London’s underground system is set to endure this year’s暖 heatwave without fresh air‑conditioned trains, as the last new units were delivered in 2017. Only 190 trains carry AC, all on shallow lines that represent 60% of the network, leaving deep‑level routes—where 40C temperatures were recorded last June—without relief.

The Piccadilly line is the first deep‑level route slated to receive AC cars, delivered by Siemens at the end of the year. The design, which reduces wheel count to freeęb space, suffered teething problems that pushed the launch from December 2025 to December 2026. TfL’s director of customer operations, Nick Dent, said the agency is investing millions to keep services resilient as pairs of new trains roll out.

Funding gaps remain for the Bakerloo, Central and Waterloo & City lines, all of which run older models dated to 1972 and 1992. Without capital approval, it could take decades before every line sees AC. The delay highlights a broader challenge: the city’s transport budget must balance legacy infrastructure with climate adaptation.

Investors watching TfL’s procurement pipeline should note that Siemens’ contract could reach multi‑hundred‑million‑pound levels, while the capital‑intensive upgrade will test London’s ability to deliver large‑scale projects under fiscal pressure.