5 ms·

If you don't want to ventilate, it would likely need to be non-contact electric rail, unless you want the tunnels to have extremely high concentrations of ozone

If you don't want to ventilate, it would likely need to be non-contact electric rail, unless you want the tunnels to have extremely high concentrations of ozone. The arcs from electric contact catenaries produce ozone, which is fine outdoors because of immediate dissipation and short half-life. Put it in a tunnel and you either have to invest in ventilation (what most subway systems do), or mitigation (via contactless power delivery, likely induction).

seanmcdirmid 3y ago
There are lots of tunnels that do electric rail in Europe and China. Even that very long one in Switzerland. https://en.m.wikipedia.org/wiki/Gotthard_Base_Tunnel https://en.m.wikipedia.org/wiki/Gotthard_Base_Tunnel I think it is using overhead wires.
- jasonwatkinspdx 3y ago
  Yes, and that tunnel has massive ventilation systems, not just for emergencies like fires too. Fun trivia: the tunnel is so deep that without ventilation the temperature in it would be 40 centigrade.
  - seanmcdirmid 3y ago
    It does, but the ventilation is still not designed for diesels. I guess we are just discussing boring, in that case, electric something is required, maybe battery would work out better than overhead or below lines. Or maybe the only way to do this right without any ventilation is via supercooled magnets or air pressure.
    - hnbad 3y ago
      As I said earlier though, the problem with batteries is they're a PITA to extinguish if they catch fire and you don't want to have that problem deep underground unless you plan to flood entire parts of the tunnel (which brings its own problems not even considering cleanup itself). As any emergency worker will tell you, the problem with batteries compared to ICE engines is that if the battery is on fire it doesn't just stop once you extinguish it. You need to keep at it until it has cooled down sufficiently to prevent spontaneous reignition and that takes a while. Plus the entire time it burns it generates large amounts of toxic fumes. Compare that to an electric line that just needs to transmit electricity and just stops if you shut it off. Yeah, ozone accumulation is a problem but so is heat so you'll need some venting anyway (plus you probably want the air in the tunnels to be breathable because we're humans after all).
      - seanmcdirmid 3y ago
        If they did the whole vacuum tube thing, you’d want to sealed anyways, and maybe propel it using maglev, although I’m not sure what the heat properties are of that. I’m guessing they have to expend energy to keep the magnets cool anyways.
bombcar 3y ago
Interestingly enough, even if you don’t have any arcing you still need to ventilate because there’s nowhere for heat to go, and eventually running enough trains over many years heats up the ground.

seanmcdirmid 3y ago

There are lots of tunnels that do electric rail in Europe and China. Even that very long one in Switzerland. https://en.m.wikipedia.org/wiki/Gotthard_Base_Tunnel https://en.m.wikipedia.org/wiki/Gotthard_Base_Tunnel I think it is using overhead wires.

jasonwatkinspdx 3y ago
Yes, and that tunnel has massive ventilation systems, not just for emergencies like fires too. Fun trivia: the tunnel is so deep that without ventilation the temperature in it would be 40 centigrade.
- seanmcdirmid 3y ago
  It does, but the ventilation is still not designed for diesels. I guess we are just discussing boring, in that case, electric something is required, maybe battery would work out better than overhead or below lines. Or maybe the only way to do this right without any ventilation is via supercooled magnets or air pressure.
  - hnbad 3y ago
    As I said earlier though, the problem with batteries is they're a PITA to extinguish if they catch fire and you don't want to have that problem deep underground unless you plan to flood entire parts of the tunnel (which brings its own problems not even considering cleanup itself). As any emergency worker will tell you, the problem with batteries compared to ICE engines is that if the battery is on fire it doesn't just stop once you extinguish it. You need to keep at it until it has cooled down sufficiently to prevent spontaneous reignition and that takes a while. Plus the entire time it burns it generates large amounts of toxic fumes. Compare that to an electric line that just needs to transmit electricity and just stops if you shut it off. Yeah, ozone accumulation is a problem but so is heat so you'll need some venting anyway (plus you probably want the air in the tunnels to be breathable because we're humans after all).
    - seanmcdirmid 3y ago
      If they did the whole vacuum tube thing, you’d want to sealed anyways, and maybe propel it using maglev, although I’m not sure what the heat properties are of that. I’m guessing they have to expend energy to keep the magnets cool anyways.

bombcar 3y ago

Interestingly enough, even if you don’t have any arcing you still need to ventilate because there’s nowhere for heat to go, and eventually running enough trains over many years heats up the ground.