Third rail is old fashioned and should be done away with

[The Ham]

I suspect that the wholesale replacement of third rail would be something which isn't likely.

BMU's change the picture for replacement a bit. For example IF there was a plan to replace Basingstoke to Southampton (and to wire up to Salisbury from Basingstoke and Southampton) you could potentially put in a (say) 500m gap in the electrification between Basingstoke and Hook as well as where the lines from Eastleigh and St Denys cross the Itchen and again just west of Redbridge. In doing so you remove the complex overlap issues, the distances involved would be short enough that a fairly limited battery would cope with moving the train from a stand 1cm off the point of the last electric pick up to 2km beyond the start of the next.

Such a battery key also aid with extra services to Weymouth or not having to limit acceleration in very busy areas and other issues with the third rail.

What you might be able to sell to the ORR is a compromise where for every 3km of third rail removed from the network 1km of new could be added (i.e. overall the risk would be reduced from the do nothing option).

Given the limited supply on third rail, the use of BMU's for long distance travel beyond the extent of the third rail might not be as straightforward as it is with OHLE where it doesn't have the same power draw issues that third rail has. Not unless the battery has had a lot of time to charge up.

 

[Bikeman78]

That'd go down well in the rest of the country - Billions being spent in the South East to replace one sort of electrification with another.

It was seriously suggested, around 2010 if I recall correctly. 14 years later and I don't think a single mile has been converted. I'm reasonably confident that the same will apply 14 years from now.

== Doublepost prevention - post automatically merged: 4 Jan 2024 ==

Nowhere did I say it should be a shuttle. Uckfield trains absolutely should continue to London. However electrification doesn't allow half-hourly unless you're also redoubling, and Uckfield doesn't need to go half hourly unless it opens through to the coast.

The position of the loops does allow half hourly. Happens in the peaks and there was a DEMU gala weekend in the mid 1990s with half hourly all day. As you say, the demand probably doesn't justify it though.

 

[BrianW]

It was seriously suggested, around 2010 if I recall correctly. 14 years later and I don't think a single mile has been converted. I'm reasonably confident that the same will apply 14 years from now.

== Doublepost prevention - post automatically merged: 4 Jan 2024 ==


The position of the loops does allow half hourly. Happens in the peaks and there was a DEMU gala weekend in the mid 1990s with half hourly all day. As you say, the demand probably doesn't justify it though.

What progress, if any, has been achieved sine the Decarbonisation Strategy of 2020;

https://www.networkrail.co.uk/wp-content/uploads/2020/09/Traction-Decarbonisation-Network-Strategy-Interim-Programme-Business-Case.pdf

p84 sets out a suumary for the Southern region.

Was the document useless; the work worthless?

Strategies need to be AGREED, plans for implementation drawn up and implemented and all plans reviewed and amended as circumstances change. What has changed since that 2020 'vision'?

 

[Richard Scott]

What progress, if any, has been achieved sine the Decarbonisation Strategy of 2020;

https://www.networkrail.co.uk/wp-content/uploads/2020/09/Traction-Decarbonisation-Network-Strategy-Interim-Programme-Business-Case.pdf

p84 sets out a suumary for the Southern region.

Was the document useless; the work worthless?

Strategies need to be AGREED, plans for implementation drawn up and implemented and all plans reviewed and amended as circumstances change. What has changed since that 2020 'vision'?

What's changed is country is broke after blowing a fortune on virus issues.

 

[Bikeman78]

Oh please, the "unauthorised access" argument outside of urban areas is meaningless worry-gutzing.

Given that almost every wall and signalling cabinet is covered in graffiti, there is clearly plenty of trespass throughout London. I expect the amount of trespass at Pluckley, for example, is rather less!

 

[stuu]

What's changed is country is broke after blowing a fortune on virus issues.

