How to Keep Subways and Trains Cool in an Ever Hotter World
TfL, to its credit, has made many efforts over the years to try to deal with the problem of hot tunnels, including attaching cooling panels to tunnel walls. The panels, which circulate water to extract heat from the air, were deployed in a trial in 2022, although they are not currently in use. Paul claims that such a system could be too expensive.
Hassan Hemida at the University of Birmingham says Paul's water-cooling technology is a “good idea”, although it remains to be seen how much heat it could actually remove from a real, busy tube station full of people.
Certain railroads just pushed the limits of our ability to cool things down, Hemida says. He gives the example of super-fast trains that travel, for example, 400 kilometers per hour. They force air out of the way at high speeds, which means the air pressure surrounding the 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, that can cause the air conditioning unit to fail. “I have been contacted by colleagues from China, and they want to find a solution to this problem,” adds Hemida.
However, more and more train operators are adopting air conditioning systems as standard. The still relatively new Elizabeth Line of London, for example, has air conditioning. And a spokesman for Škoda Transportation, which recently rolled out air-conditioned metro trains in the capital of Bulgariasays, “Generally, every car we manufacture now is equipped with AC.” Sharon Hedges, senior engagement manager at Transport Focus, an industry watchdog, adds: “When people think about acquiring new rolling stock, these are the kinds of things that should be top of mind right now.”
Heatwaves are one thing in Britain. What about the Egyptian desert? German tech company Siemens is supplying Egypt with a new set of high-speed trains that can travel at speeds of up to 230 kilometers per hour. The company's Velaro trains are used in many places around Europe, but for Egypt Siemens has really put them through their paces. Last summer, the company took one of the trains to a test installation in Austria and exposed it to unpleasant conditions, including temperatures of up to 60 degrees Celsius and strong winds. “We reach 26 degrees inside temperature in the hottest conditions outside,” says Björn Buchholz, head of HVAC and door systems.
