First tunnel element of the Fehmarnbelt tunnel to be immersed
The first of the 89 concrete elements that will make up the future Fehmarnbelt tunnel between Denmark and Germany is now on its way to the immersion point off the coast near Rødbyhavn on the Danish island of Lolland.
The 217-metre-long and 73,500-tonne concrete element left the work harbour of the tunnel factory at 9 pm on 4 May 2026. In preparation of the immersion, the contractors added a further 4,500 tonnes of ballast concrete to ensure the element is heavy enough to sink to the seabed. Now the just over two-kilometre journey to the immersion point off the future tunnel portal has just begun.
The tunnel element contains four tubes that will in future house the motorway and the railway, in addition there will be a service tube for technical installations. The element is being transported with the help of five tugboats and a vessel built specifically to immerse the element down onto the seabed.
The tunnel element is sealed at both ends and filled with air. However, as the road traffic tubes are heavier than the railway tubes, the element is not naturally balanced. For this reason, the outer railway tube is fitted with temporary water chambers, which ensure that the element remains completely horizontal during immersion.
”This is a very complex manoeuvre, which has never been carried out on this scale before. The elements of the Fehmarnbelt tunnel are both wider, heavier and longer than those used to build the Øresund link, and we will be working in significantly deeper water,” explains Lasse Vester, Deputy Contract Director at Sund & Bælt and responsible for building the Fehmarnbelt tunnel.
The tunnel element will lie in an 18-kilometre-long trench on the seabed from Rødbyhavn to Puttgarden. Before immersion, a bedding layer of gravel has been laid in the tunnel trench to ensure that the element rests in the correct position.
”It is a major task with very little margin for error. We have to immerse an element that is as long as two football pitches, within just a few millimetres. That places great demands on the equipment and on our contractor, which is why they have been preparing for this task for a long time,” says Lasse Vester.
The transport of the element and the immersion itself are expected to take several days. Once the element has been connected to the tunnel portal, the next step is to place rocks and gravel along the sides of the element to keep it in position in the tunnel trench.
Find videos and images from the operation here: Media Kit First Immersion
The material will be updated continuously.
About the Fehmarnbelt project
The Fehmarnbelt project is one of Europe’s largest infrastructure projects and comprises the construction of an 18-kilometre-long immersed tunnel between Denmark and Germany, along with landworks on both sides. The tunnel will be the world’s longest of its kind.
The tunnel will contain a two-lane motorway in each direction and two electrified railway tracks for highspeed trains. Travel time will be 10 minutes by car and 7 minutes by train.
The Fehmarnbelt tunnel will strengthen trade, mobility, and cooperation between Northern and Southern Europe. The project is user-financed and carried out with support from the European Commission.