It isn't. Anyone who tells you that is either a liar or doesn't understand the basics of economics. A country which issues it's own currency and whose debt is in that currency can never, ever be broke

 

[HSTEd]

It isn't. Anyone who tells you that is either a liar or doesn't understand the basics of economics. A country which issues it's own currency and whose debt is in that currency can never, ever be broke

Well that isn't true in an industrial sense.

You can print all the money you want but printing money doesn't actually make industrial goods and services appear out of thin air.
The national financial position has deteriorated seriously since 2019 and running the printing presses won't change that.

EDIT: To summarise, Printing Money is not a literal ways to Print Money.

== Doublepost prevention - post automatically merged: 4 Jan 2024 ==

Strategies need to be AGREED, plans for implementation drawn up and implemented and all plans reviewed and amended as circumstances change. What has changed since that 2020 'vision'?

Primarily that Network Rail no longer has a blank cheque from the government to spend as much money as it wants, then again the consensus that had enabled that was already collapsing by the time that document was published. Coronavirus merely finished it off.

 

[BrianW]

Primarily that Network Rail no longer has a blank cheque from the government to spend as much money as it wants, then again the consensus that had enabled that was already collapsing by the time that document was published. Coronavirus merely finished it off.

I find it hard to believe that Network Rail ever had a 'blank cheque from the government'.
I do believe that climate change is real and that failure to decarbonise will result in further warming.
There are many warnings which can be looked away from. I shall be alright, living in England's green and pleasant land, but future generations and folk in low lying, arid and weather-torn parts of the world are going to hell on my behalf in hand-carts.

 

[Pigeon]

I would go further and say that there even some obvious short 3rd rail infills that are needed to eliminate diesel

For sure. Any "infill" should use the same system as the tracks it's filling in between. In which context it's useful that the overhead and 3rd-rail areas are neatly separated, and don't even overlap much, so this principle neatly avoids argument over which to use as the choice is obvious (though in areas around London the answer is probably "both").

Mixing AC and DC on the same tracks introduces new issues, and dual voltage EMUs are more complex and heavier because they also need a transformer, so some of the efficency increase in transmission is lost elsewhere.

Somewhere or other you've got to have a transformer to step down from a transmission voltage to something the traction motors are happy with. Indeed, you need lots of them. The choice is basically whether you hang them off the underneath of trains, or build little huts alongside the track to put them in...

Personally I think they're happier and healthier in the huts, where it's nice and dry and doesn't vibrate and crash about...

Which raises the question of what could be done to improve the efficency of the current 3rd rail system. I am assuming that the majority of the losses are caused by resistive losses in the conductor rails, so as conductor rail is replaced could a lower resistance per unit length rail be developed and used?

On the Underground they have become fond of using aluminium conductor rails (with a steel wearing face). They don't seem to be so popular on the national network, but I don't know if there's a proper reason for that or just a sham one. Of course with 3 rails rather than 4 you can only use them for one side of the supply, so the advantage is less.

An alternative would be heavy aluminium bus bars alongside the track with jumpers to the rails (both conductor and running) every few tens of metres, then you're not limited by any need to use conductors that fit the mechanical constraints of existing third rails.

Also, increase the density of transformers in huts (you can make them smaller at the same time) so more of the transmission distance is at high voltage.

Using bidirectional buck/boost converters in the huts instead of plain rectifiers, you can push the actual voltage on the rails higher and closer to the tolerance limit of what it's allowed to be, without exceeding it, and still allow for regeneration.

If you want to get radical, you could go to a four-rail system with one conductor rail at +750V and the other at -750V. Quarter of the losses but no greater potential to ground. You'd need to keep a low-impedance centre tap to ground for compatibility so that stock without the 4th rail pickup could still run, though, which is a bit of a bummer until three-rail stock all ages out.

To answer the OPs question it is 'old fashioned' but the only realistic way of doing away with it would be to revert to diesel operation in much the same way as happened on Tyneside back in the day, and surely no one would suggest that.

