A spokesman said: "LU is carrying out the biggest upgrade in the Tube's history while carrying record numbers of passengers, over one billion last year. There is not enough time to do this work during the four hours each night when trains do not run and as a result much of this work must take place at weekends.
"We completely understand the frustration passengers feel when confronted by closures, but to replace track there is no option but to close the railway. Under TfL nearly 200km of track has been replaced, delivering smoother more reliable journeys.
"It is also important to note that the vast majority of closures are not full line closures – but are often short sections of lines where alternative Tube or other transport services are available, or are provided by TfL.
"Following the demise of the disastrous PPP, which gave the private companies the ability to demand weekend Tube closures, we are looking at ways of managing closures in a different way. We have already cancelled a huge number of closures planned by Tube Lines on the Northern line this year and during the three-week closure of part of the Hammersmith branch this summer extensive Crossrail works were carried out alongside the Tube upgrade work.
"The new signalling system for the Circle, District, Hammersmith & City and Metropolitan lines is being tendered on the basis of the keeping weekend closures to an absolute minimum."
