Passenger action Part 2

From wikipedia:

"Most fatalities on the network are suicides. Most platforms at deep tube stations have pits beneath the track, originally constructed to aid drainage of water from the platforms, but they also help prevent death or serious injury when a passenger falls or jumps in front of a train and aid access to the unfortunate person.[15] These pits are officially called "anti-suicide pits", colloquially "suicide pits" or "dead man's trenches". Delays resulting from a person jumping or falling in front of a train as it pulls into a station are announced as a "unfortunate delay", "passenger action", "customer incident" or "a person under a train", and are referred to by staff as a "one under". London Underground has a specialist "Therapy Unit" to deal with drivers' post-traumatic stress, resulting from someone jumping under their train.
The Jubilee line extension is the first line to have platform edge doors. These prevent people from falling or jumping onto the tracks, but the main financial justification for their provision was to control station ventilation by restricting the 'piston-effect' of the moving air caused by the trains."

Well that answers that question.