Hyperloop - yes or no?

[Edwin_m]

According to Wikipedia the pod is accelerated by coils within the tube, so most of the heat will appear there and can be dissipated to the outside world.  It then continues without propulsion, though presumably would need a booster every now and again and when climbing hills.  Not sure what happens if there is a problem and the pod has to stop somewhere with no coils nearby.  

 

This report for Transport Canada raises the sorts of questions about the technology that I would want to ask: https://tcdocs.ingeniumcanada.org/sites/default/files/2020-08/Hyperloop prelim study.pdf

Edited November 9, 2020 by Edwin_m

[Nick C]

It uses linear induction motors (as Edwin says, coils in the tube), so the things generating heat are principally outside, not in the capsule. Most of the heat generated by a conventional motor/drivetrain comes from friction anyway, which is the main thing the concept is designed to remove.

[Zomboid]

I doubt anyone on here is going to come up with the silver bullet as to why it'll never work (technically) given the information that's in the public domain. If we can think of it, the engineers designing, testing and refining it are going to have found it before they tried putting people in it.

 

I can imagine that it could become part of a future transport system in a specialised fashion, like the various MagLevs around the world, but super high speed is a pretty specialised application - it's not going to replace the district line, but I could imagine a New York to Chicago Hyperloop for example might be of some use.

[Edwin_m]

1 hour ago, Zomboid said:

I can imagine that it could become part of a future transport system in a specialised fashion, like the various MagLevs around the world, but super high speed is a pretty specialised application - it's not going to replace the district line, but I could imagine a New York to Chicago Hyperloop for example might be of some use.

"Various" in this case means "about three".  When you look at the cold numbers there just aren't many places where the technology is anything other than a solution in need of a problem.  

[Christopher125]

On 11/11/2020 at 11:42, Zomboid said:

I doubt anyone on here is going to come up with the silver bullet as to why it'll never work (technically) given the information that's in the public domain. If we can think of it, the engineers designing, testing and refining it are going to have found it before they tried putting people in it.

 

I can imagine that it could become part of a future transport system in a specialised fashion, like the various MagLevs around the world, but super high speed is a pretty specialised application - it's not going to replace the district line, but I could imagine a New York to Chicago Hyperloop for example might be of some use.

 

To be fair Hyperloop has been debunked many times - theoretically possible perhaps, but a low pressure tube of the length and alignment required remains totally impractical. This low speed, short distance test doesn't address any of the fundamental issues.

[MyRule1]

On 06/05/2018 at 19:38, stivesnick said:

Underground transport systems, need a means of escape. 

 

Although removing the air from the tube, removes the fire risk, you still need to get people out and rescue staff and maintainers in.

 

The discussions on how often you need an access shaft should prove interesting ( and also very expensive) - the fire service will have views on this.

 

Second point, has anyone seen any numbers about the likely capacity of such as system? It is unlikely to match that of HS2.

 

Nick

As far as I am aware no transport system yet developed is 100% accident or risk free. I think that even the remote possibility of suffocating in capsule in a dark tunnel would put many people off this form of transport. As Nick indicates you might need a largenumber of  access hatches .

Edited November 13, 2020 by MyRule1

[jchinuk]

On 16/07/2017 at 07:26, caradoc said:

What is the carrying capacity of this system ? Given the extremely high speeds, presumably an extremely large separation will be required so that if one pod/train stops the one behind does not collide with it at 400mph !

 

I assume, if the tube is air tight, the following train would shift the one in front, a bit like a pop gun?

 

jch

[spamcan61]

Just now, jchinuk said:

 

I assume, if the tube is air tight, the following train would shift the one in front, a bit like a pop gun?

 

jch

Or squash it like an empty drinks can if there's an obstruction / distortion n the tube.

[jchinuk]

There seems to be no consideration of the acceleration forces involved.  Passengers will need to be securely strapped in, a big change for the "fidgets" you see on every train.  The overall experience will be closer to a ride at Alton Towers than the 7:55 from Basingstoke.

