The London Underground has not seen new air-conditioned trains in circulation for nearly nine years, a period that encompasses most of Mayor Sadiq Khan's tenure. This lack of updated rolling stock means passengers are enduring increasingly punishing conditions on deep-level lines, particularly as temperatures in the capital are forecast to reach 34C this week.
The National Heat Risk Commission has identified upgrading the Tube system to cope with extreme heat as an "economic necessity." However, the last new air-conditioned Tube train was introduced in June 2017, just over a year after Khan took office.
While the Elizabeth Line, which opened in 2022, is equipped with air conditioning, it operates separately from the Underground network. Of the existing Tube trains, 190 are air-conditioned, but 60% of the network, comprising deep-level lines, still lack this feature.
Transport for London (TfL) cites the constraints of narrow, Victorian-era tunnels as a primary challenge, leaving insufficient space to install cooling equipment externally on carriages. Engineers also express concerns that expelled heat from air conditioning units could dangerously increase platform temperatures.
Despite these obstacles, cooling deep-level lines is not deemed impossible. The Piccadilly line is scheduled to be the first to receive air-conditioned trains later this year. These new trains, manufactured by Siemens, incorporate compact air conditioning units fitted beneath the carriages. London TravelWatch has stated that these new trains, expected by December, "can't come soon enough" and emphasized the "real need for wider investment" in cooling systems across the public transport network.
TfL has expressed a desire to equip trains on the Bakerloo, Central, and Waterloo & City lines with air conditioning but indicates a lack of funding. Currently, there is no established timeline for introducing such systems to the Northern and Jubilee lines.
Nick Dent, TfL's director of customer operations, affirmed the authority's commitment to enhancing service resilience against more extreme and frequent hot weather. Thermal imaging from June's heatwave revealed that the floor of a Piccadilly line train reached 40C.
The situation arises as Britain prepares for another heatwave, with temperatures predicted to exceed 30C for an extended period. The UK Health Security Agency has issued health alerts for several regions, warning of potential significant impacts on health and social care services. Schools have canceled events and adjusted dress codes due to safety concerns. A rise in mortality is anticipated among older individuals and those with pre-existing health conditions, though younger age groups are also at risk. Yellow heat-health alerts, signaling a "risk to life," have been issued for northern regions.
Parts of south-east England have already experienced official heatwave conditions, with further regions expected to meet their local thresholds. London and the south-east anticipate a particular spike, with temperatures potentially reaching 34C. These conditions, while concerning, are not expected to match the record-breaking 37.7C recorded in late June. Scientists have noted that such extreme heat events bear the hallmarks of climate change.