Could third rail electrification avoid the requirement for GWR 769s?

[Energy]

That conflicts with this though.
https://www.railforums.co.uk/threads/gwr-class-165-166-turbo-diagrams.157030/page-23#post-4399617

There was never talk of them running to London, or even being cleared East of Maidenhead.

Reading to Oxford was an option if the order had been increased from the initial 19 to 23.

However, I agree that the initial press release does mention Reading to Oxford - https://www.railforums.co.uk/thread...ally-for-northern.138660/page-51#post-3430238 - seems a bit strange that all subsequent discussion has not included that with it being clear that they were not intended for Reading / Didcot to Oxford services because it meant that only Reading traincrew need to be trained.

To clarify - by talk I meant talk on this forum, nothing official. The 769s aren't quick to accelerate and would block up the GWML.

 

[Minstral25]

The OLE on large parts of the ECML is a known problem, and the MML isn't much better as both were done rather cheaply using headspans and wide spacing, so it doesn't take much to knock them out. There's currently a refurbishment programme to change headspans for Gantries (not sure on timescales). Meanwhile the third rail in winter has to have nightly departmental trains running anti-icing and de-icing circuits over the entire network to prevent freezing over the top and preventing contact.

So basically the knitting is broken unless you pay lots to fix it.

The Third rail runs fine because they have solutions for the known problem (heated rail in key locations as well) - so in reality Ice is not a reason not to build more 3rd rail. Living along the North Downs I'd rather see Third Rail installed than keep with existing diesel solution (although I'd be equally happy with OLE done properly) - not that I expect either will happen ever.

EDIT: And I just see trains cancelled as the OLE has been broken at St Neots again

 

[zwk500]

So basically the knitting is broken unless you pay lots to fix it.

*The cheap Knitting needs to be fixed. But then that's the same as cheap 3rd rail systems - e.g. Weymouth, which has restrictions on train length due to current draw. For all the comments about 'gold-plating' the GWML wiring has been fairly robust. The WCML stuff put in 15 years ago has also stood up reasonably well.

If I was handed total control of the Railway, I'd extend 3rd rail from Ash to North Camp and from Shalford Jn to Shalford Station, and use Batteries to plug the gaps. 25km Reigate-Shalford and 17km North Camp-Wokingham should be well within range given the 3 opportunities to Charge en-route. The two extensions would be to allow trains to stand clear of the main lines should a problem occur switching traction (or there's a need to charge the batteries for longer).
In the medium term, I'd convert Reading-Bracknell to OLE and extend the OLE down to North Camp. Obviously this would require making all SWR's units that go to Reading from the Windsor lines Dual-voltage so isn't going to happen but hey ho.

 

[SouthEastBuses]

*The cheap Knitting needs to be fixed. But then that's the same as cheap 3rd rail systems - e.g. Weymouth, which has restrictions on train length due to current draw. For all the comments about 'gold-plating' the GWML wiring has been fairly robust. The WCML stuff put in 15 years ago has also stood up reasonably well.

If I was handed total control of the Railway, I'd extend 3rd rail from Ash to North Camp and from Shalford Jn to Shalford Station, and use Batteries to plug the gaps. 25km Reigate-Shalford and 17km North Camp-Wokingham should be well within range given the 3 opportunities to Charge en-route. The two extensions would be to allow trains to stand clear of the main lines should a problem occur switching traction (or there's a need to charge the batteries for longer).
In the medium term, I'd convert Reading-Bracknell to OLE and extend the OLE down to North Camp. Obviously this would require making all SWR's units that go to Reading from the Windsor lines Dual-voltage so isn't going to happen but hey ho.

So this is why 444s always attach/divide at Bournemouth then

 

[Bald Rick]

For example, if Basingstoke-Salisbury was electrified with third rail (which I don't think it should be but let's just suppose), with a view to eventual, long term future conversion to OLE, how much of the infrastructure would need ripping out and replacing (other than the actual third rail)?

almost all of it would need ripping out and replacing, along with a whole load of stuff on the track related to return currents and bonding. And the signalling. Other than that….

 

[ac6000cw]

So this is why 444s always attach/divide at Bournemouth then

Yes, it will be.

