Over-run

depends how far through youve gone, if youre past the opo monitors but doors are all in the platform you get the second right from station staff. if the front set of doors is in the tunnel you can cut them out (not on all stocks though). there are procedures in place for partial and full overrun (less than or over one car length) involving wrong direction movements and things, but in reality it takes too long so you would either detrain via the butterflies or continue to the next station...

In the sixties you were allowed to push back at BR stations with signalman permission. At Kew Gardens you took it on your own bat as there were no starters either way.

Not sure about Berlin, but Stockholm allow reversing by up to 2m.

As Tom already said, here in the Stockholm Metro, you are free to back up your train up to two metres without any special ado, or even contacting the line control. Nowadays, there is a counter that puts the train into emergency if it moves in reverse more than two metres for any reason -rollback or deliberate back-up. It is possible to move longer distances in case of technical faults etc, but that is a special procedure requiring three crew, cutting out of various systems and so on.

Up until the late 90:ies however, all that happened when you threw the reverse switch was that you got an "L" cab signal code and a maximum speed of 15 km/h, and you could technically back up any distance, but was only permitted to back up two metres. Even earlier, you were in some circumstances permitted to reverse up to ten metres.

Within depot limits, no backing up is permitted without a lookout in the direction of movement. With a lookout, you can back up any distance you want.

On the mainline railways here in Sweden, you are permitted to back up in certain circumstances, depending among other things on whether you are on "station track" or "line track". These terms refer to the type and degree of signalling and control, by the way -there are tons of "rule-book stations" with no facilities for passengers whatsoever, and tons of stations in the sense of buildings for passenger exchange that are rules-wise not stations at all, but rather "line points" or "holding points". Likewise, the rules are different for trains, "vagnuttagning", roughly "vehicle movement" and shunting movements.

Anyway, basically and simplified, an EMU train on station track can, after contacting the controller responsible for that section, back up right to the station limit. If the station adjoins another station, the movement may continue over that limit into the next station section, and so on. Thus, it is technically (but hardly practically) possible for, say, an ordinary commuter train here in Stockholm to back up a distance of some 65 km.

We were briefed on RPS last year, but they have yet to install it on the 72's. I've pretty much forgotten about it! They'll have to refresh us all again! ;D