Millau Viaduct symbolizes the pride of France and a world of architectural and engineering feat in design and construction. While bridges are largely considered the territory of engineers, the close collaboration between architects and structural engineers in the design of the Millau Viaduct attests to the integral role architecture can play in the design of bridges (Foster and Partners 2). The bridge has been likened to the Millennium Bridge in its representation of the marvel in the relation between function, technology, and aesthetics in the construction of an elegant structural form. As a cable bridge spanning the Tarn River valley in France, the bridge currently holds the record as the tallest bridge in the world with a single mast summit more than 1000 feet above the structure’s base (Foster and Partners 2). With its inauguration on 14 December 2004 and official opening on 16 December, the bridge’s construction with a transparent and delicate form broke a number of records; it has the highest towers worldwide, is the highest road bridge deck in Europe, and as well, supersedes the Eiffel Tower as the tallest structure in France (Foster and Partners 2). The bridge is overly significant for France given that its conception for construction was for it to provide a solution for the A75 motorway. The need for a solution was occasioned by the long traffic jams and motor congestion on the roads, particularly during the holiday season. At its completion, the bridge won several awards, in addition to its naming as one of the greatest engineering achievements in the world.
Location of the Bridge
The laying of first stone that initiated the construction of the bridge began on 14 December 2001. This was after a number of proposals on the position and route of the bridge before settling on the Tarn River Valley (Foster and Partners 2). With its official inauguration done on 14 December 2004, the bridge’s presence blends with the valley’s environment, almost entirely fitting within the landscape. The bridge is conveniently located in southern France, and provides the previously missing connection in the A75 autoroute between Clermont-Ferrand and Beziers (Foster and Partners 2). The bridge sits in the communes of Millau and Creissels, within the Aveyron department. Before its construction, motorists drove down into Tarn River valley, passed along the N9 route near Millau, and therefore causing great traffic congestion, particularly during the holiday season. Currently, the bridge cuts across the Tarn valley joining two plateaus, the Causse du Larzac and the Causse Rouge, and is within the confines of a natural part in the area.
At its current position, the bridge provided a nonstop high-speed road from Paris through Clermont-Ferrand and through to Beziers. Through Clermont-Ferrand from Paris, the bridge additionally provides a clearway to Languedoc and into Spain, with a considerable reduction in the price of traffic when journeying through the bridge (Steelbridge 2). The bridge is moreover popular with tourists going into southern France and Spain given its directness, and the fact that apart from the bridge, the more than 300-kilometer drive between Clermont-Ferrand and Pézenas, it has not stops for tolls.
Designed by Norman Foster and Michel Virlogeux, the bridge was a result of a search for aesthetics, functionality and technology, and thus the “choice of a multi cable-stayed viaduct with slender piers and a very light deck, touching the valley at only seven points” (Steelbridge2). At the initial stages of construction, there was a necessity to choose between tow structural approaches. One of the approached involved a celebration of the act of crossing a river, while the other involved tackling the challenge of crossing more than two kilometers from one plateau to another in the cheapest and most beautiful way possible (Foster and Partners 2).
At the time of its construction, the bridge met a lot of resistance especially from Millau’s residents who believed the project would result to loss of tourist to the area, as well as damage local business (Bockmann.p.). In a turn of events however, the bridge in itself became a tourist attraction as more tourists streamed into the small town of Millau to see the bridge. Through this increased traffic, the town has not only managed to construct several hotels to house the visitors, but has also experienced booming business and tourist visits. At the time of its construction, it was estimated that about 100, 000 people had made detours to see the bridge (Bockmann.p.).
Yet the residents were not the only people opposed to the project. Other opposers included France Nature Environment, Environmental Action and the WWF among other organizations. All these had varied arguments, particularly concerning the location of the project. Among the arguments was the positioning of the pylons, which would sit on the shale of the Tarn Valley and therefore would not offer strong enough support to the structure. This, the opposers considered as technical difficulties, which were not only considerably huge, but would also make the bride dangerous and unsuitable (Gentleman n.p.).
