Denmark’s $8 Billion Lego-Like Tunnel to Germany

The record-breaking Fehmarnbelt tunnel is being built using giant Lego-like pre-fabricated elements that are then combined on the seabed, connecting Denmark and Germany. What kind of work makes this engineering feat possible?

The same country that brought Lego to the world is now building a tunnel using the same principles: by crafting 217 meter long pieces, then sliding them into place. There is no equipment in the world that can carry each 73,000 tonne piece. It takes four tugboats and sloughs to position them, then locked in place using ballast water, then concrete.

Construction is going very slowly, as engineers double and triple-check each component, valuing quality over speed. This isn’t the first tunnel that’s been built with this construction method. The tunnel under the Oresund Bridge between Denmakr and Sweden was built using a similar process. Expanding on the experience gained from that engineering project, the Fehmarnbelt tunnel has an extra basement level, allowing repairs and maintenance to be done without ever disturbing traffic inside the tunnel.

When completed in 2029, the tunnel will allow a 10 minute drive between Denmark’s Lolland Island and Germany’s Fehmarn Island. It will be the longest road tunnel in the world. The tunnel opens up economic and social benefits that will allow people to take advantage of what will soon become one of the longest railways in the world.

Courtesy of Interesting Engineering

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