Great Western Electrification Progress

[47802]

I'm surprised that they've gone ahead with ploughing on to Cardiff, rather than getting Oxford done, if only because that would make it easier to cascade stock and benefit from the faster accelerating and faster top-speed 387s. With all the IEPs being Bi-Mode now, surely it's just a lot easier to leave the intercity routes and focus on the commuter services. The way it's done now, there'll still have to be 90mph 166s taking up valuable Main Line paths between Paddington and Reading, rather than a mix of 125 mph IEPs and 110 mph 387s.

If they go for what appears to be there intended option of IEP's for Oxford fasts and mainly a shuttle service to Didcot to connect with the 387's for stoppers I doubt there will be many 166's services between Paddington and Reading.

 

[YorkshireBear]

Politics - there are more voters in Wales, all of whom might be upset if Cardiff was deferred. I agree that deferring Oxford makes no sense at all. The first thing you want is an electrified network for the high density bits. Unfortunately our new breed of politicians know all the answers.

As above, there is a balance between engineering and operations.... I really don't think the government have made a bad choice in terms of what to 'defer'.

 

[hwl]

Politics - there are more voters in Wales, all of whom might be upset if Cardiff was deferred. I agree that deferring Oxford makes no sense at all. The first thing you want is an electrified network for the high density bits. Unfortunately our new breed of politicians know all the answers.

The welsh section has already been resignalled so they know where the cables are so it is very (i.e. most) efficient use of the HOPS piling equipment at the moment.
Presumably deferring the via Bath route means they can have possessions starting slightly earlier from Swindon to Bristol Parkway to increase working hours and efficiency?

 

[DerekC]

The welsh section has already been resignalled so they know where the cables are so it is very (most) efficient use of the HOPS piling equipment at the moment.

OK - that does make sense, but deferring Oxford still doesn't. I have never been able to follow the logic of IEP - it won't be an efficient commuter train whether electric or bi-mode. Using it for short to medium haul services is a little nuts.

 

[LNW-GW Joint]

Politics - there are more voters in Wales, all of whom might be upset if Cardiff was deferred. I agree that deferring Oxford makes no sense at all. The first thing you want is an electrified network for the high density bits. Unfortunately our new breed of politicians know all the answers.

Oxford is knackered because of late resignalling and repeated changes to the planned layout. Same as Bristol TM really.
Cardiff resignalling just got done early enough not to delay electrification.

 

[Mikey C]

Politics - there are more voters in Wales, all of whom might be upset if Cardiff was deferred. I agree that deferring Oxford makes no sense at all. The first thing you want is an electrified network for the high density bits. Unfortunately our new breed of politicians know all the answers.

The devolved parliament in Cardiff means that Wales would kick up a stink, whereas Bristol doesn't have the same clout...

 

[HSTEd]

Suddenly ECML electrification techniques which produce a lightweight railway at low cost seem rather nice now.
Instead of ECML wiring over the entire route we now have "proper" wiring over half of it with no prospect of ever getting the rest.

 

[hwl]

OK - that does make sense, but deferring Oxford still doesn't. I have never been able to follow the logic of IEP - it won't be an efficient commuter train whether electric or bi-mode. Using it for short to medium haul services is a little nuts.

They got a reasonable bit of the piling done north from Didcot before realising Oxford resignalling was never going to happen in time (June '19? which is just into CP6). They also did the Bridges and Culvert work in August this year, so the sensible (traditional) thing of getting as much of the civils out of the way before sending the electrification teams in is not happening. The actual electrification to Oxford should be pretty quick if everything else has been done by that time.

If you look at the current GOBLin electrification closure it is mainly for the civils work with most (circa 80%) of the piling done before the closure, with mainly bases in station /on viaducts done during the closure along with piling where it doesn't get in the way of the civils work or the engineering trains. Most of the actual electrification work is being done post re-opening

 

[snowball]

Instead of ECML wiring over the entire route we now have "proper" wiring over half of it with no prospect of ever getting the rest.

There's no evidence for that statement. The programme for CP6 has yet to be set. The NAO report seems to take it for granted that the deferred sections will happen in CP6. The reason for the deferral was to keep spending in CP5 within the original limits as far as possible. The sections deferred seem to be the right ones to defer because they depend on preparatory works not yet completed (or indeed sometimes not yet started).

 

[coppercapped]

OK - that does make sense, but deferring Oxford still doesn't. I have never been able to follow the logic of IEP - it won't be an efficient commuter train whether electric or bi-mode. Using it for short to medium haul services is a little nuts.

