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

Posted by msmash on from the thought-exercise dept.

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?

16 of 736 comments (clear)

  1. simple by ganjadude · · Score: 5, Informative

    you will die. really no ifs ands or buts about it.

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  2. More idiotic scare-mongering by SuperKendall · · Score: 5, Informative

    IF the system started to have a slow leak the pod would have time to slow, air resistance would do it naturally if nothing else.

    Also it's not like it cannot have basically "landing gear" that would be able to slow the pod from 700 MPH in the perfectly smooth sealed tube in the case that a real breach presented itself - but you do all realize that a pressure breach would not be instantaneous across the enter length of the tube, right? Then we are back to the case where pressure changes can be reacted to and the system brought to a gradual halt.

    I sweat Slashdot has become a bastion of luddite nut-jobs, who seem to purposefully ignore physics. Shameful to see such a virulent example of this on the home page.

    You all sound like the people who wouldn't get into the first automobiles... or modern day Amish who still will not, but at least the Amish people are generally useful.

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  3. Even More Simple by ranton · · Score: 5, Insightful

    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.

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    1. Re:Even More Simple by gfxguy · · Score: 5, Interesting

      Agreed... just like plane crashes, it could be catastrophically bad, but also just like plane crashes, it would probably be so rare that it's still safer than driving.

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      Stupid sexy Flanders.
    2. Re:Even More Simple by Ami+Ganguli · · Score: 5, Insightful

      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.

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    3. Re:Even More Simple by DontBeAMoran · · Score: 5, Funny

      Maybe he thinks the hyperloop walls are made of the same material as party balloons.

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    4. Re:Even More Simple by bws111 · · Score: 5, Insightful

      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.

    5. Re:Even More Simple by MightyYar · · Score: 5, Insightful

      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.

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    6. Re:Even More Simple by Solandri · · Score: 5, Interesting

      We know exactly what will happen. The problem isn't the tube losing its pressure seal. Air is compressible, so it makes a great shock absorber (in fact that is exactly how some shock absorbers are designed - with a gas at one end of a cylinder being pressurized).

      The problem is trains moving at high speed tends to do bad things when they hit a stationary solid object. The Eschede derailment probably would've only had a dozen or so fatalities due to losing a wheel at 200 kph. In fact, the wheel failure was in the first car, but the engine and first four cars survived relatively intact, scraping the bridge supports but coasting to a stop or derailing and hitting some trees (the guy sitting above the wheel which failed survived despite being out of seat showing the wheel to the conductor when the accident happened). The bridge collapsed onto the 5th car, causing the rapid deceleration of all subsequent cars. That's where all the fatalities occurred. It was just bad luck the train happened to be passing underneath a bridge just as the accident occurred.

      Now, consider that with a hyperloop train, the cars will be traveling at speed a few inches from the stationary wall for the entire length of the track. It's not an air leak you need to worry about. It's an IED-type device placed on the side of the track wall, designed to blow it inwards just before the train arrives. At 700 MPH the explosive only needs enough energy to blow enough of the wall inwards to destroy the first train car causing it to block the subsequent cars. The kinetic energy of the train itself will then be more than sufficient to destroy it. When US Air 427 hit the ground at just 300 MPH, its kinetic energy was enough to shred all the metal into pieces smaller than a sheet of paper. United 93 hit the ground at 563 MPH, and its kinetic energy fragmented the plane into such small pieces that conspiracy theorists (who can't seem to grasp the notion that solid metal will fragment when presented with no other means of shedding kinetic energy) have gone nuts with theories that no plane actually crashed there.

      A hyperloop train is going to have more than 4x the kinetic energy per unit mass of US Air 427, 1.5x that of United 93. If one strikes the wall and crashes, it kinetic energy is literally going to turn it (and its occupants) into confetti.

      What makes it more dangerous than a plane is that planes fly miles away from the nearest solid object when they're at top speed (mid-air collisions excepted). Even systems designed to cause a deliberate collision (surface to air missiles) have a high failure rate. OTOH Hyperloop is going to be traveling a few inches from the nearest stationary object the entire length of its trip. So you're now faced with the prospect of protecting the entire length of track from vandalism or terrorism.

    7. Re:Even More Simple by jeremyp · · Score: 5, Insightful

      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.

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    8. Re:Even More Simple by sdinfoserv · · Score: 5, Insightful

      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

  4. Re:Soft failure possible too by DaHat · · Score: 5, Insightful

    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.

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  5. Re:Plane crashes are seldom fatal by networkBoy · · Score: 5, Insightful

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

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  6. Please think, even if just for a moment. by SuperKendall · · Score: 5, Insightful

    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*

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  7. Sabotage by emil · · Score: 5, Insightful

    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.

  8. Re:About the same thing that happens with aircraft by Guspaz · · Score: 5, Informative

    The whitepaper described how to handle loss of pressure in the pod. Basically it boiled down to this:

    1) If the leak is small enough, compensate with onboard emergency air supply until the destination is reached
    2) If the leak is big enough, initiate a system-wide emergency stop and rapidly repressurize the tube.

    You could arguably repressurize the tube faster than an aircraft could descend to a safe altitude.