Using Monopods for city travel utilizing linear induction motors

[anorlunda]

Of course. The elites are important. It is our duty to provide them with their every need.

We could balance the budget by adding a $100K tax per skyTran ride. The elites can afford it.

 

[256bits]

it can be built in a modular fashion over many years

Long term planning and budgeting?
Never works out the way the initial concept was planned.
As the political will changes, I would expect cancellations of parts of the project, or complete cancellation, and you end up with tracks to nowhere.

 

[Vanadium 50]

We could balance the budget by adding a $100K tax per skyTran ride. The elites can afford it.

Why not a billion? Think about all we could do with that much money!

 

[Prathyush]

What proportion of the population would get to use Skytran?

Why do you think it will be a transport system for the elite? Everyone would use it. They are spending money in the same order of magnitude. Once infrastructure is paid for you need to just pay for electricity.

"NY Boosts Infrastructure Spend to $275B in New Budget Plan, Says Governor"

New York is a unusual example because it is a very rich place compared to average.

I don't know if the cost can be trimmed from 5 million a Km. That requires detailed design considerations, coupled with factory production.

Never works out the way the initial concept was planned.
As the political will changes, I would expect cancellations of parts of the project, or complete cancellation, and you end up with tracks to nowhere.

You will have part of tracks that are functioning, Same way rail infrastructure is built in a modular fashion.

 

[Prathyush]

Why not a billion? Think about all we could do with that much money!

If 10000 people use each KM of track every day. And if you charge 10 cents per KM for infrastructure+running cost. Your pay back period is 14 years. That's a conservative estimate.

 

[Rive]

Say total cost is 5 million per KM after labor, electronics, switching mechanism and miscellaneous.

Just a small little thing.

You can never get rid of roads, and consequently: cars, since they are just the thing for any type/quality/area/time roads.
Those already existing roads costs around the same (!) for a mile.
So this is actually about to create a second set of roads (equivalents) in some areas, at the same cost and expect all this being economic?
Really?

You know, this has happened once already. The existing railroads with all the already existing infrastructure got beaten up really bad by the dumb, old, dirty roads.
And this happened exactly because roads are dumb, old, dirty: because they can be dumb, old and dirty, and they will still be roads.

Is your railroad-redesign able to be old and dirty?
Then please add some (ridiculous) amount of maintenance fee too.

 

[Prathyush]

Is your railroad-redesign able to be old and dirty?
Then please add some (ridiculous) amount of maintenance fee too.

I don't have an estimate for maintenance costs right now, but they should be low.

That is the advantage of using a friction less design. This should be a long lasting infrastructure. Copper Coils, magnets and a metal framework last for a very long time. If any parts need to be replaced then old parts are recyclable.

You should compare with the maintenance cost of cars and roads which are not cheap. That along with cost of gasoline makes a compelling case.

The following article True cost of owning a car estimates car maintenance at 99 USD per month. (though electric cars are cheaper to maintain.)

 

[sophiecentaur]

You can never get rid of roads, and consequently: cars,

I imagine there was a similar attitude to horses, when horseless carriages were introduced. We have had a love affair with the car and, more importantly my personal car. When you realize just what proportion of private vehicles are stationary / parked at anyone time, there is a strong message about over consumption (net carbon consumption). There are just too many (particularly new) cars about.
You are right about the need for some sort of general purpose road system. It's necessary for the movement of goods but the personal car is a wasteful luxury.

 

[Rive]

I imagine there was a similar attitude to horses, when horseless carriages were introduced.

I think we can extend it according to that without loosing anything from the meaning.

I don't have anything to add about the (over) consumption, you are just right.

On the other hand, the locality of (ground based) community transport (limitations of long distance ground based community transport) gives a message about the flexibility expected. Personal cars may be a luxury here and there, but some other places it's still necessary parts of everyday life.

 

[sophiecentaur]

Personal cars may be a luxury here and there, but some other places it's still necessary parts of everyday life.

