An 18 km long underwater tunnel is being built between Denmark and Germany

A record-breaking infrastructure project is being built under the Baltic Sea between Denmark and Germany, the Fehmarnbelt Tunnel, which, when completed, will be the world's longest submerged pre-assembled road and rail tunnel. It will be 18km long and will significantly reduce travel times: the journey between Rodbyhavn in Denmark and Puttgarden in Germany will take just 10 minutes by car or 7 minutes by train, instead of the 45-minute ferry crossing. This is what the BBC reports.

The tunnel consists of 90 massive concrete elements, each 217 meters long and weighing more than 73 thousand tons. Unlike tunnels that are drilled into rock, the Fehmarnbelt elements are laid directly on the seabed in a specially dug trench, connecting with each other with jeweler's precision - up to 15 mm. This approach made it possible to implement the project even in areas with soft clays and chalk, where drilling is impossible.

Each tunnel segment has five parallel tubes: two for railway tracks, two for two-way roads, and one for maintenance and evacuation. The main construction site is located on the Danish island of Lolland, where a factory for manufacturing the elements and a port for their transportation operate.

The project costs around 7.4 billion euros, of which 1.3 billion is provided by the European Commission, the rest is financed by Denmark. It is planned that the revenue from the toll will gradually return the state investment over 40 years. More than 12 thousand cars and 100 trains will use the tunnel every day.

This infrastructure giant is of great importance for the region - it will connect Scandinavia with Central Europe, promote trade, tourism and create jobs, especially in less developed areas of Denmark, such as Lolland.

Incidentally, the construction plan was accompanied by protests from environmentalists and ferry companies who feared the impact on the marine environment. But after lengthy legal proceedings, the project received permission to proceed in 2020. To reduce the environmental impact, the company Femern, which is implementing the project, is creating a 300-hectare nature reserve on reclaimed land.

The tunnel is expected to open in 2029, marking a new chapter in Europe's transport connections.