Fehmarn Belt Fixed Link: In a league of its own

The design of the Fehmarn Belt Fixed Link rethinks existing tunnel building standards and improves functionality and safety through optimisation – above and below water. Get a few insights on one of the world's most innovative, ongoing mega-engineering projects of our time.


Susanne Kalmar Pedersen

Susanne Kalmar Pedersen

Project Director
T: +45 5161 6243

By Jesper Toft Madsen, July 2015

Connecting Continental Europe with Scandinavia, the 18-km Fehmarn Belt Fixed Link will become the world’s longest immersed tunnel for cars and trains.

Above water

The design aesthetics of a tunnel concealed 40 metres below sea level can easily be overlooked. However, landscape architects have been involved to help design a natural travel experience in which commuters from both sides of the tunnel will crest a hill for a full sea view before dipping down into the bowl-shaped tunnel entrance. 


Designing immersed tunnels is all about optimising resources. After immersion, the free space in tunnel elements needs to be ballasted with concrete. For this reason, the Fehmarn Belt tunnel elements have been designed with limited space to ensure absolute minimum resource use.

As a new concept in immersed tunnel technology and design, the underwater link is constructed from 79 standard and 10 special elements to allow for a traffic deck and a maintenance deck. Systems for electricity, communication, monitoring and drainage take up space and require maintenance. These are integrated in special elements on a lower level beneath the traffic routes, thus allowing easy access for personnel without disrupting traffic.


The safety concept features two-lane traffic for motorists, a full emergency lane and emergency doors every 110 metres to make escape routes visible and easily accessible in the event of a major accident. A simple, resilient and reliable longitudinal ventilation system with jets will fan the tunnel at 400-metre intervals and is based on a new design approach that considers future EU standards for reduced car emissions.

The tunnel consists of two road tubes with a two lane motorway in each, a central gallery for escape and service and two railway tubes. Each concrete element can float, meaning that in the immersion phase the water’s own lifting power will carry the 217-metre-long elements, each weighing up to 73,500 tonnes.

The tunnel will be sited safely below the seabed, protected against ship anchors and other collisions.

The driver experience

Throughout the tunnel, travellers will pass illuminated zones ranging from lilac to blue, green and yellow. These zones will help keep drivers alert and indicate how far they have travelled.

LED lighting will also meet motorists as they enter, drive through and exit the tunnel. The lighting will form one-minute moving motifs along one of the tunnel walls. Altogether, the lighting experience will give the tunnel a sense of open space, resembling changing landscapes along normal roads.

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More about the Fehmarn Belt project

A tunnel link under the Fehmarn Belt will realise the vision of a permanent, close and direct link between Scandinavia and Central Europe. More on the megaproject.

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