Le Viaduc de Millau

Autoroute E11-A75

Aveyron
France

 

Foster and Partners (architects), Michel Virlogeux (engineer), 2004

 

The Millau Viaduct is an extraorinarily graceful structure that enhances the scenery, rather than jars with it, as it soars for 2.5 km through the air high above the Tarn valley.

 

it is the tallest bridge in the world, peaking at 343m in height where it crosses the contrastingly tiny Tarn river, and is also the world's longest cable-stayed bridge. But what's particularly impressive, beyond the figures, is the lightness and harmony with which it carries its load - and the original construction approach that was needed to create it.

 

 

As a cable-stayed bridge, the deck is suspended directly from seven masts using steel cables. But in fact much of the strength of the bridge comes from the deck itself, a skeleton 4 meters deep in the center. The strength and stability of the deck allows for relatively low masts above deck level, reinforcing the sense of driving along the top of the structure, compared with typical suspension and cable-stay bridges that have much taller towers relative the roadway; and also for the masts to support the deck only along the spine, not along the two edges, which helps to give the bridge's profile its slim elegance as you drive along it. The deck's rigidity was also critical to the construction approach, in which the deck was built on land at the edge of the valley, and gradually pushed out over the waiting piers depending on its own strength as a cantilever.

 

 

During construction, intermediate pylons were built out of steel scaffolding, and the deck pushed out over the valley using hydrauling rams at the top of each pylon, which in a slow, cyclical movement lifted the deck a few millimeters, pulled it along a fraction of a meter, let it down and repeated the cycle. Only for the span over the Tarn river itself, where there was no intermediate pylon and the two halves of the deck met together, having been pushed out from either side of the valley, met together, were the masts and the cable stays already in place above the deck. For the rest of the viaduct, the deck was first laid across the pylons, then the masts and cable stays were built in place above each concerte pylon, before the intermediate scaffolding pylons were taken down.

 

The splitting of the concrete pylons below the deck, and the masts above, further add to the visual lightness of the structure.

 

 

The result is a bridge that feels at home in its valley, with an airiness that belies the 40,000 tons of roadway it carries, and a beautiful backdrop for the now bypassed town of Millau.

 

 

Simon Glynn 2011

Additional photography Shabana Glynn

 


How to visit

 

The viaduct forms part of the A11-E75 autoroute, the main road south from Paris to Perpignan. It crosses the River Tarn just west of Millau, between exits 45 and 46.

 

A small tourist industry has sprung up above the bridge itself. There are two official places to see the viaduct, each with information and museum display about it.

 

On the A75 itself, there is an Aire (rest area) just north of the bridge, accessible from either direction, with a viewpoint for looking down onto the bridge from the North.

 

Driving west from Millau on the D992 towards St Georges de Luzençon, there is the Viaduc Espace Info, a signposted site benath the bridge (too close to be ideal for viewing it), on the south side of Tarn, with displays, models and a film about the construction.

 

The Viaduct itself has an official web site with visitor information and some construction details at www.leviaducdemillau.com.

 

In the summer, from Creissels, on the south edge of Millau, you can take a boat-trip down the (gentle) rapids of the Tarn river, on a course that goes underneath the viaduct at its tallest point. For information and booking please visit www.bateliersduviaduc.com.

 

 

 

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