Air conditioned Tube trains that will serve the London Underground Metropolitan line from 2010 and the Circle, District and Hammersmith and City lines from 2011 have been unveiled by London's mayor Boris Johnson and transport commissioner Peter Hendy.

A model of the new S-Stock trains, which will serve around 40% of the Tube network, is on show for the public to view at Euston Square Gardens until Thursday 2 October. The new trains will have air conditioning  and walk-through carriages They also feature CCTV coverage in each carriage and improved accessibility.

The first of these S-Stock trains will be delivered for testing in 2009 and will start serving the Metropolitan line from 2010, with the full capacity increase of 49% delivered by 2016. New S-Stock trains will operate on the Circle and Hammersmith and City lines from 2011. The increase in peak capacity is 49% for both lines and is due to be completed by 2016. On the District Line, where trains have recently been refurbished, new rolling stock will be introduced from 2013 with the full capacity increase of 47% due to be delivered by 2018. Trains on the Wimbledon branch will be extended from 6 to 7 cars by this date.

Boris Johnson, said: “As well as keeping passengers cooler the new trains feel far more spacious, boast the latest CCTV systems and have been designed to make life much easier for disabled passengers. When the full upgrade of our sub-surface lines is complete, including the work improving signalling, capacity on these lines will be increased by over 45%, which will mean less crowding and also mean we can cope with the continuing increase in passenger numbers."

Peter Hendy added: "The new air conditioned trains are part of vital upgrade works which will transform the oldest and most complex lines on the Tube network - the Circle, District, Hammersmith and City and the Metropolitan lines. When works are completed passengers will see faster, more reliable journeys and more trains per hour."