Pros and cons of different electrification schemes (e.g. 3rd rail / OHLE / battery power)

[edwin_m]

On "one engine in steam" single lines it might be possible to return to the previous charging point, assuming dead-end branches have one at the terminus. Otherwise it's probably a question of shutting down all but essential auxiliaries, just at would happen in an EMU with no power.

 

[O L Leigh]

Noting that much of the RSSB's website and material is only accessible to 'members' and registered users do you have a quote, link or source for this news, please?

Yet more off-topic from me, I'm afraid.

I do find that this sudden secrecy very depressing. I remember not so long ago the RSSB used to publish an annual safety report covering incidents and accidents on the railway, tracking trends and providing a statistical analysis, but this seems to have stopped in recent years. I think I know why this might have happened, but it's only a personal theory based on their personnel.

 

[O L Leigh]

On "one engine in steam" single lines it might be possible to return to the previous charging point, assuming dead-end branches have one at the terminus. Otherwise it's probably a question of shutting down all but essential auxiliaries, just at would happen in an EMU with no power.

Good grief!! Do we still have any of those?

Returning to point of origin may be the only answer, but that doesn't really help the punters. Equally it's going to take a lot of cooperation from your local signaller (waves as he passes the box) as it could involve a very lengthy wrong-direction move. And at what point do you make that call? Not so long back I got stuck the wrong side of just such a fallen tree (although I hadn't actually left my originating point). Clearly no-one had much idea that it was going to turn into a mammoth task as, although control told me I wasn't going to make my booked back working, I would be working back as the next service. Needless to say, I kept slipping further and further behind as each successive departure that my train was going to make ended up getting cancelled. This isn't so much of a problem for a conventional train, but for a battery train you're consuming charge just sitting there.

Yes you could start isolating on-train systems to help preserve the charge, but that's not likely to be popular. EMU load-shedding schedules hit the high-draw systems first, and that means HVAC. When that goes you're down to ventilation fans only, but even these are also on the load-shedding schedule and you will eventually lose the lot. Cutting all that lot back in again, especially if it's a lovely hot sunny day, will represent a huge amount of work for the HVAC to return the train to normal temperatures with it's consequent hit on the charge. Of course a battery unit will have far greater charge capacity than the batteries on an EMU, but there still needs to be some form of protection to ensure sufficient charge to complete the journey.

Of course there's no requirement for a passenger carrying battery unit to have A/C, but I can imagine that the desire to have it will be strong. Swapping air-conditioned Cl171s for something less is going to be seen as a backward step by users of the line.

 

[mr_jrt]

Good grief!! Do we still have any of those?

Watford Junction to St. Albans Abbey springs to mind.

 

[MarkyT]

Good grief!! Do we still have any of those?

Returning to point of origin may be the only answer, but that doesn't really help the punters. Equally it's going to take a lot of cooperation from your local signaller (waves as he passes the box) as it could involve a very lengthy wrong-direction move. And at what point do you make that call? Not so long back I got stuck the wrong side of just such a fallen tree (although I hadn't actually left my originating point). Clearly no-one had much idea that it was going to turn into a mammoth task as, although control told me I wasn't going to make my booked back working, I would be working back as the next service. Needless to say, I kept slipping further and further behind as each successive departure that my train was going to make ended up getting cancelled. This isn't so much of a problem for a conventional train, but for a battery train you're consuming charge just sitting there.

Yes you could start isolating on-train systems to help preserve the charge, but that's not likely to be popular. EMU load-shedding schedules hit the high-draw systems first, and that means HVAC. When that goes you're down to ventilation fans only, but even these are also on the load-shedding schedule and you will eventually lose the lot. Cutting all that lot back in again, especially if it's a lovely hot sunny day, will represent a huge amount of work for the HVAC to return the train to normal temperatures with it's consequent hit on the charge. Of course a battery unit will have far greater charge capacity than the batteries on an EMU, but there still needs to be some form of protection to ensure sufficient charge to complete the journey.