I don't follow the logic.

These days the Paddington to Bristol service is a short to medium haul route - although when it was first built it was a long distance route! Oxford is part of it as is Newbury.

Although one can argue that the layout of the IEPs is not ideal for a route which can carry large numbers of people and which stops every 20 minutes or so, they have also been designed for longer runs. In this case their use on the Oxford service makes sense. Firstly, of the two fast trains per hour between Paddington and Oxford one forms the hourly service to Morton-in-Marsh, Worcester (and Hereford) for which a bi-mode is ideal. The other train, at the moment, terminates at Oxford although there are longer term wishes to extend it further down the Cotswold line. Secondly, with their 125mph speed they can use the Mains between Didcot and London without reducing the number of paths available.

Using two different types of train for the fast services would make stock planning more difficult than it needs to be - especially if the other stock has a lower top speed it might be necessary to path some of the trains on the Reliefs. As the line limit on these is 100mph this would lengthen journey times.

 

[QueensCurve]

Swansea was a late addition to the electrification project. Short memories on this thread, I think, possibly?

Could it also be an early deletion?

 

[snowball]

Swansea was in the original Adonis announcement of 2009. The coalition government dropped it and added it back, but in recent years its timing has been extremely vague. Earlier there was a fight between DfT and WG over who would pay for it.

 

[DerekC]

I don't follow the logic.

These days the Paddington to Bristol service is a short to medium haul route - although when it was first built it was a long distance route! Oxford is part of it as is Newbury.

Although one can argue that the layout of the IEPs is not ideal for a route which can carry large numbers of people and which stops every 20 minutes or so, they have also been designed for longer runs. In this case their use on the Oxford service makes sense. Firstly, of the two fast trains per hour between Paddington and Oxford one forms the hourly service to Morton-in-Marsh, Worcester (and Hereford) for which a bi-mode is ideal. The other train, at the moment, terminates at Oxford although there are longer term wishes to extend it further down the Cotswold line. Secondly, with their 125mph speed they can use the Mains between Didcot and London without reducing the number of paths available.

Using two different types of train for the fast services would make stock planning more difficult than it needs to be - especially if the other stock has a lower top speed it might be necessary to path some of the trains on the Reliefs. As the line limit on these is 100mph this would lengthen journey times.

The logic is that the IEP design with end doors and vestibules is going to give pretty poor dwell times. It is odd (being polite) that on the Thameslink route which goes to 60 miles plus out of London we have ultra-high capacity Class 700s with everything optimised for fast dwells whereas for Oxford (60 miles out of London) we are using a train which is clearly designed (in terms of its internals) for long distance work. I also think the obsession with journey times is part of the problem. When push really comes to shove in the high capacity game you have to trade journey time for fast acceleration and deceleration. A more logical GWR would have Electrostar/Desiro type units for all services east of Cardiff and a few bi-modes for runs to Taunton and points south-west. We are going to have a bodge for the life of the Class 800s. Sorry, that's probably getting off the point of the thread.

 

[coppercapped]

The logic is that the IEP design with end doors and vestibules is going to give pretty poor dwell times. It is odd (being polite) that on the Thameslink route which goes to 60 miles plus out of London we have ultra-high capacity Class 700s with everything optimised for fast dwells whereas for Oxford (60 miles out of London) we are using a train which is clearly designed (in terms of its internals) for long distance work. I also think the obsession with journey times is part of the problem. When push really comes to shove in the high capacity game you have to trade journey time for fast acceleration and deceleration. A more logical GWR would have Electrostar/Desiro type units for all services east of Cardiff and a few bi-modes for runs to Taunton and points south-west. We are going to have a bodge for the life of the Class 800s. Sorry, that's probably getting off the point of the thread.

Ah! Now I understand. To certain extent I think we are in agreement as that is what I was trying to say when I wrote

Although one can argue that the layout of the IEPs is not ideal for a route which can carry large numbers of people and which stops every 20 minutes or so, they have also been designed for longer runs.

The point is that GWR have ordered a fair number of brand-new Class 387s which, potentially, will be able to run at 110mph in multiple. These will form the bulk of the outer suburban services as far as Newbury, Didcot and Oxford. In Oxford's case they will supply half of the number of off-peak trains - or at least they will when the wires are up! I suspect they will also form some of the peak hour extras to and from Oxford and ease the pressure on the Class 80X/AT300s which will run the longer distance services.

