As you may already know, although they are closely related, there is a big difference between what we call science and what we call technology. While through science we seek to better understand the world that surrounds us (the universe, the living beings, the meteorological phenomena…), through technology we seek to solve concrete problems that arise every day in our society in order to improve our living conditions. As an example, science is in charge of the study of galaxies, while technology is in charge of designing telecommunications satellites such as the GPS (Global Positioning System) location system.
(A distant galaxy)
(A GPS satellite)
Nonetheless, both, science and technology, are sometimes very related. Quite frequently the knowledges achieved through science allow to solve technological problems that otherwise will be unapproachable. For example, knowing the composition of the atmosphere is clue is key when putting a satellite into orbit.
To solve the different problems that we face every day, engineers, who are the people that work to solve this kind of problem, carry out a series of actions that we call technological projects. Today technological projects of many types are carried out: construction of buildings, design of electronic components, development of new materials, improvement of the environment, production of electrical energy…
All these technological projects follow a series of steps that we are now going to study with a real example: the construction of the Millau Viaduct * (France), the highest bridge built to date.
*A viaduct is a bridge that crosses a valley.
1st phase: identification of the problem.
Around 1980 one of the main highways in France was facing a problem. It was the road that linked Paris, the capital, with the south. Every year, during the summer, a large number of tourists took this road to go to the south coast of the country to spend the summer, or even crossed the border to spend their holidays in Spain. This caused significant traffic jams, especially near a little town called Millau.
As you can see in the image, it is a population that is located in the lower part of a large valley, that of the River Tarn. For that reason, on their way south, drivers were forced to go down to the bottom of the valley and then up to continue their journey. This, apart from making the trip longer, caused constant traffic jams on the roads around Millau, which annoyed both travelers and the inhabitants of the city.
In order to avoid this situation, the French government decided to undertake a project to improve road communication between the capital and the south coast. Let’s see how it was done …
2nd phase: looking for solutions.
Whenever a technological project is started, different solutions to the problem should be considered. To do this, it is convenient that different people give ideas about how the problem could be tackled. Once the different proposals have been made, it is easier to compare and decide which of them is the most appropriate or if a mixture of several of them may be the best option. On the contrary, if it is a single person who faces the problem, it is very likely that he or she will leave very good ideas along the way and that will focus on a single idea that may not be the best.
In the case we are studying, when the French government announced the project to improve communication with the south, numerous engineering and architectural companies presented their ideas about how the problem could be tackled. Finally, the four ideas that were considered were the following:
- Yellow route: go around Millau to the east by building two large bridges (800 and 1000 meters long). This option was good for improving traffic but did not allow good access to the city of Millau from the highway.
- Black route: around Millau to the west with a 12 km route (the longest option) that required the construction of four smaller bridges. This solution was simple from a technical point of view but very expensive and would also have a negative impact on the environment.
- Red route: cross the valley through the most direct path, passing very close to the town of Millau. This option had the advantage that access to the city of Millau would be easier but it also meant a problem since crossing the city would alter the urban planning of the city.
- Blue route: go around Millau to the west but with a shorter route than the black route, which required the construction of a huge viaduct 2460 meters long and 343 meters high. It was the best option in terms of improving traffic and respecting the environment, but it presented great technical difficulties due to the need to build a viaduct of great length and height.
3rd phase: choosing the best alternative.
To decide which solution is the best in a technological project, a large number of factors must be taken into account, such as:
a) How well it solves the problem to be addressed
b) The technical difficulty of carrying it out
c) How expensive it will be.
d) Its impact on the environment.
e) How long it will take to finish it.
f) Its effect on the inhabitants of the area
After considering all these factors, the team in charge of analyzing all the proposed solutions came to the conclusion that the best option was that of the blue route, which involved building a large viaduct that directly connected the two parts of the valley. The main drawback was the difficulty of building a bridge that should be higher than the Eiffel Tower, and in an area where wind reached a speed of 150 km/h. However, the benefits of this solution were very significant, as it allowed traffic to move away from the city of Millau and was the fastest option for drivers to cross the valley.
4th phase: project planning.
Although it can often go unnoticed, project planning can take a very long time, especially in unique and innovative projects that require solutions that have never been implemented before. A good example is the one we are studying on this page. The planning process for the Millau Viaduct from the moment the best solution was chosen until its construction began lasted 10 years (from 1991 to 2001) while its construction took less than 4 years.
As we will study in detail during Technical documentation unit, the planning of a project is divided into three main parts:
- Time planning: it is necessary to know how long each stage of the project will last in order to coordinate the work of the different workers. In addition, in the case of the Millau Viaduct, it was urgent to solve the circulation problems, so finishing the project as soon as possible was very important. For this reason, it was agreed that the construction company should pay a fine of 30,000 euros for each day the project was delayed. Finally, the work was completed in little more than 3 years, 25 days ahead of schedule.
- Economic planning: it is also very important to calculate what the cost of the whole project will be. This includes the purchase of materials, paying the workers’ wages, the transport of the parts… If this is not done with accuracy the construction company could run out of money in the middle of the project, not being able to finish it. In the case of the Millau Viaduct, the total cost was around 400 million euros. To help cover the huge construction costs it was agreed that travelers crossing the bridge would have to pay a toll.
- Construction/manufacturing planning: in practically any technological project it is necessary to make a series of drawings or plans that allow workers to know how to proceed during construction. This also occurs when, instead of a large work, the technological project consists in the manufacture of a part for a car. Plans must indicate, in great detail, each of the dimensions of the different pieces and how they should be joined together. Below you can see a plan of the bridge deck (left) and the highest tower seen from two views (right):
5th phase: construction.
Once the planning is complete construction can start. Although some are more innovative than others, every technological project is unique and therefore has particular difficulties that must be solved. For example, one of the main challenges in the project of Millau Viaduct was the construction of the very tall towers that would support the structure. It was necessary to install huge cranes that were fixed to the towers as they were built and the workers went up to the top using lifters whose rails were also placed as the structure grew.
Placing the deck (road) of the bridge at such height was another big challenge of the project. The huge separation between the towers made it impossible to build cranes that could lift the parts of the road. The only option was to push the deck from both sides of the bridge using machines called hydraulic jacks capable of exerting a great force (video). Apart from this, due to the complexity of matching accurately the two parts of the platform, a GPS system was used to achieve a perfect coupling.
After the deck was completed, the masts (top part of the towers) were placed and welded to the towers, as shown in the images below. Finally, the metal cables where anchored, providing support for the deck and the temporary red towers were removed:
The two images below show the bridge once finished:
And in this video you can ckeck the different steps of the construction process:
6th phase: evaluation.
Once a technological project, of any type, is finished, a series of tests must be carried out to ensure that it will fulfill its function. The tests that are carried out are quite different depending on the kind of project. In the case of a bridge, one of the most widely used tests are load tests. These tests consist of placing a weight (usually big trucks) in different parts of the structure to verify that it is not deformed more than expected. This type of test can be of two types:
- Static (as in the image): in which the trucks are stopped in a part of the bridge.
- Dynamic: in which, trucks keep moving along the bridge at different speeds.
In the image below you can see one of the static load tests of the Millau Viaduct, in which 28 trucks (more than 900 tons) were placed.
As you have seen, the development of a technological project requires a great deal of knowledge and ingenuity. Knowing what solutions have been taken in previous projects with similar characteristics is a great help when finding a good solution to a new problem. Nonetheless, it is also necessary to have the ability to adopt new innovative solutions, never used before, that adapt to the specific characteristics of the project.