My proposal to get rid of 3rd rail and convert routes to overhead lines

[21C101]

There's still places where 3rd rail is needed. Ore - Ashford for one, maybe also Appledore - Lydd too, allowing the reintroduction of passenger services to Lydd.

Ore to Ashford is the one remaining Southern passenger line east of the Waterloo to Weymouth line that I would electrify with 25kV.

Plenty of 25kV at Ashford so you could string wires most of the way without needing any substations or feeder points.

Then switch to third rail at somewhere like Doleham so you are spared the effort of getting the knitting through the tunnel near Ore and spared having to AC immunise all the signalling in the Hastings area.

And if electrified, however done, the service would likely comprise Javelins or similar coming from St Pancras over HS1s 25kV.

At the end of the day it is politically impossible to convert DC to AC until a huge chunk of diesel is done first. Then obvious candidates like Southampton- Basingstoke get converted then all the rest. Will not happen in my lifetime.

Would make more sense to electrify Reading , Basingstoke, Salisbury (including the laverstock loop) Redbridge with 25kV and send all rather than some of the freightliners that way with through roads at Andover to allow passenger services to pass them.

The bridge replacements that have been required because of electrification have been of considerable benefit to both road and railway users. We should be treating them not as an inconvenient cost associated with electrification, but a separate infrastructure enhancement in their own right.

We've put in new bridges which, for the first time, have had pavements, street lights and safe walking routes enabled, we've taken away weight limits letting refuse collection and delivery vehicles more easily get to households, and we've doubled carriageway widths, eliminating traffic light control across bridges. We've done all that whilst adding parapets and barriers that meet current Highways England guidance and minimise the risk of vehicular incursion onto the railway below, no risk of cement mixers falling on Mark 3 EMUs for our newly wired routes...

Increasing NHS cancer funding etc tends to give greater social benefits than replacing non life expired bridges so tends to win the funding battle.

There is also the slight issue of immunising all the signalling which would be a barrel of laughs on the Southern, especially as you would have to immunise for both ac and dc to cover the changeover period.

It wasn't cheap electrification it was designed to be cost efficient with a trade off to be as resilient as funds would afford.

The alternative was a slow progressive decline to eventual closure but what we delivered were routes that were rejuvenated through the sparks effect.

Quite. BR didn't let the perfect be the
enemy of the good.

It could conceivably be 30 seconds a stop.


You couldn’t. That’s not the point. The point is that by accelerating off the juice you are not calling on the battery.


There aren’t any. But they have been looked into, at least twice, and Vivarail have developed the concept. But if we waited before having proven technology in service before adopting it, we’d still be walking everywhere barefoot.

If the Uckfield line trains carried on to Lewes and then ran on quite slowly to Seaford and back on the third rail (1930s infrastructure so plenty of capacity unlike the value engineered South Croydon to EG 1980s stuff), then battery operating the Uckfield line would be easier. I doubt either will happen though given that the government has discovered third rail is cheaper than 25kV and has asked RSSB to find a safe way of doing third rail infils like Uckfield without HMRI having kittens.

 

[Philip Phlopp]

Increasing NHS cancer funding etc tends to give greater social benefits than replacing non life expired bridges so tends to win the funding battle.

What does this drivel have to do with infrastructure improvements ?

 

[21C101]

What does this drivel have to do with infrastructure improvements ?

Everything. Every infrastructure improvement funded by the government has to compete for funds with the NHS, Schools and a dozen other priorities.

So if it is not going to deliver a clear benefit like faster or more frequent rail services (or stop the railway or road if not done by becoming too dangerous to use) it aint going to happen other than for a tiny minority of bridges that are bad enough accident blackspots to get politicians attention.

Yes it might give a nicer wider road with a nice pavement in some places but for 90% of bridges in south London and semi urbanised Surrey/West Kent (which is where most of the third rail bridges concerned are) thats a very dubious claim.

.

 

[Bald Rick]

If the Uckfield line trains carried on to Lewes and then ran on quite slowly to Seaford and back on the third rail (1930s infrastructure so plenty of capacity unlike the value engineered South Croydon to EG 1980s stuff), then battery operating the Uckfield line would be easier.

I’m sorry - building 8 miles of new railway at a cost of about £300m, which would take 10 years, would be easier than putting a slightly bigger battery on about a dozen units?