Overhead is also old-fashioned. I wouldn't like to put a bet on which came first; just when you thought your money was safe someone would pop out of the woodwork with some incredibly obscure counterexample.

However, we could do with doing away with the use of "old-fashioned" as a pejorative...

 

[HSTEd]

I find it hard to believe that Network Rail ever had a 'blank cheque from the government'.

Ultimately we have lived through three decades of unprecedented public funding being poured into the railway industry.
That era is now ending, and the railway industry will have to alter its expectations accordingly.

I expect, if decarbonisation occurs, it will be based overwhelmingly on battery technologies, unless the ORR can be made to drop its effective ban on third rail.

I do believe that climate change is real and that failure to decarbonise will result in further warming.
There are many warnings which can be looked away from. I shall be alright, living in England's green and pleasant land, but future generations and folk in low lying, arid and weather-torn parts of the world are going to hell on my behalf in hand-carts.

Rail only burns half a million tonnes of fuel oil per year, and diesel hauled traffic is only a relatively small fraction of total rail traffic.
Substantial cuts to that value would be possible with no further electrification using battery systems or even electrodiesels.

If/when road transport decarbonisation is complete, the anachronism of diesel trains will become impossible to sustain and lines that cannot be operated electrically (including via battery) will likely dissapear.

 

[The Ham]

Rail only burns half a million tonnes of fuel oil per year, and diesel hauled traffic is only a relatively small fraction of total rail traffic.
Substantial cuts to that value would be possible with no further electrification using battery systems or even electrodiesels.

If/when road transport decarbonisation is complete, the anachronism of diesel trains will become impossible to sustain and lines that cannot be operated electrically (including via battery) will likely dissapear.

There would be a need for some electrification, for example are you suggesting that Newbury to Penzance would be possible without any extra wires? What about the Devon Metro services?

For both of those a section of wires between Exeter and Plymouth (plus a bit too allow at least the busier used metro services enough time to charge) would likely be needed.

I'm sure that there's other areas which would also need wires to be able to ditch all diesel use but also carry reasonable numbers if passengers.

Elsewhere (based on a £6million per single track km) I worked out that you could probably build the Dawlish Avoiding Line and electric (roughly) Bristol to Plymouth (although you'd probably cut out some sections if main line to cover some of the branches) for around £5bn.

You'd likely need a further section in Cornwall (probably west of Bodmin due to the hills there) and a bit more along the B&H and WofE line to make it work, but that would probably be enough to withdraw a significant percentage (getting on for nearly all) of the diesel burn in the Southwest.

The cost, including probably redoubling of more of the WofE line, probably around £10bn. However, that also includes the potential for some improvements in services at well.

 

[yorksrob]

EDIT: To summarise, Printing Money is not a literal ways to Print Money.

Well, it is - so long as you have the means in terms of population and resources to increase actual wealth alongside it. Of course without the increase in wealth, the ability to import goods and services remains the same.

Increasing transport capacity and transport opportunity can go a long way towards increasing wealth without needing to do too much importing.

 

[HSTEd]

There would be a need for some electrification, for example are you suggesting that Newbury to Penzance would be possible without any extra wires? What about the Devon Metro services?

Electric cars can travel hundreds of miles on a single charge, there is no reason that trains, with their much lower rolling resistance, cannot do the same.
The British Rail BEMU from the Deeside Line experiment had 17 tonnes of batteries on a two-car Derby Lightweight, with modern Li-Ion batteries you will be able to pack a lot of capacity in once you start simply filling any and all available space with batteries.
17 tonnes of 100Wh/kg batteries would be something like 1.7MWh of capacity for a two-car unit!
That's around three hours of full power traction output for a Class 158.

Using traction energy values (~1.7kWh per vehicle km) that's a range of nearly 500km! And that pack specific power is probably highly conservative

A static charging point at a station will be able to pump megawatts into a unit, so I doubt recharging will be particularly expensive compared to the £4m/stkm for 25kV electrification.

