The Millau

[Picture of Millau Viaduct]In the south of France, there is a deep 2 km wide valley in the Massif Central Mountain Range at Aveyron divided by the River Tarn. The French government decided an alternative to the nearly saturated Rhône Valley route was needed — as well as a solution to the notorious N9 Millau bottleneck — and so they approved the idea proposed by the owners ‘Compagnie Eiffage du Millau Viaduct’ (CEVM) and the client ‘SETEC’ to cross the Tarn gorges by a viaduct/ road bridge, saving 30 minutes under normal conditions and up to almost 4 hours on some weekends in the summer.

A 40km extension to the A75 (from Paris which runs through Clermont-Ferrand towards Beziers heading eventually for Barcelona), crossing the Tarn would be 60 km shorter than the Rhône Valley route and would enable road hauliers to reduce significantly the journey times for their lorries — 45 minutes on the Paris/Perpignan, Paris/Barcelona or Amsterdam/Perpignan routes.

‘SETEC’ approached the British Architect Sir Norman Foster to design a bridge to last 120 years.

[Picture of Map of the valley]

All designs have to satisfy the design brief, but Fosters knew that this bridge posed several novel problems. Tests revealed problems for drivers on such a high, long and thin structure (just two lanes either way) — despite the estimated journey time to be only about a minute by car.

[Picture of the millau at sunset]The solution was to incline the bridge slightly (3%) to improve road visibility, and to make the whole structure curved (to lessen the sensation of floating) — even though this would lengthen the bridge to 2.5 km and add to the cost. To prevent drivers from the distraction of the beautiful scenery, the hard shoulder on both sides was increased in width to three metres. Emergency phones were designed for every 500 metres along the full length on each side.

[Picture of millau bridge] [Picture of finished millau] Michel Virlogeux

Lord Foster wanted the bridge to look as transparent and lightweight as possible to reduce cost, but also to attempt to minimise the structure in its environment, reduce wind loadings and so forth (the design wind loading was 151km/hr). This implied a multicable-stayed bridge, in sections.

  • However, in branding the bridge, instead of the usual two or three columns expected, Michel Virlogeux chose an amazing SEVEN reinforced concrete pylons / columns ranging in height from 75 m to 235 m, six steel decks of 342 m long, and decided to fan the steel cables.

[Picture of Millau Viaduct]To recoup some costs, Fosters decided to use the absolute minimum amount of material: the masts rising above the road deck and the multi-span cables are all in steel. Even the deck itself is constructed from a new high-grade steel as opposed to concrete.

Three metre transparent high side screens were required to halve the effects of the wind and bring it down to the same wind levels as found at ground level around Larzac and Sauveterre.

The deck was designed to be prefabricated in 2000 sections at Eiffage’s Lauterbourg factory in Alsace and GPS-aligned, 600 mm at a time. The factory was given just 20 months to supply the elements for the deck and the piers of the viaduct.
[Picture of Millau Viaduct]

[Picture of Millau bridge]The decks are supported by multi-span cables placed in the middle. In allowing for expansion and contraction of the deck, there is a metre of empty space at its extremities and each column is split into two thinner, more flexible columns below the roadway, forming an A-frame above the deck level.

The figures began to stack up: nearly 500 workers would be required on site for the million man-hours of estimated work, along with 127000 m³ of concrete, 19000 tonnes of steel-reinforced concrete and 5000 tonnes of pre-constraint steel (cables and shrouds). It was only estimated to cost about 400 million EUR (267.4 million GBP). The bridge is designed to weigh just 290000 tonnes.

[Picture of Millau Viaduct] [Picture of Millau Viaduct] [Picture of Millau Viaduct]

‘Terrasol’ were employed as the geotechnical engineers, and it was estimated that three hundred thousand cubic metres of earth moving would be required. The main contractor was ‘Eiffage TP’, with co-contractor ‘Eiffel Construction Metallique’. ‘Enerpac’ supplied the hydraulic system for lifting and pushing the bridge spans and piers for the bridge.

  • The height above the River Tarn was going to be about 270m — but Pier 2 at 343 metres would make this the highest bridge in the world. A media buzz started as a result.

Works started in October 2001, and at a ceremony on 14 December 2001, the French minister Mr. Jean-Claude Gayssot laid the first stone, by November the following year, the highest pier had already reached 100m in height. Launching the deck started in February 2003, and was completed by May 2004.

[Picture of diagram][Picture of diagram2]

[Picture of Millau Viaduct]An 18-lane toll station 6km north of the ensures that the bridge’s capital costs would be recouped over the 75 year operating concession granted to ‘Eiffage’. A surveillance and control centre will monitor the viaduct round-the-clock. It will be equipped with high-performance security equipment such as: video surveillance linked to an automatic incident-detection system that will immediately inform the control centre if there is any anomaly in the traffic, automatic video recording, a vehicle counting facility, weather stations, and programmable message boards enabling information to be issued instantaneously.

[Picture of Millau Viaduct]Road users will also be able to enjoy the countryside and the rest areas which, according to one company director, ‘enable drivers to have some fresh air, where there is plenty of space to relax in a most beautiful environment’.

The Viaduct was officially opened on 14 December at a ceremony by Monsieur Jacques Chirac, President of the French Republic, and opened to traffic on the 17th.

[Picture of Millau from Fosters]

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8 Responses to The Millau

  1. R Penney says:

    Totally amazing. My head reels at the thought of standing on top of the piles during construction, with the clouds moving in and the high winds, a bit like the Eiger Sanction film to me. I am afraid I do not have the head for heights. I would be scared to drive across!! The windy route would do me.

  2. Duanne Gilmore says:

    I have ben lucky enough to visit this bridge and work with Norman Fosters team. It is no wonder that these people made this idea come alive. It is very much outside the limits of what was possible from an engineering point of view. Their hard work and innovation speaks for itself by way of the finished product.

  3. Ketan Kapasi says:

    I am a structural engineer by profession and live in Mumbai, India. I and my family were fortunate to visit the bridge last summer – while on a holiday in France.

    It is without doubt an amazing feat of engineering and this has been enhanced by the involvement of architects – who have managed to give this bridge that “extra” sense of character.

    We ended up spending a total of four hours here – at the north side viewing hillock and also at the souvenir shop down in the valley.

    Without doubt – the most beautiful bridge in the world !

    ADVICE to anybody wanting to see it: Approach by car from the south side. The bridge appears suddenly on a curve – and this “sudden” view is absolutely breathtaking.

  4. Oliver says:

    Hi every body brilll job on the brige!!!!!!!!!!!!!!!!!!!!

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  6. RB says:

    Wow Awesome brilliant scene

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  8. Anonymous says:

    So the type of bridge is a cable-stayed road-bridge? And he wanted it to look lightweight and delicate.

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