Basically when the time came to replace the 1967 vintage 4-REP plus 4-TC stock that had operated London-Bournemouth-Weymouth services (with the unpowered 4-TC units being push-pull diesel hauled Bournemouth-Weymouth), BR decided that it was economic to electrify Bournemouth-Weymouth instead of building a new generation of 'hybrid' trains, so that standard/existing 3rd-rail EMUs could be used on the line. But to make that business case work they had to pare down the electrification spec/cost to the minimum, hence the power supply limitations.

 

[zwk500]

A related question for the electrification experts- how compatible are things like substations, grid connections, etc. between third rail and OLE installations?

Not very, although I believe it's the DC/AC interface that is particularly problematic. There's a reason the interfaces are these systems on the network are kept as short as possible.

Another question is, how safe can third rail be made? Obviously there are side and bottom contact systems (e.g. DLR), but one would think it possible that a modified design, compatible with current trains, could reduce risk to track workers. Maybe covered sides? Having the rail mostly enclosed in some kind of trench that shoegear can get into but makes accidental contact less likely? I have no idea, but surely in nearly 100 years we can do a bit better with third rail.

Bottom contact is the safest. Potentially wooden or fibreglass boarding in problem areas like junctions and depots where staff are likely to be about on track, as already happens, but you won't be doing that along every mile of plain line.
A trench is not ideal because the shoe gear will need to be retractable in quick time when the rail changes sides. It will also fill up with rubbish like leaves and ballast and water which will make getting good contact problematic.

 

[cle]

I'm not sure this is fair. Even though the electrification infills in the sothern 3rd rail area are small, loads of stock used exclusively on 3rd rail services is already capable of running on OHLE, so it really wouldn't matter if there were a few OHLE islands in southern 3rd rail land

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==


As this line is in between OHLE and 3rd rail territory, it should clearly be electrified with OHLE for the safety and efficiency benefits, even if the SWR service becomes more important. Dual-voltage rolling stock really isn't that expensive, and loads of trains switch between OHLE and 3rd rail multiple times every day.

A related question for the electrification experts- how compatible are things like substations, grid connections, etc. between third rail and OLE installations?

For example, if Basingstoke-Salisbury was electrified with third rail (which I don't think it should be but let's just suppose), with a view to eventual, long term future conversion to OLE, how much of the infrastructure would need ripping out and replacing (other than the actual third rail)?

Another question is, how safe can third rail be made? Obviously there are side and bottom contact systems (e.g. DLR), but one would think it possible that a modified design, compatible with current trains, could reduce risk to track workers. Maybe covered sides? Having the rail mostly enclosed in some kind of trench that shoegear can get into but makes accidental contact less likely? I have no idea, but surely in nearly 100 years we can do a bit better with third rail.

Ok so it seems pretty clear that Reading-Basingstoke should be OLE. The shuttles could go EMU, and a future bi-mode XC unit could at least do Basingstoke-Oxford (FFS) - but hopefully get to Coventry by then too.

At Basingstoke itself, would you wire all lines/platforms, I guess. And would you continue? Perhaps better to go to Salisbury, and then back up around to Bath ? (FFS) And potentially Reading hosts an hourly SWT Basingstoke-Salisbury-Bath-Bristol or even Melksham/Swindon regional service? Which obviously isn't used end to end. Or another Exeter on a bi-mode, vs more diesels out of Waterloo. And a diesel/AC bi-mode sub-fleet for the Salisbury lines might make sense. And then third rail remains for the 'mainline' via Winchester and to Portsmouth.

 

[zwk500]

Ok so it seems pretty clear that Reading-Basingstoke should be OLE. The shuttles could go EMU, and a future bi-mode XC unit could at least do Basingstoke-Oxford (FFS) - but hopefully get to Coventry by then too.

Is FFS the expletive version or related to Feeder Stations? Sorry, either could apply at this point!

At Basingstoke itself, would you wire all lines/platforms, I guess.

No, you'd wire into the bay and extend 3rd rail to about the next overbridge towards Reading to allow freight to change on the fly/when detained before the junction.

And would you continue?

