RSSB looking at possible extension of 3rd rail electrification

[edwin_m]

As I have consistently described, you don't reduce the number of transformers required, you just move them from the lineside to the underframe of the trains. A 12-car 25Kv emu is going round with three substations underneath it that a DC unit just doesn't have..

Of course, in the never-never land of UK railway financing, if you are Network Rail you couldn't care less if taking cost out of your project sticks it on the rolling stock instead.

Even if you have the same number of transformers, putting them close to the motors eliminates the 20% of so of power losses caused by feeding it a long distance at a low voltage. There's also the issue of redundancy. If a transformer fails on a 12-car train then the power from the other two will be enough to get it home without blocking the line. Third rail substations have to be put closer together than strictly necessary, so the supply is maintained if one is out of use.

I'm not aware of any mixed traffic railway has adopted DC traction since 25kV became viable in the 1950s, and that includes vertically-integrated ones that have to pay for the transformer whether it's on the trackside or on the train. So if you have any evidence of third rail being cheaper on a whole-system whole-life basis then I'm sure we'd be interested in seeing why everyone else has been wrong for the past 60 years or so.

There are actually surprisingly few 3rd rail supply connections. Most of the new 3rd rail supplies /renewals come from 400/275kV GSPs with a network of 33kV 3 phase cables to supply the local substations over a wide area (e.g. Wimbledon, New Cross, Croydon, Bolney (a good chunk of Sussex), Ashford etc.) so that not dissimilar to AC...

True, noting that you have to lay the 33kV cable along the trackside, as well as the third rail itself, so that's an extra cost. Traditionally an AC feeder had to be on a higher voltage connection than a DC one, due to phase imbalance, but static converters as currently being installed on the ECML would seem to get round that problem.

 

[Taunton]

There are actually surprisingly few 3rd rail supply connections. Most of the new 3rd rail supplies /renewals come from 400/275kV GSPs with a network of 33kV 3 phase cables to supply the local substations over a wide area (e.g. Wimbledon, New Cross, Croydon, Bolney (a good chunk of Sussex), Ashford etc.) so that not dissimilar to AC...

That's how I always remember it being done too, with lineside HV in trunking. The Wirral electric lines were the same, with 33Kv (in fact possibly older 11Kv) feeders rather amateurishly marked in hand-written paint between the substations.

It is dissimilar to AC because it's a sight easier to put in these feeders in lineside casings that all the hoo-hah of OHLE, masts, spidery wiring that falls down, pantographs, etc.

 

[hwl]

I’m assuming a very long extension lead from Dungeness!

It isn't quite that bad though almost.
As the crow flies a Dungeness extension lead would be mostly through AONB.

DNO wise "Greater Sussex" i.e. coast to M25 is all fed from Bolney just west of Haywards Heath with all the local circuits taken and what spare capacity there allocated to cope in the event of a failure (also the reason for the Tonbridge supply issues). The DNO has plenty of work to do before any rail extras.
One option that would make thigns simpler in terms of upgrades overall would be a new GSP some where near Polegate or Hoathley on the 400kV route.

 

[D365]

As I have consistently described, you don't reduce the number of transformers required, you just move them from the lineside to the underframe of the trains. A 12-car 25Kv emu is going round with three substations underneath it that a DC unit just doesn't have..

Of course, in the never-never land of UK railway financing, if you are Network Rail you couldn't care less if taking cost out of your project sticks it on the rolling stock instead.

Would it be possible to find out the difference in cost between a Class 450 and a Class 350/1?

Aside from capital cost, it seems you’re deliberating ignoring the fact that 25kV is much more efficient when it comes to power delivery.

 

[yorksrob]

As the crow flies a Dungeness extension lead would be mostly through AONB.

Does it make a difference when you already own a railway line through the middle of it ?

 

[corfield]

That sounds as though it would have been sn excellent outcome for passenger comfort.

What? Ancient stock with a jolty traction change and associated delay. Reliant upon ancient locos with associated reliability. Lovely nostaligia but no way to run a modern railway so hardly surprising they didn’t do it !

Then requring bespoke replacement in the early privatisation era. Which would probably have been Turbostars.

Vs the very nice 159s. No comparison - DMU every time.

 

[Taunton]

Would it be possible to find out the difference in cost between a Class 450 and a Class 350/1?

Aside from capital cost, it seems you’re deliberating ignoring the fact that 25kV is much more efficient when it comes to power delivery.

... and the AC team is ignoring the additional power cost of rolling round many tonnes of transformer equipment for the lifetime of the system instead of having it sat at the lineside.

