The first air-conditioned tube train has made its debut on the London Underground as part of a £1.5bn rolling stock replacement programme, despite the budget being slashed by £10m in July as part of Transport for London cutbacks.
The total fleet of 191 new trains will be gradually introduced on the Metropolitan line throughout 2010, then the Circle, District and Hammersmith and City over the next five years.
A heat map that monitored the London Underground on 28 July 2008 - one of the hottest days of the year - found the Central Line was the hottest, with temperatures of up to 32C (90F).
The Metropolitan Line recorded temperatures of up to 27C (81F).
The Jubilee Line was significantly cooler with most stations recording temperatures of 25C (77F).
To help maintain the temperature the doors will close if the train needs to wait at a station for a period of time – arriving passengers will need to press a button to reopen the door.
The new arrivals also sports walk through carriages and a 25% increase in total capacity due to a reduction in passenger seating.