Seikan Tunnel

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I wonder how people going through this tunnel (and the Chunnel) avoid getting the bends when they come back up from under the water/rock? Workers in underwater tunnels get the bends when they come up if they don’t take it in stages; if this train is moving at 80-something mph, I don’t think that would be slow enough…

Laurie, there’s no need to worry about tunnel users suffering from the bends. They transit the tunnel in the dry, at normal atmospheric pressure. The workers that you’re thinking of would’ve been divers.

From Wikipedia, the bends, or decompression sickness, is “a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurisation. DCS most commonly refers to problems arising from underwater …” See: Decompression sickness - Wikipedia

It’s mostly divers, but caisson workers got the bends going up at the end of the day, too. They worked in pressurized “room” under the water, while building bridges etc under rivers- or under a bay. I didn’t realize the train was held at normal pressure, which does solve the problem.