[Yes, I know this was long ago.]
Post by firstname.lastname@example.org
Other ATO lines on the tube have a blue or white light for proceed in ATO
mode but the victoria line seems to have retained plain old red/green. Any
know if there's a particular reason for this?
The original Victoria Line ATO used:
* red: stop
* green: line clear to next signal, can be passed in manual mode
* white: line clear to next block post, can only be passed in auto mode
There were no signals between stations in general (there may be
exceptions), just block posts, which are signals as far as the ATO is
concerned but don't display anything (there is a sign in the tunnel at
the block post). So the white aspect was used to tell the driver that
the ATO knows what it's doing, rather than having the train pass a red
signal and possibly subconsiously conditioning drivers to ignore reds.
I haven't seen the detailed specification for the new ATO signalling,
but I would expect it to operate in much the same way, though block
posts might have been replaced by purely software constructs.
Clive D.W. Feather