TfL says the deal will not hit the public purse
The end of the controversial Public Private Partnership on the Tube network has been signalled with a deal to bring all maintenance work back in-house.
Transport for London said it had agreed to buy the shares of Bechtel and Amey (Ferrovial) from Tube Lines for £310m.
It said the agreement will involve no extra financial call on the government, taxpayers or farepayers.
It added that said the first priority will be to complete the upgrade of the Jubilee Line as soon as possible.
Transport for London (TfL) said that, freed from the complex PPP structure, it was confident of generating substantial savings.
The agreement will mean a "revised approach" will be taken to reduce the impact of line closures beginning with a much less disruptive upgrade programme on the Northern Line.
Tom Edwards, BBC London Transport Correspondent
The big question will be how Transport for London can afford the £310m to buy the shares.
Its budget's already being squeezed. And previously it had said it couldn't afford a £400m funding gap in the PPP.
What Tfl says is it will be able to make efficiencies on the work and is "confident of generating substantial savings" - that will be tough as the official in charge of the PPP has already found previously London Underground costs were far higher than Tube Lines.
However the Mayor's Office also says it can also cut out middle management fees and reschedule the debt at a better rate.
For passengers it also says the number of weekend closures for example on the Northern Line will be cut from 84 to 12.
Mayor of London Boris Johnson said: "This deal is excellent news for London."
He said he was confident London Underground and private contractors "are more than capable of delivering the improvements to London's transport network we need, on time and on budget".
Tube Lines was responsible for the Jubilee, Northern and Piccadilly lines.
The deal brings to an end the £30bn PPP, promoted by Gordon Brown when he was Chancellor, under which large sections of the Tube were sold off on 30-year leases.
Bob Crow, general secretary of the Rail Maritime and Transport union, said the move was "a recognition on a massive scale that transport privatisation does not work and RMT's campaign to roll out the renationalisation of the rail network will continue regardless of who forms the next government".
The takeover follows the collapse of Metronet, the maintenance giant responsible for two-thirds of the Tube, whose staff now work for TfL.