You are correct about that. It's a matter of how necessary. People will use their cars for the most trivial journey and regard that as necessary. Living at the end of a farm track could really mean necessary. But a big chunk of a journey would not need to be by conventional car. But we're all carrying different models of this in our heads.

I already made the point about it being total journey time that counts but 'changes' on the way should be minimal. Carrying heavy shopping from bus to train (seldom no changing) and to bus again is one reason why the car is used.
I have in mind something akin to what goes on in Amazon depots and Post Office sorting systems; you sit down at the nearest input to your home (50m from front door) and get off at the other end, having been shuffled between the appropriate lines. A taxi driver does this, of course but in a far from green way.

 

[Prathyush]

So this is actually about to create a second set of roads (equivalents) in some areas, at the same cost and expect all this being economic?
Really?

Road infrastructure is constantly being expanded at a heavy cost to keep up with capacity. No amount of road capacity appears to solve the traffic congestion problem. I am looking mainly at cities with a density more than 10000 people per sq KM.

The system proposed is not designed to transport heavy goods. Roads will still have place for that reason. But their purpose will shift towards bulk/heavy transportation. So road capacity will be whatever is necessary and not general purpose travel.

If you want to look at a different type of argument. New York uses ~13 million gallons of gasoline per day. So annually its roughly 16 billion USD. If the proposed transport can capture 75 pc of use cases over a car. Then it becomes very compelling, just because of the cost of gasoline alone. Add to that time savings.

The real question you should ask how often would you use this kind of transport over a car and a road. I personally would use it more than 90 pc of the time.(possibly close to 100) If there are exceptions only then roads could be used, and probably will hire a taxi for the purpose and not own a car.

 

[Prathyush]

I reworked the switching mechanism by using the horizontal guidance magnets which are there on every pod and necessary for a horizontal stability of a maglev system. This is the simplest switch mechanism between 2 lanes at high speed. It can only bifurcate, but much simpler than the originally proposed 2d array of electromagnets, which can switch into multiple lanes.

I believe the system can be made economical and compelling for any throughput above 10000 pods per hour, which should be comfortably achievable.

How far it can it can pushed in terms of throughput and speed needs very careful design considerations. Maglev designs have reached roughly .5 mach. But designing for that kind of speed needs very detailed engineering.

If standard pod specifications can be arrived at though careful research, mainly pod shape, maximum weight, number, location of poles and minimum pole strength. We can get a standardization similar to rail infrastructure.

It may even be possible to do fast installation, because once guideway shape is designed. In can be built in a factory , and transported in 10-20 m segments. Only poles need to be built and guideway can attach to the network.

Edit: Corrected mistake t = 2 seconds ->1.44 seconds

 

[Prathyush]

Designing for safety is very challenging.

This kind of system should theoretically achieve a throughput of 100000 passengers per hour (1 m headway and 1 m pod traveling at 60 m/s) under normal operation with currently available technology and modern electronic systems. You should be able to design around some kinds of failures like electronic failures, by adding redundancy of different types.

But designing around earthquakes, breakages of a track, or 10 ton concrete slab falling on guideway and minimizing danger at this kind of throughput is probably impossible(or atleast very very hard)

A pod traveling at 60m/s hitting into a hard wall experiences a ~360 g forces over ~1/60th of a second.

At 60 m/s and deceleration of 3g, coupled with airbags(weighs about 5 kgs or so) you have a headway of about 60 m. That's a theoretical throughput of about 3600 pods/ second.

You can attach say 10 pods to each other dynamically to increase throughput at this speed.

An interesting fact is faster you go lower the throughput for safe breaking distance, because breaking distance increases with square of velocity.

You can also think about attaching crumple pods specially designed to increase breaking time in events of a collision at the start of these "trains". These are all hard problems.

Just point to point transport at speed is still a very compelling consideration to carefully evaluate these problems.

 

[anorlunda]

But designing around earthquakes

Don't forget simple malfunctions and deliberate sabotage.