For both of those a section of wires between Exeter and Plymouth (plus a bit too allow at least the busier used metro services enough time to charge) would likely be needed.

Exeter to Plymouth is something like 160 single track kilometres, not including Torquay. That's going to cost over £600m, I'm not sure there is going to be money for that!

The cost, including probably redoubling of more of the WofE line, probably around £10bn. However, that also includes the potential for some improvements in services at well.

£10bn is a lot of money in the current environment though.

I'm not convinced its necessary compared to the alternative of simply piling in more batteries.

 

[The Ham]

Electric cars can travel hundreds of miles on a single charge, there is no reason that trains, with their much lower rolling resistance, cannot do the same.
The British Rail BEMU from the Deeside Line experiment had 17 tonnes of batteries on a two-car Derby Lightweight, with modern Li-Ion batteries you will be able to pack a lot of capacity in once you start simply filling any and all available space with batteries.
17 tonnes of 100Wh/kg batteries would be something like 1.7MWh of capacity for a two-car unit!
That's around three hours of full power traction output for a Class 158.

Using traction energy values (~1.7kWh per vehicle km) that's a range of nearly 500km! And that pack specific power is probably highly conservative

A static charging point at a station will be able to pump megawatts into a unit, so I doubt recharging will be particularly expensive compared to the £4m/stkm for 25kV electrification.


Exeter to Plymouth is something like 160 single track kilometres, not including Torquay. That's going to cost over £600m, I'm not sure there is going to be money for that!


£10bn is a lot of money in the current environment though.

I'm not convinced its necessary compared to the alternative of simply piling in more batteries.

Newbury to Penzance and back again is closer to 500 mills than 500km, so you'd have to top up the batteries by a reasonable amount.

Unless you have a fairly significant grid connection (which are a significant percentage of the cost of putting up the wires) you'll not be able to top up all that much at a busy station like Exeter or Plymouth (even with line side batteries as there wouldn't be much time between services to charge the batteries)

Yes £10bn is a lot, however a few things to consider:
- that had also sped up journey times between London and the West Country (Dawlish Avoiding Line and some redoubling of the WofE line)
- it would likely be a rolling program and so you'd probably be able to keep costs broadly at that price, even though inflation would be pushing prices up
- it would likely happen over a decade, so the annual costs would be noticeable, especially given the running costs would fall on lines which currently have intercity rolling stock which isn't due to reach the end of its lease for about 25 years, and there's a good chance that any changes to those trains (like significant batteries being added) would likely incur significant costs.
- whilst each train battery may not cost that much (circa £170,000 based on £100/kWh) the busy sections of line could easily have quite a few direct trains using it - these would need their batteries be replaced at least a few times over their life (you'd also need some spare capacity with the batteries so you don't need to replace elements too often as they degrade, whilst they won't degrade quickly it will be a factor).
- there would be some additional energy losses from the batteries compared to wires, so there would be some additional costs - whilst they may not be large over the course of decades they would mount up

I'm not saying that batteries wouldn't be as significant part of it, just I'm not sure that we could get away with zero additional wires.

 

[RobShipway]

Electric cars can travel hundreds of miles on a single charge, there is no reason that trains, with their much lower rolling resistance, cannot do the same.
The British Rail BEMU from the Deeside Line experiment had 17 tonnes of batteries on a two-car Derby Lightweight, with modern Li-Ion batteries you will be able to pack a lot of capacity in once you start simply filling any and all available space with batteries.
17 tonnes of 100Wh/kg batteries would be something like 1.7MWh of capacity for a two-car unit!
That's around three hours of full power traction output for a Class 158.

Using traction energy values (~1.7kWh per vehicle km) that's a range of nearly 500km! And that pack specific power is probably highly conservative

A static charging point at a station will be able to pump megawatts into a unit, so I doubt recharging will be particularly expensive compared to the £4m/stkm for 25kV electrification.


Exeter to Plymouth is something like 160 single track kilometres, not including Torquay. That's going to cost over £600m, I'm not sure there is going to be money for that!