 

[Philip Phlopp]

I’m sorry - building 8 miles of new railway at a cost of about £300m, wh I have would take 10 years if, would be easier than putting a slightly bigger battery on about a dozen units?

It's OK though, that £300m quid is coming from starving illiterate schoolchildren with cancer...

 

[21C101]

I’m sorry - building 8 miles of new railway at a cost of about £300m, which would take 10 years, would be easier than putting a slightly bigger battery on about a dozen units?

I shouldn't worry, reopening to Lewes isn't going to happen however much the government puts in the Beeching Reversal Fund unless there is a Damascne conversion at East Sussex Council, and battery operation of the Uckfield line won't happen either.

Reigate to Shalford and the North Camp gap look a better bet for battery operation.

 

[Energy]

I’m sorry - building 8 miles of new railway at a cost of about £300m, which would take 10 years, would be easier than putting a slightly bigger battery on about a dozen units?

The line is roughly 28km double track with the remaining 12km single track, assuming that double track is double the price of single track the price of electrifying the line is about 68 million assuming its £1 million per single track km. So significantly cheaper than building new track, which still requires batteries.

 

[paul1609]

I’m sorry - building 8 miles of new railway at a cost of about £300m, which would take 10 years, would be easier than putting a slightly bigger battery on about a dozen units?

With the introduction of Baldricks Barmy Batterystars due next year has the first unit gone for conversion yet? My moneys on the 171s seeing out their days on the Uckfield and Marshlink lines.

 

[21C101]

With the introduction of Baldricks Barmy Batterystars due next year has the first unit gone for conversion yet? My moneys on the 171s seeing out their days on the Uckfield and Marshlink lines.

More likely the battery trains go to Reading Gatwick and the 319s with transit engines 769s being transferred to Uckfield I suspect.

 

[paul1609]

More likely the battery trains go to Reading Gatwick and the 319s with transit engines 769s being transferred to Uckfield I suspect.

Quite fancy a 500hp 12 litre transit. Do the 769s have selective door opening for Marshlink?

 

[SouthCentral10]

More likely the battery trains go to Reading Gatwick and the 319s with transit engines 769s being transferred to Uckfield I suspect.

IIRC I don't think the BR MK3 bodyshells would fit through the Oxted tunnel.

 

[Nicholas Lewis]

If the Uckfield line trains carried on to Lewes and then ran on quite slowly to Seaford and back on the third rail (1930s infrastructure so plenty of capacity unlike the value engineered South Croydon to EG 1980s stuff), then battery operating the Uckfield line would be easier.

BR was in survival mode in the 1980's and it made the pounds go a long way that kept lines to E.Grinstead from closing and the fact they became a success as a result of those actions should be celebrated as thats the reason they were never closed and we can debate how to improve them further now. If only we had someone like Gordon Pettit around today who had the vision and leadership to drive things forward We didn't spend half the budget on options with consultants we just gone on with it and delivered for the travelling public.

 

[21C101]

Quite fancy a 500hp 12 litre transit. Do the 769s have selective door opening for Marshlink?

I don't know but I suspect they will have to be so fitted to work Reading to Redhill stoppers and the Marlowe branch etc.

I would imagine that if it is electrified at 25kV as far as Three Oaks with a short 750V third rail extension through the tunnel to Ore, with St Pancras to Eastbourne via Ashford and Hastings Javelin services, it will get platforms extended to at least six car.

I hope that they do that, as a journey time of an hour from London to Hastings would transform it's prospects. The track alterations at Ashford are probably going to cost a bit though and they might have to redouble at least a dynamic loop somewhere to avoid importing single line delays to HS1, as well as upgrading Winchelsea LC (and hopefully diverting the A259 for a mile to get rid of Star and East Guldeford AHBs)

 

[DJ_K666]

I shouldn't worry, reopening to Lewes isn't going to happen however much the government puts in the Beeching Reversal Fund unless there is a Damascne conversion at East Sussex Council, and battery operation of the Uckfield line won't happen either.

Reigate to Shalford and the North Camp gap look a better bet for battery operation.