Of course there's no requirement for a passenger carrying battery unit to have A/C, but I can imagine that the desire to have it will be strong. Swapping air-conditioned Cl171s for something less is going to be seen as a backward step by users of the line.

Perhaps the priority in such incidents needs to change. Battery equipped trains give the opportunity to get to a platform, any nearby platform, in either direction where safe detraining can occur and alternative onward travel methods arranged. Once there and empty, all or at least most on board systems can be shut down to conserve charge. At a platform, doors might be left open to avoid overheating in hot weather. This strategy could apply on an electrified section too during a supply failure if all trains had sufficient traction energy storage to at least be able to get to the nearest station. Of course there could still be some onboard failure scenarios that could strand a train elsewhere, or say in a really bad storm for instance a blockage in both directions, but many scenarios could have better outcomes with at least some traction energy storage on board. Another option might be a small emergency generator onboard with sufficient fuel to meet hotel power demands for a specified period, thus conserving battery range. The nominally all electric variants of the Hitachi AT300 design have one diesel gen set for this purpose, and it's sufficiently powerful for a slow speed emergency movement to the next station if required as well.

 

[Peter Mugridge]

Watford Junction to St. Albans Abbey springs to mind.

Romford to Upminster is another isn't it?

What about Grove park to Bromley North?

All of which are already electrified, two of which are even inside the London Travelcard zones and one of which is of course third rail and hence on topic.

 

[NotATrainspott]

So for short lines without freight, with trains not needing to reach any great speeds, why don't we consider putting up tram style overhead wiring on NR tracks, and use 750v dc?
Avoids the costs of achieving clearances for 25kv overhead and avoids the safety risks of third rail

That's pretty much what Metrolink and the Tyne & Wear Metro are. In the former case, the Bury line had a custom and life-expired side-contact 900V DC third rail, while the Altrincham line was 25kV AC after having originally been 1500V DC OHLE. The Tyneside Electrics system was electrified at 600V DC third rail before being de-electrified and run by DMUs before being re-electrified at 1500V DC OHLE for the Metro.

The Valley Lines electrification presents an interesting third way as it will use 25kV AC electrification but with greater gaps than normal neutral sections, relying on the trains having enough battery power to get under bridges and through tunnels. I'm not entirely sure on whether the tram-trains will have a low-voltage DC capability too, as the current extent of street running is planned to be short enough for battery power. I expect they probably will given the minimal cost of 750V DC pickup capability, and the fact that the Citylink design is used elsewhere with 750V and 25kV capability (e.g. in Sheffield).

The Valley Lines scheme seems to be more generalisable across the network. Going for anything other than 750V DC third/fourth rail or 25kV AC OHLE means having a microfleet. That's fine when a region has a number of rail services which can all be swapped over to metro operation in one go, but there aren't many urban rail networks across Britain. As soon as you spend much time on the mainline, it probably makes more sense to just go for 25kV AC. You won't see 750V DC OHLE on the quieter bits of the Greater Anglia network, for example.

 

[philthetube]

We have people in this thread with scars from 3rd rail incidents.
Do we have any with scars from 25kV incidents?

people dont genrally get scars from 25kv, or at least they are not able to show them people.

 

[AM9]

people dont genrally get scars from 25kv, or at least they are not able to show them people.

Even if we were to be aware of scars from 3rd rail (or any other exposed conductor) via members on this forum, it would only be anecdotal information and as such, only representative of hunch, rumour and wishful thinking. The only evidence to take seriously is that which is audited, - generally that released by the RSSB is usable in view of their role in railway safety. It really is breathtaking to read the number of comments about OLE 'spoiling the view' as a criterion for brushing aside the increased risk of death and injury of CRE.
The last time I heard something as crass was nearly 40 years ago when sombody (at work) was complaining about the removal of asbestos from his environmental test facilities. His reasoning was that "asbestos saves more deaths than it causes".

 

[corfield]

His reasoning was that "asbestos saves more deaths than it causes".

How is that logic crass?

The principle that something is risky in itself but reduces other risks by more is a hallmark of civilisation surely? Otherwise we wouldn’t make anything, move anything or do anything.

