Millau Viaduct Bridge Challenges in design and construction
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Millau viaduct bridge |
Hello friends, today we will talk about the world's tallest millau viaduct bridge the great success for an engineer French mega projects
Impossible bridge build from design to construction of the bridge, the engineering team had to face three tough challenges.
Tallest bridge in the world
The engineers had put their lives at risk to build the world's tallest bridge pillars, but now the problem of connecting them together had become a headache for them. During the construction of the world's tallest millau viaduct bridge in France, the engineers were now stuck in a big problem.
Readymade road sections had to be placed on top of them. The weight of one road section to be placed between two pillars was equal to 25 locomotive engines and there were a total of eight such sections. There was no crane in the world that could lift a 5000 ton weight to a height of 800 feet. If the road section was pulled by placing a crane on two pillars, then the pillars would easily collapse inwards due to their height. The higher the pillar, the weaker its top would be. This issue was no less than a nightmare for the construction team. The construction of the millau viaduct bridge was getting delayed due to this issue and every passing day the construction company was getting fined $30,000.
World’s tallest bridge 1
Millau Viaduct France
The millau viaduct bridge in France is the world's tallest bridge which was built in 2004 at a cost of 394 million Euros. It is a wonder of the world of engineering, standing at a height of 1125 feet from the ground. This bridge, 45 feet higher than the Afield Tower, is at such a height that it often appears to be floating on the clouds. The engineering company which had shown the courage to build this bridge was actually stuck with this project. In these valleys of France, landslides and stormy winds of 130 km per hour were pushing their work from difficult to impossible.
Engineering marvel of France
Such a high four-lane highway had never been built before nor has anyone dared to build it till date because everyone knows that the millau viaduct bridge had challenged the limits of engineering. On the other hand, building this bridge had become a compulsion for the French government. In 1980, the French government was very troubled by the tourists going from France to Spain. Especially during the holiday season, this traffic used to pass through many cities and jam the roads of every city, especially the city of millau. This city is located in the middle of the mountains at a depth of 1500 feet. The traffic coming from Northern France had to first come down from the zigzag road and then climb up again. Firstly, this zigzag journey would take hours and on top of that, at least 6 hours were spent in traffic jams in the city of Millau. Therefore, to facilitate the tourists, the French government decided to build a motorway from Paris to Spain. The motorway could have been built straight from Paris to Millau, but there was a dead end at Millau. There were 1500 feet high mountains and the Tan River passing through the middle. The only way to bypass this complicated condition was to build a bridge almost as high as the height of the mountain.
But this was easy to say but impossible to do. In 1980, when this plan was being made, the world's tallest bridge at that time was California's Golden Gate Bridge. Firstly, it was a suspension bridge and secondly, the height of the road from the water surface was only 250 feet six times less than the mountains of Millau. Seeing this, many experts said that a bridge cannot be built on Millau and even if such a high bridge is built, it would be like inviting a very big accident. For many years, this dream of building a bridge remained just a dream, but finally, when the traffic jams increased beyond limits, the French government had no other option but to swallow this bitter pill.
First, erecting the world's tallest bridge pillars, that too on the slope of a mountain.
Second, placing a four-lane highway weighing 36,000 tons on top of it.
Third, erecting steel pylons on the bridge, each steel pylon weighing two times more than an Airbus A380.
And above all, all these tasks had to be done 100 feet above the ground. For this job, the world's best architect Lord Norman Foster was hired. He had already made a name for himself in the world of bridge designing. His job was to design a bridge that would be as graceful as a butterfly, but this butterfly could withstand thousands of tons of weight even in strong winds. Even a small mistake in this design can become a big disaster.
Bridge taller than Eiffel Tower
After two years, Lord Norman Foster’s design was still on the drawing board when his reputation received a major blow. A few years back, he had also designed London's famous Millennium Foot Bridge. In the year 2000, when this bridge was opened for public, it started swaying badly just because of human walking on it. There was a very big but hidden flaw in its design. The bridge had to be closed again for one and a half years, the repair of which cost an extra 50 lakh pounds. If a similar design flaw came out in the millau viaduct bridge which was 15 times higher than the Millennium Bridge, then it would be difficult to even imagine the devastation. After years of hard work, Foster had presented a brilliant design.
A total of seven pillars of the bridge were designed and the road above it would be in a curved shape but the issue was that pillar number two would have the highest height while the other six pillars would be built on a slope. The issue was not just about taking this unique design from paper to reality. The construction team that had the courage to build this bridge was given a deadline of only four years. After the deadline, a fine was fixed for every day, that is, a fine of about Rs 25 lakh for every passing day.
Millau Bridge construction
Construction of the millau viaduct bridge started in October 2001. This bridge was being built for 120 years. The construction began with laying the foundation of the pillars but along with it came a bad news from the geologists. They warned that there is fractured limestone beneath this area due to which there are many empty spaces between the stones. Caves have formed in these cavities where a unique type of bacteria lives. This bacterium called blue mold is used to make the world's most famous Rock Ford cheese but the cheese for which it is most perfect is not for making the foundation of the world's tallest bridge. The geologists expressed the danger of landslides during drilling and excavation here. In spite of all these warnings, the work of laying the foundation was started.
But then what was feared happened. There was a twist in the construction of millau viaduct bridge, a dangerous landslide. This landslide covered the foundation of the first pillar with stones but luckily no damage was done. The construction team stabilized the slope with cement and continued with the project. Nearly 2 lakh tons of concrete was needed to make the seven big pillars of the bridge, for which a factory was built on the site itself. This was reinforced concrete in which 16000 tons of steel bars were to be used. If the rods used in the millau viaduct bridge are laid straight, then it can cover a distance of 4000 km from Dubai to China.
