Future of the GWR electrification

[Brubulus]

Every pantograph can pull down 2MW in essentially all conditions, more if the train is moving.
I suspect you'd probably standardise most units at 2MW to reduce transformer weight and avoid any need to control power based on whether the pantograph is moving.
Of course if we get really aggressive we can go to high frequency transformers and cut weight further.......

If you select your charging points properly a surprisingly short amount of overhead wiring can get you a long way.
But I think we will need trains designed from the ground up for this operation to get anywhere.

EDIT:
As a somewhat relevant example for GWR, going from Penzance to St Erth, a significant portion of which is single track, gets you 20 minutes of charging plus layover. Even with a ten minute layover it will be a whole megawatt hour per pantograph.

2MW isn't really enough - a 5 car IET would need at least 4MW to recharge in a reasonable amount of time. The test 802 had a range of 43 miles on one converted GU with a battery capacity of 700KW. If all 3 were converted this would lead to a range of 129 miles and a battery capacity of 2.1MW. If this battery were to be recharged at an average rate of 2C, enabling a full service recharge between Cogload and Exeter, this would require a power draw of 4MW before even considering operational interactions. Remember the 802 battery was nowhere near the cutting edge in battery design and that enables London-Penzance with a single section of new electrification with existing units.

 

[HSTEd]

2MW isn't really enough - a 5 car IET would need at least 4MW to recharge in a reasonable amount of time. The test 802 had a range of 43 miles on one converted GU with a battery capacity of 700KW. If all 3 were converted this would lead to a range of 129 miles and a battery capacity of 2.1MW. If this battery were to be recharged at an average rate of 2C, enabling a full service recharge between Cogload and Exeter, this would require a power draw of 4MW before even considering operational interactions. Remember the 802 battery was nowhere near the cutting edge in battery design and that enables London-Penzance with a single section of new electrification with existing units.

It should be noted that a 5-car IET has two pantographs, I mst admit when talking about 2MW I was considering units more along the lines of the Class 377 than an IET.
4MW would still allow 80A per pantograph. (EDIT #2: The battery had a peak power of 700kW, but I've not seen a solid figure for the actual kWh rating of the battery pack)

I think Exeter to Cogload junction is likely a poor place for a segment of electrification for charging.
The best places are places with low linespeeds as well as single track sections because they reduce the amount of physical electrification that must be installed. We will certainly need a powered zone in Exeter to support the various lines radiating from it, but extending out towards Taunton is probably suboptimal.
But we will also need to provide a power supply in Plymouth and Penzance/St Erth, and probably in the vicinity of Par, Truro. One long segment probably isn't optimal in that situation.

With a battery train under electrification, operational load can pretty much be smeared out to equilibrium power demand, which will be significantly under 2MW for a 9-car set at 125mph.

EDIT:
You get 20 minutes of charging for the 10 route kilometres between Saltash and Laira Depot, and the power supply can be shared with charging systems at Laira. As well as providing charging services to the local services in the Plymouth Area. The Royal Albert bridge would be annoying and expensive on a per kilometre basis but, even if it costs far more than "ordinary" electrification per metre, I think the 15mph speed limit and single track nature makes it attractive regardless.

 

[JKF]

Could they wire Filton bank in the uphill direction only? I guess the saving wouldn’t be that great over the cost of doing the whole thing, especially with the crossovers needing to be wired.

 

[Wyrleybart]

Project Churchwood (the complete renewal of the GWR diesel fleet) is very likely to use battery electric multiple units (BEMU).

New overhead line equipment (OLE) will therefore be needed to support their operation.

An extension of the current OLE from the existing OLE on the Charfield lines near Westerleigh Junction to Berkley Road is proposed. At Bristol, part of sidings at Pyle Hill (just west of BTM) is also proposed to be electrified.

Filton Bank: electrification is a stand-alone project that is currently at strategic business case submission. This would be the installation of OLE from Stoke Gifford/Patchway to Dr Days Junction.

Strangely, there do not appear to currently be any plans to install OLE at Bristol Temple Meads Station under either of the above project proposals.

Why Berkeley Road and not to Gloucester ?
It strikes me the only train that would use that OLE would be the hourly Turbo on the Bristol-Worcester route, as well as the odd 800 service going ECS to and from Stoke Gifford.
Also that route would include Wickwar tunnel which I think is long and wet, whereas I cannot recall any "problematic tunnels between Standish Junction snd Gloucester.

 

[mrmartin]

I'm not so sure, might be a bit lighter and more tightly packaged for road vehicles. But unless there is a step change in cost of the raw materials, allowing new types of battery then going to be only slightly improved compared to now. You cannot rewrite the chemical properties and laws of physics to get significantly better from similar makeup.

