On a low traffic or low speed route, the equivalent of a single 37 will probably be OK but in a busier faster traffic mix it won’t suffice. There is also just one of the FOCs that has them currently.
The costs for Didcot-Oxford would not be as astronomical as some recent projects, as a lot of the prep work was done.
The are multiple trains an hour that terminate at Oxford from London. Electrifying to Oxford would allow the current London-Didcot EMU service and Didcot-Oxford DMU service to be recombined back into a London-Oxford semi-fast, but as an EMU. It would also allow GWR to use the IETs in all-electric mode between London and Oxford. Departing on electric will help with the throughput of the platforms. It also means electric-mode shunting in the sidings.
Battery tech is better suited to the Cotswolds Line, not a mainline.
I agree that Marylebone out and the Snow Hill core would be higher priorities than Didcot-Oxford, but removing the terminating EMUs from Didcot without needing to replace the 387s would also be an improvement.
At 30-40mph with no heating and non stop, I don't think that will be a popular move, timetabling and passenger wise.
Oxford electrification would enable a minimum of three trains per hour to be fully electric, 2tph Didcot Stopper and 1tph London to Oxford fast, the North Cotsworld service would pan up and down at Hanborough which would be the limit of electrification.
This is the concept that the IETs are designed to (apparently) - in theory (yes, I know, I know) you can exchange the diesel gensets for battery packs to convert a DMU or BMMU to a BEMU/TMMU or remove them entirely for an EMU.
A Class 99 has way more power available than a Class 37. It's 2400hp vs 1750hp of engine power, and I imagine the traction system on the Class 99 is rather more efficient than that on the Class 37.
You won't get much OLE at all for the cost of a Class 99.
Ultimately, a 1970s tube train with batteries attached to it will not have performance comparable to a modern, purpose designed unit.
Not really, It has worsened the business case on slow branch lines where power needs are limited, but improved it on lines where the power needs are large (e.g., steep inclines or sections where high-speed or fast accelleration is needed).
The three minutes are for top-up charging, not from empty to full (or even from 20% to 80%)
We will need electrification islands at key locations for charging, these could be part of a mainline electrification, or they could be primarily to charge BEMUs.
However purpose designed unit will struggle to get 200 miles in revenue service, considering the GWR 230 can only do 1/3-1/4 of the range in service, with either 3 or 9 ton of batteries per coach.
3Q80 the 00:08 Reading to Paddington = https://www.realtimetrains.co.uk/service/gb-nr:V34983/2025-08-20/detailed 3Q81 the 01:17 Paddington to Oxford = https://www.realtimetrains.co.uk/service/gb-nr:V34982/2025-08-20/detailed 3Q82 the 03:02 Oxford to Paddington = https://www.realtimetrains.co.uk/service/gb-nr:V34981/2025-08-20/detailed 3Q83 the 05:12 Paddington to Reading = https://www.realtimetrains.co.uk/service/gb-nr:V34980/2025-08-20/detailed
Whilst power output required scales by the square of the speed (due to air resistance), energy required to traverse a given distance only scales linearly with speed. Doubling the speed quadrouples the power requirement, but the train arrives in half the time.
Thanks.
The issue with talking about batteries for Didcot to Oxford is that we're not looking at replacing a diesel fleet with battery bi-modes.
A Tesla Model 3 has range of 416 miles with a 79kWH battery and weights 1.8 tons. The GWR Class 230 has 6 104kWH batteries for a total capacity of 624kWH, the GWR 230 probably weights around 90 tons in total. Rail uses a third of the energy of a road vehicle to move the same load the same distance. The GWR 230 has a power to weight ration of 6.9kWH to 1ton versus 43.8kWH to 1ton for the Tesla Model 3.
The 387s could move to Govia Thameslink Railway Southern brand. The routes GWR are looking at are the short and low speed branches like Marlow, Henley, Windsor and Greenford.
With the work at Oxford done, you could even look at additional Oxford to Reading EMUs to speed up the Paddington 387s a bit and/or offer additional connections into other GWR services to/from Swindon and the West. Just reuniting the Didcot to Paddington with the Didcot to Oxford would help.
I have a feeling on Sundays the Didcot to Oxford shuttle is extended to Reading calling all stops.
I am being more realistic with thinking of an in service range of 100 miles, I am not saying nope to being optimistic, however you have to remember according to Geoff Marshall video the 230 stunt was running 4-5x more efficiently than it does on the Greenford Branch.
Like fitting extra batteries to currently non battery fitted trailer coach?
That is a good question which I don't have an answer for, however it might be possible to use completely recycled steel and copper for the OLE.
Battery units obviously have some short-term advantages over electrification in terms of upfront cost savings, but they aren't exactly light additions to rolling stock and will increase the number of moving parts for maintenance. But they also need to be charged which is definitely not a quick process, and if done at terminating stations that will increase turnaround times. They also aren't as environmentally friendly. Batteries obviously have their place in filling gaps in electrification and being a short-term way of getting diesel off the network, but long-term just put the darn wires up where we can and save the batteries for the parts where we can't. As usual the Swiss had the right approach.
I certainly hope they roll out widely, but the problem I see with rapidly developing technology is prospective customers just sit and wait for something better to come along (like that fancy term used to describe curtailing GWML electrification that I can't remember), even though they will still be getting very good products now. Plus, the way I see it, they need to be buying rather than waiting, to enable the research, development and understanding that actually enables that rapid advance in technology they think is coming.
The term is bionic duckweed, first coined by Roger Ford in 2008 when giving evidence to the Transport Committee, critiquing the 2007 White Paper Delivering a Sustainable Railway's dismissal of large-scale electrification, on the grounds that it was too expensive, would be more cost-effective if installed after ECTS had been implemented, and that "the future performance of electric and self-powered trains is unpredictable today. Developments in hybrid technology, biofuels and hydrogen fuel cells will improve the carbon performance of self-powered trains". Notably batteries were not mentioned, which I think illustrates your point very well. Certainly the train operating companies are not acting as though they think batteries can sweep the diesel engine away, and are instead ordering tri-mode rolling stock.
Especially as it continues the PFI smoke and mirrors game of avoiding government capital expenditure, keeping its costs off of the government’s debt pile and converting it into expensive & additional operational spend somewhere else for future generations to worry about.
Adding batteries to 387s (or replacing them with BEMUs and sending them to Southern) would also allow this, and would also allow the Bedwyn shuttles to be replaced with through electric trains from London.
Above ~20mph the performance at the wheel of a 99 on diesel is very similar to a Class 47