Probably not, as you've got just over a mile to Worting Jn with 3rd rail

Perhaps better to go to Salisbury, and then back up around to Bath ?

I'd personally go the other way around - approach Salisbury from Warminster having wired all routes to Bristol first.

And potentially Reading hosts an hourly SWT Basingstoke-Salisbury-Bath-Bristol or even Melksham/Swindon regional service?

Not going to happen unless you also propose a very big flyover at Basingstoke.

 

[Snow1964]

I'm not sure this is fair. Even though the electrification infills in the sothern 3rd rail area are small, loads of stock used exclusively on 3rd rail services is already capable of running on OHLE, so it really wouldn't matter if there were a few OHLE islands in southern 3rd rail land

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==


As this line is in between OHLE and 3rd rail territory, it should clearly be electrified with OHLE for the safety and efficiency benefits, even if the SWR service becomes more important. Dual-voltage rolling stock really isn't that expensive, and loads of trains switch between OHLE and 3rd rail multiple times every day.

It may turn out to be more expensive to do OHLE on the short infills, because you get get problems like should the overhead continue as an overrun into Guildford tunnel at Shalford junction.

Many substations are already positioned at junctions, so dont even need to provide that many new substations. Some of those gaps cross electrified lines (Farnborough, Dorking etc) so might be sufficient capacity (certainly enough for a 4car EMU) for few more miles.

With substations at Eastleigh and Redbridge, might be sensible to add one at Romsey junction and extend third rail there, with voltage changeover at Romsey station (otherwise got to extend OHLE into busy layouts for voltage changeover), but I wouldn’t extend third rail from Basingstoke, if anything run OHLE from Reading to Basingstoke, then separately approach from Chippenham/Bath via Westbury and Salisbury (with section to Romsey also done).

 

[cle]

Is FFS the expletive version or related to Feeder Stations? Sorry, either could apply at this point!

No, you'd wire into the bay and extend 3rd rail to about the next overbridge towards Reading to allow freight to change on the fly/when detained before the junction.

Probably not, as you've got just over a mile to Worting Jn with 3rd rail

I'd personally go the other way around - approach Salisbury from Warminster having wired all routes to Bristol first.

Not going to happen unless you also propose a very big flyover at Basingstoke.

Expletives, because I'm assuming that even Didcot-Oxford (and the Bath route to Bristol) are done in my fantasy future. But you never know.

SWT - they are running 3tpd out of Reading to Salisbury, at least - replacing the Waterloo-Bristols no doubt. But yes I take the point that the conflicts would be more - although XC in theory were doing 2tph each way through Basingstoke with the Southampton terminators.

 

[tomuk]

That was one of the DfT's better decisions to force all mainline stock to either be capable of OLE operation or at least retrofittable for it. It has driven the architecture of the traction power system such that most new trains can be offered for DC, ac or both requirements.

DfT didn't force stock to be capable of OLE operation and this didn't drive a change in traction systems. Technology evolved and VVVF AC traction motors became possible. These AC traction systems have better performance and a much lower maintenance requirement. This is why they have become the dominant technology not because of some imaginary mandate from DfT or the side benefit that dual voltage running off of AC or DC is easier.

 

[RobShipway]

... and a national grid supply.

From the original announcements, Reading to Gatwick and Reading to Oxford. There was talk of them running to London but given their unreliability I doubt GWR want them on the GWML.

I thought there was talk, but agree their pace would be questionable on the GWML even on the so called 'Slow Lines'.

That conflicts with this though.
https://www.railforums.co.uk/threads/gwr-class-165-166-turbo-diagrams.157030/page-23#post-4399617

There was never talk of them running to London, or even being cleared East of Maidenhead.

Reading to Oxford was an option if the order had been increased from the initial 19 to 23.

However, I agree that the initial press release does mention Reading to Oxford - https://www.railforums.co.uk/thread...ally-for-northern.138660/page-51#post-3430238 - seems a bit strange that all subsequent discussion has not included that with it being clear that they were not intended for Reading / Didcot to Oxford services because it meant that only Reading traincrew need to be trained.

That is why I mentioned it. As it does conflict with what some are saying on these forums.

