Behind the scenes: GWR trials fast-charging battery technology

Joe Campbell joins the team conducting trials of fast-charge battery technology on the West Ealing to Greenford branch.

In this aticle:

• Trial Progress: GWR's battery-powered train trials on the West Ealing-Greenford line are advancing, with driver training now underway.
• Fast-Charging Technology: The train charges in 85 seconds using retractable shoes at West Ealing, showing potential for broader application.
• Future Prospects: Success could expand battery-electric trains across branch lines, aiding decarbonization and reducing diesel reliance in the network.

Great Western Railway has begun training drivers as part of its trial of fast-charging battery technology on the West Ealing to Greenford branch line in west London.

Runs with the remanufactured D78 Tube stock began in March 2024, but have so far been operated by contract drivers.

“We’re starting to move now towards a passenger service,” says GWR Engineering Director Simon Green.

“A lot of the initial trial work was making sure the system works, making sure it’s reliable, making sure you can operate the train service. That’s all done. Our next challenge basically involves training our own drivers.”

Managers have already got to grips with the three-car unit, as well as (more importantly) the fast-charge technology installed at the West Ealing end of the branch.

Taking the existing diesel train off the line and putting the battery-powered prototype in its place for the fare-paying public requires “a large number of drivers”, Green explains.

Training was not able to begin while the operator remained in dispute with drivers’ union ASLEF. It has also been complicated by those who drive the trains starting or finishing their working day on the main line.

“Each day a number of different drivers drive on this route,” says Green.

“That’s purely in relation to variety of work, because it’s only a short journey. Drivers will do so many trips each day, and then they get replaced by another driver who will do the same. They are diagrammed to work these trains in between operating longer-distance services.”

Runs along the West Ealing to Greenford branch take just 12 minutes, despite three intermediate stops.

Because the drivers are drawn from those based at Paddington, the training also has to be scheduled around their route learning for diversions that are planned to run during blockades of the Great Western Route linked to HS2 work.

“We’d like to get passengers on it as quickly as we can,” says Green.

“We think, practically, that will be around Easter. But if we can do something quicker than that, we definitely will.

“There’s just a challenge around getting enough drivers and being able to roster them appropriately to start running the train in passenger service every day.”

The unit being used for the tests (230001) was the pioneer of Vivarail’s rebuilding programme for ex-LU District Line trains, which first began running as long ago as 1978.

It was initially adapted to run on diesel power, and then rebuilt once more to run on batteries, before the latest modification when it was fitted with two retractable shoes under the powered driving cars at each end of the train.

These lower onto metal rails between the running rails at West Ealing. Only then does the system go live, delivering a charge equivalent to that of a typical electric car in just 85 seconds.

Trial Manager Julian Fletcher came across to GWR when the operator acquired the fast-charge technology from Vivarail.

“We’ve run what we call ‘operation come rain or shine’, where we’ve looked at what can feasibly happen to the charging system throughout its operation here or elsewhere on the network,” he says.

“We did a lot of rig testing before we put the charging equipment on the train. That covered ice, snow and all sorts of contamination.

“The shoe is designed to push it out of the way and charge anyway, but you can’t beat the real thing.”

Most recently, as the trial entered autumn, that involved putting leaves on the charging rail to ensure that they too would be pushed clear. A pneumatic system lowered the shoe, with its twin contacts, as the train pulled into the platform at West Ealing.

On the day RAIL joins the team for several trial runs, they are monitoring the impact of running the heating continuously at a high level, to keep passengers warm in the depths of winter.

A bank of computer screens provides a visual representation of every second of the journey. Departure time, acceleration, length of journey, and of course the all-important power state of the on-board batteries, is among the mass of data being captured.

“We are looking at the extremes of operation from maximum auxiliary loads such as the heating and failure cases - what happens if we’re stuck at a signal for a couple of hours,” Fletcher explains.

“We have to understand how things operate in real life versus what we thought it would do.”

But there is a second and equally important strand to the trial, if what is happening in this corner of west London is to be the start of something bigger.

“We’re making sure we validate our computer model, which is like the crown jewels really. We’re measuring how much energy the train uses at any one time, and we can predict that with decent accuracy because we have data that we’ve measured from the train.”

Having an accurate model will enable the team to assess the suitability of the rapid charging system for use on other branch lines, from the outskirts of London to the tip of Cornwall, which are currently served by diesel units.

One place where they’re watching things keenly is an hour down the line at Twyford, the starting point for the Henley branch.

User groups and politicians there had hoped they too would see the wires come to their town, as electrification was rolled out along the Great Western route.

