GB rail electrification

Status in GB

The Task

The Rail Industry Association's submission to the Commons Transport Select Committee in 2019 estimated that in 2024 the diesel and bi-mode passenger fleet will be around 4,430 vehicles (28% of the total fleet). The Rail Industry Decarbonisation Taskforce (RIDT) also stated: "there are, or shortly will be, about 3,000-3,300 diesel passenger vehicles that will need to be replaced, re-engined or converted, to decarbonise the railway." The TDNS stated that it makes little sense for new diesel trains to be ordered. In other words, those which need to be replaced in the coming years should be replaced with new decarbonised trains.

Scotrail has stated that 43 Class 156, 40 Class 158, 25 HSTs and 34 Class 170 need to be replaced in Scotland by 2026, 2030, 2030, 2035 respectively - i.e. 142 diesel units in total.

This can be achieved either by ordering new trains, or by converting existing diesel or electric ones. This process is further advanced in several continental countries but, because of Britain's more limited loading gauge, continental trains cannot simply be operated on British track. On the continent, batteries or hydrogen supplies can be put on the roof, but this is generally not possible in Britain; British trains have to find space under the train (or occupy space which could otherwise be used for passengers).

Track Electrification

Although there is no detailed plan/funding from central government, there are effectively several teams currently at work:

See Plans page for more details.


Britain was quick off the mark to test extending the range of electric trains by adding Valence Lithium Iron Phosphate batteries to a Bombardier Class 379 Turbostar, and running it as a normal passenger service on the Manningtree-Harwich line. Although the batteries used had no cooling system, causing them to overheat in the afternoon, forcing them to be turned off, the 2016 report from Network Rail concluded that: "The IPEMU [Independently Powered Electric Multiple Unit] trial was completed successfully in 2015 with ... a publicly available passenger service running to the existing timetable under intermittent battery power." The report also said: "The IPEMU was a significant example of the practicability of a battery-powered train and paves the way for discontinuous electrification to be considered more seriously as part of electric services. However, the potential benefits are not limited to that. The effective use of IP or battery power can:

These advantages remain true, but sadly the country is no further forward than it was 6 years ago. Manufacturers have the technology, which they are starting to implement in continental countries, but they can do nothing in GB without firm orders. Consequently, there needs to be a clear plan for testing/trialing new technology and then ordering appropriate trains, aimed at replacing diesel stock across all franchises as quickly as possible.

Current orders

Several metro-type operations have ordered and/or are trialing battery-electric trains:

Other developments

Hitachi signed an MoU with Hyperdrive in 2020 for batteries to be added to Hitachi trains. Their infographic gives a range of 90km with a recharge time of 10-15 minutes, for speeds up to 100mph. The press release however targets the UK fleet of 275 trains, which seems to imply the batteries could also be fitted to the higher-speed AT-300 trains, meaning some of the current bi-modes could be converted to battery operation (see below). A 2018 interview with Hitachi's head of engineering states that the modular design means diesel can be replaced with 'new fuel sources' as required. Hitachi reportedly stated in 2019 that it would be "relatively straightforward to fit batteries under a Class 385 [Scotrail's electric trains] to enable it to travel for 20 miles beyond the wires under battery power. If required, sufficient batteries could be fitted to extend this range to 60 miles, although this would be a much more complex modification."

Hitachi is also currently trialling replacing one of the diesel engines on its AT-300 bi-mode trains with a battery, for both GWR and TPE, making them tri-modes. The objective is to use the battery and not diesel in stations and urban areas, so cutting emissions where they cause the most damage. As with bi-modes, this is an improvement on diesel only, but is not fully decarbonised.

Vivarail have deliberately designed their former London Underground D-Stock conversions (Class 230) to have swappable power modules. A diesel version of these is running on the Bedford-Bletchley line, and electric-battery-diesel versions are currently under test on the Bidston-Wrexham line, due to be operational there shortly. A pure battery-electric version was tested on the Bo'ness-Kinnell railway in 2018, and they have produced a charger, which Network Rail apparently wishes to be the standard. This could be installed in other Welsh lines to enable them to be run purely on battery power. They claim 1MW in 8 minutes, enough for 60 or more miles (say, 100km); the batteries are supplied by Hoppecke. Vivarail now also offer their traction package for use on other trains, claiming up to 100 miles (160km) between charges, with charge times of 10 minutes. They also say that batteries can be leased, i.e. contractually separated from the train.

Bombardier (now part of Alstom) advertise a battery version of their Aventra trains, with MITRAC batteries and a range of 100km.

Porterbrook announced their BatteryFLEX conversion of a Siemens Desiro Class 350/2 demonstrator in 2018, but this does not seem to have progressed further.