History
Problems with traffic on the route from Paris to Spain along the stretch passing through the valley near the town of Millau, especially during the summer when the roads became jammed with holiday traffic, necessitated the building of a bridge across the valley. The first plans were discussed in 1987 by CETE, and by October 1991 the decision was made to build a high crossing of the Tarn River by a structure of around 2,500 m (8,200 ft). During 1993–1994 there were separate consultations with seven architects and eight structural engineers; and during 1995–1996 there was a second definition study with five associated architect groups and structural engineers. In January 1995 there was a declaration of public interest; and in July 1996 the jury decided in favour of a cable-stayed design with multiple spans, as proposed by the Sogelerg consortium (Michel Virlogeux and Norman Foster). The decision to proceed by grant of contract was made in May 1998; then in June 2000 the contest for the construction contract was launched, open to four consortia. In March 2001 Eiffage established the subsidiary Compagnie Eiffage du Viaduc de Millau (CEVM) and was declared winner of the contest and awarded the prime contract in August.
Possible routes
In initial studies, four options were examined:
An option called Great Eastern (grand Est) ( yellow route ) passing east of Millau and crossing the valleys of the Tarn and Dourbie on two very high and long bridges (spans of 800 m/2,600 ft and 1,000 m/3,300 ft) whose construction was acknowledged to be problematic. This option would have allowed access to Millau only from the Larzac plateau using the long and tortuous descent from La Cavalerie. Although this option was shorter and better suited to the through traffic, it was abandoned because it did not serve the needs of Millau and its area satisfactorily.
An option called the Great Western (grand Ouest) ( black route ), longer than the eastern option by 12 km (7.5 mi), following the Cernon valley. Technically easier (requiring four viaducts), this solution was judged to have negative impacts on the environment, in particular on the picturesque villages of Peyre and Saint-Georges-de-Luzençon. More expensive than the preceding option, and serving the region badly, this option was also abandoned.
An option called near RN9 (proche de la RN9) ( red route ), would have served the town of Millau well, but presented technical difficulties and would have had a strong impact on existing or planned structures. This option was also abandoned.
An option called intermediate (médiane), west of Millau ( blue route ) had the blessing of local opinion, but presented geological difficulties, notably on the question of crossing the valley of the Tarn. Expert investigation concluded that these obstacles were not insurmountable.
The fourth option was selected by the ministerial decree on 28 June 1989. It encompassed two possibilities:
the high solution, envisaging a 2,500 m (8,200 ft) viaduct more than 200 m (660 ft) above the river;
the low solution, descending into the valley and crossing the river on a 200 m (660 ft) bridge, then a viaduct of 2,300 m (7,500 ft) extended by a tunnel on the Larzac side.
After long construction studies by the Ministry of Public Works, the low solution was abandoned because it would have intersected the water table, had a negative impact on the town, cost more, and lengthened the driving distance.
The choice of the “high” solution was decided by ministerial decree on October 29, 1991.
After the choice of the high viaduct, five teams of architects and researchers worked on a technical solution. The concept and design for the bridge was devised by French designer Michel Virlogeux. He worked with the Dutch engineering firm ARCADIS, responsible for the structural engineering of the bridge.
Construction
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.
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.
The 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. Both 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 600 mm per cycle which was roughly four minutes long.
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.
Timeline
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
25–26 February 2003: laying of first pieces of roadway
November 2003: completion of the last piers (Piers P2 at 245 m (804 ft) and P3 at 221 m (725 ft) 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
Construction records
The bridge’s construction broke several records:
The highest pylons in the world: pylons P2 and P3, 244.96 metres (803 ft 8 in) and 221.05 metres (725 ft 3 in) in height respectively, broke the French record previously held by the Tulle and Verrières Viaducts (141 m/463 ft), and the world record previously held by the Kochertal Viaduct (Germany), which is 181 metres (594 ft) at its highest;
The highest bridge tower in the world: the mast atop pylon P2 peaks at 343 metres (1,125 ft).
The highest road bridge deck in Europe, 270 m (890 ft) above the Tarn River at its highest point. It is nearly twice as tall as the previous tallest vehicular bridges in Europe, the Europabrücke in Austria and the Italia Viaduct in Italy. It is 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. Since opening in 2004 the deck height of Millau has been surpassed by several suspension bridges in China including Siduhe, Balinghe and two spans (Beipanjiang River 2003 Bridge and Beipanjiang River 2009 Bridge) over the Beipanjiang River. In 2012 Mexico's Baluarte Bridge will surpass Millau as the world's highest cable stayed bridge. The Royal Gorge suspension bridge in the U.S. state of Colorado is also higher with a bridge deck approximately 291 metres (955 ft) over the Arkansas River.
Location
The Millau Viaduct is located on the territory of the communes of Millau and Creissels, France, in the département of Aveyron. 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 holiday season. The bridge now traverses the Tarn valley above its lowest point, linking two limestone plateaus, the Causse du Larzac and 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 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 kilometres (210 mi) between Clermont-Ferrand and Pézenas, except for the bridge itself.
The Eiffage group, which constructed the viaduct, also operates it, under a government contract which allows the company to collect tolls for up to 75 years. The toll bridge costs €6.40 for light automobiles (€7.40 during the peak months of July and August).
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