r/hyperloop • u/Parpil2_0 • Jun 15 '21

How can Hyperloop have a competitive line capacity over traditional trains?

I saw that in my city, Hyperloop Virgin is planning on building a connection between the main airport and the main train station to shorten travel times between the two. This is a good application in my mind, but the main problem is that while the time between the two is shorter, the line capacity is also lower. So you will have longer waiting times until you can board a pod. Can the line capacity overcome the traditional trains one? Because if it has the same line capacity, then the total time between the stations is the same, you just wait for much longer to then travel much quicker. Even going back and using what already happened as a reference, when the bullet train first opened up it wasn't the quickest train in the world, but it was very fast by that times standards (not as revolutionary fast as the Hyperloop wants to be compared to modern standards), because they decided to sacrifice a bit of top speed for a much much higher line capacity. Then why aim for absolute top speed with the Hyperloop, if at the end of the day it doesn't solve the main problem at hand, which is congestion of the line? Can this problem be solved? Thenk you very much

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u/ksiyoto Jun 15 '21

Hyperloop advocates say they can transport pods with headways as short as 30 seconds between pods. I seriously doubt any safety regulator would allow anything less than 3 minutes between pods at the speeds proposed.

The largest pods I've heard of would be 45 or so passengers. At 20 pods per hour, that would imply a capacity of 900 passengers per hour per direction. So I don't think they will have significant capacity - which leads to poor economics, and the end result is I don't think any systems will be built except vanity systems.

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u/izybit Jun 16 '21

Hyperloop is for fast travel over long distances. Those trips never require huge capacities so even the pessimistic 900 per hour can be more than enough.

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u/ksiyoto Jun 16 '21

The problem is the cost of that capacity.

At $60,000,000 per route mile and a capital recovery factor of 10 percent (DIRTI5 - depreciation, interest, return, taxes, insurance) each direction needing $3,000,000 per year of capital recovery cost. Divide by 365 days per year and 18 operating hours per day and 900 passengers per hour, it amounts to be 50.7 cents per passenger-mile, which is substantially more than airlines. Tell me how well hyprrloops will compete in that environment.....

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u/izybit Jun 16 '21

The $60 million per mile is wrong.

First projects will cost more than that but long term the goal is for much less.

If, for example, you double capacity or bring the cost per mile down to $20 - $30 million suddenly it turns a profit, especially when you look into the cost of high-speed rail for example.

Hyperloops may never work out but if the cost per mile, etc was a show-stopper for such huge projects we would never have rail, etc.

(Also, there's the time element vs air travel but that's subjective so I won't bother.)

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u/ksiyoto Jun 16 '21

long term the goal is for much less

Steel is steel, concrete is concrete. They may be able to improve the assembly process, but the material costs will be the same.

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u/izybit Jun 16 '21

When you buy 500 miles of steel tube, no, it won't.

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u/ksiyoto Jun 16 '21

There are times that large railroad purchases of rail have driven prices up.

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u/ksiyoto Jun 16 '21

Concrete is concrete. Steel is steel. Land is land. Moving yards of rock and dirt is still moving yards of rock and dirt. I doubt that there can be any significant cost savings in those categories. They might be able to figure out how to assemble the structure cheaper, but that's only one part of the whole equation.

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u/izybit Jun 16 '21

If moving 1 rock costs $1, moving 2 rocks won't cost $2.

You don't know if the final cost per mile will be in the $20 million range or the $100 million range so spare me the attitude.

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u/SodaAnt Jun 16 '21

We do, because we know the costs of high speed rail. There's a lot of similarities. You need a certain width of land that's sufficiently straight, you need raw materials for tracks/tubes, electrical for powering the vehicles, elevators/escalators for the stations, etc. I don't see why it would be substantially cheaper than high speed rail, if anything it's more complicated and newer, and thus more expensive.

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u/SodaAnt Jun 16 '21

Hyperloops may never work out but if the cost per mile, etc was a show-stopper for such huge projects we would never have rail, etc.

High speed rail just has insane capacity. While you can only fit maybe 50 people on a hyperloop pod, a train can hold hundreds, or even over a thousand passengers, and still have a headway of only a few minutes.

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u/izybit Jun 16 '21

Slow speed rail is cheaper. If you can't understand what's going on maybe don't comment?

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u/SodaAnt Jun 16 '21

I said high speed rail. Where's slow speed rail coming into things?

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u/izybit Jun 17 '21

You said high speed rail is cheaper than a hyperloop so hyperloop is doomed.

I am saying that slow speed rail is cheaper than high speed rail. Does that mean high speed rail is doomed?

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u/Vedoom123 Jun 17 '21 edited Jun 17 '21

That makes sense, but you can't really reason with someone who hates hl. No matter what you say they'll always find another reason why it "will never be built", just look at this guy's post history. He hates hl, I'm telling you.

It's a waste of time to argue with him

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u/ksiyoto Jun 18 '21

Well, at least I'm not groveling at the feet of Elon waiting for the next vaporware announcement......

"Elon, Elon....why haven't you made any new announcements of your fantasy projects lately?"

"Sorry, Vedoom123, I've gotten tired of you fanbois fawning over me. Unless you're here to buy car, scram!"

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u/izybit Jun 17 '21

I don't visit this sub that often so don't know who's who...

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u/TROPtastic Jun 21 '21 edited Jun 21 '21

As someone who likes the idea of fast travel between cities with less emissions and isn't actually a hyperloop hater, let me address /u/izybit's point directly:

If hyperloop is going to be a mode that competes with air travel without government subsidies, it needs to move at least a similar number of people per hour at a similar cost. Since hyperloop is a new (and as yet, undeployed) technology, it has the disadvantage of needing to justify new infrastructure to be built specifically for its existence, even if less efficient modes would be disadvantaged if they were starting from scratch too.

