Tests on a China metro carriage, as before today’s fire standards, exceeded 1000 kW heat in less than three minutes. The 2B-type carriage used (internal dimensions 1.9 x 3 x 2.65 m) was manufactured early on for the China metro system, before improvements made to fire protection standards over the last ten years such as CJ/T 416-2012). Ignition was by 10 litres of gasoline. From around 1 ½ minutes after ignition, several windows break and fire spreads inside the carriage. By 3 minutes, flames are spread widely inside the carriage, along the roof and are spurting out of broken windows. Occupants would have around 10 seconds to feasibly escape such a fire. By 30’’, the temperature has reached 150°C 1.5m above the floor throughout the carriage. Breakage of windows by the fire is critical to letting in oxygen and accelerating the fire.
“Metro train carriage combustion behaviors – Full-scale experiment study”, C. Shi et al., Tunnelling and Underground Space Technology 104 (2020) 103544 https://doi.org/10.1016/j.tust.2020.103544