From the quayside of the Danish town of Rødbyhavn, the Baltic Sea sparkles in the sun and Germany is so close you can see it – a cluster of wind turbines on the horizon.
The German town of Puttgarden is only 17 kilometers away, but getting there requires either a 45-minute ferry ride – plus time for boarding and disembarking – or a six-hour drive that takes you through much of Denmark.
But under the water, construction of an alternative future is well underway: in the form of the world’s longest immersed tunnel – the name given to a tunnel that is built elsewhere and then sunk in place. When the Fehmarnbelt Tunnel opens in 2029, people will be able to cross the stretch of water in just 7 minutes by train and 10 minutes by car.
The tunnel will far eclipse the current record holder for road and rail, the four-kilometer-long Drogden Tunnel, which together with the Øresund Bridge connects Denmark and Sweden.
The new tunnel is also the final stage of a three-part infrastructure project – alongside the Øresund Bridge and the Great Belt Bridge, which spans the Danish islands of Zealand and Funen – that connects Denmark and the Nordic countries as a whole with the rest of Europe.
Once the tunnel is completed, goods, including steel, can be transported by rail from the northern tip of Norway to central and southern Europe. The rail travel time between Copenhagen and Hamburg will be significantly reduced, from 4.5 to 2.5 hours.
On a national level, it symbolises the culmination of a transformation of the Danish psyche over the last quarter century, from a relatively isolated peninsula and a collection of islands to an international centre.
“It is part of this connection that Europe wants to create between northern Norway and southern Europe. It started with the construction of the Øresund Bridge between Copenhagen and Malmö,” said Mikkel Hemmingsen, CEO of the state-owned company Sund & Bælt. “To complete the connection, we have to build this connection.”
Unlike many underwater tunnels – including the Channel Tunnel – which are built using drilling machines that dig through the ground, sections of the Fehmarnbelt Tunnel will be built above ground and underwater on the seabed. Hemmingsen said this approach is more efficient and better for the environment.
Last week, the Guardian was given exclusive access to the first 120 metres of the tunnel. Ships passed on the water above the tunnel entrance as workers welded the outer walls. Near the construction site, long lines of trucks lined up to board the ferry to Germany.
The tunnel, which consists of 90 components, each 217 metres long and weighing 73,500 tonnes, is being built in a factory specially built for this project.
The finished sections are stored floating on the water and submerged before being connected to each other on the seabed, which reaches a depth of about 30 meters.
Hemmingsen said building the tunnel was more like building electronic components than traditional construction.
“What we’re doing right now is not a normal construction project with lots of people running around like little ants in a small space. It’s more like building iPhones.”
There are six production lines – designed to be “optimised and lean” – each producing a different element of the tunnel.
Hemmingsen compared the assembly of about 900 small elements into 90 larger elements of the tunnel to “using Lego bricks”.
“If an element fails, you can actually replace it,” he said. “Once it’s done, it looks very simple, but from an engineering point of view, a lot of details have to be worked out before you can begin.”
Although the construction time of the €7 billion (£5.94 billion) The project is relatively short – work began in 2021 – but it has been a long time in the making. Engineers have been putting concrete samples into water in the region for the past 15 years to see how different mixes react to salinity. The project is funded by a government-backed loan repaid through tolls and has received more than €1 billion from the European Commission.
Anders Wede, the construction manager, grew up nearby before moving away and returning to work on the tunnel. He hopes the factory – which will be used for various projects once the tunnel is completed – can help reduce the relatively high unemployment in the area.
“The region here has suffered a lot over the last 20 to 30 years,” Wede said. “They (local authorities) really see this as a golden opportunity for a new chance, and maybe some companies see potential in the area,” he said. “So they’re really keeping their fingers crossed.”
The region will benefit from shorter travel times to Germany, he added, and more tourists from Europe are expected to come to Sweden via Denmark. “This used to be the corner of Europe,” he said. “Now it is the center of Denmark that leads to Europe.”
