At the risk of alerting the NSA, I’ll just say that you’d have to shape the charge. That’s not hard to do - if it’s in a truck, just put a heavy steel plate on the side opposite the tower.
The difference is that key parts of this infrastructure are in remote areas where you would have significant time to do something. And puncturing a fairly thin steel cylinder is a lot easier than cutting a cable on a suspension bridge. Hell, you might be able to do significant damage with just a .50 caliber rifle from a mile away. Are we going to make the cylinders strong enough to handle small arms fire? .50 caliber APC rounds?
Yeah - along its entire 350 mile length, much of which is in remote areas.
I will give you this, though: you’d think railroad tracks would be even more vulnerable. I don’t really understand why there hasn’t been a rash of train derailments, given how easy it would be to accomplish.
That sounds feasible in concept, except that in this case the front and rear of the capsule are packed with machinery. The front has a large turbine, and the rear has exhaust, intercoolers, steam outlets, etc. So we’re talking about a complete re-design of the capsule.
A simpler way would be to simply have a removable hatch. The train stops, a little crane comes over and hooks onto the hatch, the safety latches are disengaged and the entire hatch is lifted off the capsule. It’d be lighter and safer than doors.
Well, what if it was the front and bottom of the capsule that were packed with machinery? The people-carrying part could be above it all. There has to be some kind of underfloor piping and stuff anyways, right?
Because terrorism is a vastly overrated problem? Most of the existing measures are just security theater, and the reason we don’t have stuff exploding all over the place is because there are hardly any terrorists and almost all of them are incompetent. To the extent that anti-terrorism efforts work, it’s because of ordinary police work, not measures like the TSA or giant fences or whatever.
The only thing the TSA has accomplished is to create a new target (a densely packed group of hundreds of people).
A shaped charge in a big moving truck in the right hand lane would be enough to do serious damage to a suspension bridge cable, if not slice through completely.
You have two minutes: the logical thing to do is to have a carrier unit with the machinery that takes a passenger capsule cylinder – a crane or other device just swaps capsules in short order so that the carrier can be sent along its way before the next one arrives, allowing the passengers to board/exit at a pace not hastened by the arrival of the next one (helping maintain ADA compliance).
That’s exactly what I am saying. With high speed rail, someone could silently rig a bridge to blow or install a derailment rig, and an entire train that can have hundreds of people would have no warning. A derailment setup is a small object that is probably impossible to see in time before the train hits it.
With this tube setup, the moment an explosive charge blows or a .50 bullet hits the tube, you’ll be able to see the damage automatically as a rise in pressure. It’s reasonable to assume this tube system would have pressure and other sensors at extremely frequent intervals.
Automated firmware could respond to sudden pressure changes by ordering an emergency stop for all tube cars. This would limit the lost lives to 1-2 carloads at most, which is much better than an entire high speed train full.
Also, a 0.50 bullet hole would absolutely NOT raise the pressure enough to matter. Even many such holes.
You need something in the front and back to move the air. But sure, maybe you could do it. My only point was that such an idea requires a complete re-design. It’s also not the solution I would pick - it’s not the simplest solution. Just design a better hatch.
I actually agree with you. When you look at all the soft targets that are available in any modern country, two conclusions can be drawn: 1) you can’t protect them all, and 2) if none of them have been attacked in the last 10 years, there’s something wrong in terror land. Either these guys are completely incompetent, or there aren’t that many of them that have the resources to pull this stuff off, or the government is really, really good at shutting them down. The last point makes me giggle in disbelief, so the only conclusion is that the problem of domestic terror is over-hyped.
I wasn’t thinking of depressurization - more like screwing up one of the hundreds of expansion joints, causing a serious structural failure. Of course you’re right - compared to the volume of the evacuated tube, whatever could escape through a 50 cal hole would be miniscule - almost undetectable.
IMHO, this whole scheme relies on a never ending supply of people willing to seal themselves in claustrophobia inducing capsules in order to save a few minutes of travel time. That’s where it would fail, even if the technological bugs were worked out.
As I’ve found, this pont has been consistently ignored with this thread. It has become an engineering discussion, not a discussion on the liklihood of the tube becoming reality.
No, of course we don’t know whether this will ever become a reality.