Also remember that very large cities like Tokyo (37 million people) would find 100K passengers per hour a pitifully small fraction of their real needs.

 

[256bits]

Here, you look at this
https://www.vtpi.org/tranben.pdf
for some transportation pointers and analysis.

Road infrastructure is constantly being expanded at a heavy cost to keep up with capacity. No amount of road capacity appears to solve the traffic congestion problem.

Short term solution on an existing network. An additional lane on a highway does reduce congestion initially, but after time the equilibrium returns and downloads onto downstream venues, an effect rarely taken into account, or downstream changes are impossible to implement due to land confinement, so the pain is spread over a wider region. A slightly democratic approach if you like.

Where I live they have one of the crapiest transit systems around by the way.
A lot of regions have no solution but to take the car, since transit can take 3 or 4 times as long, with multiple transfers and waits ( oh gee my bus is just pulling out of the station, now I have to wait 35 more minutes )

 

[sophiecentaur]

Also remember that very large cities like Tokyo (37 million people) would find 100K passengers per hour a pitifully small fraction of their real needs.

That would depend on more than the total number of passengers (although I feel includes to believe you). It would involve the number of terminals and the area covered by the system and the everyday timetable of the travellers.

But I can't see any particular advantage with such high speeds, except in advertising blurb. Most of the comments in this thread will apply to almost any form of traction. What's really needed is journey times that are not too long and also reliability. Safety goes without saying and that will always be an influence for keeping speeds down. Traffic control will have to be excellent for a good passenger throughput. The system will need to be flexible enough to deal with last minute holdups and breakdowns. Any tracked arrangement will be less flexible than free moving vehicles. AI will do more for improving the transport for any highly populated area than going fast and with low apparent energy cost.

 

[Vanadium 50]

this thread suffers from the problem that everyone imagines a different model.

Yes, but that is entirely on the OP.

All we really know is the answer is PodZ. The question is whatever it needs to be to have PodZ as the answer.

Also, $4M/km? That's insane. You know there was a time when if you wanted to look something like this up, you would have to physically go to the public library, and spend a few hours looking at microfiche. Today, it's five seconds with Google. And people still won't do it.

Anyway, a US average is $35M/mile, with rolling stock 10% of the cost. This was pointed out by @russ_watters in Message #2 and it didn't go anywhere. This is way low, as this is mostly at grade: you have pedestrians sharing space with DeathPodz.

Perhaps a more realistic example is the O'Hare ATS, where it cost $800M to add 600m of track.

As far as stops every km, we already have that. There are very few places in DC where you need to travel more than a km to get to a Metro station: Rock Creek Park (who needs a metro station in the middle of a park?) an area to the immediate southeast, and the north part of Georgetown. They use trains, not PodZ. As Russ pointed out.

 

[sophiecentaur]

The question is whatever it needs to be to have PodZ as the answer.

10/10

 

[Prathyush]

Also remember that very large cities like Tokyo (37 million people) would find 100K passengers per hour a pitifully small fraction of their real needs.

If you reach 100 K/hr passengers you can easily stack lines and reduce it the load. At 10 cents a KM. Your pay back period is in months. They can also be vertically stacked have as they have a small footprint.

deliberate sabotage.

Ideally you would want to have some very high throughput central lines spaced out which are fortified and placed in earthquake resistant structures. And local lines connecting to them by dynamically attaching pods into trains. Fortified lines that might be too expensive,but seem necessary for safety especially if it is such a vital channel.

Say you have a build 100 pod train. You can separate them by 100 m, then you have a safe breaking acceleration of 2g at 60m/s Your throughput is 100K. At max 100 people in danger for a single fault.

$4M/km

I think you can make just the guideway for around 5 million USD per KM possibly lesser too.

 

[sophiecentaur]

I think you can make just the guideway for around 5 million USD per KM possibly lesser too.

Come on! Is this stuff all going to be suspended above existing roads? Did you consider that the public would need to be consulted and that every metre of the system would need planning permission?

