When I was constructed, the tunnel did have 3m of sediment on top of it. This was required, as the tunnel was dug horizontally. Unless that changed over time, no part of the tunnel should be exposed.
Re:Old Elbe Tunnel
by LargoLasskhyfv on Friday October 14, 2022 @01:36AM
(#33200000)
I do know that. But I think the graphics in Wikipedia visualizing the profile are wrong. I've been into exhibitions about it, which showed much more than that. Also it may have been different at different times because the river is dynamic, has been and is been dredged out, from time to time, as necessary.
The roof of the tunnel is too high in the water, to let contemporary large ships pass. Where large ships means the giant container freighters with 19.000+ TEU capacity. Mission impossible. Covered or not. This is not true for roll on/roll off ferries, which seem similarily large, but aren't, at least not below the waterline. They just manage, but barely.
This sticking out is also the reason all the terminals for larger ships are downstream of it, because their keels would crunch it, even at high tide.