Earlier quoted context omitted.
My understanding is that with newer CBTC signalling systems--not sure if Berlin is using that--the trains know pretty much exactly where they are on the track, along with the positions of all other trains, speeds, braking distance, etc. This allows the trains to run closer together than they could using fixed block signalling technology. It's not required for full automation, but it makes full automation relatively s…
It seems that often the signalling system and the real time location reporting system aren't integrated. In NYC on many lines you get reports like 'there's a Brooklyn-bound train 2 stops away' that they make over the loud-speakers. Makes me wonder whether they have a separate device that just picks up when trains pass by a track segment, rather than using the information available via the signalling.
On other lines, my understanding is that the signalling system doesn't know which train occupies a block, just that a train occupies the block. Which block is occupied isn't sent to a central control center either.
So "there's a Brooklyn-bound train 2 stops away" is the best it can do, since it can know based on which side of the tracks the train is on where the train is going. It can't know the letter or number.