Illustration of the proposed Fehmarnbelt tunnel entrance on the Denmark side.
A once-in-a-generation construction project is set to transform travel between central Europe and Scandinavia. When completed in 2029, the $8 billion Fehmarnbelt tunnel will be both the longest combined road and rail tunnel and the longest immersed tunnel anywhere in the world.
Officially known as the Fehmarnbelt Fixed Link, the 11-mile-long tunnel linking Germany and Denmark will sit in a trench at the bottom of the Baltic Sea at a depth of up to 130 feet.
It’s a key component in the development of the Scan-Med corridor, a transportation network that spans more than 3,000 miles from Malta in the south to Finland in the north. Along the way, it tunnels through Alpine mountains and crosses oceans. But approaching Scandinavia, a stretch of water known as the Fehmarn strait causes a 300-mile detour for both road and rail traffic on the north-south route.
The planned rail link will reduce travel time from Hamburg to Copenhagen from five hours to less than three hours, while the road link will replace a heavily-trafficked ferry service and reduce travel time by about one hour.
How to build an immersed tunnel
The megaproject is already well underway. From an engineering perspective, the project is truly fascinating.
The immersed tunnel will be built in segments on land and connected at sea (visualization).
The tunnel will consist of 89 standard concrete elements, each 712 feet long. Each element will contain two tubes for the highway, two for the railroad and one for service access. When complete, each element will be fitted into place in a trench 39 feet deep.
Dredging that trench is expected to produce 671 million cubic feet of soil, sand and rock, which will be turned into new land and beaches near the construction sites.
Preparatory work on the necessary harbor and tunnel factory began in 2020 to allow the actual construction work to begin on January 1, 2021. By mid-2022, dredging work was already 50% complete.
Those interested in the engineering can actually visit the site in Rødbyhavn on the Danish side of the tunnel to learn more. Tours of the exhibition center are available while a viewing platform with binoculars gives visitors the chance to explore the construction site with their own eyes.
The project has a controversial side
Not everyone is a supporter of the Fehmarnbelt tunnel. As with all megaprojects, the eye-watering cost of construction has raised many questions over its value, while environmental campaigners are concerned about the impact the dredging work will have on the local marine ecosystem.
The construction site at Rødbyhavn, Denmark, pictured in December 2022.
Almost all of the estimated $8 billion price tag is being funded by Denmark, to be repaid by hefty toll fees after opening. Many are questioning the value of such an investment but supporters of the project point to the iconic Øresund bridge that links Denmark and Sweden. It is widely deemed to have been a long-term success despite some fierce criticism of its cost during construction in the 1990s.
Now that the construction of the Fehmarnbelt tunnel is underway, environmental campaigners have switched their approach from trying to get the project canceled to monitoring its impact. The marine life in this area of the Baltic Sea thrives in clear water conditions, something the dredging of the sea bed to create the trench for the tunnel will disturb.
In an interview with B1M, local campaigner Hendrick Kerlen said “the ecology of the Fehmarn belt is very diverse. The clouding of the Fehmarn belt will reduce the growth of macrophytes and plankton and will of course have repercussions for all living fauna and marine flora.”
Femern A/S, the company responsible for the construction project, said that sedimentation is one of the most closely monitored environmental impacts on the project. Patrol boats and monitoring stations collect data on water clouding, which is published on the Femern website.
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Europe is on the brink of a major revolution in transport. The planned Fehmarnbelt Tunnel between Denmark and Germany, due to open in 2029, will slash travel times between the two countries to a fraction of what they are today, connecting them directly by road and rail. The 18.2 mile-long twin-track tunnel, which is estimated to cost around 8 billion euros, is set to become a major engineering challenge that will cut journey times between cities such as Hamburg and Copenhagen from a current 4.5 hours to just 45 minutes.
The Fehmarnbelt project, once complete, will link the two countries with a four-lane motorway as well as a twin-track high-speed railway line. The aim is to connect western and eastern Europe, and make it easier for people to travel across the continent. The tunnel is being developed by Femern A/S, a joint venture formed by the governments of Denmark and Germany, and is expected to create up to 10,000 new jobs in the region.
The environmental impact of the tunnel is expected to be rather minimal. The project designers have taken into account the possibility of strong tidal currents and created the necessary measures to minimise their effects, such as a tidal compensation fund and construction of specially designed seals. As the tunnel is being built underwater, the area’s marine life should remain largely unaffected.
In addition to reducing journey times, the tunnel will offer increased trade opportunities for businesses throughout the region, as well as improved access to jobs and services. This is especially significant as it opens up the door for increased collaboration between European nations for the benefit of their citizens.
The Fehmarnbelt Tunnel will be a milestone in the development of Europe’s transport infrastructure, revolutionising travel times and becoming part of our everyday lives. This megaproject is sure to make a huge difference to our lives, making it easier to reach cities faster, opening the door to increased trade and investment, and ultimately transforming the way we travel.
