Center seat of an L1011 is far from a window, and to me feels claustrophobic.
For values of 4 which are almost equal to five?
I will always remember today as the first and last time I heard about this project.
Did you read the sentences before that one? It’s 2x2.44 which 4.88 which is pretty close to 5. Yes, “double the material” wasn’t as accurate, but “double the material (plus .44)” seemed unnecessarily pedantic.
Actually I was thinking, “yeah, that’s California alright…”
Yeah–L1011, 747, A380, others–in pretty much all widebody aircraft you have 3 or 4 people and an aisle between you and the nearest window if you’re in the center.
I’m not claustrophobic, but I see a slight difference between the center seat of a 20 ft wide 747 cabin and a 4ft wide steel tube that you absolutely… cannot… get… out… of.
That’s not what I’m saying.
What I’m saying is “We solved <one minor aspect of the engineering problem, that shouldn’t be much different for a tunnel underwater than through a mountain> successfully in many tunnels through mountains, so it seems reasonable to think we could probably fairly easily solve it for the Chunnel, too.”
Good point about the zig-zags; pipelines are certainly more flexible overall in their layout that the hyperloop. But pipelines do go through constrained spaces, too (bridges, urban corridors, routes along train tracks, etc.).
Your other points don’t make as much sense, though. Of course you don’t run a vacuum in oil or gas pipelines, you run positive pressure. Thing is, the positive pressure is going to be more than one atmosphere in general (quick google shows long distance natural gas lines at up to 100 atmospheres of pressure), so keeping things gas-tight is actually a much harder problem for a gas pipeline; I’d expect the pressure inside an oil pipeline to be higher than 1 atm, as well. And, I think on the scale of dangerous things, a one-inch hole in a large high-pressure natural gas line is probably far worse than a one-inch hole in the hyperloop.
Look, I’m not saying there are no criticisms of the hyperloop. Again, the assumptions on ridership are so ridiculous it’s not worth looking any farther at the economics. There are certainly engineering issues too. I just think there is a fair amount of expertise in the world on thermal expansion in pipelines, and there doesn’t appear to be any of that expertise on the boards right now, so it seems silly for us to confidently say that thermal expansion is an unsolvable problem when we do know it can be solved in similar, though not identical, applications.
Quercus:
The stuff which goes through a pipeline is a fluid–either a gas or a liquid. It can easily go through a slightly different shaped pipeline. Fluids are very flexible.
The vehicle which travels through a Hyperloop is a solid, which is not flexible at at. And note the extremely limited space between the vehicle and the Hyperloop.
Think about this!
Dangerous for who? A 1-inch hole (or really any size hole) in a nat gas pipe? Isolate the section, deal with the outcome. Maybe a big explosion, maybe not.
2.44in hole in a mostly vacuum tube carrying people? Maybe some people dead, 1000+ passengers crash-stopped in a 4-ft box with no food, no water, and NO AIR (until the recompression wave hits them in which case they may have too much air) potentially 300+ miles from their destination. Okay, so include emergency exits - whoops not in the original estimates! There are literally thousands of issues like this - all of which are known for pipelines, but not for hyperloops.
Damn you, edit limit!!!
Holy shit. My wife just asked me why I was spending time on this and it hit me what Musk is REALLY doing here!
He’s crowd-sourcing (or open-sourcing) a major civil engineering project! So:
Musk1: Jeez, I can’t believe the voters passed that thing. You can’t build high-speed rail between here and there for that price?
Musk2: Well, what could you build for that price?
Musk1: No idea. And, shit, it would cost a friggin’ fortune to do all the analysis and feasibility studies and what not. Plus there might not BE a solution. In which, money down the toilet…
Musk2: Maybe not. What if we find some idea that’s JUST close enough and put it out for “free”?
Musk1: Holy shit! Thousands or millions of people will tear it apart. But, then they’ll put it back together! Better, stronger, cheaper!
Musk2: Right! And some of those people will be civil engineers, or aeronautical engineers, or mechanical engineers. And we get their services for free!