Ultimately, also cannot add too many batteries unless want track unfriendly heavy vehicles (and adding batteries pushes up the purchase cost).

The main problem with batteries is cost. The weight is not (much) of an issue, as someone pointed out, DMUs weigh a hell of a lot more. In the last 10-15 years they have went from $1000+/kWh to something more like $80. In that time UK rail infrastructure costs have absolutely ballooned.

This equation makes it clear battery trains are the future. Its just not viable to spend £billions on slow electrification projects which affect relatively small numbers of people, when for similar amounts of money you could pay the relatively small extra per train to have battery trains which deliver virtually all the same benefits. I'm not even convinced they'd have much higher running costs on an ongoing basis either once you take into account all the extra maintenance, safety procedures etc and repairs the OHLE requires.

I don't think charging is a huge issue as well. Yes some stretches of OHLE may need to be done but the cost of this will be a fraction of full schemes because a) it can be discontinuous avoiding costly bridge upgrades, b) you have flexibility where on the route you do it - avoiding poor ground conditions and c) you can do it close to National Grid infrastructure where available avoiding hugely expensive new HV supplies

 

[Zomboid]

Could they wire Filton bank in the uphill direction only? I guess the saving wouldn’t be that great over the cost of doing the whole thing, especially with the crossovers needing to be wired.

You could, but as you say you probably wouldn't save a lot by doing so, especially as the lines are paired by use, so you'd mostly need the portal structures over all lines anyway and it's highly unlikely to reduce the amount of bridge work that's needed - and it wouldn't allow downhill trains to charge.

== Doublepost prevention - post automatically merged: 9 Jul 2025 ==

The test 802 had a range of 43 miles on one converted GU with a battery capacity of 700KW. If all 3 were converted this would lead to a range of 129 miles

But what does that actually mean? 100-0%? That's not a great way to maintain battery life, and fast charging at the extreme ends of depletion isn't a great idea. If it's 80-20 then that's a realistic range.

 

[The Ham]

2MW isn't really enough - a 5 car IET would need at least 4MW to recharge in a reasonable amount of time. The test 802 had a range of 43 miles on one converted GU with a battery capacity of 700KW. If all 3 were converted this would lead to a range of 129 miles and a battery capacity of 2.1MW. If this battery were to be recharged at an average rate of 2C, enabling a full service recharge between Cogload and Exeter, this would require a power draw of 4MW before even considering operational interactions. Remember the 802 battery was nowhere near the cutting edge in battery design and that enables London-Penzance with a single section of new electrification with existing units.

The issue with batteries is that a single train drawing that much power isn't too much of an issue, however at Exeter there's likely to be several trains all wanting power as you'll have the local services as well.

Also, you have the issue that is all well and good working to the minimums when everything is working well, but if there's issues then it could cause problems.

Once you've got a power supply for electrification (as it's the big cost) it's worth having the wires run as far as possible until you get to a troublesome (read costly) structure/junction, as the extra costs aren't that significant but you gain extra reliability.

Whilst batteries are useful we shouldn't really be using them as an excuse not to wire lines with 4tph, especially where that's where there's branch lines services which could also need to charge (as is the case at Exeter).

That would mean that you'd probably want to wire from Exeter St Davids to the junction for Exmouth (at Central there's 4tph however the extra to wire to the junction wouldn't be much more, even if there's currently only 3tph - although there's a desire for that to be 4tph with Exeter to Honiton services).

 

[Mgameing123]

Are there any short to medium term plans to electrify the paused (deferred) sections of the GWR electrification? Especially the Bristol Parkway to Temple Meads and Oxford to Didcot sections, and maybe the branch lines. Given that these sections are paused and not cancelled, are they going to happen by 2030?

I can't see the section from Cardiff to Swansea done anytime soon as that is the only section that is formally cancelled.

Why just Didcot to Oxford? Lets do Didcot to Banbury so we can knock off an entire area where Class 165’s are used.

== Doublepost prevention - post automatically merged: 9 Jul 2025 ==

Is there scope to split Cardiff-Portsmouth so that Cardiff-Bristol is EMU? Certainly there are enough spare EMUs around.

We could also just use IET’s if GWR have enough around.

 

[Falcon1200]

Why just Didcot to Oxford? Lets do Didcot to Banbury so we can knock off an entire area where Class 165’s are used.

Because the Banbury GWR service is at best hourly, and sometimes two hourly, so not justifying the cost. Unless XC gets bi-modes, or the wires go to Coventry, but those are separate issues...

