Why isn't the Stourbridge Branch a Battery Tram?

[whhistle]

I know there's no real point in changing it now but why wasn't this considered before the people movers... err... moved in?

 

[Chester1]

I know there's no real point in changing it now but why wasn't this considered before the people movers... err... moved in?

Battery technology is still at an early stage today and would not have been feasible when the PPM was chosen.

 

[edwin_m]

With a round trip every 10min there wouldn't be much opportunity to charge up at either end, so the battery would have to hold enough energy for most of the day's running.

 

[Journeyman]

With a round trip every 10min there wouldn't be much opportunity to charge up at either end, so the battery would have to hold enough energy for most of the day's running.

Yup. At the moment, battery range seems to be good for about 50km. I know the branch is short, but I'm guessing the total day's running distance will exceed that.

 

[ac6000cw]

The Parry People Movers use flywheel-based energy storage, so they store energy from gravity going downhill (towards Stourbridge Town) and then use it to provide some of the energy to drive it back uphill.

 

[Bald Rick]

The Parry People Movers use flywheel-based energy storage, so they store energy from gravity going downhill (towards Stourbridge Town) and then use it to provide some of the energy to drive it back uphill.

Indeed. And Mr Parry’s original concept, around a quarter of a century ago, was that the flywheel would be ‘recharged’ at stations through a simple third rail style electric connection during station calls.

 

[duffield]

With a round trip every 10min there wouldn't be much opportunity to charge up at either end, so the battery would have to hold enough energy for most of the day's running.

There are two units - maybe you could have one on charge at all times and swap them round every few hours?

 

[edwin_m]

There are two units but only one platform, so the can't quickly be swapped (do they take one off the track when the need to swap?).

 

[ainsworth74]

There are two units but only one platform, so the can't quickly be swapped (do they take one off the track when the need to swap?).

No there's a tiny spur towards the mainline that they can use for shunt moves to get one out of the way and the other passed.

 

[edwin_m]

No there's a tiny spur towards the mainline that they can use for shunt moves to get one out of the way and the other passed.

I'd forgotten about the main line connection. Using that would be viable for an overnight changeover but not between 10min interval services.

Perhaps a battery version could have a trailer each end with batteries, which could be left plugged into a charger at the appropriate end of the line every few trips?

 

[Pigeon]

Why should it be? The flywheel has adequate capacity (though annoyingly the PPM website doesn't seem to say how much energy it does store) and it is a simple, reliable, efficient system with a much smaller recharge time and made out of commonplace materials. It's a shame they haven't converted more similar operations.

 

[edwin_m]

Why should it be? The flywheel has adequate capacity (though annoyingly the PPM website doesn't seem to say how much energy it does store) and it is a simple, reliable, efficient system with a much smaller recharge time and made out of commonplace materials. It's a shame they haven't converted more similar operations.

The Stourbridge is short and slow, so that a vehicle with 10 or so seats and a top speed of about 30mph provides a good service. I don't think there's any other rail route in the UK with similar characteristics.

 

[B&I]

The Stourbridge is short and slow, so that a vehicle with 10 or so seats and a top speed of about 30mph provides a good service. I don't think there's any other rail route in the UK with similar characteristics.

There might be other places where something similar could work well though eg Oswestry-Gobowen.

 

[Pigeon]

The Stourbridge is short and slow, so that a vehicle with 10 or so seats and a top speed of about 30mph provides a good service. I don't think there's any other rail route in the UK with similar characteristics.

Yes, the Stourbridge branch is a bit unusual, which is why it was chosen to test out the technology using a small-scale vehicle. But the test has been successful, and with that validation under their belts it appears from their website that Parry People Movers reckon that more capacious, faster vehicles using the same principle would also be viable, which increases the number of lines they would be suitable for.

The title of the thread suggests that there is something "wrong" with the Stourbridge vehicle using a flywheel rather than a battery for energy storage, when in fact it is a very suitable technology for the application. As long as it can store enough energy for a long enough time for the requirements of the service - which in this case it certainly can - there's really no reason not to use a flywheel instead of a battery. It's all good solid old technology which has been in widespread use for a very long time and is thoroughly proven (what is being proven with the Stourbridge experiment is basically the putting together of those particular already-proven components in a particular way for a particular use), it is straightforward to maintain, and it does not use any exotic materials/chemicals/techniques of manufacture.

Flywheel storage also has the major advantage of a very fast recharge time. As everyone has pointed out, the major difficulty with battery storage is the conflict between the slow recharging and the need to keep the service going. With flywheel storage this does not arise as it can be recharged rapidly during station stops without interrupting the service. (Yes, I know the Stourbridge vehicle doesn't do this and uses an onboard engine instead, but the reason for this is to make the trial possible without calling for any commitment or expenditure on the part of the railways to install charging points, which would mean a battery vehicle would also have had to use an onboard engine.)

Using that advantage would make it possible to use flywheel units on all kinds of duties that involve long running times with lots of stops, like (first one that comes to mind) the Heart of Wales line, topping up the flywheel at every station. A battery unit on the other hand would struggle to get enough range to complete the journey in the first place, and would need at least twice as many units to provide the same service since they'd spend at least half their time recharging or being taken to be recharged. Flywheel storage can be used to effectively "electrify" lines in situations where battery storage is difficult. (Flywheel storage does of course need charging points installed at stations, but it doesn't need the huge kerfuffle of full-scale knitting which would be a bit daft on something like the Heart of Wales line.) The thread title implies that flywheel storage is some quaint oddity similar to clockwork and batteries are invariably and without qualification a superior choice, and my objection is that the modern tendency to automatically consider only electrical solutions to some problem and reject non-electrical ones without thinking because they're somehow not swish enough leads to good ideas being rejected and sub-optimal alternatives used instead, and rejection of flywheel storage is an example of this tendency in action.