The architect's design had become a problem for the construction team. At one point, they wondered if they had made a mistake by taking up this project. The problem was that the shape of the pillars was not uniform, that is, they were not the same. They were thick from the bottom and thin from the top. At a time, only 4 meter sections of pillars were made. Dies were made from a heavy steel frame, then concrete was poured inside them and then the die was lowered in the next 4 meters and then a die of another shape was placed. A lot of time was being wasted in repeatedly placing and lowering this die weighing 15000 tons. This race was against time. The casting of the pillars actually took six months more than the time given. But the engineering team's problems were not just this. If the location of each pillar is not at the pin point place, then the road section placed on top of it will never be straight. If the bottom of the pillar is made even 10 centimeters away from the place, then it will create a difference of 6 meters at the top. For this pin point accuracy, GPS technology was used with the help of multiple satellites present in the sky. The foundation was laid after finding out the pin point accuracy of the pillars and GPS was also used during the casting of the pillars so that the top of the pillars was exactly where it should be.
Days and months passed and then in November 2003, seven pillars reached their final height. The 245 meter long pillar number two became the world's tallest pillar. But after this success, they did not get time to relax because the next part of the bridge construction was the most difficult. Laying a 2.5 km long road section at such a height was no joke. The weight of this entire road section was estimated to be 36000 tons. This weight is equal to 90 Airbus A380. During this process, even a small mistake can cause loss of human life and millions of dollars.
Let us tell you that 34 workers had lost their lives on the Brooklyn Bridge in New York and in 1970, 35 workers had also lost their lives on the West Gate Bridge in Australia. Keeping these historical losses in mind, it was decided to build the road on the millau viaduct bridge in steel portions. For this work, the help of Offal Steel Works, located 100 km away, was taken. It was the only company at that time that had the capability to make such large sections of steel. 2200 steel Dev Kamet sections were made for the road, that too of different designs. Each section weighed 90 tones and they were made with such accuracy that there was not even a hair's breadth of difference. The work of cutting and welding was difficult, but now the challenge was to transport them to the construction site located 100 km away. Routes were planned. Police were taken on board and road sections were dispatched one by one in convoys. Total effort was put in transporting all these steel sections to the construction site safely. More than 2000 convoys were installed. The plan was to weld all these steel sections and slide them over the pillars and push them forward as is done in the construction of a normal bridge, but the wire duct found was not normal at all.
There is a distance of 342 meters between the pillars which are about 250 meters high. If a section weighing 5 tons is slid, then by the time it reaches from one pillar to another, due to lack of support in between, the entire section may fall down. Even if it does not fall down, sliding the road sections on such high pillars will result in the pillars falling one by one. This issue had become a headache for the construction team. If this type of bridge is pushed using soft material, then the table will not be affected. Taking the help of this law of physics, it was decided that a system should be installed on the pillars of the mixed wire duct which will lift the road section and push it forward. This will ensure that the force applied from the mountain will not fall directly on the pillars. For this purpose, temporary steel structures were also erected at a distance of 170 meters between the pillars which will bear half the weight of the road section. This new system was a kind of prototype and there was no time to test it.
The future of the world's tallest bridge was hanging on just one prototype. 26 February 2003 was a very important day for the construction team. On this day, their years of hard work had to be tested in a single day. The strength of the pillars and road section and the hydraulic ramp system installed on the pillars had to lift and push the road section forward simultaneously at the same speed. If there was even a slight difference in their synchronization, then all the weight would fall on one pillar and this could collapse the entire bridge. Luckily, the hydraulic ramp system worked and in two full days, only 200 meters of road section was taken to pillar number one. All this work was being done by looking at the weather. Only those three days were selected in which there was no chance of strong winds. The reason for this is simple, strong winds can easily bring down the bridge, especially when one side of the road section is hanging in the air without support.
In 1940, the pillars of the Tomah Narrows Suspension Bridge in Washington State were resisting wind and as a result the entire bridge began to sway violently. A few days after its launch, the entire bridge collapsed and fell into the water.
Days passed by. The work of placing the road section on the pillars was going on in full swing. By 2004, the road sections had been laid from both sides. Now only the part above the river was left. If this last section is not placed properly, then all the hard work will be multiplied by zero. In this section, the road is also getting curved. That is why it is very important that it is placed at the pin point place. The whole of France was watching this moment on live broadcast while the French Prime Minister himself was present on the spot. The button of the hydraulic ramp was pressed for the last time. For the first time in four years, the roads of the north and south sections had joined each other, that too with 99.9% accuracy. After the road was connected, a 90 meter high steel pylon also had to be installed for extra support. One pylon weighed 700 tons and there were seven such pylons. It was being attempted for the first time in the world to install such a heavy pylon at such a height. The total weight of the road of millau Viaduct Bridge alone is 40,000 tons. After this, an asphalt road was laid on top of it, which by adding 10000 tons, the total weight of the road was made 50000 tons. For estimation, let us tell you that this weight is equal to the weight of 1200 battle tanks or a large cruise ship.
To check its strength, 28 trucks were driven over it simultaneously. The surprising thing was that the road section which was designed to swing up to 50 centimeters, swayed only 25 centimeters due to the weight of all these trucks.
On 16 December 2004, the millau viaduct bridge was opened to the public for the first time. This was the result of the hard work of the engineering team day and night, who not only successfully built the world's tallest bridge, but also created a new record by constructing it.
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