Located in Southern France, the Millau Viaduct is the tallest bridge in the world. Constructed in three short years, the bridge is an engineering and architectural marvel. At its highest point, the bridge soars 343 meters (1,125 ft) above ground, that’s 19 meters (62 ft) taller than the Eiffer Tower! Check out the incredible photographs below along with a timeline of the project’s major milestones and notable records and figures.
THE MILLAU VIADUCT – PRE-CONSTRUCTION TIMELINE
1987: the first sketches of the tracing of the A75 motorway to link the Causse rouge, to the north, to Larzac, in the south, are begun. Several proposals are put forward for crossing the Tarn valley, to the east and west of Millau.
1994: the decision is taken. A bridge will be built a few kilometres downstream of the town.
1996: following a call for tender, the solution designed by Michel Virlogeux, head engineer at the Ponts et Chaussées, drawn by Sir Norman Foster, architect, was selected. A multi-stay cabled construction will be seen on the Aveyron skyline. Its aesthetic aspect and integration into the countryside attracted the government departments. It took preference over four other potential projects: a bridge of constant thickness, a variable thickness bridge, a viaduct with stays stretched under the deck and a construction with one single arch.
1998: the government grants the concession of the construction and management of the viaduct. This is fixed for a period of 75 years.
2001: in October, following a call for tender, the alliance of concrete (pier) and steel (deck) recommended by the groupe Eiffage received state approval. Concrete has all the endurance qualities required. Steel allows for the construction of a thin, lightweight deck. On 14 December, the adventure begins with the laying of the first stone.
THE TALLEST BRIDGE IN THE WORLD – 3 YEARS TO COMPLETION
Concrete…
By spring 2002, the first piers of the Millau viaduct were rising skywards. At the same time, the anchorage points of the deck (the abutments) were appearing in the causses. A few weeks were all it took to carry out the earthworks. Twelve months after the work began, the pier “P2″ went above 100 m. A year later, on 9 December 2003, the concrete work was completed on time! And what’s more, the record for the tallest pier in the world was set at 245 m.
Steel…
Assembling the steel deck began in the summer of 2002. Two open-air sites were set up just behind the abutments. On 25 March 2003, a first section of deck (171 m) was driven out into open space: this rolling out operation was a success. 17 others followed suit, at an average rate of one rolling out every four weeks. On 28 May 2004, at 14:12 exactly, the junction – or “clavage” – of the north and south sections of the deck took place 270 m above the Tarn. Mission accomplished !
And then the rest…
On 29 May 2004, 24 hours after the junction, the installation of the pylons began, followed by the placing of 154 stays to support the deck. In three months, it was all completed. At the end of September 2004, the surface was laid on the deck. The road surface (paint, safety devices, etc.), installation of the safety systems, lighting, finishing touches to the tollgate: everything was ready on 16 December 2004 for the commercial running of the viaduct
THE MILLAU VIADUCT – RECORD FIGURES
Length: 2,460 m (8,071 ft)
Width: 32 m (105 ft)
Maximum height: 343 m (1,125 ft), or 19 m higher than the Eiffel Tower
Slope: 3.025 %, going up from north to south in the direction Clermont-Ferrand – Béziers
Curve: 20 km (12.4 miles)
Height of the tallest pier (P2): 245 m (804 ft)
Height of the pylons: 87 m (285 ft)
Number of piers: 7
Length of the spans: Two end spans of 204 m (669 ft) each and six central spans of 342 m (1,122 ft) each.
Number of stays: 154 (11 pairs per pylon laid out in one mono-axial layer)
Tension of the stays: from 900 t to 1,200 t for the longest
Weight of the steel deck: 36,000 t, or 5 times that of the Eiffel Tower
Volume of concrete: 85,000 m3, or 206,000 t
Cost of the construction: 400 Million Euros (585 m USD)
Contract duration: 78 years – 3 years for construction and 75 years of operations
Structural guarantee: 120 years
MILLAU VIADUCT ARCHITECTS: FOSTER + PARTNERS
Bridges are often considered to belong to the realm of the engineer rather than that of the architect. But the architecture of infrastructure has a powerful impact on the environment and the Millau Viaduct, designed in close collaboration with structural engineers, illustrates how the architect can play an integral role in the design of bridges. It follows the Millennium Bridge over the River Thames, in expressing a fascination with the relationships between function, technology and aesthetics in a graceful structural form.
Located in southern France, it connects the motorway networks of France and Spain, opening up a direct route from Paris to Barcelona. The bridge crosses the River Tarn, which runs through a spectacular gorge between two high plateaux. Interestingly, alternative readings of the topography suggested two possible structural approaches: to celebrate the act of crossing the river or to articulate the challenge of spanning the 2.46 kilometres from one plateau to the other in the most economical manner. Although historically the river was the geological generator of the landscape, it is very narrow at this point, and so it was the second reading that suggested the most appropriate structural solution.
A cable-stayed, masted structure, the bridge is delicate, transparent, has the optimum span between columns. Each of its sections spans 342 metres and its columns range in height from 75 metres to 245 metres (equivalent to the height of the Eiffel Tower), with the masts rising a further 90 metres above the road deck. To accommodate the expansion and contraction of the concrete deck, each column splits into two thinner, more flexible columns below the roadway, forming an A-frame above deck level. The tapered form of the columns both expresses their structural loads and minimises their profile in elevation. The bridge not only has a dramatic silhouette, but crucially, it also makes the minimum intervention in the landscape. Lit at night, it traces a slender ribbon of light across the valley.
Client: French Ministry of Equipment, Transport, Housing, Tourism and Sea
Consultants: EEG (Europe Etudes Gecti), Sogelerg, SERF, Agence TER, Michel Virlogeux
SOURCES 1,2,3