The following references are cited as the source for that information:

1. "GWR to lease Class 769 Flex 'trimode' trainsets". Railway Gazette. 20 April 2018. Retrieved 20 April 2018.
2. Great Western Railway receives the UK’s first tri-mode train - Great Western Railway. Retrieved 26 August 2020.
3. "GWR aims for 2021 'Flex' introduction". Rail Express. May 2021. p. 26.

Yes, with GWR being one of those sources themselves which is why I was curious when people said that class 769 would not be serving Oxford. But what is not clear as JonathanH has pointed out is whether the trains would be Reading/Didcot to Oxford or Reading to Oxford without stopping at Didcot. If it is Reading/Didcot - Oxford, then those saying that the Class 769 would not be serving Didcot - Oxford are incorrect in their statements.

 

[zwk500]

It may turn out to be more expensive to do OHLE on the short infills, because you get get problems like should the overhead continue as an overrun into Guildford tunnel at Shalford junction.

Many substations are already positioned at junctions, so dont even need to provide that many new substations. Some of those gaps cross electrified lines (Farnborough, Dorking etc) so might be sufficient capacity (certainly enough for a 4car EMU) for few more miles.

Assuming those Substations are capable of delivering the 25kv AC. Might be expensive to modfiy them if they aren't already. OLE infilling between two sets of 3rd rail doesn't make a lot of sense. Covering gaps between the 2 systems with OLE makes a lot more.

With substations at Eastleigh and Redbridge, might be sensible to add one at Romsey junction and extend third rail there, with voltage changeover at Romsey station (otherwise got to extend OHLE into busy layouts for voltage changeover), but I wouldn’t extend third rail from Basingstoke, if anything run OHLE from Reading to Basingstoke, then separately approach from Chippenham/Bath via Westbury and Salisbury (with section to Romsey also done).

Romsey is a fair way from either of those stations (especially Eastleigh). Changing outside of a station is rare but perfectly possible (The West London Line does it, not sure if the Javelins do at Ashford. Eurostar used to, of course, but no longer does). Extending 3rd rail for a couple of hundred yards to facilitate a changeover zone on plain track would be a reasonable short extension, especially at Redbridge and Eastleigh where the signalling allows reversals should the changeover.

 

[AM9]

DfT didn't force stock to be capable of OLE operation and this didn't drive a change in traction systems. Technology evolved and VVVF AC traction motors became possible. These AC traction systems have better performance and a much lower maintenance requirement. This is why they have become the dominant technology not because of some imaginary mandate from DfT or the side benefit that dual voltage running off of AC or DC is easier.

So who mandated that all new mainline EMUs had pantograph wells even if they were 3rd rail DC only at the point of delivery?

 

[tomuk]

Assuming those Substations are capable of delivering the 25kv AC. Might be expensive to modfiy them if they aren't already.

750V DC and 25kv AC are completely different. Why would anybody assume that existing DC substations could supply AC? It's nonsensical.

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==

So who mandated that all new mainline EMUs had pantograph wells even if they were 3rd rail DC only at the point of delivery?

A combination of the leasing companies and manufacturers.

 

[AM9]

750V DC and 25kv AC are completely different. Why would anybody assume that existing DC substations could supply AC? It's nonsensical.

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==


A combination of the leasing companies and manufacturers.

OK, I seem to remember the DfT being involved in that because it improved cascading options, in theory at least.

 

[Bald Rick]

So who mandated that all new mainline EMUs had pantograph wells even if they were 3rd rail DC only at the point of delivery?

it was the leasing companies, to boost residual values.

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==

No, you'd wire into the bay and extend 3rd rail to about the next overbridge towards Reading to allow freight to change on the fly/when detained before the junction.

You might wire into the bay, but you would do everything possible to avoid wiring up all of Basingstoke Unless you were to remove all the DC kit. The bonding for the Dc return would be a nightmare, not to mention all the OLE required.

 

[zwk500]

You might wire into the bay, but you would do everything possible to avoid wiring up all of Basingstoke Unless you were to remove all the DC kit. The bonding for the Dc return would be a nightmare, not to mention all the OLE required.