There’s lots of things that could be done to mitigate the claustrophobia issue, easiest of which is keeping regular bus/train/airline service going until we in fact confirm that enough people want to ride this thing. Sure, that’s a chicken-and-egg problem, yet we often find a way to solve those.
For the claustrophobia, my quick idea is simply to provide each seat with a simple map showing travel progress and time of arrival. More than that, it shouldn’t be too difficult to provide screens with virtual windows, a real-time video of the view outside the tube.
No, nothing will satisfy everyone. It’s only got to satisfy enough people, exact number now unavailable.
Suppose you do shoot a bullet into the tube though- what happens?
Will it just ricochet along the inside of the tube until it hits a train? The tube is polished steel and there’s almost no air.
That’s a good question. I don’t have an answer. There are lots of other questions I don’t have answers for either - such as whether the air flow will have resonances and standing waves, whether the volumetric change due to expansion will affect air flow in the tube, whether the movement of the cars will cause pressure waves, etc. That’s where small scale models, wind tunnel tests and other techniques will be required to actually prove out the concept.
A reasonable question. Musk thinks he’s conquered the claustrophobia problem with video screens. I’m not convinced of that. I’d like to see actual experiments where people are sealed in tight spaces with video screens looking out, vs people who have windows, vs people with neither, and see just how much of the claustrophobic effect can be reduced with fake windows. I honestly don’t know whether this is a serious issue or not. People readily get into elevators, some of which can be quite small and ride for some time. They can get stuck between floors too.
You’re right. Is it not catastrophic, though? to Chronos’s point, if you hit a stream of air going 700mph, what happens? What does it do to the impeller in the front? Would you feel it as a pulse in the cabin? A vibration?
But if I wanted to damage this thing, I wouldn’t just shoot a random hole into the pressure vessel - I’d shoot upwards into the bottom, hoping to deform the track. A 50 cal can leave a lot of bent metal in its wake. We might have to add armor plating for the bottom of the tube to the list of extra costs.
Am I right in thinking that the air rushing in through a bullet hole would cool due to expansion?
Because a sudden temperature change combined with a pressure change could be a Big Deal.
It’s not just the air friction that would stop it Bullet’s collision with the wall is not a perfectly elastic collision. See Coefficient of restitution - Wikipedia
You also wouldn’t just have to worry about terrorism per se. I would expect that the same folks who routinely shoot up road signs (“redneck braille”) might also do the same with the tubes-- Not out of a desire to cause mayhem, but just from boredom and drunkenness.
There’s a Bond flick where someone is spirited out of an Eastern Bloc country through a tube in a coffin- like capsule. That’s what this reminds me of.
There are still engineering problems to solve before it becomes reality.
The reason we haven’t discussed issues like claustrophobia is because no one here seems to be an expert in vehicular psychology. It would be nice if someone was.
At any rate, I’m not seeing a huge problem. People fly in smaller, more cramped aircraft all the time. The only difference is that the plane has tiny windows that don’t look forward, and not much field of view. Sometimes they’re blocked by an engine, missing, or just closed. In larger aircraft, many people can’t see a window at all.
But the plane has vibration and turbulence and other weird accelerations, while the Hypertube does not. Windows sometimes help with motion sickness, but it’s better if the ride is smooth enough that it’s not a problem in the first place.
It’s not like the capsule is coffin size. There’s significantly more width and legroom than a typical airline seat. There’s room to stretch your arms and legs, even if you can’t get up.
I suspect that, as with planes, a small percentage of the population will be unable to use it, and they can continue to use cars or trains.
One way to address the heat expansion issue as well as the “redneck braille” issue would be a double-walled tube with a layer of moving air between the walls, to maintain a consistent temperature for the inner tube, that might also prevent penetration by random objects. It seems to me that part of the issue with thermal expansion would be that the tube would not be a uniform temperature from one end to the other. And anyway, if you have a series electromagnet drive system capable of accelerating 16 tons to 800mph, you would probably need to actively cool those coils, so, one way or the other, you need an active cooling system.
Personally, I find hyperloop a pretty absurd, impractical idea. What would make more sense would be a 100mph train/monorail that could effect milk-runs without stopping (swap cars on the fly). That would surely be faster, more efficient and more desirable that traditional stop/start rail travel and could serve a much wider customer base.
But the technical discussion of hyperloop is interesting.
Bullet’s collision with the wall is not a perfectly elastic collision. See