Fehmarnbelt Tunnel: The longest underwater rail and road tunnel in the world will connect Germany and Denmark

An 18-kilometer underwater tunnel will soon connect Germany and Denmark. It should be mentioned that when it is finished, in 2029, the Fehmarnbelt Tunnel will be the longest combined rail and road tunnel ever built. The Fehmarnbelt Fixed Link, as the tunnel is formally known, will include two double-lane highways and two electrified rail tracks.  

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. Today, millions of people use a very crowded ferry service that will be replaced with a road link, cutting travel times by over an hour.  

Bypassing it, one can go through Denmark in seven rail minutes and ten minutes by vehicle while avoiding a 160-kilometer detour. 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 40 meters 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.