TfL has made many efforts in recent years to tackle the problem of hot tunnels, including attaching cooling panels to tunnel walls. The panels, which circulate water to extract heat from the air, were used in a trial in 2022 but are currently not in use. Paul argues that such a system could be prohibitively expensive.
Hassan Hemida of the University of Birmingham says Paul's water cooling technology is a “good idea”, although it remains to be seen how much heat it can actually remove from a real, busy tube station full of people.
Certain railroads are simply pushing the limits of our ability to cool things down, Hemida says. He gives the example of super high-speed trains that travel at 400 kilometers per hour. They force air out of the way at high speeds, meaning the air pressure around heating, ventilation, and air conditioning (HVAC) equipment on the roofs of those trains can drop significantly. “Then you can't suck air into the HVAC system,” he says. Ultimately, this can cause the air conditioner to break down. “I have been contacted by colleagues from China and they want to find a solution to this problem,” Hemida adds.
However, more and more train operators are using air conditioning systems as standard. For example, the relatively new Elizabeth Line in London is equipped with air conditioning. And a spokesperson for Škoda Transportation, which recently rolled out air-conditioned metro trains in Bulgaria's capital, says: “In general, every vehicle we produce now is equipped with air conditioning.” Sharon Hedges, senior engagement manager at Transport Focus, an industry watchdog, added: “When people are thinking about purchasing new rolling stock, these are the kinds of things that should be top of mind now.”
Heat waves are one thing in Britain. What about the Egyptian desert? German technology company Siemens is providing Egypt with a new set of high-speed trains that can reach speeds of up to 230 kilometers per hour. The company's Velaro trains are used in many places in Europe, but for Egypt, Siemens really put them to the test. Last summer, the company took one of the trains to a test facility in Austria and exposed it to unpleasant conditions, including temperatures of up to 60 degrees Celsius and strong winds. “We achieve an indoor temperature of 26 degrees under the hottest outdoor conditions,” says Björn Buchholz, head of HVAC and door systems.
