A monumental engineering project is underway which will reshape the transport landscape of Europe. The Fehmarnbelt tunnel, an underwater structure connecting Denmark and Germany, is about to become the longest road and rail tunnel in the world, as well as the longest “submerged” tunnel never built.
At 18 kilometers (11.2 miles), the Fehmarnbelt tunnel will carry two road traffic lanes and two electrified train lines under one of the most frequented shipping channels in the world. Unlike traditional tunnels that are excavated through solid earth, Fehmarnbelt will be built using prefabricated concrete sections which are floated towards the seabed, linked together and submerged in a trench.
The project should considerably reduce the journeys between Denmark and Germany, reducing a 45 -minute ferry route just 10 minutes by car and 7 minutes by train. The tunnel will make half the journey time in two between Hamburg and Copenhagen, which changes the situation for the transport of passengers and freight.
Currently under construction with an estimated cost of 7.4 billion euros ($ 7.7 billion), the Fehmarnbelt tunnel is a colossal company. The first sections of prefabricated concrete, called “elements”, were recently completed in February 2025 in a Rødbyhavn factory, Denmark, marking a key step.
These giant tunnel sections are 217 meters long, 42 meters wide and 9 meters deep, each peels 73,000 tonnes – the equivalent of 10 Eiffel laps.
The construction of the portals of the tunnel in Rødbyhavn and Puttgarden is progressing, in order to finish the project by 2029. The tunnel should not only improve the efficiency of transport, but also to promote a larger tourism, offering visitors more practical access to the Scandavave region.
Mads Schreiner, director of the international market at Visitdemark, provides for an increase in autonomous tourism, weekend getaway and environmentally friendly travel options such as cycling and train tourism.
However, the massive project is not without environmental concerns. Despite several judicial challenges linked to its environmental impact, FEMMEN A / S, the Danish company supervising the project, is committed to mitigating the harmful effects. The company has already started to create new natural areas, such as wetlands and meadows, to compensate for the environmental footprint.
Once finished, the Fehmarnbelt tunnel will not only be an engineering marvel, but also a central link in European transport infrastructure, fundamentally changing the way people and goods move through the continent.
