The world’s longest immersed tunnel

How the Fehmarnbelt tunnel is being built


The Fehmarnbelt tunnel between Rødbyhavn on Lolland and Puttgarden in Germany will be the world’s longest immersed tunnel.

The construction of the Fehmarnbelt Tunnel is taking place both on land and at sea in the waters between Denmark and Germany.

The 40m deep, 18km long tunnel will contain a total of five tubes – two for rail, two for roads and one for service.

A total of 89 elements will be connected together to make up the length of the tunnel, 79 of these weighing 73,500 tonnes each, the remaining 10 weighing 21,000 tonnes each.

Each will have been cast incrementally in concrete segments over a skeleton of reinforced steel in large casting moulds in a purpose-built factory on the Danish side.

Once set, the elements are pushed out to a dry dock one by one and sealed at both ends with a bulkhead before being towed by tug and lowered on to the seabed.

With millimetre precision, they are fitted together, water is pumped out and a partial vacuum ensures they are locked together.

A layer of protective stone then covers the elements, and over time this will in turn be layered naturally with gravel and sand.

To guarantee unimpeded and safe marine traffic during offshore construction works, a joint Danish-German Vessel Traffic Service Centre (VTS) is beginning its service today. It is located in Travemünde, Germany.

German and Danish navigators jointly operate the new VTS Centre. They are specially trained and have all the necessary technology at their disposal.

The navigators can thus monitor the movement of every vessel around the clock and keep direct radio contact to any vessel on its journey through the Fehmarnbelt.

Enak Ferlemann, Parliamentary State Secretary for the Federal Ministry of Transport and Digital Infrastructure: “The Fehmarnbelt Project is the central element of the new European north-south axis, particularly by rail. It is important to us, during the construction works, to impair marine traffic as little as possible. The Danish-German Vessel Traffic Service Centre has a leading role in this.”

To ensure a service life of at least 120 years for the upcoming 18km immersed tunnel between Lolland and Fehmarn, the quality of the tunnel elements has to be second to none.

Also at a meeting on 21 June 2022, the EU member states approved the European Commission’s proposal for the allocation of funding for European infrastructure projects.

The construction of the Fehmarnbelt tunnel between Denmark and Germany has received EUR 540 million (DKK 4 billion) from the fund.

This article is shared by courtesy of Femern

For more articles about tunnel projects, click here.




Narjiss Ghajour

Editor-in-Chief of Maritime Professionals

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