Having said that, 3rd rail is so obviously inferior on efficiency and safety that it is indeed staggering that people are still promoting it.

With the hurdle or electrification cost overruns, building of knowledge and experience plus the post Covid need to generate activity - it seems sense is returning in terms of the need for progressive electrification program, at 25kv.

 

[O L Leigh]

Even if we were to be aware of scars from 3rd rail (or any other exposed conductor) via members on this forum, it would only be anecdotal information and as such, only representative of hunch, rumour and wishful thinking. The only evidence to take seriously is that which is audited, - generally that released by the RSSB is usable in view of their role in railway safety.

I agree that in terms of calculating risk and other metrics you do need to have properly compiled stats (subject to the usual caveats), but anecdotal evidence can be useful too. Dismissing it as "hunch, rumour and wishful thinking" is a bit strong.

How is that logic crass?

The principle that something is risky in itself but reduces other risks by more is a hallmark of civilisation surely? Otherwise we wouldn’t make anything, move anything or do anything.

It's crass in the sense that there is no need to have the additional risk of asbestos to help insulate or fire-proof a building when the same objectives can be achieved with less risky materials.

 

[hwl]

The same length of time as putting up OLE. The longest lead time item is getting a connection to the national grid or DNO, and that is roughly 5 years. And it’s needed regardless of what type of electrification.

The general availability of spare DNO capacity in both those areas is poor so not at the quick and easy end of getting a connection either.

 

[corfield]

It' crass in the sense that there is no need to have the additional risk of asbestos to help insulate or fire-proof a building when the same objectives can be achieved with less risky materials.

That isn’t what was said viz alternative. Which also labelled it as crass to suggest otherwise.

It is not a lack of intelligence or sympathy to suggest a product that works albeit at risk, not be removed at great cost for things that often do not work as well. Especially when the opportunity cost of removing and replacing it could have gone on other risk reducing measures at greater overall benefit. The massive costs now associated with asbestos removal, which if left alone is not unsafe, are evidence of that and that this is arguable is evident by the many, many places asbestos is now left albeit marked.
Anyway, rather off topic!

 

[HSTEd]

people dont genrally get scars from 25kv, or at least they are not able to show them people.

Well that was my point.
There will be a certain degree of survivor bias given the higher consequences of a workforce 25kV shock than a third rail one.

 

[Grumpy]

NotATrainspott

Thank you.

Many of the threads on these forums are like Hamster wheels and this one is the same. Thus we have the 25kv overhead enthusiasts claiming that theirs is the only one to be pursued being the best technically. Then someone points out that the costs of implementing 25kv have risen to the point where it is impossible to show an economic return in a business case. This is followed by someone suggesting that 750v third rail costs much less to install, is quicker to implement, less unsightly, and more likely to be economically viable. Which in turn leads to the response that “third rail is less efficient, we mustn’t do this for safety reasons and the only true way is 25kv overhead”. And round we go again.

No-one ever seems to ask whether you can have electrification without 25kv overhead/750v third rail, seemingly oblivious to the fact that the systems you mentioned seem to work ok

I can’t understand why some of the Southern branches such as Uckfield couldn’t be electrified with a basic 750v tramway style overhead system. Relatively low speed lines, stops every 3-4 miles. Yes you would need units with a pantograph but that should be relatively simple. Electrification without the seemingly huge clearance etc. costs and risks of 25kv, and without the safety risks to track workers. And foxes of course

 

[Bald Rick]

I can’t understand why some of the Southern branches such as Uckfield couldn’t be electrified with a basic 750v tramway style overhead system. Relatively low speed lines, stops every 3-4 miles. Yes you would need units with a pantograph but that should be relatively simple. Electrification without the seemingly huge clearance etc. costs and risks of 25kv, and without the safety risks to track workers.

750v D.C. OLE is all very well for trams that weigh 40t, travel at 50mph max and draw at most half a megawatt for half a minute at most. It is absolutely not suited for trains that weigh 10 times as much, with 10 times the power, travelling at 70mph, as would be the case at Uckfield. Clearances would need to be the same as well - it’s the pantograph that triggers most clearance issues, not the wire.

