World’s longest tunnel takes historic step forward

A 73,500-tonne concrete element has been successfully lowered onto the Fehmarn Belt seabed, marking the start of tunnel assembly for one of Europe's largest infrastructure projects.

The Fehmarn Belt tunnel, set to become the world’s longest immersed tunnel, has reached a historic milestone. The first of 89 concrete elements has been successfully lowered onto the seabed.

The operation began on 4 May. After more than 14 hours of controlled immersion, the element was in place at the tunnel portal near Rødbyhavn on Thursday 5 May.

The element is a colossal hollow concrete structure measuring 217 metres and weighing over 73,500 tonnes. It is the first time in history that mass-produced tunnel elements of this size have been used to build a tunnel.

Five tugboats and a specialised immersion vessel transported the element from the factory at Rødbyhavn before lowering it into a pre-dug trench up to 40 metres below the surface.

– We are both happy and relieved. Our technology, our equipment and our contractors have done something no one has done before, says Mikkel Hemmingsen, CEO of Sund & Bælt.

At 18 kilometres, the Fehmarn Belt tunnel will be the longest immersed tunnel in the world. When complete, it will cut the crossing time to 10 minutes by car and just 7 minutes by train, reducing the Copenhagen to Hamburg journey to 2.5 hours.

The project is one of the EU’s priority infrastructure schemes and has received more than DKK 10 billion in EU funding.