The longest immersed tunnel in the world is currently being built by Germany and Denmark.
The longest immersed tunnel in the world will connect Germany and Denmark in 2029, reducing
travel times between the two nations as it descends up to 40 metres beneath the Baltic Sea.
Construction of the Fehmarnbelt Tunnel began in 2020 after more than a decade of preparation,
and in the months since, a temporary port has been finished on the Danish side. It will serve as the
location of the plant that will shortly construct the 89 enormous concrete pieces that make up the
According to Henrik Vincentsen, CEO of Femern A/S, the state-owned Danish company in charge
of the project, “by the beginning of 2024 we have to be ready to immerse the first tunnel element.”
the first production line is anticipated to be completed around the end of the current year or the
start of the following year.
With a building expenditure of more than 7 billion euros ($7.1 billion), the tunnel, which will be 18
kilometres (11.1 miles) long, is one of the greatest infrastructural projects in Europe.
Comparatively, the 50-kilometer (31-mile) Channel Tunnel between England and France, which
was finished in 1993, cost $13.6 million ($12 billion) in today’s dollars. The Channel Tunnel was
constructed using a boring machine rather than by submerging pre-built tunnel sections, although
being longer than the Fehmarnbelt Tunnel.
It is intended to replace the present ferry service from Rdby and Puttgarden, which ferries millions
of people each year across the Fehmarn Belt, a strait between the Danish island of Lolland and the
German island of Fehmarn. Instead of the 45 minutes it currently takes to cross by ferry, it will only
take seven minutes by rail and ten minutes by automobile.
Faster travel by tunnel
The Fehmarnbelt Fixed Link, as the tunnel’s official name is, will be the world’s longest combined
road and rail tunnel. There will be two electrified rail tracks, two double-lane roads, and a service
tunnel between them.
The tunnel will be finished when it will take just two and a half hours to travel from Copenhagen to
Hamburg instead of the current four and a half hours, according to Jens Ole Kaslund, technical
director at Femern A/S, the state-owned Danish corporation in charge of the project.
Many people go by plane between the two cities now, but taking the railway will be preferable in the
future, he continues. Taking into account the time saved by not waiting in line for the ferry, the
identical trip by automobile will be completed around an hour faster than it did today.
According to Kaslund, the tunnel will have good effects on freight vehicles and trains in addition to
passenger trains and automobiles since it shortens the land route between Sweden and Central
Europe by 160 kilometres from the current route.
A lengthier route through bridges connecting the islands of Zealand, Funen, and the Jutland
peninsula is now available for traffic travelling from the Scandinavian peninsula to Germany via
The tunnel construction project began in 2008 when Germany and Denmark agreed to build it.
The passage of the requisite legislation by both nations and the completion of geotechnical and
environmental impact assessments, however, took more than ten years.
While the procedure went without a hitch on the Danish side, a number of parties, including ferry
companies, environmentalists, and local governments, appealed against the project’s approval due
to allegations of unfair competition or noise and environmental concerns.
A German federal court dismissed the objections in November 2020.
“The judgement came with a series of restrictions, which we kind of expected and we were prepared
for, on how we monitor the environment while we are building, on things like noise and sediment
spill,” explains Vincentsen.
Several additional project phases, including the drilling of the actual trench that will house the
tunnel and the construction of the factory that will produce the tunnel sections, are under way now
that the temporary harbour on the Danish site has been completed.
Each segment will be 217 metres long 42 metres broad, and 9 metres tall, or almost half the length
of the largest container ship in the world. They will each weigh 73,000 metric tonnes, which is
equivalent to more than 13,000 elephants.
Six manufacturing lines and three halls will make up the facility, which is already 95% finished,
according to Vincentsen. The sections will be positioned immediately below the seabed, about 40
metres below sea level at its deepest point, and will take around three years to complete.
A bigger effect :
The building project, which has been hampered by the issues with the global supply chain, will
employ up to 2,500 people directly.
We do get the materials we need, but it’s challenging and our contractors have had to increase the
number of suppliers to make sure they can get what they need. That’s one of the things that we’re
really watching right now, because a steady supply of raw materials is crucial. “The supply chain is a
challenge at the moment, because the price of steel and other raw materials has increased.
The Confederation of Danish Industry, one of Denmark’s main business associations, is led by
Michael Svane, who thinks the tunnel would benefit companies outside of Denmark.
Even though some environmental organisations are worried about how the tunnel may affect the
Fehmarn Belt’s porpoises, Michael Lvendal Kruse of the Danish Society for Nature Conservation
believes the project will be good for the ecosystem.
“New natural areas and stone reefs will be built as part of the Fehmarnbelt Tunnel on the Danish
and German sides. Nature requires room, and as a result, there will be more space for nature,” he
Faster Belt passage would make trains a serious competitor to air traffic, and hauling freight on
electric trains is by far the greatest option for the environment. However, the benefit for the climate
will be the biggest benefit.