Millau Viaduct
Millau Viaduct
Viaduc Millau
Millau, Midi-Pyrénées, France
909 feet high / 277 meters high
1,122 foot span / 342 meter span
2004
No other high bridge in history caught the eye of the media more than the opening of the Millau Viaduct in 2004. Comprised of 8 consecutive cable stayed spans totaling 8,100 feet (2460 mtrs), the viaduct is the tallest bridge structure in the world with a pier and mast rising a lofty 1,100 feet (335 mtrs) above the ground. With a roadway 909 feet (277 mtrs) above the Tarn River, it is also the highest cable stayed bridge in the world, a record it will retain until 2012 when Mexico’s Baluarte bridge opens. Despite being the highest bridge in Europe, the massive structure ranks only 13th among all high bridges of the world. The bridge has rightfully been described as beautiful, breathtaking, spectacular and awe-inspiring.
Located near the southern end of France, the bridge was the last major connection on the A75 motorway, a 4-lane highway that has been under construction in one form or another since 1975. Several routes were proposed that would have put the Tarn River crossing either east or west of the small town of Millau.
The design of the bridge began in 1991 with Michel Virlogeux, an engineer who at the time was working with the engineering firm Setra. Later, a design competition refined his initial multi-cable stayed concept further. This pared the team down to a handful of firms led by Bernard Gausset of EEG, Sogelerg and Serf along with famous British architect firm Norman Foster & Partners. This group continued to change the basic design until a committee of experts, politicians and specialists officially approved the 8-span cable stayed scheme in April of 1996. A final set of plans would take two more years of design and testing.
Construction began in October of 2001 and took a little over 3 years - exceptional for such a large, complicated undertaking. The bulk of the construction was undertaken by Eiffage, one of France’s largest building contractors. The steel wire cable stays were installed by Freyssinet. Several other consortiums worked on the project from France and several other European countries including Spain, Italy and Sweden.
The 3 year construction period had many unique challenges, the most significant being the unusual launching of the roadway. Instead of cantilevering the road deck outward in small sections from each of the 7 tall pylons, the deck was constructed on flat land on the north and south sides of the bridge in two large sections. Hydraulic jacks on the tops of the piers were then synchronized to move the entire deck out over the valley in small increments of about 2 feet (600 mm). Both sides eventually met over the Tarn river. To make this method work, massive temporary intermediate piers were built to prevent bending of the thin deck since the cable stays and masts above the roadway would not be erected until the entire deck was in its final position. The only exception to this was for the two river spans where the masts and several of the stays were erected on land and went along for the ride across the piers before finally meeting 890 feet (271 mtrs) above the Tarn River.
Other technical advancements that are less obvious to the eye include an array of movement and motion sensors including anemometers, accelerometers, inclinometers and extensometers. Data collected from these devices will help engineers pinpoint potential trouble spots and unwanted wear and tear that could shorten the life span of the many bridge components.
While most of the visual impact of the viaduct comes from the 7 cable stayed “sails” that seem to float across the valley, much of the structure’s greatness comes from the more subtle details that were incorporated into the design. The tall, slender piers have an unusual elegance from a narrow opening that gradually splits the column into two before closing up again within the mast above the road deck. The roadway has a slight curve that adds a third dimension of shape to the structure and offsets the boredom of repetition. The designers even made the best of an unfortunate requirement to install a tall wind barrier along the edges of the roadway with a stylish aerodynamic shape that still allows for a fantastic view of the valley beyond.
As a nearly perfect blend of art, architecture and engineering, the Millau Viaduct will continue to inspire not only the public but future engineers who are continually challenged by the demand to create beauty and grace within the confines of functionality and cost.
Millau Viaduct Elevation
Image by Chris Lilley. http://www.flickr.com/people/chrislilley/
Image by Simon Campbell http://www.csp.gg/
Image by Alvaro L. Paris.
Image by Ian Bateman.
Image by Chris Lilley. http://www.flickr.com/people/chrislilley/
Image by TV Boy Cyrille.
A view of the deck during the launching phase with visible deformations prior to the tower and cable stay erection. The bending of the deck was calculated by the engineers before construction.
For those who might be interested, the list below shows the World's 10 Tallest Bridges as measured from the top of the foundation to the top of the tower. All are suspension or cable stayed bridges.
1. Millau Viaduct, France 336 meters
2. Russky Island Bridge, Russia 320 meters
3. Akashi-Kaikyo Bridge, Japan 300 meters
4. Sutong Bridge, China 300 meters
5. Stonecutters Bridge, China 290 meters
6. Gwangyang Bridge, South Korea 270 meters
7. Jingsha Bridge, China 267 meters
8. Great Belt East Bridge, Denmark 254 meters
9. Edong Yangtze Bridge, China 242.5 meters
10. Mezcala Bridge, Mexico 242 meters
Satellite image of Millau Viaduct under construction.
