Plans to introduce driverless trains on the London Underground network have officially been scrapped following a Transport for London (TfL) investigation.

In response to a written question from Alex Wilson, Reform UK’s London Assembly member, mayor Sadiq Khan said that introducing driverless trains “would cost billions of pounds on each line”.

Mr Wilson asked whether the advantages of transitioning London’s Tube fleet to driverless trains “far outweigh the costs”, citing examples of driverless transport in cities such as Paris, Tokyo and Barcelona.

The mayor of London concluded that work to launch the driver-free transport “shouldn’t be progressed any further” at the Mayor’s Question Time on 21 November.

He said: “Learning from other metros around the world, particularly Paris, which provided input into the work, the most practicable way of conversion would be for it to coincide with the introduction of new rolling stock, signalling and platform edge doors at the same time as part of a line upgrade.

“This would be needed to justify the high costs.”

Former prime minister Boris Johnson said driverless trains should be a condition of any future funding for Transport for London in 2020, following a pledge during his 2012 mayoral campaign that the Tube would have driverless trains in a decade.

Driverless technology is already used on the Docklands Light Railway (DLR), but drivers’ union Aslef has previously called the proposal for driverless Tube trains a “politically-driven fantasy”.

In 2020, Finn Brennan, Aslef’s organiser on the London Underground, said: “Leaked internal Transport for London documents demonstrate that it would cost an additional £7 billion, on top of the money needed to upgrade existing lines, to make Underground trains driverless and that TfL has concluded that there is, given the evidence, no economic case for doing so.”

Although driverless trains will be not rolled out onto Tube lines, new trains will enter service on the Piccadilly line by the end of 2025, with the full fleet of 94 trains expected to be completely rolled out by the end of 2027.

The new trains will feature walk-through carriages, wider doorways, information screens, CCTV cameras and air-conditioning – a first for deep tube trains.

TfL hopes that the trains will be more energy efficient, consuming 20 per cent less energy than the existing fleet.

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