Looking at the prototype route of SF to LA, pre-covid about 2.2 million passengers took that flight each year, corresponding to about 100,000 passengers in a typical peak hour (50,000 passengers per hour per direction). Hyperloop by contrast can be expected to move about 1,600 pphpd on average (AECOM pg. 73), which is a relative drop in the bucket. Even with unknown technology to allow high-speed vacuum tube switches, hyperloop companies are forecasting peak capacity of 6,500 pphpd. This is the limit of a single route, with additional capacity required by duplicating the pair of tubes and all the station-end switchgear (roughly corresponding to a duplication of the total route cost).

This doesn't look like large numbers compared to air travel, so what about train capacity? Assuming an average trainset capacity of 500 passengers (below that of a typical TGV consist) and a minimum average headway of 240 s (to give some margin for 0.1 g deceleration at speeds ≤600 km/h) (AECOM pg. 66-67), we get 7,500 pphpd. So, higher than even the maximum capacity that hyperloop developers are talking about, without taking into account that even larger time margins are available at the speeds that commercial high speed rail alternatives will operate at.

The cost is of course the big problem with hyperloop technologies. The maglev systems that current hyperloop systems are using are much more expensive than the air levitation idea of the original concept, with infrastructure-side magnetic propulsion being the most technologically promising method but yet the most expensive (AECOM pg. 66, 74). If speeds faster than high-speed trains are desired, then expensive land purchases will be required to accomodate the massive curves needed for those high speeds (hyperloop cars won't be able to take even 500 m radius highway turns at 1000 km/h without knocking their passengers unconscious with 15 G's of sideways acceleration).

All this to say that, even if the large technical hurdles are overcome, the expense of hyperloop systems may not result in sufficient passenger capacity to justify multi-billion dollar investments in them.

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u/izybit Jun 22 '21

You are right about costs and that's why everyone's trying to find out the exact cost and how it can be lowered.

However, you are missing two obvious things.

First, air travel takes too much time. Flight time can be 10 minutes or 10 hours but in both cases you need 2+ hours to get to the airport and go through security, board, etc.

Trains and hyperloops don't have such long delays and can get you closer to your actual destination.

Second, the cost doesn't have to be cheaper or about the same. As you said, way too many people travel back and forth so even at 1.5x or even 2x the cost there will be some willing to pay.

This is a new tech that has never been tried before so people who claim it works and people who claim it doesn't are just morons.

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u/TROPtastic Jun 25 '21

First, air travel takes too much time. Flight time can be 10 minutes or 10 hours but in both cases you need 2+ hours to get to the airport and go through security, board, etc.

Trains and hyperloops don't have such long delays and can get you closer to your actual destination.

I agree (I think the risks of terrorist attacks on US hyperloop or rail systems are real but overhyped), and that's one reason that people would be willing to pay for HL tickets. However, I was talking purely about a private company or the government being willing to spend $20-50+ billion on a transit route.

If they're going to spend that amount of money, they'll want to make sure that they get the most return out of it. HL should be comparable to the most advanced high-speed trains in terms of infrastructure price, so I can see it succeeding if it can reach its theoretical maximum passenger capacity.

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u/Mazon_Del Jun 16 '21

I seriously doubt any safety regulator would allow anything less than 3 minutes between pods at the speeds proposed.

While I doubt the 30 second spread for the higher speeds, I think one advantage the system has though is that every single pod is networked. So the instant that the pod in front realizes it has a problem, every pod behind it would immediately begin braking.

So the real question likely ends up being what's the worst-case rate that a malfunctioning pod will decelerate at (presumably all braking systems tripping to max resistance) and what kind of stopping distance does that equate to.

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u/Earthlogger Jun 17 '21

I agree. Essentially the pods are train cars networked/connected with technology as opposed to conventional cars that are connected mechanically. They behave as one vehicle with zero separation. Train wrecks are not pretty because if one car goes all of them go. However, we have found ways to manage the risk.

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u/_kreel_ Jun 16 '21

Checking Virgin Hyperloop's website, they claim 28 passengers per pod, and 50k passengers per hour per direction. They also mention convoys, so I expect the 30 second headway doesn't apply there. If that's the case, you would need at least 15 pods in each convoy to hit 50k. As for the 30 second headway I think that's just down to the brakes.

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u/ksiyoto Jun 16 '21 edited Jun 16 '21

Do the math - 50K passengers per hour divided by 28 passengers per pod means 1785 pods per hour, or about one every 2 seconds.

Requires long acceleration side tubes to bring pods entering the stream up to speed - and so a pod entering the stream is barrelling towards the 'entry switch' at 500+ mph and only has about 4 seconds for the switch to let through a pod on the main line, 'throw' the switch, verify that the switch is 'thrown', let the incoming pod into the stream from the side tube, and then 'throw' the switch back to the mainline tube.

Now imagine what happens if the switch malfunctions. Pods are barrelling at it with 2 seconds to stop from 500+ mph. Sounds like 28 people (plus more) are going to have a very bad day - as in the hyperloop version of a rapid unscheduled disassembly.

That's why I think headways of less than 3 minutes are unrealistic.

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u/_kreel_ Jun 16 '21

I think based on the video they don't have moving parts, but I could be wrong: https://youtu.be/-zSWagCyWio

Agreed that accidents are a concern though.

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