A section of the Tube will shut for a month next summer, it was announced today.
Upgrade work will mean the closure of the Circle and District lines between High Street Kensington and Edgware Road from July 23 to August 23.
The work will include track and drainage renewal and enabling works to accommodate the new, longer air-conditioned trains (from six carriages to seven), which will start operating on the Hammersmith & City and Circle lines from the end of 2011.
The closure will be extended at weekends to include Hammersmith & City, Metropolitan and Circle line trains between Hammersmith and Aldgate and between Earl's Court and Gloucester Road, so additional work for the upgrade of the Hammersmith & City, Circle, Metropolitan and District lines can be carried out.
London Underground said that without the month-long closure, it would have needed at least 20 weekend shut-downs spread across six months or more.