In the deep-level tunnels (basically all lines other than the Metropolitan, Hammersmith and City, District and Circle) the trains are only a little bit smaller than the tunnels between the stations. read more
Best Answer: In the deep-level tube tunnels, the trains are a close fit within the tunnels, so you get a piston effect where air is pushed along in front of a train. The air is forced through to the platforms and station access tunnels creating wind. read more