[10] The first plans for a bridge were discussed in 1987 by CETE, and by October 1991 the decision was made to build a high crossing of the Tarn by a structure of around 2,500 metres (8,200 ft) in length.

[11] In July 1996 the jury decided in favour of a cable-stayed design with multiple spans, as proposed by the SODETEG consortium led by Michel Virlogeux, Norman Foster and Arcadis.

[15] It encompassed two possibilities: 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.

Taking into account technical, architectural, and financial issues, the Administration of Roads opened the question for competition among structural engineers and architects to widen the search for realistic designs.

Simultaneously, a school of international experts representing a wide spectrum of expertise (technical, architectural, and landscape), chaired by Jean-François Coste, was established to clarify the choices that had to be made.

[citation needed] In February 1995, on the basis of proposals of the architects and structural engineers, and with support of the school of experts, five general designs were identified.

[citation needed] The competition was relaunched: five combinations of architects and structural engineers, drawn from the best candidates of the first phase, were formed; each was to conduct in-depth studies of one of the general designs.

On 15 July 1996, Bernard Pons, minister of Public Works, announced the decision of the jury, which was constituted of elected artists and experts, and chaired by Christian Leyrit, the director of highways.

The solution of a multiple-span viaduct cable-stayed bridge, presented by the structural engineering group Sogelerg, Europe Etudes Gecti and Serf, and the architects Foster + Partners was declared the best.

After undergoing wind tunnel tests, the shape of the road deck was altered, and detailed corrections were made to the design of the pylons.

[citation needed] Once the Ministry of Public Works had taken the decision to offer the construction and operation of the viaduct as a grant of contract, an international call for tenders was issued in 1999.

[citation needed] The Compagnie Eiffage du Viaduc de Millau, working with the architect Norman Foster, was successful in obtaining the tender.

A further advantage of this process was to make negotiating the contract easier, reducing public expense, and speeding up construction, while minimising such design work as remained for the contractor.

[citation needed] The only other business that had a notable role on the building site was Freyssinet, a subsidiary of the Vinci Group specialising in prestressing.

[citation needed] Numerous organisations opposed the project, including the World Wildlife Fund (WWF), France Nature Environnement, the national federation of motorway users, and Environmental Action.

Opponents advanced several arguments:[citation needed] Two weeks after the laying of the first stone on 14 December 2001, workers started digging deep shafts for the pilings.

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 wedges were hydraulically operated, and moved repeatedly in the following sequence: The launching advanced the road deck at 600 millimetres (24 in) per cycle which was roughly four minutes long.

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 Béziers, except for the bridge.

[citation needed] 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.

Each strand has triple protection against corrosion (galvanisation, a coating of petroleum wax, and an extruded polyethylene sheath).

The idea is to avoid running water which, in high winds, could cause vibration in the stays and compromise the stability of the viaduct.

To allow for deformations of the metal road deck under traffic, a special surface of modified bitumen was installed by research teams from Appia (company) [fr].

The surface is somewhat flexible to adapt to deformations in the steel deck without cracking, but it must nevertheless have sufficient strength to withstand motorway conditions (fatigue, density, texture, adherence, anti-rutting etc.).

[citation needed] The pylons, road deck, masts, and cable stays are equipped with a multitude of sensors to enable structural health monitoring.

[citation needed] The data is transmitted by an Ethernet network to a computer in the IT room at the management building situated near the toll plaza.

A car park and viewing station, equipped with public toilets, is situated at each side of the toll plaza.

[30] The cost of this work amounted to €5.8 million: Unusually for a bridge closed to pedestrians, a run took place in 2004, and another on 13 May 2007:[citation needed]