Other arguments against the construction of the bridge at its current location opined that a different route (westernmost) would be more convenient, although it would have been longer by 3 kilometers. Even with this increased length, the opposers argued that it would be only a third of the cost of the bridge’s three more conventional structures. Moreover, the opposers argued, following the concession between the government and the construction company over the collection of toll on the bridge for 75 years to get back the €260 million invested on the 2,460 meters bridge (Bockmann.p.), it was possible that the project would not break even. This is because the toll would not repay the amount put into the project, thus forcing the contractor to look to subsidies for support. Even more compelling of the opposing argument was that the bridge’s construction objective would not be attained as few people would use the viaduct, and therefore not solve the very problem it was meant to solve. All these opposing arguments add to the residents and other people’s arguments that the bridge would be a detour, and therefore lead away business and visitors heading to Millau, therefore not only slowing the towns economy, but also robbing the townspeople of their livelihood (Bockman n.p.).
With the completion of the bridge however, all the opposing arguments have been rested, particularly those that concerned drawing away of business from the small town. While the bridge is closed to pedestrians, it has so far held 2 sporting events; the 2004 run and the May 2007 run. Moreover, tourists have been slowing down on the bridge to view the landscape and the bridge, as well as take photos. This has had a great impact on the small town’s tourism since the construction of the bridge began (Bockmann.p.).
Part of the bridge’s feat comes from its sheer size and the expertise used in its construction. The multi cable-stayed bridge is 2460 meters in length (Steelbridge 2). With a total of 7 piers, the bridges highest pier (pier 2) stands at 343 meters, while its shortest pier (Pier 7) stands at 77 meters (Steelbridge 2). As a continuous on its length, the bridge has eight cable-stayed spans, with two end spans of 204 meters and six central spans of 342 meters (Steelbridge 2).
On its cross section, the bridge has a dual motorway carriageway, with a bordering 3 meter emergency lane for each of the carriages, and a one meter shoulder adjacent the central reservation (Steelbridge 2). The central reservation’s width of 4.5 meters gets its size from the stay-cable assembled in a single plane along the central length of the viaduct, with the resulting profile giving a summary 27-75 meters on the deck (Steelbridge 3). Further, the bridge weighs 290,000 tons, with a volume of 85,000 cubic meters. Given the difference in heights of the piers, the average height of the roadway is 270 meters, with 4.20 meters in thickness and 32.05 meters in width (Steelbridge 4).
Culture and Society
The construction of the bridge in its very design and construction was intended to be a reflection of the French in every aspect. Known as the world capital of fashion and elegance, the bridge in its very construction was supposed to give a similar reflection, particularly in marrying aesthetics, technology and engineering (Steelbridge 2). At the completion of the bridge, many praised its construction as an engineering feat, therefore underscoring the achievement of the objective intended in it construction. The bridge performs not only functional purpose, but also paints itself within the larger landscape of the Tarn River valley. It is therefore a true reflection of the French elegance and attention to detail.
France, within the realms of art and culture, has curved itself as one of the centers of Western cultural development. During the construction of the bridge, in the traditional French style, passion and art marked an important influence in the design and construction of the bridge (Zimmermann n.p.). With successive promotion of artistic creation from the government, the construction of the bridge follows the country’s culture of appreciation of art as expressed in the tapered form of the bridge’s columns, expressing the bridge’s structural load and minimizing the columns’ profile of elevation. This in effect not only “gives the bridge a dramatic silhouette, but crucially, it also makes the minimum intervention in the landscape” (Foster and Partners 2). The care in such construction was to make the bridge a part of the valley’s landscape, as well as an expression of the society’s love for art, beauty and elegance.
The French culture values originality, professionalism and sophistication in not only their art, but in dressing and their cuisine. These values are also espoused in the French law through the term haute couture (Zimmermann n.p.). This means that in their value system, sophistication and elegance take precedence, features that are all present within the design of the bridge. The Millau Viaduct is not only an original creation, but a mark of beauty, and at the time of its construction towered as the longest cable-stayed bridge, had the highest pylons, in addition to superseding the Eiffel Tower as the tallest structure in France (Foster and Partners 2). Moreover, its design – collaboration between structural engineers and an architect – make it stand out, given that most bridges are largely the works of structural engineers.
The French are great believers in secularism and equality of both men and women (Zimmermann n.p.). It is for this reason that there was a lot of debate over the route the bridge should take before its construction. Many of the opinions aired were equally heard and taken into consideration before the final decision on the route the bridge would take. Moreover, the French take pride in the nation and the government, so much that even when the intermediate route, during the discussion phase of the bridge’s construction, presented geological difficulties, it was the final choice by the ministerial decree, with the argument that the obstacles were not impossible to conquer.
