The Fehmarnbelt tunnel will be the longest submerged tunnel in the world

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(CNN) – Going down to 40 meters below the Baltic Sea, the world’s longest submerged tunnel will connect Denmark and Germany, reducing journey times between the two countries when it opens in 2029.

After more than a decade of planning, construction of the Fehmarnbelt tunnel began in 2020 and in the months following the completion of a temporary port on the Danish side. It will house the factory that will soon build the 89 massive stretches of concrete that will form the tunnel.

“The expectation is that the first production line will be ready towards the end of the year, or early next year,” said Henrik Vincentsen, CEO of Femern A / S, the Danish state-owned company in charge of the project. “By early 2024 we must be ready to submerge the first element of the tunnel.”

The tunnel, which will be 18 kilometers (11.1 miles) long, is one of the largest infrastructure projects in Europe, with a construction budget of over 7 billion euros (7.1 billion dollars).

By comparison, the 50-kilometer (31-mile) Channel Tunnel connecting England and France, completed in 1993, cost the equivalent of £ 12 billion ($ 13.6 billion) in cash. of today. Although longer than the Fehmarnbelt tunnel, the Channel Tunnel was made using a boring machine, rather than by dipping prefabricated tunnel sections.

It will be built across the Fehmarn Belt, a strait between the German island of Fehmarn and the Danish island of Lolland, and is designed as an alternative to the current ferry service from Rødby and Puttgarden, which carries millions of passengers annually. Where the crossing now takes 45 minutes by ferry, it will only take seven minutes by train and 10 minutes by car.

The roof of the first production hall where the tunnel sections will be built in Denmark was completed on June 8, 2022.

The roof of the first production hall where the tunnel sections will be built in Denmark was completed on June 8, 2022.

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Travel faster

The tunnel, whose official name is Fehmarnbelt Fixed Link, will also be the longest combined road and rail tunnel in the world. It will include two dual carriageways, separated by a service passage, and two electrified tracks.

“Today, if you were to take a train journey from Copenhagen to Hamburg, it would take you about four and a half hours,” says Jens Ole Kaslund, technical director of Femern A / S, the Danish state company responsible for the project. “When the tunnel is completed, the same journey will take two and a half hours.

“Today many people fly between the two cities, but in the future it will be better to just take the train,” he adds. The same journey by car will be about an hour faster than today, taking into account the time saved by missing lines for the ferry.

In addition to the benefits for passenger trains and cars, the tunnel will have a positive impact on trucks and freight trains, says Kaslund, because it creates a land route between Sweden and Central Europe that will be 160 kilometers shorter than it is today.

At present, traffic between the Scandinavian Peninsula and Germany via Denmark can take the ferry across the Fehmarnbelt or a longer route across the bridges between the islands of Zeeland, Funen and the Jutland Peninsula.

Work begins

The project dates back to 2008, when Germany and Denmark signed a treaty to build the tunnel. It then took over a decade for both countries to approve the necessary legislation and to carry out geotechnical and environmental impact studies.

While the process went smoothly on the Danish side, in Germany a number of organizations, including ferry companies, environmental groups and local municipalities, filed an appeal against the approval of the project for allegations of unfair competition or environmental concerns and acoustics.

Dredging work began off the German coast in the autumn of 2021.

Dredging work began off the German coast in the autumn of 2021.

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In November 2020, a German federal court dismissed the complaints: “The ruling came with a number of conditions, which we expected and were prepared for, on how we monitor the environment as we build, on things like noise and sediment. we really make sure that the impact on the environment is as small as possible, ”says Vincentsen.

Now the temporary port at the Danish site is finished, several other phases of the project are underway, including the excavation of the actual trench that will house the tunnel, as well as the construction of the factory that will build the sections of the tunnel. Each section will be 217 meters long (about half the length of the largest container ship in the world), 42 meters wide and 9 meters high. Weighing 73,000 tons each, they will weigh as much as 13,000 elephants.

“We will have six production lines and the factory will consist of three halls, with the first one now 95% complete,” says Vincentsen. The sections will be positioned just below the seabed, approximately 40 meters below sea level at the deepest point, and moved into position by barges and cranes. The placement of the sections will take approximately three years.

A counter impact

Up to 2,500 people will work directly on the construction project, which was impacted by global supply chain problems.

“The supply chain is a challenge at the moment, as the price of steel and other raw materials has risen. We get the materials we need, but it’s difficult and our contractors had to increase the number of suppliers to make sure they could get what they need. That’s one of the things we’re really looking at right now, because a constant supply of raw materials is key, “says Vincentsen.

Michael Svane of the Confederation of Danish Industry, one of Denmark’s largest business organizations, believes the tunnel will be beneficial to businesses outside of Denmark.

This life-size test cast of a tunnel element was built in July 2022.

This life-size test cast of a tunnel element was built in July 2022.

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“The Fehmarnbelt tunnel will create a strategic corridor between Scandinavia and Central Europe. Enhanced rail transfer means that more freight moves from road to rail, supporting a climate-friendly means of transport. We see cross-border connections as a tool to create growth and employment not only locally, but also nationally, “he tells CNN.

While some environmental groups have expressed concern about the tunnel’s impact on porpoises in the Fehmarn belt, Michael Løvendal Kruse of the Danish Society for Nature Conservation believes the project will have environmental benefits.

“As part of the Fehmarnbelt tunnel, new natural areas and stone cliffs will be created on the Danish and German side. Nature needs space and as a result there will be more space for nature,” he says.

“But the biggest benefit will be the benefit for the climate. The faster passage of the Belt will make trains a strong challenger for air traffic and the load on electric trains is by far the best solution for the environment.”