Fans ventilate Metro's tunnels

Metro demonstrates operation of fan shafts that allow a free-flow of clean air through their underground tunnel network. In the event of an emergency, like the underground fire on Jan. 12, 2015, which left one rider dead from smoke inhalation, these air channels are critical to the safe passage of riders. ​The video was taken in a tunnel fan shaft between the Fort Totten and Georgia Avenue-Petworth stations.