Works are well underway on a once-in-a-generation construction project that is set to transform travel between central Europe and Scandinavia.

When completed in 2029, the €10 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. The tunnel will ultimately cost €10 billion, of which €1.1 billion will come from the European Union. This €10 billion project will link Puttgarden in northern Germany to Rdbyhavn on the Danish island of Lolland across the Fehmarn Belt in the Baltic Sea.  It will take less than three hours to travel by train from Hamburg, Germany, to Copenhagen, Denmark, as opposed to the current five-plus hours. Additionally, Denmark intends to construct high-speed electric rail lines to and from the tunnel. Rail service will continue to Sweden, Norway, and Finland after crossing the Danish border. 

The tunnel construction is not a novel concept. Construction started in 2020 on the Danish side after ten years of planning, and in 2021 on the German side. It will be constructed from 89 massive concrete sections 130 feet below the Baltic Sea. A crane will be used to lower these into the water after their construction on land. The project’s state-owned Danish contractor, Femern A/S, anticipates completing the first of these sections by 2024. 

The concrete sections will be assembled once they are in position, and additional components like railway tracks, ventilation, and cameras will be then installed. 

The effect of the tunnel on animals in the Fehmarn Belt, a protected region by the EU, has been questioned by several environmental organizations. However, the tunnel will ” increase capacity and relieve congestion on the rail and road networks in Denmark”, according to Fermern A/S. Additionally, the company asserts that “substantial” time, energy, fuel, and CO2 emissions savings will result from it.