Ask Slashdot: What Would Happen If a Hyperloop Train Failed?

dryriver writes: I've been following Elon Musk's Hyperloop initiative with great interest. The idea of getting from one city to another at 700 MPH without having to suffer through an airport and all that jazz is revolutionary. I'm glad that somebody is trying to innovate in the area of land travel. My question though: When conventional trains going at much slower speeds derail or crash, the result is often serious injuries or deaths. What happens if something goes wrong with a 700 MPH Hyperloop train/pod or with part of the track? Would a Hyperloop accident at that speed even be survivable?

Comments

Trains are not strongly attached to the rail...

[JcMorin]

Trains derail because of a century-old standard makes them very badly attached to its rail. If you run into a tube, even if the tube cracks a bit, there is a good chance you still continue in the same direction the same way I can run peas in a straw with crack. I don't think catastrophic can't occur. I just think it's inherently more secure to run in a 360 degrees boundary tube than 2 littles track with no grip else than your own weight.

Even More Simple

[ranton]

We don't know what will happen because it hasn't been engineered and built yet. Determining how it handles various types of failures will certainly be part of the engineering process. Worst case scenario is everyone dies, which isn't much different than a plane crash. But just like with a plane, plenty of fail safes will be there to allow for managed failures. Most catastrophic failures will probably just cause the train to come to a gradual halt.

Re:Even More Simple

[Kiuas]

Worst case scenario is everyone dies, which isn't much different than a plane crash.

There's a notable difference to plane crashes though: failures of the tube or even a singular capsule will halt all traffic on the route, potentially for an extended period of time if pressurisation of tube tube fails due to the tube itself being damaged.

Re:Even More Simple

[Ami Ganguli]

A containment failure doesn't need to implode - it can just leak. Depends on the materials and the details of the design. And if it leaks, then everything slows down and stops.

I can't imagine they'd build this thing without any sort of safe failure mode.

Re:Even More Simple

[bws111]

Huh? The pressure difference, if they manage to make a perfect vacuum, is 1 atmosphere, about 15PSI. Pretty sure regular old steel can handle that. Natural gas in pumped through pipelines at about 250PSI, and a leak does not cause the entire pipeline to catastrophically fail.

Re:Even More Simple

[Guspaz]

If the largest concern in a failure is "people will be delayed" instead of "people will die", I think that's a pretty successful disaster mitigation strategy.

Re:Even More Simple

[bws111]

There is not 'a lot more pressure' outside than inside. IF they managed to create a perfect vacuum, the pressure difference would be about 15PSI. There are tons of materials that can handle that puny pressure difference. For comparison, natural gas is pumped through pipelines at about 250PSI. A leak does not cause a catastophic failure of the pipeline.

Re:Even More Simple

[MightyYar]

Tanker cars are designed to keep the contents inside, not contain a vacuum. The forces are literally the opposite of what was designed. You might as well claim that the pyramids are a poor design because they'd fly apart if turned on their side.

Re:Even More Simple

[jeremyp]

What do you mean by a containment failure? The tube is going to have a near vacuum in it so it has to be built to withstand a pressure difference of only one atmosphere. That's like a submarine diving to 10 metres. I think we can manage that.

I think it's much more likely that the tube will develop a leak. When a train traveling at 700 mph hits the air, it's going to slow down, probably quite rapidly. I couldn't begin to tell you how that will pan out. It may be that it is not a big deal because there probably won't be a wall of air so much as a pressure gradient.

Re:Even More Simple

[sdinfoserv]

I don't buy it. The average cruising speed of a jet is (c) 525 miles per hour. Plane crashes are not survivable when the plane is going at cruising speed. Survival happens then the plan lands ungracefully at a landing speed, or (c) 150mph. Forced landings ie:, a plane hits something and is forced to turn around, or an in flight failure forces a landing. This is when survival happens.
Assuming a hyperloop cruses at 700 mph or 25% faster, the notion of survive ability of virtually any crash, regardless of how the system is engineered, is ludicrous

Re:Even More Simple

[Immerman]

Unless you actually blow up the tube, you won't get a "wall of air" like that. Not with any real pressure behind it anyway. (for comparison Martian winds are routinely several hundred miles per hour, and they hit with the force of a light breeze because there's not enough pressure to give them any momentum.)

And if you're blowing up the tube, then you'll probably want to wait until a car's far too close to stop and slams into the wreckage at 700mph, so there's not much point in worrying about it. A terrorist attack killing a couple dozen people is trivially easy to pull off and basically impossible to defend against - every corner coffee shop offers a target that size, and is a lot easier to take out.

For anything less severe, you stop - 700mph= 313m/s. 3 to 10g's of braking is eminently survivable, though some injuries may occur. And at 30-100m/s^2 it only takes 3-10 seconds to stop. You'll still travel a goodly portion of a kilometer in that time, but you're not actually going to get a lot of air through the leak that quickly either. And if you somehow *do* have a huge column of dense air rushing at you, can also open emergency hatches between you and it - you'll get buffeted a bit by the closer air that hasn't had time to build up speed, and the first air column will plow into a long column of slower-moving air, dissipating the energy far more gracefully as fresh jets of pressurized air out the emergency hatches.

Re:Soft failure possible too

[DaHat]

Hatch doors... which would be separate failure points along the way for the pressure difference to be changed.

Assume perfect seals and no malicious or accidental misuse of even a single hatch door. A tech team is sent out to to assist the passengers in getting out. You can't just open the hatch, you've 14.7 lbs of pressure per square inch trying to keep that door closed, assuming it swings out. Now you've got to pressurize either the entire system (so largely shutting it down), or the particular leg you are on. How long does this take? Now how long does it take to undo these steps?

Short of a 9/11, when there is an airplane crash, even an entire airport (or state) is shut down due to weather, the rest of the system keeps going.

This also aside from all of the issues related to thermal expansion & contraction of the materials, making the sealing even more difficult.

Re:Plane crashes are seldom fatal

[networkBoy]

The mortality rate for national newsworthy and international newsworthy airplane accidents is near 100%, hence the cognitive disconnect.

Please think, even if just for a moment.

[SuperKendall]

Air fills the vacuum at the speed of sound.

Yes, exactly. Sound is not all that fast (six seconds to travel just a mile), mostly the pod would be so remote from the source of the leak it would have plenty of time to slow down to a reasonable speed before substantial pressure reached it. Also if we are talking about small leak its not like it would INSTANTLY be a huge volume of air in front of the pod, it would be a gradual loss of vacuum and therefore simply not the "wall of air" you are scare-mongering about.

And of course, the leak would have to occur in front of a moving pod instead of behind it to even be that much of a potential danger...

A wall of air hitting you at that speed would likely kill you.

Not at 70MPH instead of 700MPH, you blithering retard.

Also I've not seen any arguments for why emergency vacuum pumps placed along the tube would help eliminate the danger from common leaks? But you didn't even think that far you were just like YABBER YABBER YABBER FLOOM DOOM!! *throws hands in air and waves frantically like muppet on acid*

Re:About the same thing that happens with aircraft

[Lab Rat Jason]

Actually, I suspect the most likely fatal failure is going to be loss of passenger pressurization, resulting in *loss of cargo*. Cabin depressurization of an airplane is bad, but still not as bad as being exposed to total vacuum, and a plane can dive to regain air pressure. When a hyperloop pod looses pressure, there's no place to run.

Sabotage

[emil]

Perhaps a more salient question is sabotage.

Explosive charges attached to the tube that detonated five seconds before the arrival of a pod would likely kill everyone on board.