THE number of people travelling on London Underground has hit a new record, topping 1.1 billion for the first time, according to Transport for London.

The new total was for 2010-2011, in which some 42 million more people travelled on the system -- not far short of another million a week.

The network also broke its record for the number of passengers carried over a four week period – topping 90.6 million in the four weeks leading up to Christmas. London Underground has seen a rise in passenger numbers of 14 per cent over the past seven years and 40 per cent over 15 years.

The record ridership figures have been reported as London Underground is coming under increasing fire for the extent and frequency of weekend closures, as work continues with the biggest upgrade in the system's 148-year history.

Bombardier has just been revealed as the preferred bidder to replace the signalling on the subsurface network, which consists of the Metropolitan, District, Hammersmith & City and Circle lines, and London Underground has promised that this new work will not be allowed to involve major closures.

New walk-through air conditioned S stock trains built in Derby by Bombardier for the subservice lines are now coming into service. Some of the trains it will replace were built 50 years ago.

Elsewhere on the system, upgrades of the Jubilee and Victoria lines are nearing completion, and full upgrade work will start on the Northern line once the Jubilee line is complete.

In response to its critics, London Underground said it was 'determined  to keep disruption to passengers to a minimum', but that 'the huge amount of work that needs to be carried out cannot be done in the four hours at night when trains are not running'.

The Underground's managing director Mike Brown admitted that the scale of the work needed can be a problem. He said: "The combination of this huge increase in passengers and a reliance on some of the oldest railway infrastructure in the world does of course present a number of challenges, which is why our work to upgrade it is so critical for London.

"Over the next decade we will deliver 30 per cent more capacity through the introduction of new trains, signalling and track and we are also rebuilding some of our busiest stations, including Bond Street, Tottenham Court Road and Victoria. Over half of the Victoria line fleet now comprises brand new trains, and the first ever air-conditioned trains on the Underground are now serving the Metropolitan."