Last edited 15 Nov 2016

The Millau Viaduct

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[edit] The Millau Viaduct

Millau pic.png

== Contents ==

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[edit] Introduction

The region surrounding the town of Millau is famous for Roquefort cheese and until the inauguration of the Millau Viaduct on the 14th December 2003 it was also famous as a traffic bottleneck.

The Millau Viaduct is a multi span cable stayed bridge that links the two sides of the A75 connecting Paris to Barcelona and relieving Millau's roads from summer gridlock. (Reed n.d.) The project cost 400 million euros and was entirely privately financed and constructed by EIEFFAGE. (V.Ryan 2005) (The Millau Viaduct a World Record Breaker n.d.) The structure is the tallest cable stayed bridge in the world standing at 343m tall spanning a length of 2460m. (LATRASSE 2004)

[edit] Overview

French engineer Michael Virlogeux created the original concept for the Millau Viaduct in 1991, however his designs were dismissed by local authorities as unfeasible. The authorities then ran a design competition that was won by English architect Sir Norman Foster who presented a modified version of Michael Virlogeux's original, leading to their collaboration. (Bartlett School of Planning n.d.)

The project pushed engineering boundaries with the viaduct being built across one of the deepest valleys in France, taller than the Eiffel Tower. This was the bridge that was meant to be impossible to be build, bringing the challenges of; the tallest bridge piers in the world, a 36,000 tonne motorway and 7 steel pylons above every pier each weighing 700 tonnes. The local geology was also very testing with susceptibility to mud slides due to fluctuating river levels and plagued by deep caves. (CAMPAGNAC n.d.)

[edit] Construction

Construction started in October 2001 with deep foundations set into the bedrock. Along with the abutments and piers a total of 250,000 tonnes of concrete was used, necessitating the creation of a concrete factory on site.

With the highest pier being 234m tall precision was of paramount importance; a tollerance of just 1cm per 4m casting would result in misalignment at the top of the pier by as much as 6m. To prevent this constant GPS checks were carried out, ensuring a final precision of 5mm in all directions on completion.

The construction of the deck was an innovation in itself; due to its height and the distance between piers deck sections could not be craned into position. Instead, they were 'pushed' from both sides. Temporary piers were erected to help support the deck during this process and to reduce the span. Cable-stayed pylons were used to support the overhanging sections, with a rail like structure installed below the deck. (Bartlett School of Planning n.d.)

The pylons and deck sections were pre-constructed at Eiffel's Lauterbourg factory, which in total required more than 2,000 deliveries. This in itself required improvements in the regions roads.Prefabrication allowed quick assembly in two on-site factories.

Winds were a concern especially during the positioning of the decks, and to reduce the chance of the deck flying out of control, engineers would wait for 3-day weather windows with wind speeds forecast to be less than 85km/hour. (Saxton 2007)

The project was a huge success taking only three years to complete, three months ahead of schedule and on budget. It had a near perfect record for health and safety with no serious accidents recorded.

Millau Viaduct.jpg

[edit] Economy

Millau's residents originally opposed the project, believing that is would stop people visiting Millau and so damage local business. However Millau's mayor, Jacques Godfrain used his political connections to push the project through (Bockman 2003). In fact, on completion the viaduct proved to be a major tourist draw, resulting in several new hotels adn shops being built

Other local attractions have also benefited such as the Roquefort cheese cellars and Sylvanes Abbey, which have seen visitors increase by 28% and 18% respectively. A local glove factory even re-opened due to increased interest in the town and because of the improved logistical links. (Godfrain 2006) (Millau Vaiduct OFFICIAL WEBSITE 2012)

Opponents originally believed that income from tolls would not be enough to pay for the investment, or that the tolls would direct traffic back into Millau. (Opposition, Milau Viaduct Bridge n.d.) However, Millau Viaduct became a vital link and offered new competition for existing tolled roads. Since opening, trucks have increased by 20% on the route. It is seen to be a cheaper route, as the motorway leading up to the charged viaduct is free.

Unlike many construction projects Eiffel promised not to bring makeshift accommodation but instead built new or refurbished older buildings for the labour force, boosting the local housing market (Godfrain 2006)

[edit] Politics

From the first sketches in 1987 to starting construction on site took 14 years despite the great need for the viaduct. Disagreements over location, design, financing and two long enquiries meant that planning permission was not granted in until 1998. (Millau Vaiduct OFFICIAL WEBSITE 2012)

Private investment was sought in 1999 through a concession agreement (Millau Viaduct Bridge - France n.d.) with a requirement that 1% of the project budget would be spent on local economic development projects. (Bartlett School of Planning n.d.)

The viaduct has also became a strong political lever for locals to voice their grievances. The first protest was staged before the bridge was completed when locals with tractors blocked access to the viaduct to draw attention to the risk of the local hospital being closed. (Gentleman 2003)

The Millau Viaduct was opened by president Jacques Chirac during a ceremony in which fighter jets soared above. (LATRASSE 2004)

[edit] Ecology

Originally local ecologists were against the viaduct. However, ecological standards were actually very high.

A wastewater treatment system was installed during construction to avoid polluting the soil, and rainwater was collected from the viaduct and treated in clarification tanks. (The Millau Viaduct a World Record Breaker n.d.) (Godfrain 2006)

The choice of steel reduced the time the local environment was subject to the impacts of construction. Prefabrication also meant that there was less equipment on site and less transportation. The use of steel allowed the structure to be as minimal and delicate as possible and to merge its surroundings. The deck is so high that in the morning mist and on cloudy days it disappears above the Tarn Valley. (Steelbridge 2004)

The project carbon footprint was great due to its scale, however because of the new direct route that has been established (the journey from Paris to Perpignan is now 67km shorter) it is thought that fuel savings will offset the viaducts carbon footprint

The bridge is intended to last at least 120 years. (Millau Vaiduct OFFICIAL WEBSITE 2012)

Read about bridge construction here.

Read about the most famous bridges in the world here.

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Comments

Fantastic bridge! If you haven't been there you should! Nice to see the ecological impacts were low too!