A revolutionary 18 km long tunnel is being built under the Baltic Sea between Denmark and Germany, the “Femarnbelt”, which will connect southern Denmark with northern Germany. It will be the world’s longest underwater modular road and rail tunnel and will significantly reduce travel times and improve Scandinavia’s connectivity to Europe, on Tuesday, the 22nd of April, reports the British broadcaster BBC.
The tunnel is a remarkable feat of engineering, with massive pre-assembled segments laid on the seabed and interconnected.
The project’s main construction site is at the tunnel’s northern entrance on the coast of the island of Lolland in south-east Denmark. The site is more than 500 hectares in size and includes a harbour and a production facility for the tunnel sections or “elements”.
“It is a huge facility,” said Henrik Vincentsen, CEO of the Danish state company Femern, which is building the tunnel.
Reinforced concrete is cast together with concrete to create each 217m-long and 42m-wide element.
Most of the underwater tunnels are buried in bedrock beneath the seabed. In this case, however, the 90 individual elements will be joined together piece by piece like Lego bricks.
“We are breaking records with this project,” Vincentsen told the BBC. “Submerged tunnels have been built before, but never on this scale.”
The project costs around 7.4 billion euros and is mainly paid for by Denmark, with 1.3 billion euros provided by the European Commission.
IT IS ONE OF THE LARGEST CONSTRUCTION PROJECTS IN THE REGION AND PART OF THE EU’S PLAN TO MAKE TRAVELLING AROUND EUROPE EASIER AND REDUCE AIR TRAFFIC.
When completed, instead of a 45-minute ferry journey, the journey between Rødbyhavn in Denmark and Puttgarten in Germany will take just 10 minutes by car or seven minutes by train.
Bypassing western Denmark, the new rail route will also halve the journey time between Copenhagen and Hamburg from five hours to 2.5 hours and provide a greener and shorter alternative for freight and passenger transport.
“It not only connects Denmark with Germany, but also Scandinavia with Central Europe,” said Vincentsen, adding that “everyone benefits”. He said that driving 160 km less would also reduce carbon emissions.
According to the BBC, the tunnel consists of two railway lines, two lines for motorways with two lanes in each direction and one for maintenance and emergencies.
These massive tunnel elements, weighing more than 73 000 tonnes each, are hermetically sealed and fitted with ballast tanks so they can float and be pulled into place. They are then lowered 40 metres into the seabed trench using underwater cameras and GPS and carefully locked in place.
A bridge was initially considered, but the risk of high winds and ship collisions made it less practical, particularly because of the high volume of shipping in that stretch of sea, Professor Per Goltermann of the Technical University of Denmark told the BBC, and experts chose a submerged tunnel as a safer and more cost-effective solution.
Denmark and Germany agreed on the tunnel as early as 2008, but the project was delayed due to opposition from ferry companies and German environmental groups concerned about the tunnel’s impact on the environment.
One group was concerned about the impact on Baltic Sea animals, including larvae and porpoises, which are sensitive to underwater noise. However, in 2020, a German court rejected the claim and allowed construction.
Vincentsen stressed efforts to reduce the impact on nature, for example by creating a 300-hectare wetland nature area using dredged sand and stones.
MORE THAN 100 TRAINS AND 12 000 CARS ARE EXPECTED TO USE THE TUNNEL DAILY WHEN IT OPENS IN 2029.
The toll revenue will repay the loans granted by the State for the construction, which Vincentsen estimates will take about 40 years.
The project is also expected to boost employment, business and tourism in Lolland, one of Denmark’s poorest regions.
Video: How the Fehmarnbelt Tunnel is being built