Services on the Uxbridge branch of the Metropolitan and Piccadilly lines have resumed after a 23 day block closure.
Commuters along the lines in Uxbridge have been without trains while engineers worked to improve old infrastructure.
From July 19, the Met Line was closed during the week between Uxbridge and Ruislip while the Piccadilly Line was closed between Uxbridge and Rayners Lane.
But just what exactly was going on while borough people were sweating it out on replacement buses?
Over the 23 days a Track Partnership team - with workers from London Underground (LU) and Balfour Beatty - worked around the clock to replace 6.1km of new ballasted track which included 18,000 tonnes of new ballast, 10,000 new sleepers and 5,000 conductor rail pots.
Two new sets of points have been installed at Harrow-on-the-Hill station, three bridges along the line were water-proofed, 4km of track drainage work was completed, a 70 metre retaining wall was put up at Uxbridge, 6.3km of rail grinding completed - which will prevent broken rails and future delays - and points at Uxbridge station were upgraded.
Stuart Burnett, LU’s Head of Strategy and Planning, said: "I would like to take this opportunity to thank customers for their patience while these works took place. 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 enabled us to complete the work in just over three weeks as opposed to fourteen weekend closures, which meant that we didn't lose time to set-up and hand-back works.
"We were able to complete the works on time and on budget and even managed to run a preview service the Metropolitan line on Friday afternoon before the final weekend of the closure."