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

Editor’s Note — This Month’s Entry is a CNN Travel series highlighting some of the most fascinating topics in the world of travel. September’s theme is “Build it Big” as we share the stories behind the world’s most impressive feats of engineering.

(CNN) – Dropping 40 meters below the Baltic Sea, the world’s longest submerged tunnel will connect Denmark and Germany, cutting travel 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 months after a temporary port on the Danish side was completed. The 89 massive concrete blocks that will make up the tunnel will host the factory that will soon be built there.

“The hope is that the first production line will be ready by the end of the year or early next year,” said Henrik Vincentsen, CEO of Femern A/S, the Danish state-owned company responsible for the project. “We should be ready to submerge the first element of the tunnel at the beginning of 2024.”

The tunnel, which will be 18 kilometers (11.1 miles) long, is one of Europe’s largest infrastructure projects, with a construction budget of more than 7 billion euros ($7.1 billion).

By comparison, the 50-kilometer (31-mile) Channel Tunnel connecting England and France, completed in 1993, cost the equivalent of 12 billion pounds ($13.6 million) in today’s money. Although longer than the Fehmarnbelt Tunnel, the Channel Tunnel was built using a boring machine, rather than pre-built tunnel sections being sunk.

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

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

Femern A/S

Faster travel

The tunnel, officially named the Fehmarnbelt Fixed Link, will also be the world’s longest combined road and rail tunnel. It will have two dual-lane highways — separated by a service crossing — and two electrified railways.

“Today, if you were to make 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-owned company. the project “When the tunnel is finished, the journey itself will last two and a half hours.

“Today many people fly between the two cities, but in the future it will be better to take the train,” he added. The journey by car itself will be about an hour faster than today, given the time saved by not queuing for the ferry.

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

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

The work begins

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

Although the process ended well on the Danish side, several organizations in Germany — including ferry companies, environmental groups and local municipalities — appealed the project’s approval over concerns of unfair competition or environmental and noise concerns.

Dredging began in the fall of 2021 off the German coast.

Dredging began in the fall of 2021 off the German coast.

Femern A/S

In November 2020, a German federal court rejected the complaints: “The judgment came with some conditions, which we expected and were ready for, how we control the environment while we are building, with things like noise and sediment discharge. I think we really need to make sure that the impact on the environment is as low as possible.” and that it is the smallest,” says Vincentsen.

Now that the temporary port at the Danish site is complete, several other phases of the project are underway, including the digging of the actual trench that will accommodate the tunnel, as well as the construction of the plant that will build the tunnel sections. Each section will be 217 meters long (roughly half the length of the world’s largest container ship), 42 meters wide and 9 meters high. Weighing 73,000 metric tons each, they will be as heavy as more than 13,000 elephants.

“We will have six production lines and the factory will consist of three halls, the first of which is now 95% complete,” says Vincentsen. The sections will be located under the seabed, about 40 meters below sea level, at the deepest point, and will be transported by barges and cranes. The placement of the sections will take approximately three years.

Wider impact

Up to 2,500 people will work directly on the construction project, affected by global supply chain issues.

“The supply chain is a challenge right now because the price of steel and other raw materials has gone up. We get the materials we need, but it’s difficult and our contractors have had to increase the number of suppliers to make sure they can get what they need. That’s what we’re really seeing. one of the things we are, because a constant supply of raw materials is crucial,” says Vincentsen.

Michael Svane of the Confederation of Danish Industry, one of Denmark’s largest business organizations, believes the tunnel will benefit companies beyond Denmark.

This full-scale test casting of a tunnel element was built in July 2022.

This full-scale test casting of a tunnel element was built in July 2022.

Femern A/S

“The Fehmarnbelt tunnel will create a strategic corridor between Scandinavia and Central Europe. The renewed rail transfer means moving more freight from road to rail, contributing to a climate-friendly mode of transport. We see cross-border connections as a tool for growth and job creation. not only locally, but also nationally “, he told CNN.

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

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

“But the biggest advantage will be the benefit to the climate. Faster passage of the belt will make trains a big challenge for air traffic, and electric train cargo is by far the best solution for the environment.”