£10bn is a lot of money in the current environment though.

I'm not convinced its necessary compared to the alternative of simply piling in more batteries.

Newbury to Penzance and back again is closer to 500 mills than 500km, so you'd have to top up the batteries by a reasonable amount.

Unless you have a fairly significant grid connection (which are a significant percentage of the cost of putting up the wires) you'll not be able to top up all that much at a busy station like Exeter or Plymouth (even with line side batteries as there wouldn't be much time between services to charge the batteries)

Yes £10bn is a lot, however a few things to consider:
- that had also sped up journey times between London and the West Country (Dawlish Avoiding Line and some redoubling of the WofE line)
- it would likely be a rolling program and so you'd probably be able to keep costs broadly at that price, even though inflation would be pushing prices up
- it would likely happen over a decade, so the annual costs would be noticeable, especially given the running costs would fall on lines which currently have intercity rolling stock which isn't due to reach the end of its lease for about 25 years, and there's a good chance that any changes to those trains (like significant batteries being added) would likely incur significant costs.
- whilst each train battery may not cost that much (circa £170,000 based on £100/kWh) the busy sections of line could easily have quite a few direct trains using it - these would need their batteries be replaced at least a few times over their life (you'd also need some spare capacity with the batteries so you don't need to replace elements too often as they degrade, whilst they won't degrade quickly it will be a factor).
- there would be some additional energy losses from the batteries compared to wires, so there would be some additional costs - whilst they may not be large over the course of decades they would mount up

I'm not saying that batteries wouldn't be as significant part of it, just I'm not sure that we could get away with zero additional wires.

I think that you also have to remember that there is still a fair bit of electricity generated using fossil fuels, so until the country gets to a point where fossil fuels are not used in generating electricity, is there any point in changing from using diesel?

I personally think that you need to be having as much OHLE as possible between Newbury and Penzance, but for the areas where OHLE is impossible, yes have the trains should be running on battery power rather than diesel. The problem with that is I think that we are a long way from being able to replace the diesel engines under the carriages of the class 8xx trains, such that they would be able to power a train any great distance. A good example of this is the class 803, although I believe it only has one set of batteries within one of the carriages, rather than all 5 carriages per unit. You really need a power unit carriage such as is in the class 755/756 units to be having batteries rather than the diesel engines within it, to be able to be travelling any great distance.

An example of a battery car was used, but look at the weight difference between that car and just one carriage of say a class 8xx train. Also, look at how many batteries a BYd or Tesla car has within them and where they are placed to counter the weight balance. Many of the electric cars currently, are almost twice the weight of cars running on petrol or diesel engines. Yes, batteries are getting lighter. But you need to think of the type of batteries to be used in a train, as there is more than one type and also how many batteries would be needed per carriage for the train to be powered?

In doing this, you also need to be making sure that people can board the doorways of the carriages at platform level. This may limit the space you have below the seating area of the train in each carriage as to how many batteries you can place within it, as you will also need to include safety devices in case of fire to protect the passengers.

 

[D365]

But you need to think of the type of batteries to be used in a train, as there is more than one type and also how many batteries would be needed per carriage for the train to be powered?

In doing this, you also need to be making sure that people can board the doorways of the carriages at platform level. This may limit the space you have below the seating area of the train in each carriage as to how many batteries you can place within it, as you will also need to include safety devices in case of fire to protect the passengers.

There are specialist engineers that do this work for a living… perhaps you fancy retraining?

 

[CarrotPie]

but for the areas where OHLE is impossible

And remind me what was done for the areas of the ECML and WCML where electrification was deemed "impossible"? Oh!

 

[stuu]

Many of the electric cars currently, are almost twice the weight of cars running on petrol or diesel engines. Yes, batteries are getting lighter.