Unfortunately that could be true. I'll be really pleased if it isn't, though as I feel the line ought not to have closed if not for ESCC touching it inappropriately. The BML2 campaign has upgraded to a new set of crayons however. next step. Felt tips!
I reckon ESCC can be leapfrogged and certain councillors ability to block it removed. Remember the 2008 study was to try and get Government funding via local authorities and central Government, kind of like a consortium. Unfortunately ESCC brought in its usual demolition squad, Mott McDonald and had them do a very very restricted scope study to make sure it got a poor business case. It's almost like ESCC are allergic to anything positive about railways. I did actually speak to a County councillor while doing Railway Replacement bus work at Lewes and very pointedly said "You've got to get the line to Uckfield open as soon as possible" and she said very quickly "Yes!"

 

[paul1609]

Unfortunately that could be true. I'll be really pleased if it isn't, though as I feel the line ought not to have closed if not for ESCC touching it inappropriately. The BML2 campaign has upgraded to a new set of crayons however. next step. Felt tips!
I reckon ESCC can be leapfrogged and certain councillors ability to block it removed. Remember the 2008 study was to try and get Government funding via local authorities and central Government, kind of like a consortium. Unfortunately ESCC brought in its usual demolition squad, Mott McDonald and had them do a very very restricted scope study to make sure it got a poor business case. It's almost like ESCC are allergic to anything positive about railways. I did actually speak to a County councillor while doing Railway Replacement bus work at Lewes and very pointedly said "You've got to get the line to Uckfield open as soon as possible" and she said very quickly "Yes!"

Not sure that ESCC is anti the re-opening tbh. Generally they are quite positive about public transport. What really destroyed the cost benefit case for the re-opening was the rail industry insistence that 5 very quiet C class roads and Uckfield High Street that were previously level crossings were crossed with full rail industry gold plated bridges (everybody understood that the A22 Uckfield bypass needed a bridge). If you push up the costs so much eventually it won't fly.
It's unfortunate that most of the housing development in the Lewes to Uckfield gap has taken place away from the line in villages like Ringmer where there is easy access to Lewes main line station.
ESCC even at the time of closure wanted the line diverted at its Southern End to the original route the blood for the closure was fully on the hands of BR and the government not really local government.

 

[Bald Rick]

What really destroyed the cost benefit case for the re-opening was the rail industry insistence that 5 very quiet C class roads and Uckfield High Street that were previously level crossings were crossed with full rail industry gold plated bridges (everybody understood that the A22 Uckfield bypass needed a bridge).

That’s not true. The business case didn’t work simply because there wasn’t enough passenger demand. The business case was tested with level crossings, and was worse, as the whole life cost of a new highway level crossing on a new line is more than a bridge.

 

[paul1609]

That’s not true. The business case didn’t work simply because there wasn’t enough passenger demand. The business case was tested with level crossings, and was worse, as the whole life cost of a new highway level crossing on a new line is more than a bridge.

Of course if the level crossings are expensive enough and the passenger figures are depressed enough thats true. On the similar era re-opening Stirling to Alloa a similar number of much busier level crossings were simply re-opened with new barriers. The passenger numbers exceed the estimates by a factor of three within the first year of re-opening.

 

[mr_jrt]

I'm curious...would bridging the roads through Uckfield mean a massive new embankment through the town or viaduct with an elevated station on it, or road underpasses?

 

[paul1609]

I'm curious...would bridging the roads through Uckfield mean a massive new embankment through the town or viaduct with an elevated station on it, or road underpasses?

The 2008 plan was a road over bridge funded by ESCC roughly where the old station building was.

 

[Bald Rick]

Of course if the level crossings are expensive enough and the passenger figures are depressed enough thats true.

You are implying that the costs and passenger numbers were somehow falsified. Evidence?

On the similar era re-opening Stirling to Alloa a similar number of much busier level crossings were simply re-opened with new barriers.

If you know that line you’ll know that a) the line and crossings were already in existence, and therefore it wasn’t a line reopening as such, b) the crossings were upgraded (expensively), and c) none of them are remotely busy, and neither are any of them busier than the roads at Uckfield, Isfield, or Barcombe.

The passenger numbers exceed the estimates by a factor of three within the first year of re-opening.

And have stayed the same ever since. Whereas the business case assumed growth. It seems the growth all came in year 1.

 

[paul1609]

You are implying that the costs and passenger numbers were somehow falsified. Evidence?



