Journey Beneath the Waves: The Revolutionary Tunnel Linking Denmark and Germany

A record-breaking tunnel is currently under construction beneath the Baltic Sea, connecting Denmark and Germany, and is set to vastly improve travel times and strengthen Scandinavia’s ties with central Europe. Spanning 18 km (11 miles), the Fehmarnbelt will be the world’s longest pre-fabricated road and rail tunnel, designed to be assembled like Lego bricks under the seabed, and is recognized as a remarkable feat of engineering.

The main site for the project is situated on the shores of Lolland island in southeastern Denmark, encompassing over 500 hectares (1,235 acres) that includes a manufacturing facility for these tunnel segments referred to as “elements.” Each 217m (712ft) long and 42m wide segment will be constructed using cast concrete and reinforced steel. Unlike traditional underwater tunnels that drill through bedrock, this tunnel uses 90 individual elements that will be immersed and connected under the sea.

The construction, which costs approximately €7.4 billion ($8.1 billion) and is primarily funded by Denmark, is part of a larger EU initiative aimed at enhancing travel links and reducing air travel. Once completed, the crossing between Rødbyhavn in Denmark and Puttgarten in Germany will take just 10 minutes by car or 7 minutes by train, replacing the current 45-minute ferry ride and significantly reducing overall trip times between Copenhagen and Hamburg.

The tunnel’s complex construction involves substantial logistics, including the careful lowering of over 73,000-tonne tunnel elements into a 40-metre deep trench on the seabed with extreme precision, using advanced underwater cameras and GPS. The decision to build a tunnel rather than a bridge, which faced obstacles from shipping traffic and strong winds, was made for both cost and safety.

Despite initial opposition related to ecological concerns from groups like Nabu regarding the impact on marine life, including harbour porpoises, construction was allowed to proceed after legal challenges were dismissed.

Once operational in 2029, the tunnel is projected to accommodate over 100 trains and 12,000 cars daily, generating revenue through toll fees to help repay state-backed loans over approximately four decades. The anticipation of this infrastructure project promises to revitalize Lolland, one of Denmark’s economically challenged regions, fostering jobs and tourism. As stated by local construction managers, the community eagerly awaits the economic boost that the tunnel will bring.