We'll have to see how it all works out - but whichever layout the coach interiors have they will be a compromise between conflicting requirements. See also the thread on the Class 700 where the layout of these trains is considered by many not to be suitable for the longer journeys to Peterborough and elsewhere.

I don't think it is getting off the point of the thread - the electrification hardware is not there just so it looks pretty (huh?!) but in order to be able to provide a reliable, economic and frequent service. Arguably this discussion is the point of the thread!

 

[Hellzapoppin]

The welsh section has already been resignalled so they know where the cables are so it is very (i.e. most) efficient use of the HOPS piling equipment at the moment.
Presumably deferring the via Bath route means they can have possessions starting slightly earlier from Swindon to Bristol Parkway to increase working hours and efficiency?

Actually the fact that the area has been resignalled makes absolutely no difference what so ever to the piling. The same processes apply regardless of whether the cables are in use or not. The only thing it may speed up is the redesign of foundation locations when conflicts arise.

 

[snowball]

Actually the fact that the area has been resignalled makes absolutely no difference what so ever to the piling. The same processes apply regardless of whether the cables are in use or not. The only thing it may speed up is the redesign of foundation locations when conflicts arise.

So how come that we've been told a couple of dozen times that one of the main causes of the delays and cost overruns on the GW electrification has been piling through old signalling cables?

(Edit: or piling so close to cables so fragile with age that they break?)

 

[HSTEd]

There's no evidence for that statement. The programme for CP6 has yet to be set. The NAO report seems to take it for granted that the deferred sections will happen in CP6. The reason for the deferral was to keep spending in CP5 within the original limits as far as possible. The sections deferred seem to be the right ones to defer because they depend on preparatory works not yet completed (or indeed sometimes not yet started).

Under normal circumstances with public sector projects [which this effectively is] "indefinite deferral" is short hand for "we are cancelling it but don't dare announce that we are doing so".

If for no other reason that it would hand the Oxford anti electrification NIMBYs a huge propaganda victory and set a dangerous precedent. And the excoriation of the government in the press for commiting all this stuff and then abandoning half of it would be painful considering its very small working majority.

 

[YorkshireBear]

Actually the fact that the area has been resignalled makes absolutely no difference what so ever to the piling. The same processes apply regardless of whether the cables are in use or not. The only thing it may speed up is the redesign of foundation locations when conflicts arise.

The main point of recently re-signalled is that these conflicts are much more unlikely to arise reducing cost and time taken.

 

[snowball]

Under normal circumstances with public sector projects [which this effectively is] "indefinite deferral" is short hand for "we are cancelling it but don't dare announce that we are doing so".

As a long-term watcher of the road programme I've seen lots of projects removed from the programme, put back, removed again, put back again, and eventually built.

MML and TP have already been paused and unpaused again.

Are you saying all electrification will stop at the end of CP5?

 

[ian959]

Can't see the Marlow branch ever being knitted unless some company comes up with a viable 2 car AC unit or the branch goes over to using trams

I am forever puzzled by this issue with "viable 2 car AC units" given that relatively comfortable, air conditioned 25kv AC EMUs run past my place at least 8 times an hour... how come something that is so easy to do in other countries is so hard to do in the United Kingdom?

The again I still shake my head at governments who think deferring projects creates "savings". No, they create short term changes in budget allocations which ALWAYS leads to overall increased costs when the project (inevitably) gets completed. The staggering short termist views of elected governments are why countries get into infrastructure problems in the first place.

Maybe they should close the National Audit Office instead and make the "savings" there?

 

[SpacePhoenix]

I am forever puzzled by this issue with "viable 2 car AC units" given that relatively comfortable, air conditioned 25kv AC EMUs run past my place at least 8 times an hour... how come something that is so easy to do in other countries is so hard to do in the United Kingdom?

It's about trying to squeeze everything required underneath just two carriages things like compressors, transformers and whatever else is normally found under an EMU (excluding water tanks and toilets)

 

[otomous]

It's about trying to squeeze everything required underneath just two carriages things like compressors, transformers and whatever else is normally found under an EMU (excluding water tanks and toilets)

There are two car EMUs - 456s on South West and 466s on South Eastern. I'm guessing here but the limitation might be that one car has to be a trailer as there isn't room for a compressor and motors etc on one car. Whether new build units that have this vulnerability to motor failure are not permitted any more I don't know. Or it could be that a short production line run of such units is not deemed viable anymore - the ones we have now were built by BR which had the economy of scale.