I costed out having our back service road rebuilt (a very minor road with just tarmac) and the ball park price would have been about £2k / metre. Re-do your sums with that figure and add track costs, services, interchanges, terminals.

The proposed system could be part of a funfair and possibly pay for itself over a few years.

 

[Prathyush]

Did you consider that the public would need to be consulted and that every metre of the system would need planning permission?

Yes, that tricky always for anything.

Re-do your sums with that figure and add track costs, services, interchanges, terminals.

Yea perhaps. It was a crude estimate indeed.

 

[Prathyush]

All we really know is the answer is PodZ. The question is whatever it needs to be to have PodZ as the answer.

This is what 100k passengers per hour looks like in Mumbai local.

 

[Prathyush]

The proposed system could be part of a funfair and possibly pay for itself over a few years.

Another company that was incubated by NASA, Sky tran is quoting prices in the ball park of 15 million per KM(I believe all inclusive). One of the largest Indian company Reliance has taken interest in it. They claim it is equivalent to a 6 lane highway in terms of throughput.

The first company TransitX that quoted 4 million per km was not a maglev system it was a wheeled system.

I think the idea is worth exploring.

 

[sophiecentaur]

Yes, that trick always for anything.

I don't know the expression. What does it mean?

15 million per KM(I believe all inclusive).

Is that on a green field site or inserted in an existing city transport system?

I think you have taken this as far as it can go without a lot more in-depth study, involving a more than enthusiastic advertising figures. You obviously like the idea but that's as far as we can take it here, I think.

 

[Prathyush]

I don't know the expression. What does it mean?

My bad, I wanted to say "that's always tricky".

Is that on a green field site or inserted in an existing city transport system?

Couple of test projects they are building I think. One in Israel, in an important place and I think they are planning something in India also.(possibly 1-2 others too)

 

[Vanadium 50]

This is in the engineering section. Engineering is about numbers. Number as they actually are, not as we wish them to be. Don't you think that if it were feasible to lay track for one or two orders of magnitude less cost than today they would be doing this already.

 

[Prathyush]

Don't you think that if it were feasible to lay track for one or two orders of magnitude less cost than today they would be doing this already.

You can find some interesting numbers in this paper.(published 2014)

Infrastructure cost for easy parts are in the range of 1-4 M euros per km for double track. Bridges cost between 10-20 million per KM for single track.

So guideway (which is the motor) for our system being 5 million is not completely impossible. I estimated it from the prices of cost of copper, iron supports and permaalloy poles. I assumed 1 cm thick poles can achieve desired thrust. Perhaps that is optimistic, I need to evaluate it in more detail.

 

[Vanadium 50]

You can find some interesting numbers in this paper.(published 2014)

Which do not support your claim. This requires that there be zero tunneling, zero overpasses, and everything be at the easy end of medium. This is not realistic. That's why they don't match actual costs. Let me say it again: Engineering is about numbers. Number as they actually are, not as we wish them to be.

 

[Prathyush]

Engineering is about numbers.

What do you think it will cost to safely suspend a track with a maximum load of 2 tons per m ?

 

[Vanadium 50]

What do you think it will cost to safely suspend a track with a maximum load of 2 tons per m ?

That's a bridge. What does your paper say bridge costs are?

 

[Vanadium 50]

Since we are becoming increasingly untethered from reality, let's go one more step forward: Robot Rickshaws! (Maybe stylized as Robot RickshawZ) Have the PodZ propelled by anthropomorphic robots! If traffic slows, music can be piped in and the robots break into dance!

I maintain this is superior to monopods in every conceivable way. Who wouldn't want dancing robits?

 

[Prathyush]

That's a bridge. What doies your paper say bridge costs are?

My point is we should see significant cost saving because of how light the track and load are. How can something designed to bear several 1000's of tons of load compare with something that designed to bear peak load 2 tons/m, or even lesser. Building pillars can hold that kind of load.

Perhaps I am underestimating the cost of the support pillars, but fact that it is cheaper per line should be non controversial.