 

[edwin_m]

There might be other places where something similar could work well though eg Oswestry-Gobowen.

There are very few. Even fewer that currently have a passenger service and therefore only require the complication of the operator wanting to use a novel vehicle. If it's also a re-opening then there's the whole extra layer of complication to do with the necessary permissions and funding.

Using that advantage would make it possible to use flywheel units on all kinds of duties that involve long running times with lots of stops, like (first one that comes to mind) the Heart of Wales line, topping up the flywheel at every station. A battery unit on the other hand would struggle to get enough range to complete the journey in the first place, and would need at least twice as many units to provide the same service since they'd spend at least half their time recharging or being taken to be recharged. Flywheel storage can be used to effectively "electrify" lines in situations where battery storage is difficult. (Flywheel storage does of course need charging points installed at stations, but it doesn't need the huge kerfuffle of full-scale knitting which would be a bit daft on something like the Heart of Wales line.) The thread title implies that flywheel storage is some quaint oddity similar to clockwork and batteries are invariably and without qualification a superior choice, and my objection is that the modern tendency to automatically consider only electrical solutions to some problem and reject non-electrical ones without thinking because they're somehow not swish enough leads to good ideas being rejected and sub-optimal alternatives used instead, and rejection of flywheel storage is an example of this tendency in action.

You have to bear in mind the other disadvantage of the current technology, its relatively low maximum speed of around 30mph, which makes it unsuitable as it stands for nearly all routes on the national network. Also, although the vehicles are cheap, the cost per seat is similar to that of a conventional train. So it is only the best option for routes where the optimum train size is much smaller than a Class 153 and the speed doesn't go much above 30mph. Most of these routes would have been closed in the past as having too few numbers to be vialble for train service, perhaps because competing buses are faster. Stourbridge really is a special case here. It may well be possible to scale it up to the sort of size and speed that would make it more widely useful, but that would most likely remove the inherent simplicity of the solution and make it less competitive against higher-tech options.

 

[ainsworth74]

Hasn't the company that built them gone bust? You know, due to a lack of orders...

 

[Clip]

Not that ive seen - dont they maintain the vehicles too which would keep them in business

 

[CharlieSpotted]

Hasn't the company that built them gone bust? You know, due to a lack of orders...

No sign of them going bust on Companies House, with their last (unaudited) accounts as of Dec 17 looking pretty healthy.

https://beta.companieshouse.gov.uk/company/02652429

 

[Bletchleyite]

Not that ive seen - dont they maintain the vehicles too which would keep them in business

Pretty sure they are on a build, maintain *and operate* contract - Pre Metro Operations Ltd operate them on behalf of WMT with their own crew of 2, who I believe share driver and guard duties.

JPM Parry & Associates did fail as a company, but the People Mover part of the business was separate and continues. Indeed, this probably bodes fairly well for a smallish Vivarail.

 

[ainsworth74]

JPM Parry & Associates did fail as a company, but the People Mover part of the business was separate and continues. Indeed, this probably bodes fairly well for a smallish Vivarail.

Aha that's probably what I'm thinking of!

 

[Pigeon]

You have to bear in mind the other disadvantage of the current technology, its relatively low maximum speed of around 30mph, which makes it unsuitable as it stands for nearly all routes on the national network.

They're only operating it at up to 20mph (pretty sure it's only 20), but according to the PPM website that model is capable of 50mph. They do offer bigger ones as well; they seem to be more concerned about increasing capacity than speed, which I guess makes sense in the context of using them on lines where stops are so frequent it never really has a chance to get moving very fast anyway.

It may well be possible to scale it up to the sort of size and speed that would make it more widely useful, but that would most likely remove the inherent simplicity of the solution and make it less competitive against higher-tech options.

No reason why it should - it scales in much the same way as diesel engines do, ie. big ones are basically just the same thing as small ones only bigger. (Up to a point, at least, but not a point we're exceeding.) Looking at the larger designs on the PPM website that is indeed what they are.

 

[edwin_m]

They're only operating it at up to 20mph (pretty sure it's only 20), but according to the PPM website that model is capable of 50mph. They do offer bigger ones as well; they seem to be more concerned about increasing capacity than speed, which I guess makes sense in the context of using them on lines where stops are so frequent it never really has a chance to get moving very fast anyway.

No reason why it should - it scales in much the same way as diesel engines do, ie. big ones are basically just the same thing as small ones only bigger. (Up to a point, at least, but not a point we're exceeding.) Looking at the larger designs on the PPM website that is indeed what they are.

I have to disagree on the scaling. The flywheel is limited by size and weight, so a larger vehicle would need several flywheel transmissions running in "multiple" even if they don't plan to run coupled vehicles. It would also need bogies, introducing a lot of dynamic complexity especially if they are to run faster as well.

Despite what is says on the website they've never produced a larger vehicle and I suspect they've never run one much faster than at Stoubridge. My view (from a position of some technical knowledge of their system) is that their simple-tech approach would have difficulty stretching to that extent. The problems Porterbrook have had in making two gensets work together on the 769 illustrate how even people with extensive railway engineering knowledge can struggle with something apparently simple.