Great British Railways' Long Term Rolling Stock and Infrastructure Strategy (LTRS&IS), currently in development, will determine how much of Britain's future fleet runs on batteries and how much of the network still needs wires. The industry evidence now stacking up behind that decision points one way; the Department for Transport's position points another.

The sharpest case comes from freight. In July, the Railway Industry Association (RIA) published 'Growing rail freight: the need for targeted electrification', concluding that electric haulage must be maximised to unlock the full economic and environmental value of rail freight. The operational argument is concrete: diesel-hauled intermodal services on the West Coast Main Line can only run at night north of Preston because they manage just 25mph over the northern fells. RIA's modelling shows five timetable clashes with 125mph passenger trains between Preston and Glasgow if such trains ran by day. At 90mph — only achievable with electric traction — there would be no clashes, because a non-stop 90mph freight train behaves like a stopping 125mph passenger train. Faster freight also improves crew and asset utilisation, potentially allowing a round trip in a day.

Research from the University of Birmingham underpinning the report found electric locomotives are the optimum long-term solution, with bi-modes acceptable as an interim option. Battery-only locomotives, it concluded, lack the energy storage for main line freight haulage and suit only shunting and very short trips. RIA Senior Technical Advisor David Clarke said the report shows that maximising electric freight "unlocks additional freight and passenger capacity, improves reliability, reduces costs and delivers great economic benefits."

RIA's 2024 report 'A lower cost, higher performing net-zero railway' analysed 216 unelectrified passenger routes and found 83 could be served by battery EMUs without new electrification, since they spend enough time under the wires to recharge. But it also concluded that 28% more of the network needs electrification, leaving 34% to be operated by battery or other non-diesel traction. It recommended a rolling programme rather than project-by-project electrification to break the boom-and-bust cost cycle.

Scotland has already gone that route. Since rail powers were devolved, the Scottish Government has delivered 587 single track kilometres of electrification through a rolling programme that has reduced cost. Its fleet transition strategy, published in November 2025, backs electrification as the end state for InterCity routes with freight traffic, with Class 222 Meridian units proposed as an interim replacement for the aging HST fleet, and battery-electric trains on routes without a freight market.

Battery technology itself is maturing. An IMechE seminar cited new DART trains for Dublin running at least 80km off the wires, discontinuous electrification of 170 stk of the Welsh Core Valley lines, and a trial replacing one generator unit on a Class 802 with a 575kWh battery — scaling which, the seminar heard, would make a 135km off-wire return run feasible. But battery sizing is route-specific, complicating cascades, and cost data remains scarce. University of Birmingham's Professor Stuart Hillmansen reminded delegates that train power demand is proportional to the cube of speed: a 125mph train needs almost three times the power per tonne of a 90mph suburban train.

A Campaign to Electrify Britain's Railways report calculated that £1.35 billion would have been saved over the past 11 years had all passenger trains been electric, at recent diesel prices. Only 7% of rail freight is electrically powered, against 74% of passenger services.

East West Rail remains the contested test case. The 2018 decision not to electrify was never supported by published analysis, and the project now proposes discontinuous electrification with BEMUs, partial wiring between Oxford Parkway and Bicester Village, and a 27km 25kV feed from Bletchley — costs the author argues are comparable to full OLE on the unbuilt Oxford–Bletchley section. ScotRail puts BEMU operating costs 23% above EMUs, and industry sources put BEMU lease costs around £150,000 per vehicle per year higher.

The DfT told Rail Engineer it is "committed to decarbonising our railway, and electrification is the most effective way to do this," and that the LTRS&IS "will set out a coordinated and more cost-effective approach to rolling out new trains and electrification." But it rejects a rolling programme, arguing "the optimal solution will vary by corridor and network context." RIA reports a 68% fall in staff with electrification competencies between 2018 and 2025, including more than 300 redundancies after the Midland Main Line pause. India, by contrast, has electrified 40,000km since 2014 and now has 99.2% of its broad gauge network wired.

The LTRS&IS, when published, will show whether GBR adopts the engineering-led approach seen in Scotland — or whether battery technology and corridor-by-corridor appraisal continue to shape Britain's traction mix.