 

[Zomboid]

Why just Didcot to Oxford? Lets do Didcot to Banbury so we can knock off an entire area where Class 165’s are used.

Don't they still run some services on the Cotswold line?

Until such time as XC replace their trains or Chiltern electrify, it's hard to make much of a case for Oxford to Banbury.

The suburban service from London really ought to run to Oxford, and the IC services would benefit from Didcot to Oxford, too. But there's just not enough potentially electric traffic on the Oxford to Banbury section at the moment.

 

[Annetts key]

Why Berkeley Road and not to Gloucester ?
It strikes me the only train that would use that OLE would be the hourly Turbo on the Bristol-Worcester route, as well as the odd 800 service going ECS to and from Stoke Gifford.
Also that route would include Wickwar tunnel which I think is long and wet, whereas I cannot recall any "problematic tunnels between Standish Junction snd Gloucester.

No idea. However, I do know this:

Currently the signalling between Westerleigh and just short of Berkeley Road (109½ miles) is controlled by TVSC and hence was resignalled not long ago using OLE compatible signalling.

The signalling beyond this point is currently controlled by Gloucester Panel (PSB) and is a 1970s BR Western Region free wired route relay interlocking, which is not OLE compatible. Now, there are plans to replace this. But I don't know the timescale for this work.

Westerleigh Junction has a large sub-station and feeder for the OLE.

Yes, Wickwar Tunnel is VERY wet. Nearly as bad as Chipping Sodbury Tunnel, which has successfully had OLE installed.

 

[FGWHST43009]

Don't they still run some services on the Cotswold line?

Until such time as XC replace their trains or Chiltern electrify, it's hard to make much of a case for Oxford to Banbury.

The suburban service from London really ought to run to Oxford, and the IC services would benefit from Didcot to Oxford, too. But there's just not enough potentially electric traffic on the Oxford to Banbury section at the moment.

Freight? Electric traction is much better for performance than diesel especially for freight, and there's a lot of freight using that line

 

[zwk500]

Could they wire Filton bank in the uphill direction only? I guess the saving wouldn’t be that great over the cost of doing the whole thing, especially with the crossovers needing to be wired.

There'd be absolutely no point in doing so as it's paired by use so the uphill Filton Main track is on the inside of the formation.

 

[WAO]

You can also regenerate on downhill sections.

WAO

 

[Zomboid]

You can also regenerate on downhill sections.

WAO

You can, but you won't get as much as if you're charging as well.

 

[HSTEd]

Freight? Electric traction is much better for performance than diesel especially for freight, and there's a lot of freight using that line

Without cast iron guarantees that the freight operators will not just cite "commercial requirements" and put a Class 66 on it regardless, you can't really make a case based on freight.

 

[Zomboid]

Freight would need the whole route doing, not just an expansion from Oxford to Banbury.

 

[HSTEd]

Once you've got a power supply for electrification (as it's the big cost)

It was the big cost in the BR era.
But overhead line electrification costs have ballooned to the point that I am not sure that is true any more.

The entire East Coast Main Line PSU2 programme only cost circa £220m.

You won't get many route kilometres of electrification for that price (25-50km or so four double track line), and that was three new static frequency converters, a 132kV grid connection and lots of other upgrades.

 

[The Planner]

No idea. However, I do know this:

Currently the signalling between Westerleigh and just short of Berkeley Road (109½ miles) is controlled by TVSC and hence was resignalled not long ago using OLE compatible signalling.

The signalling beyond this point is currently controlled by Gloucester Panel (PSB) and is a 1970s BR Western Region free wired route relay interlocking, which is not OLE compatible. Now, there are plans to replace this. But I don't know the timescale for this work.

Westerleigh Junction has a large sub=station and feeder for the OLE.

Yes, Wickwar Tunnel is VERY wet. Nearly as bad as Chipping Sodbury Tunnel, which has successfully had OLE installed.

GARS (Gloucester Area ReSignalling) as they like to call it was meant to be this control period.

 

[Topological]

Why just Didcot to Oxford? Lets do Didcot to Banbury so we can knock off an entire area where Class 165’s are used.

== Doublepost prevention - post automatically merged: 9 Jul 2025 ==


We could also just use IET’s if GWR have enough around.

I see the rationale for Banbury, but really then you are continuing further to Birmingham and all of Manchester - Reading would be wired. Although battery trains may negate the need, having an electric service could free voyagers for other purposes.

