London's scorching heatwave is set to continue, but relief can be found for millions of commuters on four out of 11 main Tube lines. While the Elizabeth line, London Overground, and London Trams offer air-conditioned carriages, nearly two-thirds of the Underground network remains sweltering – and that includes some of the busiest routes.
Of the 11 main Tube lines, only the Circle Line, District Line, Hammersmith & City Line, and Metropolitan Line are equipped with air conditioning. This means approximately 40 per cent of the Underground network, comprising over 190 Tube trains, now offers climate-controlled travel – but not all is as it seems. The S8 stock on the Metropolitan Line was introduced between 2010 and 2013, while the S7 stock on the District, Circle, and Hammersmith & City lines rolled out between 2012 and 2017.
The deep Tube lines – Central, Northern, Victoria, Jubilee, and Bakerloo – which account for 60 per cent of the network, still lack air conditioning. During June's record-breaking heatwave, temperatures inside London Underground carriages reached almost 40C, with readings on the Central line hitting a staggering 39.4C.
While some deep Tube trains have full air conditioning units in their driver's cabs to improve working conditions for operators, passengers are left sweltering – and there's been a nine-year gap since new air-conditioned trains were introduced to the network. However, a welcome development is on the horizon: new Piccadilly line trains due later this year will be the first deep Tube trains to feature air conditioning.
A significant concern for commuters is the lack of progress in introducing more air-conditioned trains. Transport for London (TfL) has introduced station cooling systems, particularly in older parts of the network with fewer ventilation shafts – but it's not enough. TfL's Chief Safety, Health and Environment Officer, Lilli Matson, highlighted the increasing risks posed by extreme heat to critical infrastructure like transport.