Viaduc de Millau

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Coordinates: 44 ° 4 ′ 48 ″  N , 3 ° 1 ′ 21 ″  E

Viaduc de Millau
Viaduc de Millau
Overview of the bridge, May 2005
use A75
place Millau
construction multi-hip, 7 pylons cable-stayed bridge
overall length 2460 m
Longest span 342 m
height 270 m
building-costs 400 million euros
start of building 2001
completion 2004
opening 2004
planner Michel Virlogeux
toll Car 11.00  (June 15 - September 15, 2020),
€ 8.90 the rest of the time
location
Viaduc de Millau (France)
Viaduc de Millau
Location of the bridge
Autoroutes Nord-Sud et viaduc de Millau.JPG
Location of the bridge on the Clermont-Ferrand – Perpignan route ( Aveyron department )
p1

The Millau Viaduct (or Millau Bridge ), in French Viaduc de Millau , leads the A75 autoroute over the Tarn in southern France . It was designed by Michel Virlogeux and elaborated by Norman Foster . The then French President Jacques Chirac inaugurated the building on December 14, 2004, and general commissioning followed two days later. At 2,460 m, the viaduct is the longest cable-stayed bridge in the world and, with a maximum pillar height of 343 m, it is the highest structure in France. The concessionaire for the motorway bridge, which will be financed by a bridge toll until 2079, is a subsidiary of Eiffage , a company that goes back to Gustave Eiffel among others . In 2006 the building and the architects and engineers responsible received the IABSE'sOutstanding Structure Award ” .

location

The bridge is located in the Massif Central on the A75 from Clermont-Ferrand to Béziers five kilometers west of the southern French city of Millau between exits 45 and 46. The carriageway spans the Tarn Valley at a height of up to 270 m. For holiday traffic, Millau in the Tarn Valley used to be a bottleneck, which often resulted in accidents and traffic jams.

There are vantage points with a view of the viaduct along the route and at the places Brunas / Rastplatz Cazalous, Peyre , St. Martin du Larzac, Luzençon, Beffroi and Soulobres. The toll station for paying the bridge toll has 18 lanes and is four kilometers north of the bridge, immediately south of exit number 45.

An information center on the construction and operation of the bridge, a sales pavilion and a restaurant are located at the Aire de Viaduc de Millau rest area. They can be reached from the A75 as well as from the main road.

draft

More than 20 years passed with the planning of various routes, the exploration of the terrain and the elaboration of drafts. The technical concept and the final design of the bridge come from the French civil engineer Michel Virlogeux, the architectural design of the bridge derived from it goes back to the British Norman Foster. In the summer of 1996, a jury decided from five designs for their project with seven stay cable pylons above the road deck. The update of the draft until 1998 led to two variants, one with a road deck and pylon in concrete and one alternatively in steel.

implementation

In autumn 2001, the French group of companies Eiffage , whose co-founder was the builder of the Eiffel Tower, Gustave Eiffel, was commissioned as a concessionaire to carry out the construction. The Eiffage was the only one to offer the version with a superstructure and pylon made of steel. She founded the company Compagnie Eiffage du Viaduc de Millau (CEVM) for the project . The company bore the cost of building the bridge of around 400 million euros and was granted the toll concession for crossing the bridge for over 75 years . After that, the building becomes state property. Until then, the company will also be responsible for maintaining the bridge.

Work on building bridges began in October 2001, and the foundation stone was laid on December 14, 2001. In December 2003 the abutments, the seven reinforced concrete pillars and some of the auxiliary supports were completed. The bridge between the two superstructures was completed on May 28, 2004. Then the pylons were put in place, the stay cables were installed, the covering was applied and the structure was approved, among other things with a heavy load test. The construction work thus remained within the contractually stipulated time limit of four years, the excess of which would have cost penalties of up to 30,000 euros per day. This was achieved, among other things, by the simultaneous construction of all reinforced concrete pillars, the parallel production of the carriageway box girders and pylons in factories and the advance of the box girders from both sides of the slope. In addition, climbing formwork was used, which independently moved upwards using hydraulic systems.

Technical specifications

Bridge height compared to the Eiffel Tower

In the area of ​​the bridge, the motorway has a longitudinal gradient of 3% from north to south and has a radius of curvature of 20,000 m in plan. The curve is intended to give users a better view of the structure. The two directional lanes each have two lanes 3.5 m wide and one 3 m wide hard shoulder. They are secured by guardrails, emergency telephones, fire extinguishers, visual round-the-clock surveillance, patrols and 3.2 m high windproof protective windows.

construction

The bridge is 2,460 m long and has spans of 204 m for the two end spans and 342 m for the six inner spans. The 32 m wide, maximum 4.2 m high, diamond-shaped girder is at a height of up to 270 m above the Tarn.