It does seem that each side just advances their own arguments here, of course. But one thing that cannot be denied is that Southern is already 95% DC installed, 5% diesel, and it does seem crackers to now say a different, incompatible system should now be used for the remaining 5%, lines that if BR had a bit more money in the 1960s-90s would have been converted to DC long ago.

 

[yorksrob]

What? Ancient stock with a jolty traction change and associated delay. Reliant upon ancient locos with associated reliability. Lovely nostaligia but no way to run a modern railway so hardly surprising they didn’t do it !

Then requring bespoke replacement in the early privatisation era. Which would probably have been Turbostars.

Vs the very nice 159s. No comparison - DMU every time.

There's usually a jolty delay at Salisbury anyway when they attach/detatch units !

 

[corfield]

There's usually a jolty delay at Salisbury anyway when they attach/detatch units !

Fair one - but the idea is a solution looking for a problem when you can just buy a new generation DMU and the problem goes away.

 

[Taunton]

What? Ancient stock with a jolty traction change and associated delay. Reliant upon ancient locos with associated reliability.

Hands up all who actually did Waterloo to Weymouth in those times. I don't remember any jolt or any delay at Bournemouth, the Southern used to manage it in about 3 minutes, honestly.

Notably Adrian Shooter writes about exactly this in the current Modern Railways, he favoured locos over multiple units for the IEP, with snap changes to diesels. In a discussion with then Transport Secretary Philip Hammond. Shooter actually cited the experience of 3-minute change at Bournemouth. Hammond, disagreeing, said he remembered Euston to North Wales also from the 1980s and it taking 20 minutes to change locos. Actually both were right. Bournemouth did used to do it in 3 minutes. Crewe did used to take 20 minutes of faffing around, and never learned any better. Both from my experience too. It's all down to management.

 

[Domh245]

... and the AC team is ignoring the additional power cost of rolling round many tonnes of transformer equipment for the lifetime of the system instead of having it sat at the lineside.

Based on the 350s / 450s, a transformer (as well as pantograph, VCB, etc) adds an extra 5.4 tonnes to the vehicle - this is ~3% of the total weight of a 4 car Cl.350. I'm pretty sure that the efficiency losses of DC are higher than 3%

 

[corfield]

... and the AC team is ignoring the additional power cost of rolling round many tonnes of transformer equipment for the lifetime of the system instead of having it sat at the lineside.

It does seem that each side just advances their own arguments here, of course. But one thing that cannot be denied is that Southern is already 95% DC installed, 5% diesel, and it does seem crackers to now say a different, incompatible system should now be used for the remaining 5%, lines that if BR had a bit more money in the 1960s-90s would have been converted to DC long ago.

Hmmm, but that stuff doesnt need all the infra running to it through the countryside and towns does it.

And as we know well, it is the infra costs that overwhelmingly dominate the railway. In contrast the train mounted stuff is peanuts - easy to fit, easy to maintain, easy to replace, mobile, directly linked to the services being run. As we see with the sheer amount of train orders, this isn’t a constraint or major concern.

Yet trying to work on the railway puts money through the roof.

Your comparison is false, and since BR didnt electrify them, then the situation we face is whether to continue with an obesolete and dangerous system (at very large costs), or remain diesal until we convert the entire network or something new turns up. That seems the obvious choice, hence why they’ve made it.

 

[D365]

... and the AC team is ignoring the additional power cost of rolling round many tonnes of transformer equipment for the lifetime of the system instead of having it sat at the lineside.

Which is significantly outweighed by the additional power available from high voltage electrification.

I’ve got the respective masses for a Class 450 and Class 350 unit saved on one of my hard drives somewhere, and could make a calculation from that. But bearing in mind that the batteries on the Class 379 added eight tons, an AC transformer + ancillary equipment is going to be nowhere near that.

 

[corfield]

Hands up all who actually did Waterloo to Weymouth in those times. I don't remember any jolt or any delay at Bournemouth, the Southern used to manage it in about 3 minutes, honestly.

Notably Adrian Shooter writes about exactly this in the current Modern Railways, he favoured locos over multiple units for the IEP, with snap changes to diesels. In a discussion with then Transport Secretary Philip Hammond. Shooter actually cited the experience of 3-minute change at Bournemouth. Hammond, disagreeing, said he remembered Euston to North Wales also from the 1980s and it taking 20 minutes to change locos. Actually both were right. Bournemouth did used to do it in 3 minutes. Crewe did used to take 20 minutes of faffing around, and never learned any better. Both from my experience too. It's all down to management.