Musk1: And then when the answer is close to feasible (assuming there IS an answer), we step in and announce…
Musk2: That we are magnanimously willing to take on the project for a lower cost.
Musk1: And if there is no answer, we’re out for the cost of a press release!
Musk2: To the Web! We need to find a suitably plausible old idea!
Fucking brilliant. I truly mean that. I am seriously impressed.
To start with, the tube is not a hard vacuum, though the difference is kind of trivial. Musk suggests multiple pumping stations, which might ultimately mean that there would be constant evacuation going on, drawing a small amount of air through small filtered gaps at the expansion seams (I think this would create a pressure gradient, with the thinnest air in the center of the tube and a denser layer at the periphery, for the bearing skids). Being aware of the possibility of a catastrophic breach (engineers sometimes consider such things), the entire tube is heavily decorated with sensors capable of detecting the onset of a breach in a microsecond time frame, so the air evacuation system would be able to react to a breach even before a hole has been made, flooding air into the section as the problem is occuring – it would still be pretty disastrous, but the whole system would be responding even as the breach was in progress. At 800 mph, with lots of humans involved, the hyperloop has to be designed to fail gracefully. Then, with an impassible tube, the drive coils can be used to slowly pull the capsules to the accessible terminals away from the breach (because, if the system is designed so that a breach renders the capsules immobile, it should just not be built).
I think that the previously claimed average trips per person for the cities is a totally misleading statistic. LA’s 3.1m and SF’s 800k populations indeed equate to ~3 trips per person per year. However considering the greater metropolitan areas of 18.1m and 8.4m gives an average of 0.55 trips per person per year.
Also, in page 6 of the pdf it explicitly mentions that the average capsule departure interval is 2 minutes, as often as 30 seconds during rush hour, and slower at night (duh, seriously?). Maintenance would take place like it does today on freeways and subways, at night (another duh). There could be a niche to be filled with the drunk party crowd on weekends, but weekday nights are open for maintenance.
One other factor that might alleviate concerns about ridership during rush hour is to build capsules of different capacity. There are after all a projected 40 capsules to be built. Some of these might be stretch models that could fit 50 people, for example.
Lastly I would like to mention that it is not feasible to take a magical price-doubler wand and wave it all over the place willy nilly with no facts to back it up. Raw material and component prices are available on the open market and are known quantities, labor and construction costs are a larger variable, but it can be realistically estimated to +/- 25%. And it bears repeating that real estate prices would be vastly cheaper than a traditional rail line, since the tube would go between the median of the I-5, something that a traditional high-speed train can’t do for an affordable price. The real-estate costs within populated areas would be similar between a hyper loop and a high-speed rail line, or even lower, since there would be no need for ground-level crossings, etc.
I think it’s pretty obvious that the answer is a distributed pump/blowout-valve system that quickly re-pressurizes the entire system within seconds of an accident happening. I mean… wouldn’t this be the natural no-nonsense solution? :dubious:
No. Read the PDF, page 6.
Care to answer Post #198 which deals with a direct comparison to a pipeline (albeit oil) built relatively recently? One that was build out of similar raw materials no less (at least the pipeline was also steel). Not sure why you’re so invested in this, but it ain’t gonna get built anytime soon and even Musk isn’t saying it is. It’s a thought experiment, a trial balloon. I’m personally convinced that I interpreted his thinking in my last post. He’s hoping this will spur discussion (and kudos to the poster who mentioned that all the way back on Page 1 IIRC) nothing more, nothing less.
Tell you what, I’ll bet you $1,000 right now that a HyperLoop is not built between LA and SF anytime in the next 10 years. Hell, I’ll bet one is not even STARTED in the next 10 years. Do we have a bet?
Wait sorry, I missed this:
Then how are they going to leave every 30 seconds? That’s a gap of less than 6 miles between capsules meaning more than 60 would be needed just to fill one tube going in one direction.