If you know that line you’ll know that a) the line and crossings were already in existence, and therefore it wasn’t a line reopening as such, b) the crossings were upgraded (expensively), and c) none of them are remotely busy, and neither are any of them busier than the roads at Uckfield, Isfield, or Barcombe.



And have stayed the same ever since. Whereas the business case assumed growth. It seems the growth all came in year 1.

No I'm saying that very different attitudes applied in Scotland to Sussex by the national government and the rail industry.

a)That is not correct, the line had closed in 1988, some of the rail still remained in place derelict, some had been completely removed along with some of the level crossings. The excellent Railscot site has several photos providing evidence.
b) they weren't upgraded the line hadn't seen a train in 20 years. If the Uckfield Line Criterior had been applied they should have all been replaced by bridges.
c) that is not correct either, some of the crossings give major access to industrial sites including Diadgeos major warehousing facilities with hundreds of hgv movements per day. There is nothing approaching that on Uckfield - Lewes. https://www.google.co.uk/maps/@56.1321253,-3.8693956,3a,75y,186.86h,90t/data=!3m7!1e1!3m5!1sWy18TFh3omfpQVCELb7glw!2e0!6s//geo2.ggpht.com/cbk?panoid=Wy18TFh3omfpQVCELb7glw&output=thumbnail&cb_client=search.revgeo_and_fetch.gps&thumb=2&w=96&h=64&yaw=186.86087&pitch=0&thumbfov=100!7i13312!8i6656 (This is one of the stretches that the track had been completely removed from)

The electrification and through services to Glasgow only started in December 2018. The figures won't reflect that yet.

 

[zwk500]

Long post, please bear with:

No I'm saying that very different attitudes applied in Scotland to Sussex by the national government and the rail industry.

Important to bear in mind who's providing the money each organisation is spending.

b) they weren't upgraded the line hadn't seen a train in 20 years. If the Uckfield Line Criterior had been applied they should have all been replaced by bridges.

*Criteria (multiple), or criterion (singular), and it's not specific to the Lewes-Uckfield line but the current national standards. Also, there's a massive difference between a line that's formally still open and a line that has not physcially existied for 50 years, regardless of traffic. I don't know why, but there is.

c) that is not correct either, some of the crossings give major access to industrial sites including Diadgeos major warehousing facilities with hundreds of hgv movements per day. There is nothing approaching that on Uckfield - Lewes.

Don't underestimate the amount of seasonal farm traffic in Sussex, and generally rubbish connections other than to London. Including rubbish connections between London Radials. Lots of small pockets of industry generating HGV movements over country lanes masquerading as A roads from miles and miles away that you wouldn't think of looking at Google maps.

I'm curious...would bridging the roads through Uckfield mean a massive new embankment through the town or viaduct with an elevated station on it, or road underpasses?

River Uck floods pretty regularly, no way is a new road going anywhere other than over the top. The last proposal I saw (2012? consultation, ended up with wider pavements only) was for the northern end to be basically where the bus station is, and the southern end to face Bridge Farm Road.

Not sure that ESCC is anti the re-opening tbh. Generally they are quite positive about public transport.

My impression was always that ESCC were anti-funding the line, not against the line per se.

It's unfortunate that most of the housing development in the Lewes to Uckfield gap has taken place away from the line in villages like Ringmer where there is easy access to Lewes main line station.

Lots of housing development has taken place in Uckfield as well. Ringmer is popular because it's the only flat, open land that isn't a floodplain or a National Park. Also, if you think Ringmer has 'easy' access to Lewes and it's station you've clearly never tried to do that journey on a weekday morning.

ESCC even at the time of closure wanted the line diverted at its Southern End to the original route the blood for the closure was fully on the hands of BR and the government not really local government.

ESCC wanted the line out of it's way for it's proposed relief road (it's incredible what people proposed in the 60s), it wasn't particularly bothered what happened to the railway. BR did petition government for funds to restore the Hamsey Link (which is now the main focus of re-opening) to keep the line open, but Westminster said no so BR was left with only 1 way out.