 

[tbtc]

And to suggest as some have done on here, that it shows what a disaster renationalisation would be, I would say firstly when in the public sector, BR largely decided how to spend the much less money given to it, and secondly the "deeply innefficient" BR managed to electrify three main lines , plus major third rail extensions, plus suburban electrifications round London, Birmingham, Leeds, Manchester, Liverpool, and Glasgow

Yes, BR did a lot over the course of a few decades, some of which was built as planned and some of which was watered down to save money (with some stupid penny pinching/ single tracking – e.g. a hundred metres of siding at Morpeth would have allowed EMUs to operate a Newcastle – Morpeth shuttle).

But much of their experience is as far removed from twenty first century operations as 1960s electrification was to the old Victorian approach (“bring in boat loads of Irish Navvies”).

The world has moved on. Construction is now much more complicated – more expensive – more stakeholders – more environmental concerns – more H&S legislation – more appeals and protests – not just “rail” construction but also roads/ buildings etc.

The railway have moved on – BR had the luxury of being able to shut down lines for prolonged periods to focus on electrification – no such spare capacity nowadays to dump traffic on a parallel route or to close down for weekends.

The Public Sector has moved on – not the stable employer where Governments left Civil Servants/ Teachers/ Doctors alone – permanent restructure is the order of the day now.

The problems we’ve had on the GWML have been because a bit of the State (the publically owned Network Rail) and a branch of Government (the DfT) have failed to price/ manage/ budget/ co-ordinate.

Maybe NR should never have agreed to such an ambitious scheme, for that budget.

Maybe NR should have done some more feasibility before signing up to anything (e.g. something as apparently basic as knowing where your cables are, having up to date inventories).

Maybe NR should focus more on the job in hand, and less on regular restructures.

Maybe lots of things could be handled differently. But, realistically, nationalisation wouldn’t solve any of the problems we’ve had here. And please nobody tell me that the answer is “get rid of all the Accountants and bring in Proper Railwaymen”. We’re not on Sodor any more, Toto.

I think that Bi-modes change everything.

This is because end to end electrification becomes uneconomic and instead you electrify the low cost sections, avoid high cost sections and uprate engines to do 125mph.

GWR have already asked that the Devon banks are electrified in isolation.

Bi-modes do not need end to end wires, but they do need wires on high usage sections (London - Swindon), most 125mph sections and on hilly bits.

Suburban electrification is another matter and that rather than IEPs will drive electrification in the Bristol & Oxford areas.

If you’ll excuse the pseudo-management speak – this is potentially a game changer with lots of low hanging fruit now in play…

We could remove most diesel fumes from Snow Hill/ Moor Street in Birmingham by electrifying the section of that line that gets a ten minute frequency, without the need to wire all the way to Stratford on Avon etc.

We could focus on short sections out of cities (e.g. Newcastle to Metro Centre) without having to have all of the money to wire the quieter/ rural sections beyond (e.g. Metro Centre to Carlisle).

Maybe focus on air quality in London will mean wiring the Chiltern line from Marylebone as far as the M25 (with a ban on any passengers diesels inside the capital?).

We could avoid difficult long term decisions over tricky infrastructure whilst at least electrifying the busy urban bits where air pollution is more of a problem (e.g. as far as Dalmeny without the need to deal with electrification of The Bridge).

If the WAG ever find the funds to match their grand ambitions, I’d expect the line electrified part way up the valleys with no urgency to wire up each individual branch.

The days of the whole electrification budget being swallowed up by one “region” are over – future ambitions could be a hundred miles in one region and a hundred miles in another region.

The idea that if straight electrics were ordered Network Rail would simply just deliver GWML electrification is absurd at best

Agreed – though apparently it needs repeating!

I saw nothing to suggest that anything other than “straight electrics” would be ordered for the MML, yet it was kicked into the long grass, so that resources could be focussed on the GWML – if the GWML really was such a soft touch that it was easy to cancel then how come it was kept alive whilst MML and TPE were being “paused”?

The other problem is that “straight electrics” wouldn’t have worked on the GWML, given the need to keep direct services to Hereford/ Gloucester/ Weston etc.

As above, there is a balance between engineering and operations.... I really don't think the government have made a bad choice in terms of what to 'defer'.

Good summary.

If this means that we get an improved station/ track layout at Oxford and an improved station/ track layout at Bristol then fair enough – a pragmatic compromise that still gives us most of the benefits in the short term, but doesn’t “lock in” unsatisfactory track layouts at busy stations – especially given that both Bristol and Oxford could see suburban enhancements in the medium term that will require capacity increases (i.e. locking in the platform layout and tracks to the 2016 position may not be satisfactory by 2026).

