Overview

• The Victoria line regularly exceeds 35 °C in tunnels because it runs entirely underground and lacks air conditioning
• TfL advises carrying water, travelling at quieter times and offering seats to more vulnerable passengers during extreme heat
• Record temperatures may force slow orders that reduce train speeds and increase the risk of delays by affecting rails, overhead power lines and signalling equipment
• Only the Circle, Hammersmith & City, District and Metropolitan lines currently have air-conditioned trains, with mechanical chillers and large fans installed at key stations
• A £2.9 billion programme will introduce air-conditioned Piccadilly line trains by late 2025, and funding is being sought for Bakerloo line replacements with cooling technology by 2030