https://en.wikipedia.org/wiki/Platform_screen_doors
A person might be drunk or naturally disoriented and clumsy.
https://en.wikipedia.org/wiki/Platform_screen_doors#Types
They might collapse or intentionally want to jump onto the tracks.
https://en.wikipedia.org/wiki/Platform_screen_doors#Variable-type_platform_screen_doors
Some day such a safety barrier will become standard all over the world.
https://www.reddit.com/r/vancouver/comments/1umw7oe/everyone_getting_kicked_off_the_train_at/
