Lolland is a Danish Island located in the Baltic Sea, separated by 18 km distance from the nearest German island called Fehmarn. This belt of water is known as the Fehmarn Belt, and it is home to the largest infrastructure under construction in northern Europe. An underwater tunnel is being built between Germany and Denmark that will be a transcontinental highway moving thousands of people a year. 

The route will consist of a four-lane highway and two rail lines that would serve both freight and high-speed passenger trains.

Unlike other links built on the mainland, the Fehmarn Fixed Link consists of prefabricated concrete elements. These elements are pulled out into a trench that is excavated in the seabed, which is considered a great solution for a site with such a pronounced ecosystem as in the Fehmarn Belt.

Render de enlace Fehmarnbelt
3D rendering of the process of joining the tunnel elements - Source: Femern A/S

However, this type of construction is usually used for fairly short distances, such as rivers and harbors. The Drogden Tunnel, for example, is one of the world’s longest submerged tunnels at four kilometers. The Fehmarn tunnel will be five times longer.

How is a project of this magnitude going to be built?

It all starts on the coast of Rødbyhavn, where we will find the large factory where the tunnel segments are built.

This surface area is required for the production lines that will manufacture the 89 concrete elements of the tunnel, which are 220 meters long, 12 meters high and 40 meters wide. Once in operation, these factories will work 24 hours a day, every day for the next three years. The tunnel elements will be lowered 40 meters into an 18-kilometer-long trench.

The Rødbyhavn construction site with the tunnel factory under construction in the center. - Source: Femern A/S

As for the construction method of the Fehmarn Fixed Link, the tunnel parts will be prefabricated and fitted into the seabed by a series of movable steel and concrete transverse gates.


Industrias Metálicas Anro will be in charge of producing the second gate of the dry dock where the concrete segments will be manufactured. The gate, 110m long and 750ton, will be an essential element in the assembly of the tunnel components. It will include a movement and sealing system that allows the gate to be lifted and moved to any desired location.


Some 19 million cubic meters of rock and sand are expected to be excavated from the bottom of the Baltic Sea, which will be used to gain ground along the Danish coast.

Enlace Fijo de Fehmarn
Digital reproduction of the tunnel entrance. Image courtesy of Femern A/S.

Once this tunnel is completed, thousands of cars and hundreds of trains will pass through it every day for the next decade. A new route will be opened to improve the quality of our connections, raising new challenges to overcome that will allow the immediate evolution of our continent.

You can follow the live broadcast from Rødbyhavn on the Youtube profile of Femern A/S.