 

[Grumpy]

Can I refer you to @Bald Rick 's posts #194 and #201 - that's even before you go down the rabbit hole of introducing a different standard to those currently in use by NR.

I have read Bald Rick's posts. I always read his posts as he clearly knows what he is talking about. These Forums are lucky to have the likes of him posting.
I don't see that I have suggested anything that conflicts with what he has posted.
Similarly I don't see why you think it appropriate to use the phrase "down the rabbit hole". The whole point is that the current NR standards might not be appropriate for many lines, and another standard might allow progress to be made.

 

[A0wen]

I have read Bald Rick's posts. I always read his posts as he clearly knows what he is talking about. These Forums are lucky to have the likes of him posting.
I don't see that I have suggested anything that conflicts with what he has posted.
Similarly I don't see why you think it appropriate to use the phrase "down the rabbit hole". The whole point is that the current NR standards might not be appropriate for many lines, and another standard might allow progress to be made.

The point is it won't be quicker, cheaper or easier to go down that path if the first challenge is to get a connection to the National Grid - and that's on a 5 year lead time whatever system you use.

And introducing a different standard will open up a whole can of worms, not least in getting things like type approval for every component needed, the potential increased cost of keeping components for a couple of relatively small schemes. If you look at the schemes where conversions took place from 1,500v DC overhead to 25kv overhead between 30 and 60 years ago, just about the only original part which was retained were the gantries. There's no guarantee the equipment used for existing OHLE could be used as part of this. That's before things like rolling stock come into play.

 

[HSTEd]

Ofcourse, given the proliferation of multi voltage standard rail vehicles - remember when quad-voltage Eurostars were a very large investment and a huge challenge to engineer?
We now have multi voltage units and locomotives popping up all over the place.

For new line electrification, it would be interesting to see a bottom contact 1500Vdc third rail standard put against 25kVac.
Some gauge clearing would likely be required for the third rail, but if you use balises to have active-retraction you can make the rail swap sides or just gap it without too much trouble.

Or the costs of retrofitting fourth rail compatible bogies so we can have an isolated 4 rail standard.

 

[A0wen]

Ofcourse, given the proliferation of multi voltage standard rail vehicles - remember when quad-voltage Eurostars were a very large investment and a huge challenge to engineer?
We now have multi voltage units and locomotives popping up all over the place.

For new line electrification, it would be interesting to see a bottom contact 1500Vdc third rail standard put against 25kVac.
Some gauge clearing would likely be required for the third rail, but if you use balises to have active-retraction you can make the rail swap sides or just gap it without too much trouble.

Or the costs of retrofitting fourth rail compatible bogies so we can have an isolated 4 rail standard.

I think the obvious question is why?

Introducing another pick up standard simply complicates matters. Shrouding 3rd rail may mitigate some of the risks and there are potentially a few bits of in-fill 3rd rail which are desirable. For each new standard you need a new set of designs, new set of approvals, new set of kit (yes there may be some overlap, but it won't be total) - it's not as simple as saying 'well just copy what's been used for Metrolink / Tramlink / Supertram' - those designs are for light rail - do they translate to heavy rail, even lightly used ? Everyone bemoans the cost of doing things, but equally adding another standard just adds even more - as you'll incur cost getting the approvals, that's before you can start to use the scheme. And I genuinely don't get the logic of trying out 1500v DC on 3rd rail - perhaps you could explain your logic?

As Bald Rick pointed out upthread, the two 'big' schemes everyone keeps touting for 3rd rail extension - Uckfield and Marshlink - both need a link to the National Grid and those are on a 5 year lead time. So those two schemes aren't going to happen in the next 5 minutes - which means other technologies may provide the answer - 3rd rail and battery units perhaps with a charge point at one place could be the solution.