The choice of Norman Foster as the architect and Michel Virlogeux as the structural engineer, as well as Eiffage as the construction company followed the reputation of all the three entities (Bockmann.p.). Both Foster and Virlogeux have well established reputations, with foster being a world-renowned architect. For the construction company, Eiffage had previously built the Eiffel Tower, one of Paris and France’s constructional highlights, and its reputation therefore preceded it in winning the contract for the construction of the bridge (Bockman n.p.).
Construction of the Bridge
The bridge used some of the most advanced systems and construction method. Given that the bridge’s construction began at a time of considerable advancement in construction technology, more power tools and advanced technology was used for the construction. Moreover, most of the deck was pre-fabricated in the factory making the construction faster, while reducing the time required for transportation of material from the factory to the site of construction (Steelbrideg 10). The pre-fabrication therefore meant that the deck would simply require transportation, on-site assembly and launching, making the whole process not only faster, but also safer and cost effective (Steelbrideg 10).
The construction also accounted for the wind in the valley given the bridge’s placement high above the valley. With the knowledge of the effect of the wind on the structure, the construction benefitted from the latest knowledge at the time through studies and trials (Steelbrideg 10). The studies took into consideration the nature of the wind at the site; they determined the wind model, the aerodynamics of the diverse elements of the bridge when exposed to the wind such as piers, deck and pylons (Steelbrideg 10). These studies also took into consideration safety measures by applying extreme conditions on the bridge when under construction and during its time in service.
The facilities used for construction were spread over four zones taking up approximately eight ha (Steelbrideg 10). At the foot of each support however, there were other facilities averaging 3,500m2. The minimal space in land used as construction facilities was occasion by the fact that the deck and pylons were steel constructed, and the steel used for their construction was fabricated elsewhere. This meant that only the piers and abutments’ construction was done at the Millau site, while the deck installation and launching operations were all from pre-fabricated elements (Steelbrideg 10).
The geological difficulties in the area played a significant role in the construction. Due to the complexity of the site, which made access difficult especially the areas with steep slopes, there was need to limit the number of piers, within their positioning at either the slopes’ tops or bottoms (Steelbrideg 3). Moreover, given that the construction required huge amounts of concrete, it was necessary to build a concrete factory on site. This was to make it easier to get the concrete for construction, in addition to reducing travel time and reduce the cost of transportation to and from the concrete factory.
Steel and concrete were the main materials used in the construction of the bridge. The piers and abutments used up 250,000 tons of concrete (Steelbrideg 5). B60 concrete was used for the piers and abutments’ construction, largely for the concrete’s durability rather than its mechanical resistance. On the other hand, the pylons and the deck are completely made of metal. These use grade S355 and S460 steels.
The bridge has 11 pairs of cables supporting each span. These have a single plane arrangement in a half-fan pattern (Steelbrideg 5). “The cables consist of T 15 strands of class 1,860 MPa which are super-galvanised, sheathed and waxed.Each cable is protected by a white, overall aerodynamic sheath made of non-injected PEHD” (Steelbridge 5). The PEHD sheath protects the cables from UV light, while some discontinuous spirals on the cable fight against vibrations resulting from wind and rain.
The bridge’s construction used both manual and machine labor. Workers dug up the 15m foundations for the pylons. The workers installed treads in the pylons as a way of reinforcing the deep shafts. With the constructions reaching above the ground, a new method known as sliding shuttering was used, making the construction faster. Using shoe anchorages and fixed rails in the middle of the pylons, it was possible to add a new layer of concrete in approximately a quarter of an hour. Further, each pier was its independent worksite, and therefore each of the seven piers had seven different worksites. With varying geometry on each of the steps of the piers, there was need for constant adaptation of the formwork. The outer surface has a self-climbing formwork while the inner surfaces required crane assistance. Therefore, the site had seven different formworks (Steelbridge 9). To check for precision, altimetric checks were done by GPS within a 5mm range on both the X and Y directions.
Prefabrication was additionally a method used in the construction of the bridge. Through prefabrication, the steel elements of the bridge were fabricated in a factory and only transported to the site for assembly and launching (Steelbrideg 10). The deck’s construction was also done on land, and the deck rolled in place from one pylon to another.
