World’s longest underwater rail-road tunnel to connect Germany and Denmark

The work is already underway from both sides and completion is expected at the end of the decade

Back in 2007, the governments of Germany and Denmark signed an agreement to build a fixed transport link through the narrowest stretch of sea separating the two countries – the Fehmarn Belt. The project, officially called the Fehmarnbelt Fixed Link, was initially meant to be a bridge but it was then considered better to build an underwater tunnel, whose construction began in 2021.

When completed (reportedly in 2029), the tunnel will be the longest such facility combining rail and road infrastructure in its body. The entire length of the tunnel will be some 18 kilometres and crossing it will take seven minutes by train and ten minutes by car.

What’s more important, though, is the amount of time it will save to drivers and passengers travelling between the two countries. The planned rail link will reduce travel time from Hamburg to Copenhagen from five hours to less than three hours, while the road link will replace a heavily-trafficked ferry service and reduce travel time by about one hour.

The missing link of the Scan-Med corridor

The construction of the tunnel will differ from the one linking the United Kingdom and France under the La Manche Strait since the latter was bored in the seabed. The Fehmarn tunnel will be of the immersed type, meaning that its components are first manufactured on land before being submersed under the water to be assembled.

The entrance to the tunnel on the German side will be in Puttgarden on the island of Fehmarn and on the Danish side it will be at Rødbyhavn on the island of Lolland. Once complete, there will be a straightforward transport connection between Hamburg and Copenhagen.

The total cost of the project is estimated at 10 billion euros, and it counts on 10% financial support from European funds, as well as support from the Swedish government. The latter should come as no surprise since completing the tunnel would put an essential link in the chain that is the Scandinavian-Mediterranean Corridor – a crucial north-south axis for the European economy from Malta to Sweden and Finland.

Both Danish and Swedish trains will be able to reach continental Europe uninterruptedly.