Just watching something on Tv that I presume is set in London (Above Suspicion) and it looked like they now have platform doors on the Tube to stop people accessing (chucking themselves onto) the actual tracks before the train gets there. I haven't been to London in over five years so I don't know if I have got the wrong end of the stick.
I used to be really paranoid about tube stations, think the door things would make me feel 'safer' (I am a nutter magnet and was always convinced that someone would try to push me under a train!).
If you ask employees of the service they will tell you it is part of the softening up process for complete automation, driverless trains and unstaffed stations.