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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?
https://www.youtube.com/watch?v=RNFesa01llk
Thunderfoot has done a series of videos on this topic. Even if you assume you could make a HUGE 99% perfect vaccuum with that volume of air; any failure causes its occupants to get exploded out the end somewhere. Lots and lots of energy in that system.
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.
Stupid sexy Flanders.
An airplane can glide quite some distance without power. It can even be controlled during this phase.
If a hyperloop tube suffers a catastrophic breach, think of the pressure wave of air rushing in and what that will do to any near by vehicle. Now, what happens to the vehicles in front of the one that just became a bullet in a gun?
Help Brendan pay off his student loans
That's ok, I'm game to start one. First we need to define the hyperloop as a system.
Next, we imagine, and list all of the possible failure modes for each one.
Rapid depressurization
Rapid depressurization
Thermal event
Explosive event
Then we discuss the effect of each failure mode, and steps that can be taken to mitigate it... Completing an FMEA usually takes hours in meetings with large numbers of engineers brainstorming all of the possibilities.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
Unlike a train or plane, a hyperloop is an enclosed tube where collisions *should* be non-existent unless you put multiple cars in the same tube. The most likely failure is likely stalling in which case you will need to have some way of extracting the stalled car but everyone should be uninjured. The mostly likely fatal failure would likely be a break in the tube causing a derailment and the closest we have to that would be roller coasters and large oil pipelines. Looking at the failure rate of large oil pipelines and roller coaster derailment should give a pretty good idea of the failure rate of a hyperloop.
If a hyperloop tube suffers a catastrophic breach, think of the pressure wave of air rushing in and what that will do to any near by vehicle. Now, what happens to the vehicles in front of the one that just became a bullet in a gun?
The problem is, from some of the physicists I've read, is that *any* breach of the tube would be catastrophic. Unless they make the tube out of some ridiculously thick, high-tensile strength steel, any sized rupture would blow a huge hole in the wall of the structure. The problem is you have a huge mass of low pressure in the tube, with a lot of air that wants to get in on the outside. The pressure differential is massive.
An explosive charge on an aircraft or train (or runway or train track) would also likely have a similar effect.
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.
To bleed altitude. Commercial airliners make terrible gliders, but still, they technically are gliders when the engines are no longer operational. In this case, the airplane glided to the Azores but had too much altitude and needed to stay in the air a little bit longer while not moving too far away: a perfect use case for flying in a circle.
24 beers in a case, 24 hours in a day. Coincidence? I think not!
It depends on the kind of failure. I am sure that the designers will make every effort to make the more likely failures (power loss, reasonable or minor track damage, etc.) survivable. You won't ever have many of the risks associated with conventional trains (inattentive conductors, cars or other obstructions on the track, excessive speed for the track, etc.) That said, if a terrorist blows up the track just short of the train in motion (less than stopping distance) you are very likely going to be red paste in the wreckage.
Compare the risk of death in an airplane:
loss of power - very likely everyone dies unless there is a runway nearby
any failure that causes loss of control - everyone dies
etc.
The main problem I see with the hyperloop is that in this era of terrorism, it is virtually impossible to secure hundreds of miles of tracks, whereas airports are fairly well secured, and planes are immune to terrorist attack from outside while in flight (so far terrorists haven't managed to design and build stinger missiles, fighter jets or SAM missile batteries.)
If you disagree, please post your argument. (-1, Overrated) isn't your personal censorship tool for views you don't like