Denmark and Germany now build world’s longest immersed tunnel

(CNN) — The longest immersed tunnel in the world, which descends up to 40 meters below the Baltic Sea, will connect Denmark and Germany and cut 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 in the months since a temporary harbor on the Danish side has been completed. It will house the factory that will soon build the 89 solid concrete sections that will form the tunnel.

“The first production line is expected to be ready around 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 sink the first tunnel element in early 2024.”

The tunnel, which will be 18 kilometers 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 Channel Tunnel connecting England and France, completed in 1993, cost the equivalent of £12 billion ($13.6 million) in today’s money. Although the Channel Tunnel was longer than the Fehmarnbelt Tunnel, it was made using a drilling machine, rather than by submerging pre-built 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 every year. Where the crossing now takes 45 minutes by ferry, it takes seven minutes by train and 10 minutes by car.

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

Femern A/S

Faster trip

Officially called Fehmarnbelt Fixed Link, the tunnel will also be the longest combined road and rail tunnel in the world. It will consist of two double-lane highways – separated by a service passage – and two electrified railway lines.

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

“Today many people fly between the two cities, but in the future it is better to just take the train,” he adds. The same journey by car will be about an hour faster than today, taking into account 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 trucks and trains, Kaslund says, as it creates a land route between Sweden and Central Europe that will be 160 kilometers shorter than it is now.

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

The work begins

The project dates back to 2008, when Germany and Denmark signed a treaty to build the tunnel. After that, it took more than ten years for the necessary legislation to be passed by both countries and geotechnical and environmental impact studies to be conducted.

Although the process went smoothly on the Danish side, in Germany a number of organizations – including ferry companies, environmental groups and local municipalities – appealed the project’s approval over claims of unfair competition or environmental and noise problems.

In the autumn of 2021, the dredging works off the German coast started.

Femern A/S

Now that the temporary harbor on the Danish site has been completed, several other phases of the project are underway, including the digging of the actual trench that will house the tunnel, as well as construction of the factory that will build the tunnel sections. Each section will be 217 meters long (about half the length of the world’s largest container ship), 42 meters wide and 9 meters high. Weighing 73,000 tons each, they will be as heavy as over 13,000 elephants.

“We will have six production lines and the factory will consist of three halls, the first of which is now 95% ready,” says Vincentsen. The sections are placed just below the seabed, at the deepest point about 40 meters below sea level, and placed in place with pontoons and cranes. Placing the sections will take approximately three years.

A greater impact

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

“The supply chain is challenging right now as the price of steel and other raw materials has gone up. We are getting the materials we need but it is difficult and our contractors have had to increase the number of suppliers to ensure that they can get what they need, which is one of the things we’re really looking at right now, 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 associations, believes the tunnel will benefit companies outside of Denmark itself.

This life-size test cast 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 improved rail transfer means more freight goes from road to rail, supporting a climate-friendly mode of transport. We consider cross-border connections as a tool for creating growth and jobs not only locally, but also nationally,” he told CNN.

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

“As part of the Fehmarnbelttunnel, new nature reserves and rock reefs are being created on the Danish and German sides. Nature needs space and therefore there is more room for nature,” he says.

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