100%. The bay justifies it to avoid a traction change, and allow AC-only EMUs for fleet flexibility. The junction... does not.

 

[Bald Rick]

100%. The bay justifies it to avoid a traction change, and allow AC-only EMUs for fleet flexibility. The junction... does not.

I suggest you’d go to the third over bridge, partly because it is almost exactly a mile from the junction, but mostly because it is the very appropriately named Faraday Road.

 

[JonathanH]

Yes, with GWR being one of those sources themselves which is why I was curious when people said that class 769 would not be serving Oxford. But what is not clear as JonathanH has pointed out is whether the trains would be Reading/Didcot to Oxford or Reading to Oxford without stopping at Didcot. If it is Reading/Didcot - Oxford, then those saying that the Class 769 would not be serving Didcot - Oxford are incorrect in their statements.

Whatever the press release said in April 2018, it has been subsequently confirmed on this forum by people directly involved in the planning of operation of these units, that 769s are not expected to serve Oxford.

The deployment of 19 769s was planned pre-March 2020 to be 16 diagrams. 10 for North Downs, 4 for Basingstoke, 1 for Henley and 1 for Bourne End, with 3 spare.

Subsequent postings have indicated that an expectation of 16 in service is unlikely but that is matched by a lower requirement for units on the North Downs Line because 3tph isn't happening.

It has been indicated that not using them for Oxford services means that fewer staff need to be trained. As staff training seems to be a reason why they are not in service yet, that seems sensible.

What has to be remembered is that in April 2018 when that press release was made, they were expected to be introduced to service between February 2019 and December 2019, at which time GWR was still operating all services west of Hayes & Harlington. TfL Rail didn't take over Reading services until December 2019. The needs of GWR were different. It is now nearly four years later.

Sources
https://www.railforums.co.uk/threads/gwr-class-769-information-discussion.174866/page-47#post-5
https://www.railforums.co.uk/thread...mation-discussion.174866/page-15#post-4778221

 

[zwk500]

I suggest you’d go to the third over bridge, partly because it is almost exactly a mile from the junction, but mostly because it is the very appropriately named Faraday Road.

Seems sensible. On Signalling plans I've definitely seen a limit of DC immunisation marked, can't quite remember where and can no longer check.

 

[RobShipway]

Whatever the press release said in April 2018, it has been subsequently confirmed on this forum by people directly involved in the planning of operation of these units, that 769s are not expected to serve Oxford.

The deployment of 19 769s was planned pre-March 2020 to be 16 diagrams. 10 for North Downs, 4 for Basingstoke, 1 for Henley and 1 for Bourne End, with 3 spare.

Subsequent postings have indicated that an expectation of 16 in service is unlikely but that is matched by a lower requirement for units on the North Downs Line because 3tph isn't happening.

It has been indicated that not using them for Oxford services means that fewer staff need to be trained. As staff training seems to be a reason why they are not in service yet, that seems sensible.

What has to be remembered is that in April 2018 when that press release was made, they were expected to be introduced to service between February 2019 and December 2019, at which time GWR was still operating all services west of Hayes & Harlington. TfL Rail didn't take over Reading services until December 2019. The needs of GWR were different. It is now nearly four years later.

Sources
https://www.railforums.co.uk/threads/gwr-class-769-information-discussion.174866/page-47#post-5
https://www.railforums.co.uk/thread...mation-discussion.174866/page-15#post-4778221

Okay, thanks.

 

[Bald Rick]

Seems sensible. On Signalling plans I've definitely seen a limit of DC immunisation marked, can't quite remember where and can no longer check.

Its usually 1km or 2km from the nearest Dc electrified section

 

[alf]

almost all of it would need ripping out and replacing, along with a whole load of stuff on the track related to return currents and bonding. And the signalling. Other than that….

This did not happen when the East Grinstead line was electrified from South Croydon.
Nor did it happen when North woolwich on the North London line was third railed in a weekend in the 1980’s.

And I watched them third railing the long siding at Eastleigh a year or two ago into the siding fan where the poor sad 701’s live.
Nothing was ripped out & replaced.