“Like all these big projects, it took longer than it should,” says Neil Gunnell, of the Henley Trains Group.

“The money ran out. Oxford suffers because it doesn’t have electrification, and we certainly are lower down the queue than them.

“There was concern that branch lines would just fritter and die, but actually we gained a better service in the short term. Our old diesel trains had no place on the main line once we had longer electric trains going into London [from Twyford].”

The result was a shuttle service which, because of its increased frequency, offers greater capacity than previously, with trains well integrated into the main line timetable.

At peak times, however, Gunnell says the two-car trains can be incredibly busy, so a three-car unit such as that involved in the trial (in his words) “would be welcome”.

Services on the Henley branch run to a similar 12-minute journey pattern to that on the Greenford to West Ealing route, with little more than three minutes between arrival and departure from the stations at each end of the line.

According to Fletcher, the trial has shown that this would not present a problem to the rapid-charge system.

“The train comes to a halt, and then the rails (under the shoe) become powered and charge up the train. And that all happens in the time it takes the driver to walk from one end to the other.

“The train turns up in the morning, probably around three-quarters or more full on the batteries. All the charging system does really is keep the battery topped up, so it’s not a question that the train is on its knees and requires a massive charge.”

Power for the charging rails at each end of the train comes from an industrial power bank. It uses off-the-shelf industrial batteries located in shipping containers, just inside the railway boundary, next to the bay platform serving the branch line at West Ealing. It, in turn, takes a trickle charge from the grid.

Drivers are being taught to use the three-car marker on the platform as a guide to ensure the shoes line up with the charging points. A light in the cab then illuminates to tell them charging is under way.

Lights on poles at track level also show that the process has begun, along with flashing lights above the side windows on the powered cars. The pole-mounted lights change colour depending on whether the rails are powered - a vital safety feature for anyone working on the track, although signs warn that the system should be considered live at all times.

“We expect the batteries will last eight to ten years. That’s what the industry would tell us,” says Green.

“However, evidence is emerging that that is starting to stretch to 15 years. A lot will depend on how hard a life they have.

“But once they’ve finished in this train, they’ll be taken out and there’s a market for the secondary use of batteries in less onerous applications - for example, from being on the train to providing the storage supply lineside.”

Rapid-charging technology may require less up-front expenditure than electrification, but with its fixed charging points, back in Oxfordshire there are concerns about how it will cope with the surge in demand for rail travel during the Henley Regatta.

A maximum of four carriages can be accommodated on the platform at Twyford, so two units are coupled together for the service during the regatta, on every day except Saturday.

“On the Saturday, they couple up three trains together and run it off the main line platforms,” explains Neil Gunnell from Henley Trains.

“In the week it can be 600 or 700 people on each train. On Regatta Saturday we get 1,000, so I don’t see it working unless there was charging on the main line too.”

Longer term, that issue might be addressed by the adoption of battery-powered trains such as those being developed by Hitachi at Newton Aycliffe.

These run on the wires, like GWR’s existing bi-mode fleet of Class 800 IETs, but instead of switching to diesel where the overhead lines stop, they instead rely on on-board battery power.

Ultimately, that is the ambition, according to GWR’s Green. In the shorter term, the operator does have enough D78 units, acquired from Vivarail, to put a re-engineered fleet into service for places such as Henley.

He adds: “It depends on whether we approach things through re-purposing existing trains or a much larger replacement of our diesel fleet across the entire Great Western network, so not just considering the London and Thames Valley branch lines, but also considering trains that operate in the West and South West as well.”

GWR is already working with the government on a battery-electric plan, he says.

“The question is: does it make economic sense to try and do something more quickly? Or does it make sense to wait for that [the wider fleet replacement] and bring those trains into London and the Thames Valley at an appropriate time in the programme?’

Not using 390001’s sister units, which are currently in store, would of course avoid the optics of replacing diesel trains with even older (if re-engineered) battery ones. But that doesn’t worry Green.

“I think, ultimately, this is about the passenger environment and service we are providing. I would argue the environment in this train is as good as it is in our diesel trains. Some might argue it’s slightly better.

“Therefore, from a passenger perspective on the lines we are talking about, predominantly the Thames Valley, I think it is a really good solution taking you along that path of decarbonisation.

“It allows us to remove diesel trains from those services, which I think customers and most neighbours of the railway would be really pleased to see.”

About the author: Joe Campbell, Contributing Writer, has worked across national and regional press and broadcasting for 40 years, including specialist roles in politics, defence and aviation.

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