Yet now we have IEP, who in their right mind would still want locos and drags? The bimodes dug us out of a massive hole in terms of infra failing to deliver, and allow us largely to now disconnect rolling stock from further works as given the flexibility they offer. That has huge operational and program benefits.
This loco thing is a massive backwards looking approach when the answer is already in service.

 

[Bletchleyite]

Yet now we have IEP, who in their right mind would still want locos and drags? The bimodes dug us out of a massive hole in terms of infra failing to deliver, and allow us largely to now disconnect rolling stock from further works as given the flexibility they offer. That has huge operational and program benefits.
This loco thing is a massive backwards looking approach when the answer is already in service.

A modular solution of a loco designed to pull an EMU and properly working with it could have worked - that's the 33+REP/TC model. It's been tried once with the Pendolinos and 57s, but that was really a bodge job rather than a brand-new loco specifically designed for the purpose. That said I agree bi-modes do add flexibility and make it easier.

 

[A0]

As I have consistently described, you don't reduce the number of transformers required, you just move them from the lineside to the underframe of the trains. A 12-car 25Kv emu is going round with three substations underneath it that a DC unit just doesn't have..

Of course, in the never-never land of UK railway financing, if you are Network Rail you couldn't care less if taking cost out of your project sticks it on the rolling stock instead.

There's an element of "so what" there though.

It doesn't seem to make DC units any lighter - although now obsolete comparing the weight of a Class 314 with a 507, the latter appears to be a smidge heavier.

So are DC only EMUs cheaper to buy or lease on a like for like basis?

 

[mr_jrt]

...don't a lot of the DC EMUs have a dead weight to simulate transformers anyway so the suspension etc can be identical?

 

[corfield]

It would have worked like the sleeper, slow, needing more people and at specific locations with supporting infra.

In comparison bimodes eliminate the problem entirely in a seamless manner, and as so many said (including me), allow us to easily adapt to the ups and downs of electrification.

The loco option was only ever used because it was the best technology could deliver. Technology can now do much better.

 

[Philip Phlopp]

... and the AC team is ignoring the additional power cost of rolling round many tonnes of transformer equipment for the lifetime of the system instead of having it sat at the lineside.

It's OK, nobody likes being on the losing team. Edison didn't like it either, but DC is yesterday's technology no matter how you dress it up.

The distribution losses with the DC network are vastly more than the additional power consumption of carrying around a transformer, and for most stock, they're ballasted to the same weight to avoid having to re-work bogie settings. The weight difference on the PEP units is around 4 tonnes (MerseyRail Class 507 is 98 tonnes, ScotRail Class 314 was 102 tonnes) though modern transformers are down in mass by around a quarter.

 

[yorksrob]

Fair one - but the idea is a solution looking for a problem when you can just buy a new generation DMU and the problem goes away.

Well, I do like the 159's as well !

 

[corfield]

Well, I do like the 159's as well !

They aren’t 444s but they seem well suited to their role and have held up well given their age.
Bimode seems the obvious answer for southern DMU replacements.

 

[AM9]

It's OK, nobody likes being on the losing team. Edison didn't like it either, but DC is yesterday's technology no matter how you dress it up.

The distribution losses with the DC network are vastly more than the additional power consumption of carrying around a transformer, and for most stock, they're ballasted to the same weight to avoid having to re-work bogie settings. The weight difference on the PEP units is around 4 tonnes (MerseyRail Class 507 is 98 tonnes, ScotRail Class 314 was 102 tonnes) though modern transformers are down in mass by around a quarter.

Indeed, the difference of energy consumption in modern ac vs DC EMUs is even less, as the energy required to accelerate the additional weight of the transformer is in part returned to the supply by regeneration on braking.

 

[Dunfanaghy Rd]

Which is significantly outweighed by the additional power available from high voltage electrification.

I’ve got the respective masses for a Class 450 and Class 350 unit saved on one of my hard drives somewhere, and could make a calculation from that. But bearing in mind that the batteries on the Class 379 added eight tons, an AC transformer + ancillary equipment is going to be nowhere near that.

As a resident of the area of the Southern I am familiar with the 450s. Had a ride in a 350 a couple of years ago and 'WOW'! When the driver opened the tap it flew. Essentially the same train, except for the power supply (and decor). Says it all for me.
Pat

 

[Class 170101]

Yet now we have IEP, who in their right mind would still want locos and drags? The bimodes dug us out of a massive hole in terms of infra failing to deliver, and allow us largely to now disconnect rolling stock from further works as given the flexibility they offer. That has huge operational and program benefits.
This loco thing is a massive backwards looking approach when the answer is already in service.

