Underground lines will be suspended this weekend as engineers begin scheduled summer track replacement.
Transport for London will be starting major work on the Metropolitan and Piccadilly lines through Harrow tomorrow.
There will be no service on the Metropolitan line between Wembley Park and Uxbridge or Northwood while points are replaced at Harrow-on-the-Hill on Saturday July 19 and Sunday July 20.
On the same days and until August 10 there will be no service on the Piccadilly Line from Rayners Lane to Uxbridge.
The work is the start of more than 20 days of closures during the summer months for track replacement around Hillingdon.
TfL says there will be rail replacement busses in operation during the works.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here