The Fehmarnbelt Tunnel, a project underway that could be completed in 2029, promises to become the longest underwater tunnel for vehicles in Europe and the world, exceeding 18 kilometers in length. It is also projected to connect Germany and Denmark, via the islands of Fehmarn and Lolland.

The structure will allow travel between the two countries by private cars and trains, breaking the ferry's exclusive status as a travel alternative.

The underwater tunnel will have concrete sections at the seabed

Construction began four years ago and it stands out both for its size and the method chosen for its construction. Unlike other famous underwater tunnels, such as the Channel Tunnel connecting France and the United Kingdom, this infrastructure is not being excavated with a tunnel boring machine under the seabed.

Instead, the engineers have opted for a technique known as submerged tunneling, explains Motor Pasion. This system involves manufacturing enormous sections of concrete on land and then placing them on the seabed. In total, the tunnel will be composed of 89 sections, each 217 meters long and weighing approximately 73,000 tons. Each of these sections includes two road lanes, two electrified railway tracks, and a service corridor for maintenance and security. The design allows vehicles and trains to travel simultaneously, optimizing the flow of transport between Germany and Denmark. A tunnel 40 meters below sea level: The Fehmarnbelt Tunnel is being built at a depth of up to 40 meters below sea level. This depth ensures the stability of the structure and avoids interference with maritime navigation. In Latin America, they are also building the deepest metro system, with stations 65 meters underground. Once completed, the impact on travel times will be significant. The journey, which today requires about 45 minutes by ferry, will be possible in just 10 minutes by car or seven minutes by train.This will facilitate the transport of people and goods, strengthening economic and social ties between the two countries. The concrete sections are manufactured in a factory of exceptional dimensions located in Denmark. Once completed, they are sealed at both ends and transported by sea to their final location using tugboats. There, one of the most delicate phases of the project begins: the controlled sinking of each section into an 18-kilometer trench previously excavated on the seabed. The process is designed to achieve a millimeter-perfect fit between the different sections.

The estimated cost of the project amounts to approximately €7 billion (more than $8 billion), an investment that the authorities consider strategic.