 

[HSTEd]

For each new standard you need a new set of designs, new set of approvals, new set of kit (yes there may be some overlap, but it won't be total) - it's not as simple as saying 'well just copy what's been used for Metrolink / Tramlink / Supertram' - those designs are for light rail - do they translate to heavy rail, even lightly used ? Everyone bemoans the cost of doing things, but equally adding another standard just adds even more - as you'll incur cost getting the approvals, that's before you can start to use the scheme.

It is exceptionally unlikely that developing a new set of standards is going to cost anything like as much as large scale electrification schemes cost.

The sheffield tram train project developed a new set of adaptable 25kV/750Vdc dual voltage capable overhead line equipment, and got it type approved, then paid for the project itself.
It cost ~£75m.

Overruns in the 25kV schemes have run to hugely more than that.
The settup costs very rapidly become negligible.

If standardisation actually mattered we wouldn't have the zoo of equipment and technologies that characterises the rest of the railway's operations.

And I genuinely don't get the logic of trying out 1500v DC on 3rd rail - perhaps you could explain your logic?

It avoids the structural work required of overhead lines, a bottom contact third rail will tend to drastically reduce safety risks, especially if it is covered entirely in "Don't stick hand in" stickers, and probably painted a bright shade of orange to hammer the point home.

And at 1500Vdc, the power distribution concerns often used to attack third rail installations start to vanish.
It cuts resistive losses by three quarters.

As Bald Rick pointed out upthread, the two 'big' schemes everyone keeps touting for 3rd rail extension - Uckfield and Marshlink - both need a link to the National Grid and those are on a 5 year lead time. So those two schemes aren't going to happen in the next 5 minutes - which means other technologies may provide the answer - 3rd rail and battery units perhaps with a charge point at one place could be the solution.

Because in five years time, when the magical battery technologies haven't appeared, the same argument will be used again.
It's just a ruse to avoid ever doing anything.

And how do you propose to supply your chargers without grid connections?

 

[A0wen]

It is exceptionally unlikely that developing a new set of standards is going to cost anything like as much as large scale electrification schemes cost.

The sheffield tram train project developed and type approved a new set of adaptable 25kV/750Vdc dual voltage capable overhead line equipment, and got it type approved, then paid for the project itself.
It cost ~£75m.

Overruns in the 25kV schemes have run to hugely more than that.

That's funny - the way you're painting that one is it was quick and easy - yet The Railway Magazine appears not to agree with you:

South Yorkshire tram-train project 400% over budget | The Railway Magazine

By Ben Jones A report by the National Audit Office (NAO) has revealed that the cost of the heavily delayed South Yorkshire tram-train pilot sc ...

www.railwaymagazine.co.uk

" A report by the National Audit Office (NAO) has revealed that the cost of the heavily delayed South Yorkshire tram-train pilot scheme has soared to more than five times its original budget.

Authorised in 2012 for completion by December 2015 at a cost of £15million, the project has been repeatedly delayed by changes to the specification and additional work required. It is now expected to cost £75.1m with the first tram-trains not expected to run to Rotherham Parkgate until summer 2018.

Network Rail says that the need to develop bespoke overhead line equipment (OHLE) suitable for 750V DC operation as well as possible later conversion to 25kV AC is responsible for much of the delay"

 

[HSTEd]

That's funny - the way you're painting that one is it was quick and easy - yet The Railway Magazine appears not to agree with you:

I did no such thing.

I merely pointed out that it cost £75m.

Even if £60m of it was the type approval, it still proves my point.

25kV Electrification schemes cost billions of pounds, and tend to run over by billions more.

Let's say it costs £100m to develop and get type approval on a new set of electrification standards.
It almost doesn't matter.

We are going to be spending tens of billions on electrification.
It's a rounding error.

 

[AlastairFraser]

Just one thing I've seen no one mention. Could a mainline 3rd rail derivative of the APS tram power system not be considered as one of the options? Obviously,there is a small risk of electrocution if the transponder or receiver malfunctioned and it would probably be reasonably expensive to implement, but it would make 3rd rail a lot safer than the current system. The new system may be unsuitable for lines with high line speeds or traffic, but,for most of the infill schemes proposed, it would work reasonably well, providing such a scheme could be developed.

