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Under the English Channel: the Eurotunnel

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Under the English Channel: the Eurotunnel

In 1994 a long dream and a technical masterpiece came true: the Channel Tunnel under the English Channel was inaugurated. It connects Folkstone in Kent (England) and Coquelles near Calais in northern France. After many unsuccessful attempts and great difficulties during construction, the railway tunnel was officially opened on May 6, 1994 by the British King Elizabeth II and the French President Francois Mitterand.

On December 1, 1990, the French tunnel worker Philippe Cozette greeted his British counterpart, Graham Fagg. The British and French sections will be merged!

The idea

Even under Napoelon there were attempts to "bridge" the English Channel with a tunnel. But the difficult relationship between England and France and the major technical challenges caused previous projects to fail again and again.

But it was not until 1957 that a mutual channel tunnel working group was founded. The goal was a rail tunnel with two main tubes and a smaller service tunnel. The project started in 1973 but had to be discontinued in 1975 due to financial problems. In 1984 the British and French governments revisited the plan. However, it should be financed privately. In 1987 the project was officially signed and construction began. Up to 15,000 workers were employed in the execution for seven years.

The special

An average of 40 meters below the sea floor was built in a nearly watertight layer of limestone and clay. Construction began simultaneously on the French and British sides, with the southern section being deeper than that in the north. The total length of the tunnel is 50.45 kilometers, with 37.5 kilometers under the water - making the Eurotunnel the longest underwater tunnel in the world!

Some facts

1000 people worked in 8-hour shifts in the tunnel during the construction period. The tunnel grew by a kilometer every month. To be on the safe side, all three tunnels were connected by cross tunnels every 375 meters. The tunnel is built in such a way that passengers need a maximum of 90 minutes to get outside in an emergency.

There are two crossings along the route. Here the trains can safely switch to the other tunnel tube. Should water penetrate, pumps were installed that can pump out 153 liters per second. For safety reasons, certain goods are not allowed to be transported through the tunnel. For example, gas, petroleum, nuclear materials or dangerous chemicals.

On December 1, 1990, the French and British tunnel workers met for the first time in what is now one of the "crossover halls" in which trains can be diverted from one main tube to the other. Thanks to the latest laser measurement during tunnel construction, the two tubes met with a deviation of less than two centimeters.

The drilling machines used

Huge, specially developed drilling machines, which can also be referred to as movable "excavation factories", were used for the construction. Eleven TB4 "Virgine" tunnel boring machines developed in the USA are used. They pierced the rock and removed the rock, the so-called overburden, with conveyor belts. That was around 2,400 tons per hour. Then they built in the necessary precast concrete and laid the rails. Each of these drilling machines cost around 20 million euros.

The Eurostar leaves the tunnel on the French side

Extra stations and a special train: "Le Shuttle"

Of course, special stations had to be built for loading trucks, cars and passengers onto the trains in Coquelles near Calais on the French side and in Cheriton near Folkstone on the English side.

The train that was specially designed for the Eurotunnel is called "Le Shuttle". Its locomotives are the most powerful (but not the fastest) in the world. The trains have special wagons to transport people and trucks through the tunnel. Each train carries up to 120 passenger cars and twelve buses. At peak times, trains run through the tunnel every 3 minutes at 160 kilometers per hour.

In 1993 and 1994 the tunnel was subjected to tough tests. Then, on June 1, 1994, the time had come: the first freight train passed the Eurotunnel and in December of the same year passenger traffic started rolling.

The total cost was almost 12.5 billion euros. This made the project twice as expensive as planned and the most expensive privately financed project in the world - which, unfortunately, has not yet paid off for the shareholders and has therefore repeatedly been heavily criticized.

Accidents in the tunnel

There have been three fire accidents in the tunnel so far. Twice a truck that was being transported on the train caught fire, another time it was the train itself that was on fire. There was considerable damage to property in each case. From September 2008 to February 2009 one of the two tunnel tubes had to remain closed to repair the damage caused by the last accident.

You can find out more about the construction and safety in tunnels in WAS IST WAS Volume 91 Bridges and Tunnels.

-from 06.05.04 text / photos: www.eurotunnel.com

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