The deck’s installation using successive launching operations required the erection of temporary piers. These were made of metal frames. The longer temporary piers, due to their heights, employed telescoping in their installation, while the two end spans had cranes lifting them directly to place given their sheer sizes (Steelbridge 9).The deck had consecutive sections of 171m, which were launched when ready. The launching involved “moving the leading edge of the deck over the 171 m which separated each support (pier or temporary pier) from the next” (Steelbridge 12). After this, the launch of the successive pylon and the stayed cables followed, with each deck and pylon launched successively at the completion of a deck section.
Given the time of its construction, the bridge used some of the most advanced equipment in its construction. The top of the piers were “equipped with a metal trimmer on which the launching system, consisting of fourequilibrium devices and four translators were placed” (Steelbridge 13). The deck’s launch used jacks with hydraulic mechanisms, which ensured equality in pressure. These jacks were part of cradles, each of which had translators, which could produce a force of 250 tons. The jacks were 60 tons and could retract to allow the deck’s movement of about 600m (Steelbridge 13). These jacks were largely computer-controlled and moved in a lower-upper sequence allowing the movement of the deck.
Most of the calculations for the launch of the deck were GPS measured to ensure minimal errors. This was in addition to the use of telescopes especially for the installation of the temporary piers. For the launching of the deck, the contractor used temporary piers, which were used in the movement of the deck, as well as provide additional support. While the higher piers used telescoping, cranes were used in the launching of the two shorter temporary piers (Steelbridge 9).
Given that France is a developed country, most of the labor force was skilled. Skilled labor was particularly important for the design of the bridge given the engineering expertise that the project required. Both Michel Virlogeux and Norman Foster are experts in their own right, with years of experience in construction and design (Bockmann.p.). Such skilled labor was therefore available in France at the time of the bridge’s construction, meaning that there would be no shortage in labor. Moreover, there were many engineering companies with expertise and enough labor to produce the engineering equipment needed for the completion of the project.
Mechanization of most of the construction meant that manual labor would be used at minimal, although manual labor was heavily present at the prefabrication factories in laborer such as welders and drivers (Steelbridge 9). The construction could therefore not be halted because of lack of labor force. Besides, France had, and still has, one the highest natural population growths in Europe. Labor was therefore not a problem during the bridge’s construction.
If It Were Built Today
Part of the outstanding feature of the Millau Viaduct is its construction in just about 38 months, 5 months ahead of schedule and within the estimated budget. This is not too long ago, and therefore the methods used in the construction of the bridge are largely similar to those used today. There are currently man cable-stayed bridge (both complete and under construction) that employ part construction of the decks and launch them on piers. Moreover, steel is still used in the construction of buildings and bridges due to its strength, durability and affordability.
The level of advancement in construction machinery is currently very high. However, the hydraulic cradles are still much in use today. These may use similar technology, or a little advance, particularly in precision, but they still use the same mechanism as the cradles used in the construction the Millau Viaduct. Most of the improvements would include the human-machine interface, their size and efficiency, apart from the aforementioned improvements on precision. Additionally, cranes are still in use in most construction sites today. These however can carry higher payloads and can even be automated given the advancement in robotics and computer precision software.
Most tall buildings and huge bridge projects currently use prefabrication. Similar to the offsite factory built during the construction of the Millau Viaduct, prefabrication has proven cost effective, efficient, easier and quicker for many construction companies. If it were built today therefore, the Millau Viaduct would only benefit from better and faster prefabrication of equipment due to the advancement in technology. However, the basic idea would be quite similar to the one used during its construction. Another benefit would be in construction material, which through research and development, has been improved to become lighter, yet stronger than what was used in the construction of the bridge.
Transportation of construction material toady may also be much faster and easier that it was in 2004. There is heavy reliance on technology, which makes work easier, with the option of completely automatic some of the construction processes. Moreover, research and development has discovered far better and cheaper materials that can be used in construction. Conclusively, many construction companies today care about global warming, and are therefore working towards the reduction of their carbon footprint during construction. There may therefore be a lot of recycling of materials during the construction process than it was in 2004.
Bockman, Chris. “France builds world’s tallest bridge.” BBC, 2003.Web. 11 February 2015
Foster and Partners. Millau Viaduct. London: Foster and Partners, 2006.Web. 11 February 2015
Gentleman, Amelia. “Angry French halt bridge to save hospital,” The Guardian, 2003. Web. 11 February 2015
Steelbridge.The design and the construction of the Millau Viaduct, 2004. Web. 11 February 2015
Zimmermann, Kim. “French Culture: Customs & Traditions.” Live Science, 2015. Web. 11 February 2015