This is nonsense. They are generally around 20-30% heavier than ICE cars

 

[popeter45]

Somebody referenced the underground earlier in the threat as part of the pro 3rd/4th rail argument

Actually the tube is once place batteries could help to remove live rails from the certain areas like stations therefore improving safety via discontunus electrification Vs the current situation

Also do we really need to keep 3rd rail on distance areas like the SWML?, with the amount of dual power units it would make way more sense to change power past Clapham and therefore improving line speed

 

[CarrotPie]

They are generally around 20-30% heavier than ICE cars

What is an ICE car?

Actually the tube is once place batteries could help to remove live rails from the certain areas like stations therefore improving safety via discontunus electrification Vs the current situation

You'd need some beefy batteries to achieve Tube-style acceleration, which would need a lot of space. I remind you that the 2024TS has four bogieless cars, and that's just to fit the aircon in!

Also do we really need to keep 3rd rail on distance areas like the SWML?, with the amount of dual power units it would make way more sense to change power past Clapham and therefore improving line speed

Does the track geometry allow for higher speeds? Is it worth the massive capital expenditure of AC conversion to shave just a couple of minutes of journey times? Surely it'd be cheaper to knock off a station call or two, no?

 

[JamesT]

What is an ICE car?

Internal Combustion Engine, usually petrol/diesel. As opposed to an external combustion engine such as a steam engine.

 

[HSTEd]

I think that you also have to remember that there is still a fair bit of electricity generated using fossil fuels, so until the country gets to a point where fossil fuels are not used in generating electricity, is there any point in changing from using diesel?

Yes, thanks to modern power plants not having to be small and light enough to fit inside a train and produce wildly varying power outputs, they are substantially more efficient than any diesel traction system.

We are already at the point that electric resistive heating is lower carbon than a gas boiler, let alone in terms of a diesel engine versus an electric motor for producing shaft power.

I personally think that you need to be having as much OHLE as possible between Newbury and Penzance, but for the areas where OHLE is impossible, yes have the trains should be running on battery power rather than diesel. The problem with that is I think that we are a long way from being able to replace the diesel engines under the carriages of the class 8xx trains, such that they would be able to power a train any great distance. A good example of this is the class 803, although I believe it only has one set of batteries within one of the carriages, rather than all 5 carriages per unit. You really need a power unit carriage such as is in the class 755/756 units to be having batteries rather than the diesel engines within it, to be able to be travelling any great distance.

It is highly unlikely that retrofit of diesel trains into meaningful battery-electric trains will be practical.
The trains will have to be scrapped and replaced with new ones designed from the ground up to be battery electric trains.

Retrofit is just a hiding to nothing, as it has proven in terms of trying to convert electric trains into diesel ones - it simply isn't worth it 99% of the time.
The electro-diesel class 80x are going to end up having a very short service life and probably should never have been ordered, but we are where we are. Blame the utter failure of the Great Western Electriciation project for the situation we are in now. If we're lucky they can be salvaged to make up 10-car electric-only sets for capacity improvement or to replace the Pendolinos.

 

[CarrotPie]

Internal Combustion Engine, usually petrol/diesel. As opposed to an external combustion engine such as a steam engine.

Ah right, thanks for that.

 

[LBMPSB]

Network Rail estimated in 2012 that up to 27% of power input was lost in the DC transmission system and track power. Hundreds of millions of pounds every year going to waste. It's really not a sensible system for long distance use

Are there any figures for OHL?

 

[renegademaster]

And remind me what was done for the areas of the ECML and WCML where electrification was deemed "impossible"? Oh!

They happened back when nimbys and architectural preservation were less well organized

 

[CarrotPie]

Are there any figures for OHL?

5%, according to this.

 

[RobShipway]

Yes, thanks to modern power plants not having to be small and light enough to fit inside a train and produce wildly varying power outputs, they are substantially more efficient than any diesel traction system.

We are already at the point that electric resistive heating is lower carbon than a gas boiler, let alone in terms of a diesel engine versus an electric motor for producing shaft power.


