On Mon, 27 Feb 2012 04:16:20 -0800 (PST)
77002 wrote:
The line isn't installed yet never mind any technology but relevant
technology is already in use elsewhere; a train cannot be signalled
from the DC line to LU at Queens Park if it does not pass current
through the 4th rail.
Similar methods can prevent an LU train going to 3rd rail territory
but are AFAIAA not currently used anywhere, possibly because the
consequences are non-destructive (except for the timetable). For new
work other technology such as e.g. identification transponders could
achieve the same job.

One is aware that transponders could solve this problem. However,
AFAIK, LUL have yet to utilize such technology for the above stated
purpose.

Just out of interest , has an LU train ever accidentally been routed onto
a 3rd rail line by mistake, eg at the aformentioned locations or
gunnersbury?

B2003