Germany and Denmark are jointly building the largest underwater tunnel in the world, which will be located under the Baltic Sea and will connect the German island of Fehmarn to the Danish island of Lolland. The tunnel, whose official name is Fehmarnbelt Fixed Link, will be 18 kilometers long and is scheduled to be completed in 2029.
Unlike excavated tunnels, the structure is being made using the immersed tunnel method. According to those responsible for the work, huge concrete blocks are being manufactured on dry land and are then transported by boats to the construction site, where they are sunk and fitted to the seabed. Before installation, the blocks receive special seals to prevent water from entering. Already at the bottom of the sea, they are being supported on a gravel base and connected with millimeter adjustment, using automated equipment and remote control. Only after this process should internal systems be installed, such as rails, highway pavement, ventilation, lighting and security.
The tunnel will concentrate two types of traffic: a two-line electrified railway and a four-lane highway. According to the project, cars, trucks and trains will circulate in separate areas, with emergency exits along the entire length.
When ready, the Fehmarnbelt will allow you to cross between Germany and Denmark in around 10 minutes by car or 7 minutes by train. Currently, crossing the region depends on a ferry or a long road detour, which can exceed 160 kilometers.
According to the governments of both countries, the new link should facilitate freight transport between Scandinavia and Central Europe and make the train a more competitive alternative to short-haul flights. The work is one of the largest ever carried out in Europe and has an estimated cost of around 7.4 billion euros, financed by loans that will have to be paid by the tunnel users themselves over time.