It could even be that they’re being seen to “cancel” it now, so that they can come back in a few months and announce it as a new improved scheme (as per TPE – where the “paused” electrification was used as an opportunity to marry it to better alignments).

Worth remembering that Governments have cancelled entire projects before – the fact that the chaotic GWML is still going to see wires as far as Cardiff shouldn’t be taken for granted.

 

[jimm]

I believe that both Siemens and Bombardier are saying they could offer their newer designs for 125mph (I'm sure I read that in MR mag) both in Intercity configuration.

So this is your idea of an "off-the-shelf" train, is it?

An indication that a train manufacturer could build a 125mph-capable train. Who'd have thought it...?

Which is a world away from such a thing being fully designed, costed, contracts signed, metal cut and a prototype or pre-production version undergoing extensive testing before being unleashed into passenger service.

Rather different from buying a can of beans off the shelf at Tesco.

The way it's done now, there'll still have to be 90mph 166s taking up valuable Main Line paths between Paddington and Reading, rather than a mix of 125 mph IEPs and 110 mph 387s.

What do you think Turbos will be doing on the fast line? The Newbury wires are going ahead as planned, so no 166s on that run and the Oxford/Cotswold fasts will be IETs, whether 800s or 802s. The only Turbos likely to be seen on the GWML in future anywhere between London and Didcot will be empty stock moves for the Thames Valley branches and remaining diesel duties around Oxford - all using the relief lines, first thing in the morning and late at night.

The logic is that the IEP design with end doors and vestibules is going to give pretty poor dwell times. It is odd (being polite) that on the Thameslink route which goes to 60 miles plus out of London we have ultra-high capacity Class 700s with everything optimised for fast dwells whereas for Oxford (60 miles out of London) we are using a train which is clearly designed (in terms of its internals) for long distance work. I also think the obsession with journey times is part of the problem. When push really comes to shove in the high capacity game you have to trade journey time for fast acceleration and deceleration. A more logical GWR would have Electrostar/Desiro type units for all services east of Cardiff and a few bi-modes for runs to Taunton and points south-west. We are going to have a bodge for the life of the Class 800s. Sorry, that's probably getting off the point of the thread.

Do you actually understand how the Oxford fast service is provided - about half of is already longer-distance, ie to and from the Cotswold Line. That proportion will increase post December 2018 and it will need bi-mode traction.

If the Oxford fasts'off-peak Slough stops are transferred to some other service the only stop IETs on Oxford fasts will be making is Reading - and in the case of both Oxford and Reading the dwell times will never look like a Formula 1 pitstop because of the numbers of people getting off and boarding - so hardly a commuter-style 'stop every five minutes' operation.

Electrostars between London, Cardiff and Bristol? That would go down well with the people who pay £220 for an anytime first class return from Cardiff.

I don't follow the logic.

These days the Paddington to Bristol service is a short to medium haul route - although when it was first built it was a long distance route! Oxford is part of it as is Newbury.

Although one can argue that the layout of the IEPs is not ideal for a route which can carry large numbers of people and which stops every 20 minutes or so, they have also been designed for longer runs. In this case their use on the Oxford service makes sense. Firstly, of the two fast trains per hour between Paddington and Oxford one forms the hourly service to Morton-in-Marsh, Worcester (and Hereford) for which a bi-mode is ideal. The other train, at the moment, terminates at Oxford although there are longer term wishes to extend it further down the Cotswold line. Secondly, with their 125mph speed they can use the Mains between Didcot and London without reducing the number of paths available.

Using two different types of train for the fast services would make stock planning more difficult than it needs to be - especially if the other stock has a lower top speed it might be necessary to path some of the trains on the Reliefs. As the line limit on these is 100mph this would lengthen journey times.

You are right to highlight the IETs' ability to shift a lot of people - and that is just what you need on Oxford fasts - no one does Oxford-London on a Turbo semi-fast now, nor will they on a 387 - so IEPs make perfect sense for the fasts - same as HSTs are clearly the best option to provide the required capacity for much of the day on the route right now.

Also, in the peaks pretty much the entire fast service from Oxford towards London in the morning and back in the evening already comes off/continues on to the Cotswold Line. Post December 2018 it is likely that there will be an extended afternoon/evening period where all the trains - or at least a portion of them - out of London continue up the Cotswold Line, so Class 387s would be no use whatever on the Oxford fasts in that period of the day - when they are eventually able to reach Oxford.

