Tube passengers swelter as lines get hotter

Passengers on London Underground’s Victoria Line often swelter in temperatures of over 31 degrees, and Transport for London has admitted that the situation is getting worse despite efforts to cool down stations and install air conditioning on trains.

New figures for all lines on the capital’s 272-station network between the weekday peak hours of 4pm-7pm show that four lines have seen the average temperature rise over the last ten years.

Despite TfL’s efforts to install new equipment, it has little money to make wholesale improvements, and puts the blame on the increasingly intensive use of the Underground, and climate change.

The problems in deep tunnels are worsening because there is nowhere for the excess heat to go as they cannot absorb what is expelled from trains. Over a century of continuous heavy use has turned the once-cool clay into ovens, and this is worsened by the trains’ regenerative braking systems and high-powered motors, coupled with aerodynamic drag, and the passengers themselves. There are also not enough ventilation shafts.

The Victoria Line is a particular problem, with little opportunity for improvements as it is entirely below ground. While the Central Line is very hot in the summer months, it fares better in other seasons. Overall, the above-surface Circle, Hammersmith & City, District and Metropolitan lines are the best places to be, with relatively modern air-conditioned stock, and are therefore the coolest (19.3C).

The situation will soon be eased on the Piccadilly Line, where sophisticated air-cooling equipment has been specified for the soon-to-be-delivered new rolling stock from Siemens, which also use 20% less power.

TfL has little money in invest in other routes much beyond modest experiments with platform-based air coolers. It has staged a variety of small trials, including reversing the tunnel ventilation fans overnight to pump cold air into stations, and recycling cold ground water at Green Park station, which has suffered issues with fan noise and dirt.

Other stations can be improved during redevelopment schemes, but this will be a slow process.