171–180 of 322 posts
3.5 years on my prediction holds well: https://news.ycombinator.com/item?id=13811365
Technically it might qualify as a hyperloop so your prediction may already be wrong.
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Three words: vacuum expansion seals.
There are multiple ways to solve this problem. It’s not a showstopper. 1) Bury the lines. Basically isothermal at depth. 2) insulate the tube and maintain stable temperature 3) use materials that don’t drastically change length with temperature 3) allow the tubes to change length. Put them on rollers. 4) use vacuum expansion joints just like us common in vacuum engineering. People act like vacuum is this new thing. P…
2) Kaa-ching! Both upfront and ongoing.
3) Kaa-ching! There is reason materials such as Invar are not found in railways, and cost is only one of them.
4) There is no precedent to using vacuum seals at that scale (or maintaining vacuum in that sort of volume).
Elon Musk just says "let it be suspended on roller supports so the terminals slide dozens of meters". Nothing wrong with that surely.
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Say what? That’s crazy talk. Underground would be many times more expensive, and has much worse failure modes. What happens if the train loses power?
Didn't Musk's "Boring Company" solve the problem of underground boring cost ?
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There are multiple ways to solve this problem. It’s not a showstopper. 1) Bury the lines. Basically isothermal at depth. 2) insulate the tube and maintain stable temperature 3) use materials that don’t drastically change length with temperature 3) allow the tubes to change length. Put them on rollers. 4) use vacuum expansion joints just like us common in vacuum engineering. People act like vacuum is this new thing. P…
Good point. A little hyperloop is nothing compared with CERN.
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That "Gadgetbahn" article is great, but I do have one criticism. From the article: "If the idea is viable and the people behind it are competent, it should have attracted private investment, as there should be a potential to make profit selling the technology. After all, the proposal has been around for 23 years." High speed rail on a large scale is really something that has to come from the government. While there a…
Since this is getting to be a bit popular, I'm going to push the "technology really doesn't matter" point a bit more here: in 1955 the French built this [0] (just look at the picture!) and sent it down a traditional (wooden sleepers, rocks for ballast) rail line between Bordeaux and Irun [1]. It got up to 333 km/h, which is faster than any TGV currently operates in the year 2020 on their fancy concrete HSR tracks. [0…
For comparison, a tgv test run in 2007 got up to 575km/h on fancy new track, also with some prep but no damage, but operating at this speed would make little economic sense at this point.
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> the TGV is also profitable Correct me if I’m wrong, but my impression is that this is only true if one excludes the capital costs associated with the railroad (tracks, right of way, and I think also rolling stock). If you factor in the infrastructure construction costs (and reasonable lifetimes for replacing rolling stock), a high speed trail line will never be profitable without significantly higher fare prices th…
Public transit is almost always unprofitable without some way of capturing the increased land value near the stations. Supposedly some subways (eg Hong Kong?) own the land near the stations and use the rents to fund the subway, rather than just using fares. A land value tax that goes back into public transit would probably work too.
The Dubai hyperloop project is supposedly proceeding. The 10km test track was supposed to open this year. Can't find any info later than January 2020. The Dubai to Abu Dhabi link is the ideal case. The route is mostly flat, open desert. Funding is available. There is government support. There's considerable traffic between those points. If that doesn't work, not much else will.
If built, it would compete directly with Etihad Rail, which is building a regular rail network throughout the entire UAE and already has its first phase operational: https://en.wikipedia.org/wiki/Etihad_Rail This focuses primarily on cargo, but is built with passenger trains at up to 200 km/h in mind. And most Hyperloop business plans also seem to rely heavily on freight.
This is a total contrast to "hyperloops". It does a useful but boring job with useful but boring technology.
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> the TGV is also profitable Correct me if I’m wrong, but my impression is that this is only true if one excludes the capital costs associated with the railroad (tracks, right of way, and I think also rolling stock). If you factor in the infrastructure construction costs (and reasonable lifetimes for replacing rolling stock), a high speed trail line will never be profitable without significantly higher fare prices th…
Public transit is almost always unprofitable without some way of capturing the increased land value near the stations. Supposedly some subways (eg Hong Kong?) own the land near the stations and use the rents to fund the subway, rather than just using fares. A land value tax that goes back into public transit would probably work too.
Here's one, just follow the links to the group companies.
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>The problems with building this have nothing to do with technology but with right-of-way, investment, and politics. If those factors were solved, we'd already have high-speed rail in places where Hyperloop has been proposed. The fact that we don't says that Hyperloop is unlikely to be feasible as well. I disagree with your conclusion. Hyperloop technology is so lucrative that it might galvanize America to update its…
> - 2-3x speed of bullet trains. Can change the way we perceive geographic distance. > - Cost isn't as much of a concern because a national hyperloop network would create a lot more value than a bullet train equivalent. High speed brings with it some pretty severe problems. The most well-known is curve geometry: curve radii scale with the square of velocity. Transition track (how long the "S" of a S bend needs to be)…
As for the curvature issue, there seem to be a couple ways around that. One is to straighten the route to the maximum extent possible (not trivial but not impossible for some routes). The other is to build massive curves and decelerate into them. Again, there are tradeoffs (cost,speed) but it's not impossible. There are just so many variables. A hyperloop could end up being great for some areas and unworkable in others.
Lastly, right of way/land clearance should never be a key constraint. That won't stop us if we really want to build a hyperloop.
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Not if it’s underground. You can get the right of way much cheaper depending on what’s on top.
Ok, so how is this cheaper than high-speed rail in a tunnel? It seems to me that hyperloop is high speed rail with the addition of a vacuum, which gets you higher speed. The additional requirement of a giant vacuum tube should make the system cost more, not less. Personally, I’m rooting for Elon Musk to figure out how to make tunnels cheaply with the Boring Company, so we can take that tech and use it to build a bunc…
A large amount of cost is in the stations.
In the us, a large amount of cost is inefficiency, projects cost much more than elsewhere, even considering purchasing power parities. Alon levy has written and talked about it extensively, e.g. https://pedestrianobservations.com/2019/03/03/why-american-c...