 

I am not convinced that the speed is a major selling point to a lot of people, I feel that reliable and comfortable trains are what most people want, indeed a seat would be welcome if you are commuting into most cities.

 

jch

[jchinuk]

Of course there are "models" of the hyperloop in many buildings, the vacuum tube delivery systems.  Not much to see from the outside though.

 

jch

[pete_mcfarlane]

2 hours ago, jchinuk said:

There seems to be no consideration of the acceleration forces involved.  Passengers will need to be securely strapped in, a big change for the "fidgets" you see on every train.  The overall experience will be closer to a ride at Alton Towers than the 7:55 from Basingstoke.

 

Oh I don't know, strapping the passengers in might be a good idea if it avoids having to sit next to somebody who spends 10 minutes faffing around working out the perfect distribution of their stuff between the table and their bag in the luggage rack above. 

[Edwin_m]

3 hours ago, jchinuk said:

 

I assume, if the tube is air tight, the following train would shift the one in front, a bit like a pop gun?

 

jch

The tube is intended to be a vacuum, to eliminate air resistance, so there would be no air to compress and the only "shifting" would occur when they collided.  

3 hours ago, jchinuk said:

There seems to be no consideration of the acceleration forces involved.  Passengers will need to be securely strapped in, a big change for the "fidgets" you see on every train.  The overall experience will be closer to a ride at Alton Towers than the 7:55 from Basingstoke.

 

I am not convinced that the speed is a major selling point to a lot of people, I feel that reliable and comfortable trains are what most people want, indeed a seat would be welcome if you are commuting into most cities.

 

jch

You probably get a seat as standing would be impractical.  In fact it would be much more like a flight than a train - people and baggage properly restrained, little or no chance to get up and move around. 

 

Very significantly, its susceptibility to explosive attack is probably similar to that of a plane, in that a relatively small device could cause decompression and/or collision of the vehicle with the surrounding tube.  While bombs can and do cause casualties on trains they are much more limited as seen from the London and Madrid attacks.  So it's likely any Hyperloop passengers would have to undergo airport-style screening, and this would nullify the journey time advantage over a train except for very long journeys.  And longer journeys almost always attract fewer passengers than those between similar-sized places that are closer together.  The only fixed infrastructure needed for an air route is an airport each end, whose costs are independent of distance, whereas a "long haul" Hyperloop would have to pay for a tube over its entire route.  

41 minutes ago, pete_mcfarlane said:

Oh I don't know, strapping the passengers in might be a good idea if it avoids having to sit next to somebody who spends 10 minutes faffing around working out the perfect distribution of their stuff between the table and their bag in the luggage rack above. 

It would be more like the equivalent scenario when you're trying to get on a plane, when you also have to stand up while the faffing is going on.  Or sometimes you can't even get down the aisle.  

[jchinuk]

1 hour ago, pete_mcfarlane said:

Oh I don't know, strapping the passengers in might be a good idea if it avoids having to sit next to somebody who spends 10 minutes faffing around working out the perfect distribution of their stuff between the table and their bag in the luggage rack above. 

Oh, I agree, but it will take a considerable change in a lot of people's attitude, as mentioned, it will be more like a flight than a train journey.  Everything would need to be secured before launch (take off?)

 

jch

[Dagworth]

Would a smaller tube and single occupancy pods where the passenger lays down make more structural sense? 
Removes the potential for someone to blow up a pod too if they are only going to kill themselves and not a

whole carriage full of innocent bystanders. 
 

Andi

Edited November 13, 2020 by Dagworth

[Edwin_m]

1 hour ago, Dagworth said:

Would a smaller tube and single occupancy pods where the passenger lays down make more structural sense? 
Removes the potential for someone to blow up a pod too if they are only going to kill themselves and not a

whole carriage full of innocent bystanders. 
 

Andi

Firstly, probably nobody wants to travel in something the size and shape of a coffin, and rescue if there was a problem would be nearly impossible.  

 

If they run singly separated by braking distance the throughput is terrible.  "Platooning" multiple ones in close sequence, like a train but with no physical coupling, means if the first one crashes all the others pile into it, so no safer than a larger vehicle carrying more people.  

