In message , Clive D. W. Feather
writes

There is a connection both east/northbound and west/southbound between
the Picc and Victoria lines for engineers trains. As the signalling
systems are so different from each other (the Victoria is automatic),
it would not be possible to run 73 stock on the Vic. or 67 stock on
the Picc. other than under a total possession.

67 stock can be fitted with tripcocks; somewhere I have the exact rules
for trains moving between the two lines and cutting various bits of kit
in and out.

Quite true as this is (was?) frequently done to move these trains to and
from Acton works. I doubt very much we would see them in public service
in this condition though. Mind you as we're now going to be another 3
car unit short who knows what they might come up with?

Another bit of useless information is that the tripcock tester on the
south bound Victoria is the only one on the combine actually linked into
the signalling system - if a train fails the tripcock test here, the
signaller can't set the route onto the Westbound Picc.
--
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