 

[coppercapped]

Yes, BR did a lot over the course of a few decades, some of which was built as planned and some of which was watered down to save money (with some stupid penny pinching/ single tracking – e.g. a hundred metres of siding at Morpeth would have allowed EMUs to operate a Newcastle – Morpeth shuttle).

But much of their experience is as far removed from twenty first century operations as 1960s electrification was to the old Victorian approach (“bring in boat loads of Irish Navvies”).

The world has moved on. Construction is now much more complicated – more expensive – more stakeholders – more environmental concerns – more H&S legislation – more appeals and protests – not just “rail” construction but also roads/ buildings etc.

<BIG SNIP of good stuff!>

Worth remembering that Governments have cancelled entire projects before – the fact that the chaotic GWML is still going to see wires as far as Cardiff shouldn’t be taken for granted.

A very clear summary - but I suspect it won't convince those whose minds are already made up.

It is also worth pointing out - again - that one of the other significant reasons for the delay is that there is a critical shortage of signal engineers for all of the three main aspects of re-signalling: design, installation and commissioning.

Until the civils work and the re-signalling is complete it does not make sense - or is even possible - to electrify.

 

[The Ham]

A very clear summary - but I suspect it won't convince those whose minds are already made up.

It is also worth pointing out - again - that one of the other significant reasons for the delay is that there is a critical shortage of signal engineers for all of the three main aspects of re-signalling: design, installation and commissioning.

Until the civils work and the re-signalling is complete it does not make sense - or is even possible - to electrify.

Quite. to continue would be akin to trying to fit a kitchen when you don't know where your cables and gas pipes are and you need to rewire the house as well as have plans to buy a new cooker and fridge where you think that you might want something a bit bigger than what you have at present.

 

[HSTEd]

It's about trying to squeeze everything required underneath just two carriages things like compressors, transformers and whatever else is normally found under an EMU (excluding water tanks and toilets)

And yet BR EMUs have been built that have effectively all the traction related equipment on one vehicle.
--- old post above --- --- new post below ---

As a long-term watcher of the road programme I've seen lots of projects removed from the programme, put back, removed again, put back again, and eventually built.

The road programme is a different kettle of fish however - as roads are almost always vote winners in the long run. Noone really cares about railways to the same degree.

Are you saying all electrification will stop at the end of CP5?

Why wouldn't it - now that we have seen that the "network effect" is well and truly dead, with mass purchases of electrodiesels of multiple types (we now have Stadler EDs for Anglia after all) - there is no reason to electrify any line which does not have the traffic to justify it on that specific section.

And almost all of those lines are already done, the only ones left are the MML but with the annihilation of London-MML traffic North of Derby/Nottingham the remaining scheme is reduced to something resembling an infill project.

Overspeccing of the electrification projects to enable "minimum life-cycle cost" [a laudable aim] has left the headline costs so high that the politicians have decided it is cheaper not to bother. The programme is on the verge of total collapse given the constant overspends and delays on the GWML.

 

[DY444]

It's about trying to squeeze everything required underneath just two carriages things like compressors, transformers and whatever else is normally found under an EMU (excluding water tanks and toilets)

BR built 2 car AC emus so it has been done before.

 

[swt_passenger]

BR built 2 car AC emus so it has been done before.

I've never understood this idea that they cannot be built either.

I'd agree that if newly built they would be an expensive choice as they'd be non-standard, and there'd be increased costs because you'd need a certain size of fleet plus dedicated spares. And small bespoke fleets are always going to be relatively more expensive to run, maintain, etc...

I'd also agree that conversion of an existing three (or four) car might be technically difficult, but it cannot actually be impossible.

Not cost-effective doesn't mean not possible.

 

[edwin_m]

The problem with a 2-car AC EMU is not so much that it might not be feasible, but that it would cost a lot more for a very small demand. All the manufacturers' standard designs for the British market have the pantograph and transformer in an intermediate car, so a non-standard design would be needed to incorporate these in a cab car (with the traction motors in the other cab car which is largely standard).

However in the UK any route that justifies electrification generally has enough passengers to justify at least at 3-car and more usually a 4-car unit. So we're actually talking about a tiny micro-fleet of 2-car units when the manufacturers can make more money with less hassle selling standard units of 3 cars or more. As an extra complication, 2-car AC units might face speed restrictions in multiple, due to the short distance between pantographs.