The cross-section consists of a steel box with an orthotropic roadway. Special heavy steel plate , including high-strength fine-grain structural steel DI-MC 460, manufactured by Dillinger Hütte in Saarland , was used to build the road construction .

With a height of up to 245 m, the reinforced concrete piers of the bridge were the highest bridge piers in the world until then. The hollow reinforced concrete pillars have a constantly changing cross-section. They are divided in a Y-shape 90 m below the carriageway structure and are vertically prestressed in this section . Their base area, which begins with 200 m², tapers to twice 30 m². In the longitudinal direction of the bridge, the split piers at the head have a total length of 16 m, which grows down to a maximum of 17 m. The width in the transverse direction of the bridge varies between 10 m at the top and 27 m at the foot of the highest pier. 53,000 m³ of concrete were built into the reinforced concrete pillars . A total of 206,000 tons of concrete were required. The formwork technology for the pillars came from Peri GmbH.

In the middle of the pillars stand 98 m high and 700 ton heavy steel pylons , from which the roadway is suspended with fan-shaped stay cables arranged in one level. The construction is only a tenth the weight of a comparable concrete construction. Each of the 342 m long steel segments has a mass of approximately 5000 tons. In total, the steel of the superstructure has a mass of 36,000 tons. The 7 cm thick pavement that was applied later consists of 9000 tons of asphalt .

Due to its exposed position in the main wind direction, the bridge is designed for wind loads up to a speed of 205 km / h. The cross-sectional geometries of the superstructure and the octagonal pylons were aerodynamically optimized in wind tunnel tests . The Y-shaped division of the pillars 90 m below the carriageway serves to make the pillars resilient to longitudinal deformations of the superstructure.

The area below the roadway was shaped like a curved aircraft wing in order to be able to take advantage of the effects of the wind flow. A continuous curvature below the roadway creates a downforce or contact pressure from above down onto the roadway, as the wind now accelerates below the wing. This aerodynamic principle was first applied to the Welsh suspension bridge Severn Bridge by civil engineer Gilbert Roberts and his team.

Assembly

Northern construction section, early 2004

The superstructure of the viaduct was made of steel , which had advantages over concrete in terms of weight and assembly. With the help of up to 175 m high auxiliary supports with a square edge length of 12 m, which halved the spans during assembly, the track girder was pushed in from both abutments in units of 171 m length using the incremental launching method . Here kragte the superstructure of the bridge with a launching nose of 59 m length of up to 112 m. For stabilization, a pylon with stranding was installed and inserted 171 m after the top of the track girder. For the displacement, a device was installed at all support points, which lifted the bridge with two opposing wedges and advanced it by 600 mm per movement in 4 minutes. The sliding surface between the wedges was coated with the lubricant PTFE or "Teflon".

After the bridge was closed, the other five pylons weighing around 700 tons were transported to the piers lying on the superstructure and erected by tilting them. This was followed by tensioning the eleven ropes on each side of the pylon, and then the auxiliary supports could be removed.

The process enabled the construction workers to spend more than 95% of their working hours on the ground floor and the risk of accidents was significantly reduced.

Costs, importance for the region and national traffic

The client was the Compagnie Eiffage du Viaduc de Millau. The cost of the structure, which required 2.2 million man hours, was around 400 million euros (the planned figure was around 350 million euros). In contrast to the usual motorway tolls in France, this was waived for the A75, as the gap closure was expected to provide an economic boost to the structurally weak area. Depending on the season, a toll of almost EUR 10 per crossing (car) is only charged for crossing the viaduct.

Panoramas

The Millau Viaduct, here still under construction (June 2004), about six months before the opening. The bridge superstructure was additionally supported by the red auxiliary piers until the pylons and stay cables were installed. In the right part of the picture, one of the steel pylons of the stay cable construction is still in a horizontal position shortly before it is installed above the roadway.
The Millau Viaduct (August 2009), view from the east from Millau
The Millau Viaduct (October 2010), view from the west. In the valley of the Tarn, over which a “conventional” prestressed concrete bridge leads (size comparison).

Brocuéjouls rest area

Brocuéjouls rest area

At the northern end of the bridge is the Brocuéjouls rest area on the A75 , which opened on June 30, 2006. The construction costs totaled 5.8 million euros.