It is highly unlikely that retrofit of diesel trains into meaningful battery-electric trains will be practical.
The trains will have to be scrapped and replaced with new ones designed from the ground up to be battery electric trains.

Retrofit is just a hiding to nothing, as it has proven in terms of trying to convert electric trains into diesel ones - it simply isn't worth it 99% of the time.
The electro-diesel class 80x are going to end up having a very short service life and probably should never have been ordered, but we are where we are. Blame the utter failure of the Great Western Electriciation project for the situation we are in now. If we're lucky they can be salvaged to make up 10-car electric-only sets for capacity improvement or to replace the Pendolinos.

But what distance can those electric resistive heating power plants do, if built in a train to the same weight as a five carriage class 8xx unit?

I would has a guess that it is not even close to the mileage that a Byd or Tesla electric car can do and the reason for that is the power to weight ratio which has been discussed in threads many times within these forums and it has still come out that even though those power plants are more efficient than diesel power in the amount of power output, you cannot get the same amount of mileage as yet from those battery packs without the need to be recharging the power packs enroute for about 2 - 4 hours, before a train service could continue. What are the passengers suppose to do for those 2 - 4 hours, while the batteries recharge?

For instance if you took a BEMU trains from Plymouth to say Birmingham New Street, you would be lucky if the train on battery power got as far as Cheltenham, more likely the train would only get as far as Bristol Temple Meads or Taunton before the batteries need to be recharged. Once a train on battery can do 1000 miles, than we have an answer to areas where OHL cannot be achieved. But many battery trains within the UK can barely do 200 miles if you are lucky, before they need to switch power.

There are specialist engineers that do this work for a living… perhaps you fancy retraining?

Is there any jobs going and can I work from home..........

 

[HSTEd]

But what distance can those electric resistive heating power plants do, if built in a train to the same weight as a five carriage class 8xx unit?

Well you wouldn't use a resistive heating plant in this situation, but a battery train would expect a reduction in carbon emissions of 80% or more relative to a diesel train. Comparable to electric car vs diesel car - indeed the lower rolling resistance will further favour electric. Weight is not really that relevant because only a small portion of energy use of a train corresponds to actually carrying weight around, and the carbon emissions advnatages are too overwhelming.

For instance if you took a BEMU trains from Plymouth to say Birmingham New Street, you would be lucky if the train on battery power got as far as Cheltenham, more likely the train would only get as far as Bristol Temple Meads or Taunton before the batteries need to be recharged. Once a train on battery can do 1000 miles, than we have an answer to areas where OHL cannot be achieved. But many battery trains within the UK can barely do 200 miles if you are lucky, before they need to switch power.

A battery train will definitely be able to do 300+ miles on a single charge if one is built from scratch.
Even electric cars can do that.

I don't think 400 miles is an unreasonable expectation for a battery electric train built from the ground up to do that.

EDIT:

Getting to Cheltenham gets you almost as far as you need to go, because the Birmingham-Bromsgrove line is electrified, you only need around ~325km of reliable battery range to do Plymouth to Birmingham, even if you take no credit for the few kilometres you spend under electrification near Bristol Parkway.

 

[Richard Scott]

EDIT:

Getting to Cheltenham gets you almost as far as you need to go, because the Birmingham-Bromsgrove line is electrified, you only need around ~325km of reliable battery range to do Plymouth to Birmingham, even if you take no credit for the few kilometres you spend under electrification near Bristol Parkway.

I thought only the slow lines were electrified from Longbridge to Kings Norton?

 

[HSTEd]

I thought only the slow lines were electrified from Longbridge to Kings Norton?

This is correct, however if a train arrives at Longbridge with insufficient battery power to reach Kings Norton, the consequences are rather less severe than if it fails to reach Bromsgrove. The train is merely delayed as it has to crawl into New Street behind the stopper rather than getting stranded somewhere.

So I don't think that portion of the journey requires anything like the assurance that the leg to Bromsgrove does.