[stivesnick]

Some interesting points being raised here. 

 

My understanding is that the tube would not be a complete vacuum, just the pressure would reduce the futher you travelled from the station. This would avoid the issue of having an airlock between the station and the main tunnel. 

 

As noted before the issue of such as system is the capacity. Not just the number of passengers in a partcular pod, but how frequently the pods could depart and the seperating distance. 

 

On HS2 or a TGV line, you can run 15 trains per hour each carrying 1100 passengers so 16500 passengers per hour in each direction. For a hyperloop, 50 passengers per pod say at 30 second intervals is only 6000 people per hour and that time interval would require people to be strapped in to allow for some very hard braking if the pod in front had a problem. If this requirement prevented the use by say wheelchair users or children, the whole thing could be declared illegal under equality laws. 

 

Although people would claim the hyperloop is much cheaper than a high speed line, it does not deliver the same capacity. 

 

Nick 

 

 

[SHMD]

1 hour ago, stivesnick said:

 

My understanding is that the tube would not be a complete vacuum, just the pressure would reduce the futher you travelled from the station. This would avoid the issue of having an airlock between the station and the main tunnel. 

 

 

This is not possible.

Or, at least, not possible without huge great strong powerful heavy sealing doors, along the tubes length, to isolate each section.

 

"Air", in a vacuum, behaves outside the realms of human experience.

The Hypertube's vacuum, (for the Virgin trial), was stated to be 100Pa. this is 1/1000 of an atmosphere.

At these pressures the "air" molecules bounce off the walls more than they bounce of each other (look up the term "mean free path"). This means that their velocity is determined by the energy of the molecular collisions (KE, Temperature, angle, etc). I would expect molecules, at 0.1Bar, to be travelling at about the same speed as the intended capsule speed BUT in completely random directions until the next molecular collision.

 

A "Silver Bullet" was asked for?

Here it is.

 

Cost.

 

Vacuum is very, very, VERY expensive - and very, very slow to achieve.

In capital costs, in maintenance costs, and in operational up (read down) time - vacuum costs heaps of money and is VERY unforgiving for any failure.

A vacuum chamber take a very long time to pump down (an exponential law, or if you will, a law of diminishing returns - and then - you can't just switch off the electric/maintenance hungry pumps, or you will lose your vacuum - even if there is no leaks in the system - which there will be!

You can speed up the pump down of the chamber, of course, by buying more of those expensive power/maintenance hungry pumps and associated pipework.

At least you can turn off the MAGLEV current, if no trains are due, but you can't with the vacuum pumps!

 

Realistically, you would have to build two tubes, side by side, as the whole tube would be blocked until a capsule reached its destination.

You need two tubes, one in each direction, if you are going to have any kind of frequent service.

You would then need transfer points between each tube (cross overs) and then you would need the equivalent of a signalling system.

All major complexities and added MASSIVE cost. A lot more than just doubling the cost!

 

The Hypertube is not cheaper than 4"8.5 track, ballast, infrastructure and signalling PER MILE.

600, or 700, mph track has to be much "straighter" than 300mph conventional high speed railways - which are already very expensive / mile - and then you enclose it in a strong chamber with a lot of mechanicals / mile!

Conventional rail can be left, for quite long periods, without power or regular maintenance - maglevs and vacuum chambers cannot!

 

 

Kev.

[mdvle]

On 11/11/2020 at 07:49, Edwin_m said:

"Various" in this case means "about three".  When you look at the cold numbers there just aren't many places where the technology is anything other than a solution in need of a problem.  

 

There is a pattern to (almost?) everything Musk has been doing for the last decade  - Mars.

 

Space-X - get off of Earth

Starlink - communication system for low person density Mars

Hyperloop - connect Mars outposts

Tesla - electric vehicles for exploring Mars (the battery/drivetrain/autopilot)

Solar Panel - power on Mars

Battery Storage - night on Mars

Boring Company - creating underground space for living/storage on Mars

etc.