All of this has got rather far from the topic of converting 3rd Rail to OHL, to which I'd agree with Bald Rick about extending the 3rd rail from Hurst green a little and using battery units on Uckfield-Hurst green. I'd also look at rapid charge facilities at uckfield and Rye to allow battery operation of Marshlink. Hastings will not be turned around by a 60min connection to London, nor is it feasible to add the connections without completely removing the Eurostar platforms.
For the rest, budget notwithstanding I'd pick routes already partially served by OHL (or with potential to be) and push the wires down. Reading-Basingstoke-Andover-Redbridge would probably be first target, then Weymouth-Soton-Eastleigh-Basingstoke, etc. Keep Pushing eastwards with a full-time permanent team and eventually we'd be standardised. It's a wonderful dream....

 

[Bald Rick]

The electrification and through services to Glasgow only started in December 2018. The figures won't reflect that yet.

Ok, I stand corrected on some of what you say, although I’d contend that Uckfield High Street is busier than any of the roads over crossings on the Alloa line.

Also the Alloa line was authorised in 2004, which was before the ORR got tough on its Level Crossings policy (in 2005, following Upton Nervet and Elsenham). I happen to know that the ORR got rather shirty about the Alloa line at opening, and made the point that they wouldn’t be allowing crossings on such lines in future. And so it has proved.

The point about electrification and through services to Glasgow is irrelevant. That was a separate project with a separate business case, delivered a decade later. The point is that the business case assumed growth after reopening, and that didn’t happen.


Anyway back on topic.

The complexities involved in converting 3R D.C. to OLE AC are rather significant; sufficiently so that it is expensive and thus rarely done, and notably usually in a big blockade (as per the North London Line, twice).

 

[Metal_gee_man]

Remember that lots of the OHLE is cheap BR electrification, you don't hear the wires on HS1 coming down much.

The lines have come down at least once on HS1, I remember having a nightmare journey from Stratford Int in Sept 2015 the RWC was on, I went to see SA vs USA at the London Stadium and the wires came down in the station on top of a 395 in Stratford Station.
The LST services and the Jubilee line took a lot of passengers that day 3hrs later I got back to Canterbury

 

[zwk500]

The lines have come down at least once on HS1, I remember having a nightmare journey from Stratford Int in Sept 2015 the RWC was on, I went to see SA vs USA at the London Stadium and the wires came down in the station on top of a 395 in Stratford Station.
The LST services and the Jubilee line took a lot of passengers that day 3hrs later I got back to Canterbury

To be fair, Energy said you don't hear [about] the wires coming down 'much', not ever. Any mechanical and electrical system can (will) fail, it's impossible to prevent.

 

[paul1609]

All of this has got rather far from the topic of converting 3rd Rail to OHL, to which I'd agree with Bald Rick about extending the 3rd rail from Hurst green a little and using battery units on Uckfield-Hurst green. I'd also look at rapid charge facilities at uckfield and Rye to allow battery operation of Marshlink. Hastings will not be turned around by a 60min connection to London, nor is it feasible to add the connections without completely removing the Eurostar platforms.
For the rest, budget notwithstanding I'd pick routes already partially served by OHL (or with potential to be) and push the wires down. Reading-Basingstoke-Andover-Redbridge would probably be first target, then Weymouth-Soton-Eastleigh-Basingstoke, etc. Keep Pushing eastwards with a full-time permanent team and eventually we'd be standardised. It's a wonderful dream....

So quite how are Baldricks Barmy Batterystars going to work when they are introduced in 9 months time?
The are apparently going to be accelerating off the end of their specially installed extension rails drawing max current through one conductor shoe?
Presumably then the batteries are going to be floating on the 750vdc supply system to allow a smooth transition to battery power?
All this on a 20 year old multiple unit with a control system that runs on Windows 95 and has a 50/50 chance of throwing a tantrum when changing from ac to dc on the move.
The batteries that are crammed underneath are indeed going to be super duper when they can be recharged during a 2 minute station stop at Rye or even a 10 minute turnaround at Uckfield,even from the super high energy conductor rail that the ORR are going to authorise alongside the platforms despite those locations being the highest electrocution risk.
As for Ashford International your statement is complete tosh. The latest NR plan is for a new platform 2A to be built on the site of the dc through roads. The dc through roads were originally for non stop Eurostars before HS1 opened. Since then they've been used by empty stock movements and about 2 freight trains per day, all of which can be accommodated through the currently disused platforms 3/4.

