In the 1980s, high levels of road traffic near Millau in the Tarn valley were causing congestion, especially in the summer due to holiday traffic on the route from Paris to Spain. A method of bypassing Millau had long been considered, not only to ease the flow and reduce journey times for long-distance traffic, but also to improve the quality of access to Millau for its local businesses and residents. One of the solutions considered was the construction of a road bridge to span the river and gorge valley.[1] 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. During 1993–1994, the government consulted with seven architects and eight structural engineers. During 1995–1996, a second definition study was made by five associated architect groups and structural engineers. In January 1995, the government issued a declaration of public interest to solicit design approaches for a competition.[2]

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.[3][4] 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.[5][6]

Possible routes  The four proposed routes for the new A75 autoroute around Millau

In initial studies, four potential options were examined:[citation needed]

Great Eastern (French: 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 and 1,000 metres or 2,600 and 3,300 feet) whose construction was acknowledged to be problematic.[citation needed] 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 through-traffic, it did not satisfactorily serve the needs of Millau and its area. Great Western (French: grand Ouest) (black route) – longer than the eastern option by 12 kilometres (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.[citation needed] It was more expensive than the preceding option, and served the region badly. Near RN9 (French: proche de la RN9) (red route) – would have served the town of Millau well, but presented technical difficulties,[clarification needed] and would have had a strong impact on existing or planned structures.[citation needed] Intermediate (French: médiane), west of Millau (blue route) – was supported by 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.[citation needed]

The fourth option was selected by ministerial decree on 28 June 1989.[7] It encompassed two possibilities:

the high solution, envisaging a 2,500-metre-long (8,200 ft) viaduct more than 200 metres (660 ft) above the river; the low solution, descending into the valley and crossing the river on a 200-metre-long (660 ft) bridge, then a viaduct of 2,300 metres (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 29 October 1991.[7]

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 and structural engineer Michel Virlogeux. He worked with the Dutch engineering firm Arcadis, responsible for the structural engineering of the bridge.[8]

Choosing the definitive route  Satellite image of the proposed route before construction of the bridge

The 'high solution' required the construction of a 2,500-metre-long (8,200 ft) viaduct. From 1991 to 1993, the structures division of Sétra, directed by Virlogeux, carried out preliminary studies, and examined the feasibility of a single structure spanning the valley. 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. By July 1993, seventeen structural engineers and thirty-eight architects applied as candidates for the preliminary studies. With the assistance of a multidisciplinary commission, the Administration of Roads selected eight structural engineers for a technical study, and seven architects for the architectural study.

Choice of technical design

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.[citation needed]

Detailed studies were carried out by the successful consortium, steered by the highways authority until mid-1998. After undergoing wind tunnel tests, the shape of the road deck was altered, and detailed corrections were made to the design of the pylons. When the details were eventually finalised, the whole design was approved in late 1998.[citation needed]

Contractors

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. Five consortia tendered:[citation needed]

Compagnie Eiffage du Viaduc de Millau (CEVM), a new subsidiary created by Eiffage; PAECH Construction Enterprise, Poland; a consortium led by the Spanish company Dragados, with Skanska, Sweden, and Bec, France; Société du Viaduc de Millau, including the French companies ASF, Egis Projects, GTM Construction, Bouygues Travaux Publics, SGE, CDC Projets, Tofinso, and the Italian company Autostrade; a consortium led by Générale Routière, with Via GTI (France) and Cintra, Nesco, Acciona, and Ferrovial Agroman (Spain).

Piers were built with Lafarge high performance concrete. The pylons of the Millau Viaduct, which are the tallest elements (the tallest one being 244.96 metres (803.7 ft)) were produced and mounted by PAECH Construction Enterprise from Poland.[citation needed]

The Compagnie Eiffage du Viaduc de Millau, working with the architect Norman Foster, was successful in obtaining the tender.[6] Because the government had already taken the design work to an advanced stage, the technical uncertainties were considerably reduced. 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]

All the member companies of the Eiffage group had some role in the construction work. The construction consortium was 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 railway bridge in the neighbouring Cantal département), and the Enerpac company[9] for the roadway's hydraulic supports. The engineering group Setec has authority in the project, with SNCF engineering having partial control.[clarification needed] Appia (company) [fr] was responsible for the job of the bituminous road surface on the bridge deck, and Forclum (fr) for electrical installations. Management was handled by Eiffage Concessions.[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. It installed the cable stays and put them under tension, while the prestress division of Eiffage was responsible for prestressing the pillar heads.[citation needed]

The steel road deck, and the hydraulic action of the road deck were designed by the Walloon engineering firm Greisch from Liège, Belgium,[10] also an information and communication technologies (ICT) company of the Walloon Region.[11] They carried out the general calculations and the resistance calculations for winds of up to 225 kilometres per hour (140 mph). They also applied the launching technology.[12]

The sliding shutter technology for the bridge piers came from PERI.[citation needed]

Costs and resources

The bridge's construction cost up to €394 million,[13] with a toll plaza 6 kilometres (3.7 mi) 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,[13][14] until 2080. However, if the concession yields high revenues, the French government can assume control of the bridge as early as 2044.[citation needed]

The project required about 127,000 cubic metres (166,000 cu yd) of concrete, 19,000 tonnes (21,000 short tons) of steel for the reinforced concrete, and 5,000 tonnes (5,500 short tons) of pre-stressed steel for the cables and shrouds. The builder claims that the lifetime of the bridge will be at least 120 years.[citation needed]

Opposition

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]

The westernmost route would be better, longer by 3 kilometres (1.9 mi), but a third of the cost with its three more conventional structures. The objective of the viaduct would not be achieved; because of the toll, the viaduct would be little used, and the project would not solve Millau's congestion problems. The project would never break even; toll income would never amortise the initial investment, and the contractor would have to be supported by subsidies. The technical difficulties were too great, and the bridge would be dangerous and unsustainable; the pylons, sitting on the shale of the Tarn Valley, would not support the structure adequately. The viaduct represented a detour, reducing the number of visitors passing through Millau and slowing its economy.