I maintain this is superior to monopods in every conceivable way.

I don't understand why you hate very concept of using monopods. Personalized rapid transport has been an idea that has been explored by many researchers. Slow switching times is one of the reasons why they could not succeed before. This is a nice paper from 1984 evaluating the concept, for that time period.

You can theoretically show a safe breaking distance of 100 m by attaching 100 pods dynamically and separating them by 100 m and achieving a theoretical throughput of 100000 people per hour at 60m/s. How is that less safer than a train?

Why don't you think it's possible to improve a trains to point where you can travel without stopping at stations? Building a dense network is strictly not a necessity for this kind of infrastructure. But point to point transport without waiting at stations is still worth evaluating.

 

[Prathyush]

This is a nice paper from 1984 evaluating the concept, for that time period.

You can find a later review by the same author. He says

"Second, guideways that must support conventional-sized rail cars weigh between about 2000
to 3000 Ib/ft. If the capacity of those cars is divided into many units of the smallest practical size with attention to vehicle-weight minimization, we found that we could reduce the weight of the guideway to
140 lb/ft, which makes a dramatic difference in cost and size. This finding is not only due to the difference in static loading, but also the dynamic loading, which is discussed below."Maglev is suited for PRT, because engines need one engine per pod. However maglev is a system where the track itself is the motor. The conventional cost savings that come with using one engine per train do not apply to a maglev system. Maglev is an expensive technology, so making it cheaper by minimizing requirements for thrust and levitation load is important for the technology to be economical.

 

[Vanadium 50]

I don't understand why you hate very concept of using monopods.

I don't hate the concept. But.

0. The onus is on you is to defend it. It's intellectually lazy to dump an idea on the group and say "poke holes at it", especially before doing your own homework first.

1. We keep asking...what problem is this supposed to solve? We almost got there with a "a system where you can get anywhere with no more than a 1 km walk." Until it was pointed out that the entirely Pos-less DC Metro pretty much does this now, with trains. Then you pivoted to "But Mumbai trains are so crowded!"

(By the way, there is a straightforward solution to that. Buy more rolling stock)

2. Your cost estimates are very low, and they are unsupported by your references. The second part bothers me more than the first.

3. Your scaling costs don't make sense. Yes, a monopod weighs less than a train car. But is also carries fewer people. Do you win? Probably not, but without an answer to 1 how can we tell? How could anyone?

 

[Prathyush]

before doing your own homework first

There was a lot of time spent evaluating this idea before and during this thread. It has developed significatly during the course of this thread, because of the questions, and pointers(ex the squirrel comment), for that I am thankful.

Then you pivoted to "But Mumbai trains are so crowded!"

(By the way, there is a straightforward solution to that. Buy more rolling stock)

Mumbai metro pretty much runs at max capacity during rush hour. They use roughly 15-20 trains per hour each carrying like 5-6K passengers. That's great its does what it does well, and pretty much the life line of the city. They try to add more lines, but space is difficult.

We keep asking...what problem is this supposed to solve?

Main things are point to point transport and light weight infrastructure. There are other reasons too, easy stacking of lines vertically and maximal utilization of volumetric space.

From what I can understand DC metro has a high station density( I believe you still need to stop between stations, transfer between lines etc.) I am sure the metro system is great for what it does. However, point to point, means from the closest station you can reach to any other station without stops or transfers.

You have not even once considered the fact that the track that is lightweight has advantages over elevated rail. After repeating it several times. That is the most important difference over trains.

Your cost estimates are very low.

That is entirely possible. I had mainly estimated the guideway cost, that too very roughly.

While, I had assumed pillar cost in the same ball park as the track, because of the light weight nature after looking up RCC prices per m^3.

(100 pillars of 2m*2m pillar 10 M height, RCC price of 900 USD/m^3 gives 3.6 million USD). I had taken a lower estimate earlier.

they are unsupported by your references

Which one ? I am assuming it is some kind of miscommunication.