 

His outrage at the cost of the California high speed rail merely gave him the ability to throw Hyperloop out to the public and get others to work (often it seems for free) on solving the implementation problems for him.

Edited November 14, 2020 by mdvle

[Edwin_m]

10 hours ago, mdvle said:

 

There is a pattern to (almost?) everything Musk has been doing for the last decade  - Mars.

 

Space-X - get off of Earth

Starlink - communication system for low person density Mars

Hyperloop - connect Mars outposts

Tesla - electric vehicles for exploring Mars (the battery/drivetrain/autopilot)

Solar Panel - power on Mars

Battery Storage - night on Mars

Boring Company - creating underground space for living/storage on Mars

etc.

 

His outrage at the cost of the California high speed rail merely gave him the ability to throw Hyperloop out to the public and get others to work (often it seems for free) on solving the implementation problems for him.

Hmm, you may have a point  there.  Conventional railways probably wouldn't work on Mars as with lower gravity something else might be needed to ensure they stay on the rails (to say nothing of the problems of the air brake in a thin atmosphere).  Whereas maglevs and Hyperloops would be easier than on Earth as they would need less force for levitation.  

 

I'm tempted to suggest Musk should just be allowed to push off to Mars and get on with it.  

[pete_mcfarlane]

15 hours ago, SHMD said:

The Hypertube is not cheaper than 4"8.5 track, ballast, infrastructure and signalling PER MILE.

600, or 700, mph track has to be much "straighter" than 300mph conventional high speed railways - which are already very expensive / mile - and then you enclose it in a strong chamber with a lot of mechanicals / mile!

Conventional rail can be left, for quite long periods, without power or regular maintenance - maglevs and vacuum chambers cannot!

 

Hyperloop seems to have come out of opposition to conventional high speed rail schemes in California, which were very expensive (mainly because they're building in an earthquake zone, which pushed the cost up compared to Northern European schemes).  Hyperloop is the California tech industry's cool new solution to the the problem, so it must be cheap and better, right?  

 

(The 'cheaper' bit seems to have come from the smaller size of the pods compared to  high speed rail, although I'm not convinced that drilling a 10' diameter tunnel through a mountain is  going to be massively cheaper than a 20' diameter one.) 

Edited November 14, 2020 by pete_mcfarlane

[jchinuk]

I'm slightly confused by the reference in the various descriptions of the "vacuum tube" that the Hyperloop runs in, judging from the video the carriage is not propelled by the vacuum, there is a wide clearance gap between the carriage and the tube, I assume it's driven along by an electric motor / linear motor.  

 

I assume that the tube is a vacuum, to reduce air resistance, which means that the carriage must be pressurised, though it also means that the air pressure in the tube only needs to be reduced, rather than a complete vacuum.  It also means that any leak, removing the vacuum / low pressure, will just slow the carriage, arguably a safety factor.

 

jch

[SHMD]

The idea is that it runs in a vacuum to reduce the "air resistance" to negligible levels so that much higher speeds can be attained.

It is not the means of propelling the vehicle.

 

The second premise is that it hovers (Maglev) above the track, by means of high current magnets, to reduce friction with the ground. Again, allowing much higher speeds to be had.

The Maglev will also be the main propulsion for the capsule. (As you say, a linear motor.)

 

The capsule is pressurised but to a much higher specification than, say, aircraft cabins.

The Hyperloop will be at a vacuum level of 100Pa. That is the same as 0.1 of the Earth's atmosphere, or 0.1 Bar, or 0.76 Torr, or 0.03 inches of mercury (in railway brake terms)!

 

 

Kev.

[Dagworth]

7 hours ago, SHMD said:

0.03 inches of mercury (in railway brake terms)

You sure about that? A vacuum that thin will support quite a lot of inches of mercury!

 

Andi

[Edwin_m]

From a quick search, 0.1 atmospheres seems to be 3in of mercury.  

[Dagworth]

100 Pascals is 1 millibar, 1000th of "normal" atmospheric pressure.

 

Put a vacuum that strong above a column of mercury and it will lift close to 30 inches.

 

Andi

Edited November 15, 2020 by Dagworth