But I'd be interested to know what the IEP Bi-mode pays in Track access charges compared to a HST or Class 91 and Mark IV set carrying all the gubbins and fuel for both diesel and electric mode. The same questiobn could be asked of the Class 319s compared to the converted Class 769s.

Whilst infrastructure might have failed to deliver in terms of electrification I would say it is now paying in terms of track maintenance and wear and tear and potentially more access being required to maintain it or better tools / more staff at a given standard when compared against potentially lighter trains.

However it should be pointed out that loco changes consume track capacity for no gain in terms of more passenger trains. I should point out that stations like Birmingham, Norwich, Preston and doubtless many others would not be able to provide the capacity needed today if additional shunt moves were needed changing (in the case of Birmingham) from Class 47s to Class 86s compared to todays Class 220 / 221 Voyager trains on Cross Country services.

 

[hwl]

Does it make a difference when you already own a railway line through the middle of it ?

The problem is the much bigger AONB without a railway through it...

 

[corfield]

But I'd be interested to know what the IEP Bi-mode pays in Track access charges compared to a HST or Class 91 and Mark IV set carrying all the gubbins and fuel for both diesel and electric mode. The same questiobn could be asked of the Class 319s compared to the converted Class 769s.

Whilst infrastructure might have failed to deliver in terms of electrification I would say it is now paying in terms of track maintenance and wear and tear and potentially more access being required to maintain it or better tools / more staff at a given standard when compared against potentially lighter trains.

However it should be pointed out that loco changes consume track capacity for no gain in terms of more passenger trains. I should point out that stations like Birmingham, Norwich, Preston and doubtless many others would not be able to provide the capacity needed today if additional shunt moves were needed changing (in the case of Birmingham) from Class 47s to Class 86s compared to todays Class 220 / 221 Voyager trains on Cross Country services.

Exactly, it is logistically impossible in places and unwise in others plus comes with fixed infra needs. Bimodes are seamless.

I very much doubt the extra few % weight (distributed as it is vs concentrated in a loco eg Class 67 or something) is making any notable difference to track maintenance vs the train itself - and that pales into nothing vs the costs of electrification.

 

[Class 170101]

I very much doubt the extra few % weight (distributed as it is vs concentrated in a loco eg Class 67 or something) is making any notable difference to track maintenance vs the train itself - and that pales into nothing vs the costs of electrification.

I believe it has made a difference. Compare a Class 158 with a Class 170 and then again with a Class 755 Bi-mode.

Class 158 definitely a Sprinter and allowed to use Sprinter differentials, Class 170s usually allowed to use the same differentials but there was an argument in Anglia a few years back to disallow it above, I think, 75mph. The Class 755s weren't allowed, in the event I think the speeds were changed to MU vice SP speeds due to, I understand, the latter being a heavier train than a Class 170. Note Class 185s weren't allowed to use SP speeds and NR didn't change anything there to assist TPE.

 

[Bald Rick]

...don't a lot of the DC EMUs have a dead weight to simulate transformers anyway so the suspension etc can be identical?

Indeed they do.

 

[Taunton]

However it should be pointed out that loco changes consume track capacity for no gain in terms of more passenger trains. I should point out that stations like Birmingham, Norwich, Preston and doubtless many others would not be able to provide the capacity needed today if additional shunt moves were needed changing (in the case of Birmingham) from Class 47s to Class 86s compared to todays Class 220 / 221 Voyager trains on Cross Country services.

You do understand that the Bournemouth snap-change was done with just one platform in each direction. Even then there were commonly four services an hour east of there. The only shame about the old arrangement was the changeover was done at Bournemouth, not Poole, and so the electric service only covered half the conurbation.

 

[Class 170101]

You do understand that the Bournemouth snap-change was done with just one platform in each direction. Even then there were commonly four services an hour east of there. The only shame about the old arrangement was the changeover was done at Bournemouth, not Poole, and so the electric service only covered half the conurbation.

Not familiar with Bournemouth in that sense but even if the trains existed now I would be surprised if either signalling had changed to its deteriment or the safety standards changed or both. Today I would consider 20 minutes the bare minimum (and its probably more) to complete such a move. Just look at long it took for Class 67s to attach to Mark IVs to drag them off the East Coast Main Line via the alternative unwired routes.