 

[Skie]

It might be slightly off-topic, but as a driver I’m a little nervous about some of the claims for battery units. Given that you’re relying on battery power for all systems, including A/C where fitted, I’d also like a little comfort about how long the charge can last off the juice as much as how far it can travel. The instance that I’m concerned about being a stranding due to, say, signal failure or an obstruction on the line.

Trip out all the non-essentials. If it's a hot day, pop some windows open if your unit has them. If not, enjoy the temporary sauna. As long as the 'phantom draw' on the batteries isn't too high, you will be fine to resume when the line is clear. Electric cars can sit on drives unplugged for many weeks and still have plenty of charge, so an BEMU with significantly more battery capacity just needing to power it's radios, emergency LED lighting and compressors should be fine for a few hours.

Plus, I can't see the initial areas for BEMU's being anywhere but metro systems, so you should never be too far away from a station. Merseyrail will have at least one 777 fitted with plans for more if the trial proves successful and the Skem extension goes ahead, and that is the ideal location for this type of kit.

 

[HSTEd]

Trip out all the non-essentials. If it's a hot day, pop some windows open if your unit has them. If not, enjoy the temporary sauna.

And then your passengers detrain and it all goes to hell.

 

[Bald Rick]

I think perhaps we need to take a step back into reality.

There is zero prospect of the introduction of another type of electrification system on the main line in this country, let alone one that is novel. The supertram type approval was pretty straightforward, because it was based on using existing methods (and voltages!) and adapting them. 1500v D.C. bottom contact is none of that. There’s also the small matter of compliance with TSIs.

Battery trains are already here, and will be in service in this country within 5 years. Battery trams already are. Clearly, they are not the answer everywhere, or even for many routes. But for routes like Uckfield and Marshlink they may be applicable. (And you don’t need a major new grid connection on either for battery application) .

Yes, electrification is expensive. Let’s not forget that a significant part of electrification is getting the power from the grid to immediately adjacent to the track, and that cost is incurred whether it is 25kV AC or 750v D.C., and is much more expensive for the latter. There’s also many other issues with D.C. that don’t apply with AC, not least whole life cost and reliability. Nevertheless, whilst I personally don’t think it is the right thing to do, I suspect we will see some extensions to the third rail, which might include Uckfield and/or Marshlink, but more likely to be Skelmersdale and the Isle of Grain.

 

[AlastairFraser]

I think perhaps we need to take a step back into reality.

There is zero prospect of the introduction of another type of electrification system on the main line in this country, let alone one that is novel. The supertram type approval was pretty straightforward, because it was based on using existing methods (and voltages!) and adapting them. 1500v D.C. bottom contact is none of that. There’s also the small matter of compliance with TSIs.

Battery trains are already here, and will be in service in this country within 5 years. Battery trams already are. Clearly, they are not the answer everywhere, or even for many routes. But for routes like Uckfield and Marshlink they may be applicable. (And you don’t need a major new grid connection on either for battery application) .

Yes, electrification is expensive. Let’s not forget that a significant part of electrification is getting the power from the grid to immediately adjacent to the track, and that cost is incurred whether it is 25kV AC or 750v D.C., and is much more expensive for the latter. There’s also many other issues with D.C. that don’t apply with AC, not least whole life cost and reliability. Nevertheless, whilst I personally don’t think it is the right thing to do, I suspect we will see some extensions to the third rail, which might include Uckfield and/or Marshlink, but more likely to be Skelmersdale and the Isle of Grain.

The Isle of Grain?! I had no idea passenger services would be run to Hoo Junction again!

 

[Bald Rick]

The Isle of Grain?! I had no idea passenger services would be run to Hoo Junction again!

It’s a possibility.

 

[Dr Hoo]

The Isle of Grain?! I had no idea passenger services would be run to Hoo Junction again!

Possible 'North East to South East Chord' for through running to Strood (rather than via Gravesend). More strictly for a new area of housing part way along the branch rather than the Isle of Grain itself.

(My user name gives a clue to my interest.)