A former farm on the site has been renovated, expanded and surrounded by parking spaces. In 2016, the facility was expanded to include the bridge information center. All facilities can be reached from the A75 or the country road. A nearby lookout point offers a panoramic view of the viaduct.

literature

  • Marc Buonomo, Francis Roos, Falko Schröter: The large Millau viaduct - steel construction and assembly with high-strength fine-grain structural steels . In: Stahlbau , Vol. 74, 2005, pp. 313–318, doi : 10.1002 / stab.200590060 , ( online file , PDF; 6 pp., 1.6 MB).
  • Michel Virlogeux: The viaduct over the Tarntal near Millau - from the first design ideas to completion . In: Bautechnik , Vol. 83, 2006, pp. 85-107, doi : 10.1002 / bate.200610010 .
  • Le Viaduc de Millau. Motorway E11 – A75. A world record in terms of…. Information sheet from the construction company Eiffage , 2009, 4 pp.
  • Le Viaduc de Millau - The Millau Viaduct: Portfolio. Éditions CVEM, 2005, 176 pages, ISBN 978-2-9524478-0-5 , (French and English).
  • The tallest bridge in the world . In: PM magazine . April 2004, p. 12 . ( Online file ).
  • Jens Frantzen: Bridge construction - giants made of reinforced concrete . In: Technology Review . December 2004, p. 62-71 . ( Online file , PDF; 10 pages, 990 kB).

Movies

  • Ingenious technology - the Millau Bridge. (OT: Millau Viaduct. ) Documentary, Great Britain, 2015, 46:51 min., Written and directed: Tim Williams and Tom Weller, production: Science Channel US, series: Geniale Technik , (OT: Impossible Engineering ), German premiere: February 18, 2016 on n-tv , synopsis from n-tv, film clips from Science Channel (English). Chief engineer Virlogeux explains the properties and construction methods of this bridge construction on site; with many archive recordings.
  • Xenius - How are gigantic bridges built? Knowledge broadcast, Germany, France, 2015, 26:12 min., Book: Christine Voges, director: Angela Volkner, moderation: Emilie Langlade, Adrian Pflug , production: AVE, ZDF , arte , series: Xenius , first broadcast: September 11, 2015 at arte, synopsis from ARD , online video .
  • The biggest projects in the world. High above Millau - the superviaduct. (OT: Millau Viaduct. ) Documentary, USA, 2004, 50:16 min., Book: Megan Reilly, director: Chris Schmidt, production: Discovery Channel , series: The biggest projects in the world (OT: Build It Bigger ), first broadcast : October 12, 2004 on Discovery Channel, table of contents from wunschliste.de, online video .

Web links

Commons : Viaduc de Millau  - collection of images, videos and audio files
File category Files: Viaduc de Millau  - local collection of images and media files

Individual evidence

  1. Tarifs du péage. In: leviaducdemillau.com , 2020, scroll down , (French).
  2. ^ Hanns-Jochen Kaffsack: French super viaduct. The tallest bridge in the world. In: dpa , December 13, 2004.
  3. a b c d e Ingenious technology - The Millau Bridge. In: n-tv , February 18, 2016.
  4. Michel Virlogeux: The viaduct over the Tarntal near Millau - from the first design ideas to completion . In: Bautechnik , vol. 83, 2006, p. 96.
  5. Millau Viaduct. In: Structurae
  6. a b c Heavy plate for the Millau Viaduct. The longest cable-stayed bridge in the world: made of DI-MC. ( Memento from January 18, 2016 in the Internet Archive ). In: Dillinger Hütte Group .
  7. Marc Buonomo, Francis Roos, Falko Schröter, Das Großes Viadukt von Millau , p. 314, (PDF; 6 p., 1.6 MB).
  8. Michel Virlogeux: The viaduct over the Tarntal near Millau - from the first design ideas to completion . In: Bautechnik , vol. 83, 2006, p. 96.
  9. Marc Buonomo, Francis Roos, Falko Schröter, Das große Viadukt von Millau , p. 318, (PDF; 6 p., 1.6 MB).
  10. Bernd Nebel: Viaduc de Millau.
  11. Tarifs du péage (= tolls). In: Compagnie Eiffage du Viaduc de Millau (bridge operator), accessed on October 20, 2016.
  12. Press release: Inauguration de l'aire de repos du viaduc de Millau. ( Memento of July 4, 2007 in the Internet Archive ). In: Préfecture de l'Aveyron , 2006, (PDF; 9 p., 56 kB).