Commuters face 23 days of closures on two London underground services while 6km of track is replaced.
Transport for London has announced engineering work will take place this summer to replace track on the Uxbridge branch of the Metropolitan and Piccadilly lines.
The work will be carried out between July 19 and August 10, which TfL says is the quietest time on the Tube network and will reduce the number of weekend closures.
George McInulty, London Underground's programme director of infrastructure, said: "The track replacement work on the Uxbridge branch is a crucial part of the Metropolitan line upgrade.
"Carrying out a block closure of this section of the network will enable us to complete the work in just over three weeks as opposed to fourteen weekend closures.
“This approach means that there will be no time lost due to set-up and hand-back of works, which minimises working time and helps to significantly reduce the cost - saving around £3 million of tax and fare payers’ money- and ultimately keeping disruption to customers to an absolute minimum.”
During the work, tickets will be accepted be accepted on local buses and a rail replacement bus service will be in operation connecting with the Central line at West Ruislip.