 

[zwk500]

So quite how are Baldricks Barmy Batterystars going to work when they are introduced in 9 months time?

Who said anything about 9 months, the turbostars aren't going anywhere. Also worth pointing out, as has been done to me, that battery operation is already in use abroad without issue. Austria & Germany are testing units with ranges of 80km and speeds of 100kph. The Uckfield line, for reference, is 25m/40km and 70mph/115kph.

The are apparently going to be accelerating off the end of their specially installed extension rails drawing max current through one conductor shoe?

They would have all shoes on for getting away from a stand (the difficult bit), and the rails would be installed for long enough for them to get to 40-50mph.

Presumably then the batteries are going to be floating on the 750vdc supply system to allow a smooth transition to battery power?
All this on a 20 year old multiple unit with a control system that runs on Windows 95 and has a 50/50 chance of throwing a tantrum when changing from ac to dc on the move.

I've not said anything about tacking them under an electrostar, just that units with batteries on them should be used. And given the MK-Clapham Jn service rarely has an issue changing power I'd say 50/50 is a bit of an exaggeration.

The batteries that are crammed underneath are indeed going to be super duper when they can be recharged during a 2 minute station stop at Rye or even a 10 minute turnaround at Uckfield,even from the super high energy conductor rail that the ORR are going to authorise alongside the platforms despite those locations being the highest electrocution risk.

The fast-charge would be equivalent to a 'splash and dash', not charging the whole thing up. The times at Rye would probably have to be extended if it was decided to use it as a charging station. You'd have an inductive loop/conductor plate in the centre of the track, activated by a beacon on the train so it's only ever live when the train is on top of it, like APS. The substantial charging would be done between Hastings-Eastbourne or Hurst Green-London Bridge. Rye may not even be needed, if the turnround at Ashford gave sufficient time to charge.

As for Ashford International your statement is complete tosh. The latest NR plan is for a new platform 2A to be built on the site of the dc through roads.

Do you have a link to this plan from a NR source? Because adding a platform 2A that allows Hastings-Tonbridge trains is fairly straightforward. Adding one that allows Hastings-HS1 trains is very much not. I'd also be interested to see if this plan was floated under the previous MP for Hastings, and how seriously it has been pursued since she left office.

The dc through roads were originally for non stop Eurostars before HS1 opened. Since then they've been used by empty stock movements and about 2 freight trains per day, all of which can be accommodated through the currently disused platforms 3/4.

The DC through roads were originally for non-stop boat trains and freight to Dover, and date from the SECR. The through lines are currently booked to be used by 1 or 2 trains per hour. RTT list Although the actual number of trains that use these paths is lower, you still have to account for all of them. Platforms 3/4 are temporarily mothballed by Eurostar, but are highly likely to be reinstated once the economic conditions recover. There's also the complication of 3/4 being designated 'Airside' for border security, and if domestic & international trains were to both be routed through there it could potentially cause issues. Nothing insurmountable, but adds to the operating cost. There's also the additional crossing moves to be considered, with the potential for more conflicts, and the time penalty to the trains that were able to run through the centre roads at 60 or 90mph, and now have to slow for the crossovers to 3/4.

 

[paul1609]

Who said anything about 9 months, the turbostars aren't going anywhere. Also worth pointing out, as has been done to me, that battery operation is already in use abroad without issue. Austria & Germany are testing units with ranges of 80km and speeds of 100kph. The Uckfield line, for reference, is 25m/40km and 70mph/115kph.

They would have all shoes on for getting away from a stand (the difficult bit), and the rails would be installed for long enough for them to get to 40-50mph.

I've not said anything about tacking them under an electrostar, just that units with batteries on them should be used. And given the MK-Clapham Jn service rarely has an issue changing power I'd say 50/50 is a bit of an exaggeration.

The fast-charge would be equivalent to a 'splash and dash', not charging the whole thing up. The times at Rye would probably have to be extended if it was decided to use it as a charging station. You'd have an inductive loop/conductor plate in the centre of the track, activated by a beacon on the train so it's only ever live when the train is on top of it, like APS. The substantial charging would be done between Hastings-Eastbourne or Hurst Green-London Bridge. Rye may not even be needed, if the turnround at Ashford gave sufficient time to charge.

