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Transport Expert Insists 'Don't Dismiss Wacky Hyperloop'
DavidGilbert99 writes "Since Elon Musk announced the details of Hyperloop earlier this week, we've seen a number of experts debunking the technology involved, but at least one is more upbeat about the possibility of 600MPH train travel. Speaking to Alistair Charlton at IBTimes UK, professor Phil Blythe from the Institute of Engineering and Technology said: 'My gut feeling is, don't dismiss it out of hand just because it sounds a bit wacky,' adding 'You're always going to have long distance travel, and if there was something that could replace air travel between cities and hubs, and is low carbon [with] low energy requirements, it make sense to explore it, it really does.'"
A quick look at the freeways between LA and SF shows that they are mostly straight, with only very minor turns occasionally. A quick look shows that there's only two places where the route curves more tightly than the 14km radius turn required to keep under 1g acceleration at 800mph. Both of these locations are close to the end points, where the thing would still be under acceleration anyway, and if you really wanted to run at 800mph through them, there are 14km radius turns available in the area.
An actual transit engineer crunches the numbers here:
http://greatergreaterwashington.org/post/19848/musks-hyperloop-math-doesnt-add-up/
And finds that while the journey for individuals may be faster, the system as a whole would have one-tenth the capacity (i.e., the ability to move people in numbers) than the planned high-speed rail system. You could solve this problem by building 10 times as many tubes, of course, but that would eliminate the 90% cost savings Musk is touting.
The radically reduced travel times vs. HSR are also deceiving. The maps Musk released show the system travelling from the fringes of the Bay Area to the fringes of the LA area, because it's hard/expensive/impossible to get land for the straightaways you'd need for the project within densely built up urban areas. To get from San Francisco to the hyperloop station, or from the hyperloop station to downtown LA, you'd have to switch to local transit or drive, which will double or triple travel time. Not coincidentally, must of the construction and expense that adds to HSR's very high price tag will come in SF and LA urban areas, since that system goes from downtown to downtown.
Uh. nope. The passenger-only capsule is 15,000kg and the passenger+vehicle is 26,000kg. The only number close to 3,500lbs in the documents is the 3,500kg weight of the capsule external structure.
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Why not just look at Elon's PDF, which already has a map with all the radius circles drawn on it?
What do you crash into? There is a big difference between a head-on collision, and merely a slide along the tube without air cushioning. When you're in a tube, the only other thing you can crash into is another train that goes the same way (or has stopped). Since there's no on-board propulsion, there's no scenario in which a train can propulsively overtake and hit a train in the front. It can only happen if the train in the front brakes, and somehow this doesn't get the trains behind it to stop. Very, very unlikely. The braking systems would be entirely passive, so basically if you blow the fuses on all the on-board batteries, the thing mechanically brakes an in entirely passive fashion. Also, for the trains to stay unbraked, they must be in constant communications with the control center. Presumably if the communications are lost for more than a 100ms, the brakes come out.
Oh, and they are not stupid, they did plan the route in detail, with bend radii and speed profiles all included.
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