The cost of the Keystone pipeline is a good starting point, but you have to consider some specific costs of it do not apply to the hyper loop tube structure. First, the Keystone pipeline costs include the 39 pumping stations required to keep 830000 barrels of crude flowing through everyday. Second, crude pipelines require more expensive grades of steel to sustain corrosive chemical action. In my math, creating a hyper loop double tube out of 1-in plate at a wholesale price of $.20/lb is $1800000 per mile. Compare this raw material cost with about a $1/lb if you were buying a single plate, and 0.06/lbs if you were buying wholesale at the London Metal Exchange. I suppose the final price is dependent on the negotiated price between the project managers and dozens of steel mills, but I believe .20/lb is reasonable for a project of this magnitude. These plates would then be rolled and welded with a friction stir welding machine, which goes for no more than $5000000 (a Canadian company owns the copyright to this industrial process and manufactures these machines, I forget the name).
Clarifying the point about rush hour traffic, it is short lived, and it need not be sustained for hours on end (at least, from the preliminary estimated usage). And if 40 capsules are not enough, then build 80, or build them longer.
And finally, I don’t know why it bothers you that I’m “invested” in this. First of all, I’m a resident of CA so color me biased. This is, however GQ, so I’m going to do my part to fight ignorance, especially with all the low-lying fruit put out there as apparent show stoppers.
First, you start with a price for a steel billet futures contract and just assume that’s the wholesale price for actual delivery. Second, steel billet is REBAR. Are you really going to build your high-tolerance, polished steel tube out of rebar? Probably not. So, you’ll need a higher grade of steel rolled into plates which can then be rolled into tubes and welded. Can you buy steel plate 100ft long and approx. 88 inches wide? Don’t know, but most of it I’ve seen is around 20ft long (width wouldn’t be a problem).
Are you going to do that on-site? Probably not, so now you need someone to get the steel, store it, roll it, weld it (can your 5M machine handle items that big?) into tubes, then weld the tubes into 100ft sections, and then deliver those sections (which require special transport - or you can keep them shorter, but now you have to weld on-site) along a 350m construction route (conveniently near an interstate). Speaking of which, you’re also going to be dealing with interstate lane closures, rerouting, traffic control, etc. Don’t see estimates for that in there anywhere.
This is the kind of stuff I’m talking about. You complain that we put numbers on things without justification, but then you take a price for cheap unfinished steel bar, decide that a 3x price increase “is reasonable” and then magically get it delivered to somewhere. Hell, you don’t even know (nor does Musk) what KIND of steel you want to use.
Great! Make sure to add that to your cost!
What bothers me is that you seem utterly willing to just assume it’s all going to work out when people with engineering and/or large construction experience are all saying the cost estimates are extremely understated. Not to mention the HUGE number of engineering challenges that still have to be overcome. Hand waving all of those things is promoting ignorance, not fighting it.
Look. It’s a really cool idea. I get it. You guys need some sort of solution. I get it. But this is NOT it. It may form the basis for A solution, but this is (to quote someone above - or in the other thread) a cover story for Popular Mechanics, not a serious, well-considered proposal.
Tube sections will be the size of single-wide modular homes. You can move them on the freeway, more or less, but it’s not cheap.
Delivering 350,000 pipe sections will cost billions separately from the money spent to buy and fabricate the materials.
And really, you need more land. A buffer zone around each pylon to ward off car bombs.
Taking out a pylon doesn’t kill many people, but it inconveniences millions and costs a fortune in lost revenue to the cities.
In my experience, most metro/underground systems do not run at less than 3 minute intervals for safety reasons. And this is with a train that can stop just before reaching a station and wait 30 seconds, if needed. Is there an example of a train that runs in 30 second intervals? Or even 2 minute intervals?
If the sections are 100ft long, a hyperloop of 350 miles would need 36,960 of them (18,480 in each of 2 tubes). Which is still going to be seriously expensive, but not as bad as 350,000.
Why would this (which would certainly add dramatically to the cost) be needed for a hyperloop any more than for high-speed rail, or other forms of transportation? A would-be bomber could do a fine job inside an existing tunnel or on a large bridge.
And if you propose to exclude all cars from car-bomb range, you really can’t have roads that cross the hyperloop anywhere along its length. You’ll also need to exclude all people, as a precaution against backpack bombs.