Do you have a link to this plan from a NR source? Because adding a platform 2A that allows Hastings-Tonbridge trains is fairly straightforward. Adding one that allows Hastings-HS1 trains is very much not. I'd also be interested to see if this plan was floated under the previous MP for Hastings, and how seriously it has been pursued since she left office.

The DC through roads were originally for non-stop boat trains and freight to Dover, and date from the SECR. The through lines are currently booked to be used by 1 or 2 trains per hour. RTT list Although the actual number of trains that use these paths is lower, you still have to account for all of them. Platforms 3/4 are temporarily mothballed by Eurostar, but are highly likely to be reinstated once the economic conditions recover. There's also the complication of 3/4 being designated 'Airside' for border security, and if domestic & international trains were to both be routed through there it could potentially cause issues. Nothing insurmountable, but adds to the operating cost. There's also the additional crossing moves to be considered, with the potential for more conflicts, and the time penalty to the trains that were able to run through the centre roads at 60 or 90mph, and now have to slow for the crossovers to 3/4.

Batterystars:
As far as I aware the plan for the Uckfield Line has always been to fit batteries to existing rolling stock. I believe that when Southern did their original investigation (which dismissed the project as impractical) they considered classes 313 and 377. This was based on the work previously done on the 379 in East Anglia. It seems unlikely that new battery units could have been ordered and commissioned in time for the 171s to be transferred to the midlands.
There are no battery units under test anywhere that:
a) charge off a limited power dc system
b) run in multiples of 10 coaches (like the Uckfield Line)
The 377/2s on the Milton Keynes service stop to change over from ac to dc on the West London Lines. I think if 377s are modified with batteries they would almost certainly stop to change over which makes the extension of the conductor rails pointless.

Ashford International:
The plans for incorporating Marshlink in to HS1 are in the Kent Future Route strategy published in 2018. At the time this was conceived to be a connection to Platform 2 along with ac electrification.
Network Rail has apparently decided its better to remove one of the through lines and build a new platform 2A. The plans were supposed to be published in Spring 2021 see a report of a meeting between the local rail users groups and Network Rail/ TOCs here: https://www.ryenews.org.uk/news/high-speed-rail-getting-closer
All the freight train paths that you mention can be accommodated through the international platforms 3/4 there is no issue with an airside restriction on non stop freight trains. Even assuming Eurostar return to the station there no more than 4 services a day call at these platforms.
Most of the freight trains travel through Ashford quite slowly because they are taking the Maidstone East line there being very few freight paths on the SEML north of Tonbridge.

 

[Nicholas Lewis]

Who said anything about 9 months, the turbostars aren't going anywhere. Also worth pointing out, as has been done to me, that battery operation is already in use abroad without issue. Austria & Germany are testing units with ranges of 80km and speeds of 100kph. The Uckfield line, for reference, is 25m/40km and 70mph/115kph.

The Japanese also have a number of routes running with 20Kv OH / battery powered units built by Hitachi. They are only 2 cars and they quick part recharge every 10km or so because of the hefty hotel load of air con or heating depending on the seasons. This needs factoring in to what level of battery capacity you select which in terms drives sizing of the charging system if your going to recharge in under 10mins. On the Uckfield line only Edenbridge or Uckfield would lend themselves to a cost effective multi MW local grid connection which would be needed. Charging whilst running on third rail could well be limited to times when the train isn't motoring as the units are limited to max line current of 1500Amps/4 car.

 

[Bald Rick]

There are no battery units under test anywhere that:
a) charge off a limited power dc system

Yes there are, including some in this country (Birmingham trams). It’s just a matter of scaling up, noting line capacity limits.

The 377/2s on the Milton Keynes service stop to change over from ac to dc on the West London Lines. I think if 377s are modified with batteries they would almost certainly stop to change over which makes the extension of the conductor rails pointless.

The 377/2 only stop to change over because the former Southern Driver Standards Manager didn’t trust his drivers to do it on the move, specifically raising and lowering the pantograph in the correct location. The MITRAC doesn’t need the train stationary to swap voltages; They are perfectly capable of doing it on the move, as their sister units do several times an hour, in the same place, on London Overground services. Occasionally an LO driver does forget to drop the pantograph, as the various marks on Westway bridge testify.