RE Portsmouth, I think that the IETs are needed back on the main services out of Paddington. There are still a lot of 5-car running about that need to be 10. A split would allow use of suitable local EMU on the Cardiff-Bristol section with the potential to call at the privately funded larger station in East Cardiff if that ever happens.

 

[Technologist]

Freight? Electric traction is much better for performance than diesel especially for freight, and there's a lot of freight using that line

Given that electric locomotives are frequently ballasted a dual mode battery loco could potentially carry a pretty big battery.

For illustrative purposes if we take BYD Seal which has an 82.5KWh LFP battery and scale it up to a 113t Class 99. We would get:

4300 KWh battery
20MWe power output which we would probably trade some of that mass/inverter capacity into the DC-DC converter to replace the transformer.

I think this is relatively conservative as the car obviously devotes a decent proportion of its mass to accommodating and protecting its passengers. So at max diesel power output of class 99 this battery train could run for 2.5hours, this should be easily enough to get it on to a wire for most routes. For routes where this isn't possible we could put extra batteries onto a "tender" or even distribute them onto freight cars.

Freight trains also tend to stop for a much longer time than passenger trains leaving much greater opportunities to charge at container ports, most of these places having hefty electrical connections.

Progress Rail will sell you the EMD Joule Charging Station, though what I found amusing was that this is rated for 700-1400KW. There are already car charger standard which exist in this range and HGV standards which exceed it. I suspect that we will end up with rail freight just adopting an HGV charger standard and maybe using 2-3 if the power rating isn't enough. Wireless is also likely a pretty good option.

https://s7d2.scene7.com/is/content/Caterpillar/CM20230131-2f763-0b8b3

 

[Mgameing123]

Don't they still run some services on the Cotswold line?

Until such time as XC replace their trains or Chiltern electrify, it's hard to make much of a case for Oxford to Banbury.

The suburban service from London really ought to run to Oxford, and the IC services would benefit from Didcot to Oxford, too. But there's just not enough potentially electric traffic on the Oxford to Banbury section at the moment.

The case is simple. At some point XC will need new trains and we need to make sure they become electric. By already having Didcot to Banbury electrified then there would also be a good case for further electrification.

 

[Zomboid]

Voyagers are a long way from being replaced.
Didcot to Oxford should be a top priority route for electrification, but Oxford to Banbury should be way down the list, behind routes that might actually see some electric trains in the medium term.

 

[takno]

The case is simple. At some point XC will need new trains and we need to make sure they become electric. By already having Didcot to Banbury electrified then there would also be a good case for further electrification.

Surely Kings Norton to Barnt Green and Bromsgrove to Westerleigh Junction would be a higher priority than Oxford to Banbury

 

[Nicholas Lewis]

Every pantograph can pull down 2MW in essentially all conditions, more if the train is moving.
I suspect you'd probably standardise most units at 2MW to reduce transformer weight and avoid any need to control power based on whether the pantograph is moving.
Of course if we get really aggressive we can go to high frequency transformers and cut weight further.......

Network Rail limit the current per pantograph to 300A or nominally 7.5MW but the vehicle has to be moving. Can't find the static current limit but it will be lower as there will be heat build up at the point of interface so this becomes the limiting factor.

 

[brad465]

Is Filton Bank really being considered ahead of Didcot-Oxford? I'd like to see both but of the two the one with the best BCR is definitely not the former.

 

[zwk500]

Is Filton Bank really being considered ahead of Didcot-Oxford? I'd like to see both but of the two the one with the best BCR is definitely not the former.

Filton Bank wiring is being given a big push by WECA (West of England Mayoral Combined Authority). There's no equivalent body with similar powers and funding to lobby for Didcot-Oxford.

 

[eldomtom2]

Is Filton Bank really being considered ahead of Didcot-Oxford? I'd like to see both but of the two the one with the best BCR is definitely not the former.

The thing about Filton Bank is that there's less of it compared to Didcot-Oxford.

 

[DJ_K666]

When I was down there for a family gathering a couple of months ago, I got a train from Newport to Cwmbran, which means the west side of Maindee Junction. One thing I noticed was the wires run almost to the north part, where the freight only curve heads east. I wonder if this is passive provision or if the wires might one day head towards Abergavenny and on to Hereford.

 

[Xavi]

That would mean that you'd probably want to wire from Exeter St Davids to the junction for Exmouth (at Central there's 4tph however the extra to wire to the junction wouldn't be much more, even if there's currently only 3tph - although there's a desire for that to be 4tph with Exeter to Honiton services).

5tph from Exeter St Davids to Exmouth Junction as the Okehampton and Barnstaple services run through to the turn back siding, which is a must for wiring / charging if BEMUs are to operate in the south west.