4 ms·

Asking because I really don't know: How are fluctuations in water level dealt with safely with this sort of thing?

avar 10y ago
How much the tide varies in any given area is well-known, you just take that into account when deciding how high to make the ceiling.
- mnw21cam 10y ago
  Presumably the tide isn't ever sufficiently different on either side of the tunnel to cause a large current through the tunnel.
  - caf 10y ago
    It has a significant east-west displacement so you'd think there would be some tidal flows.
- jmcdiesel 10y ago
  But a storm surge would be unpredictable, right? How do the physics of "crushing" a boat by raising water level in a confined space work?
  - avar 10y ago
    > But a storm surge would be unpredictable, right? No we know what sort of storm surges are 10, 100, 1000 year events etc. At that point it's just a question of what you design the tunnel to withstand. > How do the physics of "crushing" a boat by > raising water level in a confined space work? This is an elementary application of Archimedes' principle. The weight of the ship is equivalent to the weight of the water it displaces[1]. If the ship is stuck against the ceiling of a confined space the pressure it's excreting on the ceiling is going to be the equivalent to the displacement of that "extra" water. 1. Leaving aside the full calculation which takes the difference in the weight of air & water into account for the purposes of this explanation.
ThrustVectoring 10y ago
Gate off the water for the canal separate from the sea, so that it doesn't fluctuate. Usually this involves building a set of locks so that ships can traverse between the different levels - basically, a pair of floodgates with mechanisms to drain water into and out of the pound between them. Push ship in, lock the near gate, drain or fill the pound, unlock other end.
- arethuza 10y ago
  So it's a dock that is open at both ends and has a stone roof?
  - ThrustVectoring 10y ago
    Docks are shoreside structures used for mooring vessels. It's basically an artificial lake inside an artificial cave.
- avar 10y ago
  No, that's not how it's going to work. This proposed tunnel has no locks, the tunnel is open to the ocean on both ends.
  - ThrustVectoring 10y ago
    You sure? 100 ships a day means 14 minutes per ship, and a lock cycle takes 10-20 minutes, so that's awfully suggestive to me. OTOH, I'm not sure of the relative difficulty and expense of adding height to a tunnel vs creating and operating a lock - I'd assume at some length it makes more sense to use a lock, since tunnel cost scales with length and lock cost doesn't.
    - avar 10y ago
      I don't know why the limit is 100 per day, I'm just going by the article & the pictures in it which very clearly show a tunnel open to the ocean with no lock system. The photos also show a mountain going straight into the ocean, which means raising the ship with a lock wouldn't save you any money, since you'd need an unbroken sequence of locks going all the way to the top of the mountain.

avar 10y ago

How much the tide varies in any given area is well-known, you just take that into account when deciding how high to make the ceiling.

mnw21cam 10y ago
Presumably the tide isn't ever sufficiently different on either side of the tunnel to cause a large current through the tunnel.
- caf 10y ago
  It has a significant east-west displacement so you'd think there would be some tidal flows.
jmcdiesel 10y ago
But a storm surge would be unpredictable, right? How do the physics of "crushing" a boat by raising water level in a confined space work?
- avar 10y ago
  > But a storm surge would be unpredictable, right? No we know what sort of storm surges are 10, 100, 1000 year events etc. At that point it's just a question of what you design the tunnel to withstand. > How do the physics of "crushing" a boat by > raising water level in a confined space work? This is an elementary application of Archimedes' principle. The weight of the ship is equivalent to the weight of the water it displaces[1]. If the ship is stuck against the ceiling of a confined space the pressure it's excreting on the ceiling is going to be the equivalent to the displacement of that "extra" water. 1. Leaving aside the full calculation which takes the difference in the weight of air & water into account for the purposes of this explanation.

ThrustVectoring 10y ago

Gate off the water for the canal separate from the sea, so that it doesn't fluctuate. Usually this involves building a set of locks so that ships can traverse between the different levels - basically, a pair of floodgates with mechanisms to drain water into and out of the pound between them. Push ship in, lock the near gate, drain or fill the pound, unlock other end.

arethuza 10y ago
So it's a dock that is open at both ends and has a stone roof?
- ThrustVectoring 10y ago
  Docks are shoreside structures used for mooring vessels. It's basically an artificial lake inside an artificial cave.
avar 10y ago
No, that's not how it's going to work. This proposed tunnel has no locks, the tunnel is open to the ocean on both ends.
- ThrustVectoring 10y ago
  You sure? 100 ships a day means 14 minutes per ship, and a lock cycle takes 10-20 minutes, so that's awfully suggestive to me. OTOH, I'm not sure of the relative difficulty and expense of adding height to a tunnel vs creating and operating a lock - I'd assume at some length it makes more sense to use a lock, since tunnel cost scales with length and lock cost doesn't.
  - avar 10y ago
    I don't know why the limit is 100 per day, I'm just going by the article & the pictures in it which very clearly show a tunnel open to the ocean with no lock system. The photos also show a mountain going straight into the ocean, which means raising the ship with a lock wouldn't save you any money, since you'd need an unbroken sequence of locks going all the way to the top of the mountain.