How the Fehmarnbelt Tunnel is being built [video]

There are some great questions in here. But what I'm most curious about is how the keep the individual segments from sinking into the seabed at different rates. I can't imagine that the interfaces would remain water tight if any segment sunk by, say, more than 30cm. Can we really be certain about the stability of sediment underwater at the loads that will be applied?

Have rising sea levels and storm surges been taken into account for the planning of the entrances? Watching the video, wondering if it is an accurate depiction of size and placement, I couldn&#x27;t help the bolt of consternation that shot through me, because those entrances look awfully close in elevation to sea level.<p>And regarding air management, in Japan and HK at least, driving through lengthy tunnels can already be a stinky affair, especially in summer, so ensure your vehicle&#x27;s air conditioning system is set to cycle the air inside the car. The Tokyo Bay Aqua Line tunnel that connects Yokohama to Chiba is quite long and it uses large fans that vent at mid-way points, one doubling as a tourist stop. The Fehmarnbelt tunnel being the longest in the world is therefore longer, and I didn&#x27;t see such venting points. Yes I noted the air movers in the video. But hey, I&#x27;m hopeful that such problems will attenuate with electrification.

The idea of sealing each section and then floating it into position seems so elegant and simple. Is this a common technique for a project of this style, or a new innovation?

How do they join the tunnel segments to each other? How do they properly seal it? The video glosses over that part.

I&#x27;m curious about the seals between sections. How they do that?

How exciting this would be to cycle through the tunnel once the tunnel is completed but not yet released to public (car) traffic? Near Hamburg people enjoy riding their bikes on a nearly completed section of a new motorway although it&#x27;s strictly forbidden.

My number one question is how they plan to dredge the seabed and keep that surface flat enough for the tunnels to sit on. connecting with millimeter precision would require a flat surface, no? Fascinating.

2 million+ tons of emitted CO2 mostly from the Portland concrete elements.[0] We really need to find some low-carbon alternatives that are structurally and economically feasible.<p>Hope it&#x27;s worth it.<p>[0]: [pdf] <a href="https:&#x2F;&#x2F;vvmdokumentation.femern.dk&#x2F;39.%20E6TR02217843.pdf?filename=files&#x2F;BR&#x2F;39.%20E6TR0221.pdf" rel="nofollow">https:&#x2F;&#x2F;vvmdokumentation.femern.dk&#x2F;39.%20E6TR02217843.pdf?fi...</a>

Very cool, In Norway they are considering creating a floating tunnel that is held up with giant floating bois tederet to the ground because some places the sea is just to deep and steep. Anyway here is a video, dunno about current status: <a href="https:&#x2F;&#x2F;youtu.be&#x2F;Gt1MDQHLjF8?t=26" rel="nofollow">https:&#x2F;&#x2F;youtu.be&#x2F;Gt1MDQHLjF8?t=26</a>

I was just thinking, when was the last time we did something like this in the US? The California rail project has been going on for years, no one dares to even suggest building something like this. All great bridges were built over 50 years ago. If you suggest to do something major in the Bay Area, you would be booo&#x27;ed into oblivion for a mere suggestion.

How much time does this actually save? Just looking at the crude map it doesn&#x27;t like like a huge amount? Like slightly more than cutting a rectangle into a hypotenuse (idk the term, like cut into triangle, the new long edge, still shorter than the other two combined)<p>VERY cool though

Could probably turn that production facility into a lucrative business if those tunnel segments could be transported down the coast &#x2F; into the Mediterranean.

I remember this project being controversial back in the day. I wonder what the locals think of that today. Definitely impressive technology.