-tensioned to counteract the tensile stresses due to wind in the inner piers and due to temperature changes in the outer piers. Bearings are located between the steel girder and the concrete piers, which are stressed down against uplift. Unsymmetrical loads and extreme winds cause support reactions on each pier of up to 100 MN. A new type of spherical bearing was used. The towers above deck are made from steel to make them as light and slender as possible. The central cable plane is anchored at the tower heads between longitudinal steel plates. Due to architectural reasons the towers extend beyond the upper cables.
The piers have varying cross-sections, but dimensions were selected in such a way that they could be formed easily. Four sides have constant dimensions, and the others vary uniformly in each construction section. This permits construction with outer jumping forms and inner forms which are stepwise lifted by the tower crane. Sliding forms could have made the correct positioning of the built-in items difficult.
About 2100 stiffened panels, four per work day, were fabricated from plates and stiffeners in the shops of Eiffel Construction Métallique in Lauterbourg (Alsace). After transportation to site they were welded in the two 170 m long pre-assembly yards. The central boxes were pre-welded ahead in Fos-sur-Mer. Up to 75 welders were working in each pre-assembly yard.
Launching the beam
The detailed design and construction engineering of the steel parts – beam, towers and auxiliary piers – was provided by the consultant Greisch from Liège, Belgium. The engineer-in-charge was Jean- Marie Crémer. During launching from both abutments several special measures were introduced to control the large cantilever moments. The spans were reduced by half with temporary telescopic piers, a launching nose was used and the front tower with some of the final stay cables was launched together with the beam. These cables were not ad- justed during launching! After joint closure on 28 May 2004, the remaining towers and stay cables were installed and the auxiliary piers removed. The steel beams were launched from both ends at the same time with a closure joint above the Tarn River. In the center of the large span trussed auxiliary truss piers were installed with the exception of the center span which was bridged by cantilevering from both sides. The launching bearings on top of the piers with a distance of 20 m reduced the beam moments quite significantly in the ratio of span lengths (151 / 171)² = 0.78.
The auxiliary piers are built from prefabricated sections with 12 m heights. They are designed like a crane. The elements prefabricated on the ground from steel sections are lifted with an inside lifting device in such way that the next sections could be installed from underneath and also lifted until these telescoping auxiliary piers reached a height of up to 175 m. Their highest load came to 7 000 t roughly equal to the total weight of the Eifel Tower. The final piers were only provided with an auxiliary scaffolding for launching. A unique characteristic of this launching was that, for cost rea- sons, the pre-assembly yard was located at the level of the future road gradient, 4.8 m above the final bridge deck elevation. A shortened view during launching shows the elasticity of the steel beam by overcoming the gradient offset. Each of the two beam halves was launched over an auxiliary pier and a launching nose across the outer side spans. After that the final tower was installed at the front end as auxiliary support, but with a reduced height of 70 m instead of 87 m to minimize the transverse wind loads during launching. The highest wind speed permitted during launching was 3 km/h. Due to the extreme heights of the piers the friction forces during launching had to be equalized, so on top of each pier two active launching bearings were installed in each support axis. Horizontal hydraulic jacks acted between the beam and the piers in such a way that the pier tips remained in place during launching, centrally controlled by sensors. Finally the center span was bridged from each side with cantilevers, supported by towers. The design and construction on site was an extraordinary engineering achievement.
After the steel beam was in place, the remaining steel towers were pre-assembled behind the abutments. Each tower was then moved with crawler cranes over the bridge beam to its final position. The total weight of such a convoy came to 8 MN, thus acting as a test loading. The towers were lifted from their horizontal position with the help of a temporary guyed tower. Finally, they were connected with the beam, and the stay cables were installed.
The Millau Bridge is an important example for a series of cablestayed bridges. A structure with impressive elegance has been built in an impressive landscape, where it gracefully crosses the valley at great height.
Excerpt from: Svensson, Holger; Cable-Stayed Bridges, Wilhelm Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH, Berlin (Germany), ISBN 343302992X; pp. 411-417. References to figures and literature were omitted.
- EEG Europe Etudes Gecti
- Société d'études R. Foucault et Associés
Foster and Partners
- Norman Foster (architect)
- Bureau d'études Greisch
- EEG Simecsol (piers)
- Société d'études R. Foucault et Associés
- STOA Eiffage
- Thales Engineering & Consulting
- Bureau d'études Greisch (deck)
- Carl Stahl ARC GmbH (railing)
Relevant Web Sites
- archINFORM: Millau-Viadukt
- Aurelle-Verlac: Viaduc de Millau
- BBC News: France 'completes' tallest bridge (29.05.2004)
- Bernd Nebel: Brücken: Brücken in Europa: Viaduc de Millau
- Broer.no: Millau Viaduct
- Broer.no: Millau Viadukt
- Christian Tardieu: Viaduc de Millau
- ConstructionEquipmentGuide.com: Millau Viaduct Rises to a Record Height (24.01.2005)
- HighestBridges.com: Millau Viaduct
- Le Monde: web: conférence UTLS: le viaduc de Millau par M. Virlogeux
- Météo France: Le Viaduc de Millau - Une assistance météo hors normes
- OTUA: Grand Viaduc de Millau
- OTUA: Ponts et ouvrages d'art: Le viaduc de Millau: l'acier de tous les exploits
- OTUA: Viaduc de Millau
- Planète TP: Viaduc de Millau
- SETEC TPI: Références ouvrages d'art: Viaduc de Millau
- Viaduc de Millau
- Wikipedia: Millau Viaduct
- 28 poids lourds mettent le viaduc à l'épreuve. In: Le Moniteur des Travaux Publics et du Bâtiment, n. 5270 (26 November 2004), pp. 7.
- 36 000 t d'acier assemblées sur les rives du Tarn. In: Le Moniteur des Travaux Publics et du Bâtiment, n. 5210 (3 October 2003), pp. 99. (2003):
- A75. Puits de reconnaissance du Grand viaduc de Millau. Un ouvrage exceptionnel, reconnaissance géotechnique exceptionnelle. In: Travaux, n. 731 (May 1997), pp. 18-23. (1997):
- Ambient and free vibration tests of the Millau Viaduct: Evaluation of alternative processing strategies. In: Engineering Structures, v. 45 (December 2012), pp. 372-384. (2012):
- L'apogée du système Freyssinet. In: Sols et Structures, n. 220 ( 2004), pp. 6-11.
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