Some 15,700 km of track, on which predominantly diesel locomotives run, needs to be upgraded in order to meet climate change commitments.
Taxpayers are in line for a bill of up to £30bn to make the railways greener, according to a leaked Network Rail report.
The document urges Grant Shapps, the Transport Secretary, to take action immediately or risk missing the Government’s 2050 net zero carbon goal.
The 231-page analysis by state-backed tracks and stations owner, seen by The Sunday Telegraph, shines a light on how Britain’s railways have failed to keep pace with electrification overseas.
In order to meet Britain’s climate change commitments, 15,700 km (9,756 miles) of track, on which predominantly diesel locomotives run, needs to be upgraded.
Some 12,500 km must be electrified over the next 30 years, the confidential report finds. It is due to be signed off by the Network Rail board this week.
It estimates rail electrification will cost between £1m and £2.5m per kilometre, taking the total bill to up to £30bn. The costs will be funded by Government, the report says.
Network Rail also recommends 1,400 km of track on which hydrogen trains will run and 1,000 km which will be battery-powered.
The report says: “Action must be taken now in order to deliver on the required 30-year time horizon. Delaying the start of this will place pressure on achieving decarbonisation targets.”
Just 39pc of the UK’s railways are currently electrified, this compares with Italy, Spain and Germany where 65pc, 63pc and 60pc of services are electric.
While efforts to change this have been made, the pace of rail electrification has slowed. Some 246km of upgrades were completed in 2018-19, considerably down on the 392km finished in 2017-18, the analysis reveals.
The findings come as Boris Johnson’s administration grapples with a burgeoning crisis on the railways. Emergency measures to keep trains running during the pandemic are costing the taxpayer billions of pounds.
Ministers are set to unveil a series of “take it or leave it” deals – some of which are expected to leave operators no choice but to hand back the rail lines to the state.
Train companies want to be rewarded for running services more efficiently with demand for commuting unlikely to return to pre-Covid levels with Britons choosing to work from home instead of the office.