Driverless Tube trains a 'humongous' challenge that would cost billions, says Sadiq Khan

Driverless Tube trains would cost billions of pounds and involve "humongous" challenges, according to London Mayor Sadiq Khan.Mr Khan appeared to dismiss the Prime Minister's call for automated Underground trains to be a condition of any future Transport for London funding deal.The mayor said he thought Boris Johnson was speaking 'off the cuff' and the government was unlikely to underwrite the cost.TfL was given a £1.6bn interim bailout earlier this year after the coronavirus lockdown devastated its income from fares.Talks are underway about a long-term funding settlement to stabilise TfL's finances after October.

Passenger wears a face mask at a Tube station

The mayor today commissioned a review of future funding options which rivals a similar project ordered by the government.Mr Khan told MPs on the Commons transport committee he was "open minded" about the concept of driverless trains but thought Mr Johnson's demand was not a "serious conversation".

Read more: Boris Johnson calls for driverless trains as condition of future Transport for London bailout