I notice the Uckfield line has long stretches of Southern Region concrete sleepers with holes for fitting third rail in every sleeper.
Probably the same on the North Downs line & parts of Ore to Ashford.

 

[Bald Rick]

On the subject of AC OLE electrification vs DC third rail electrification, I find it really interesting that there are regular threads for when there is disruption caused by the OLE system failing, it rarely when the DC system fails.

Today for example we have had the wires down at Biggleswade, causing disruption and much comment on a dedicated thread. But not a whisper about the stranded trains and 5 hours of disruption caused by a DC short circuit at Hither Green this afternoon, which trashed a fair portion of Southeasterns services today.

== Doublepost prevention - post automatically merged: 16 Aug 2022 ==

This did not happen when the East Grinstead line was electrified from South Croydon.
Nor did it happen when North woolwich on the North London line was third railed in a weekend in the 1980’s.

And I watched them third railing the long siding at Eastleigh a year or two ago into the siding fan where the poor sad 701’s live.
Nothing was ripped out & replaced.

err, that’s because the question I was answering is: ‘if It was electrified with third rail now, and subsequently converted to 25kV AC, could the electrical equipment (except the third rail) be reused or would it all need to be ripped out’.

that‘s a rather different question to ‘what needs doing to electrify to third rail’ - which is the question you have answered.

I notice the Uckfield line has long stretches of Southern Region concrete sleepers with holes for fitting third rail in every sleeper.
Probably the same on the North Downs line & parts of Ore to Ashford.

You probably haven’t noticed the stretches of steel sleepers on the North Downs then. They would have to come out.

 

[73128]

That is a bit of a leap. The 769s seem to work to some extent. The working conditions for traincrew on 769s aren't acceptable in the modern age.


No, it is to keep the Turbos going doing the work they have been doing for the last 30 years.


Reading to Basingstoke wasn't due for electrification. 769s were never intended for Didcot to Oxford.

769s weren't directly linked to failure of the electrification plans not being completed. They were a way of releasing Turbos for other work.

Reading to Basingstoke (and to Oxford and Nuneaton via Coventry) was part of the electric spine, along with to Milton Keynes via Oxford Parkway). Mind you it would be more sensible to continue the ac via Salisbury to Southampton (for freights) and then to use this as a basis for later continuing the wires to Exeter (and Westbury) to join up with WR schemes. Better electrify more routes and replace the use of diesel traction than fiddle round converting the route through the tunnels to Winchester at this stage

 

[zwk500]

On the subject of AC OLE electrification vs DC third rail electrification, I find it really interesting that there are regular threads for when there is disruption caused by the OLE system failing, it rarely when the DC system fails.

Today for example we have had the wires down at Biggleswade, causing disruption and much comment on a dedicated thread. But not a whisper about the stranded trains and 5 hours of disruption caused by a DC short circuit at Hither Green this afternoon, which trashed a fair portion of Southeasterns services today.

Tbf, the Thameslink thread hasn't been short on complaints about the service south of the river! (Although I concede the discussion doesn't blame 3rd rail explicitly).
EDIT: speak of the devil and he shall appear: https://www.railforums.co.uk/threads/power-failure-outside-hither-green-today.235863/

I'd be interested to see a minutes-per-train/km or similar performance breakdown of delays caused by OLE vs 3rd rail problems.

 

[Bald Rick]

I'd be interested to see a minutes-per-train/km or similar performance breakdown of delays caused by OLE vs 3rd rail problems.

So would I! But of the whole system process related to OLE or 3rd rail, and not just issues specifically related to those assets. And preferably on a per passenger km basis, not train km.

I’m reasonably sure I know which would come out better, and it’s in the air (most of the time)

 

[zwk500]

So would I! But of the whole system process related to OLE or 3rd rail, and not just issues specifically related to those assets. And preferably on a per passenger km basis, not train km.

Good luck working out the delay codes to include in that search! Mind you, Capacity Planning have just created a new (sort of) Performance and Simulation team, the head of which has been very helpful to me in my former life.

I’m reasonably sure I know which would come out better, and it’s in the air (most of the time)

It's almost as if there's a reason Us and most of the world have chose one system over the other for new railways...