World's Longest Immersed Tunnel Set To Revolutionise European Logistics

Denmark and Germany are on the verge of an infrastructure milestone with the construction of the Fehmarnbelt Tunnel, an 18-kilometre undersea link beneath the Baltic Sea.

The project, which is scheduled for completion in 2029, will connect Rdbyhavn on Denmarks Lolland Island with Puttgarden on Germanys Fehmarn Island, slashing travel times between Scandinavia and Central Europe.

The tunnel will feature an electrified high-speed rail line capable of reaching 200 km/h and a four-lane highway, reducing the current 45-minute ferry crossing to just seven minutes by train and ten minutes by car.

This will significantly enhance connectivity between Hamburg and Copenhagen, with the journey time between the two cities expected to drop to just 2.5 hours.

The Fehmarnbelt Tunnel is being constructed as an immersed tunnel, with 89 concrete elements each weighing up to 73 000 tonnes cast on land and then submerged into the seabed which is too soft for drilling.

Henrik Vincentsen, CEO of Femern A/S, the Danish state-owned company responsible for the construction of the tunnel, said a bridge across the Baltic Sea was not feasible because hydrographic conditions involving exchange flows with the North Sea could cause sudden inclement gales.

However, its the tunnels submersion depth of 40 metres that will enable large maritime vessels to continue using the 19km sea stretch between Rdbyhavn and Puntgarden, without the interference of regular ferry transfers, that is a real clincher for the Fehmarnbelt Tunnel.

The project, dubbed North Europes largest construction site, has faced environmental concerns, particularly regarding water clouding from dredging.

However, stringent monitoring and specialised dredging techniques have been employed to minimise ecological impact.

With an estimated cost of 7.4 billion, the tunnel is primarily financed by Denmark, which will collect tolls to recoup expenses.

The European Union has also supported the project with over 1 billion, recognising its strategic importance as part of the TEN-T transport network, a comprehensive infrastructure initiative by the European Union aimed at creating an integrated, multimodal, and high-quality transport network across Europe.

Once operational, the tunnel is expected to serve as a vital green link, reducing carbon emissions by shifting freight and passenger traffic from road to rail.

It will also bolster economic ties between Scandinavia and mainland Europe, offering a faster, more reliable alternative to the current ferry service.

King Frederik X of Denmark recently inaugurated the first 217-metre section of the tunnel, marking a significant milestone in the projects progress.

As construction continues, the Fehmarnbelt Tunnel promises to redefine regional travel and set a new benchmark for global infrastructure projects.