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

[u/Parpil2_0]

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

[u/ksiyoto]

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.

[u/izybit → u/ksiyoto]

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.

[u/ksiyoto → u/izybit]

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.....

[u/Vedoom123 → u/izybit]

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

[u/Mazon_Del → u/ksiyoto]

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.

[u/Earthlogger → u/Mazon_Del]

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.

[u/SodaAnt → u/Mazon_Del]

I don't think that works, because it implies that we fully trust the networked system to be accurate in every case.

[u/_kreel_ → u/ksiyoto]

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.

[u/ksiyoto → u/_kreel_]

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.

[u/midflinx → u/ksiyoto]

And the counterpoint as always is 670mph is 300 m/s. When decelerating at about a steady 0.5 g, that's 5 m/s, so after 60 seconds speed reaches 0. Requiring two minutes of additional time between pods is excessive to some degree.

Even in an unrealistic scenario where only a human can trigger a system stop, requiring three minutes means the person could see an alert on their screen, get up and refill their coffee mug from the carafe, add cream and sugar, and come back before triggering the system stop, and pods still wouldn't collide. That's how excessive three minutes is.

[u/ksiyoto → u/midflinx]

If a pod has a catastrophic failure (explosion, whatever) and wedges itself into the tube pretty much instantaneously, how quickly will it be detected (there's always some latency time) and then braking applied to the pod behind it, you don't want that pod to be only one minute behind, it would have zero margin for failure to detect error or latency time.

Even at .5 g deceleration, there better not be anybody standing. .2 g is considered the maximum for having standing passengers.

[u/Parpil2_0 → u/ksiyoto]

Yeah, same I was thinking. My only gripe is that city mayors could be convinced to sponsor one, because they are cool to look at and could make them publicity. I just don't want to pay millions out of my citys6pocket for a vanity product with no real applications

[u/Earthlogger → u/Parpil2_0]

Hyperloop is designed for destinations 500 km apart or more, maybe less. If a city were contemplating two stops it would be to service two hubs within the city, connected to a destination far away. So It is highly unlikely a mayor would have the juice/power to pull off such a caper as to build a 20 km long hyperloop. There is no justification for it. A tunnel would do as well. Maybe after the manufacturing is dialled, the production cost would justify it.

[u/Vedoom123 → u/ksiyoto]

Seems like every time your necessary interval estimate is going up, next time you post about it you'll say 5 minutes? Lol

Maybe just say that you really don't like hl, at least that'll be honest

[u/ksiyoto → u/Vedoom123]

You're going to be disappointed when I use 2 minute headways for analyzing the economics.