"Boltar" wrote in message
ups.com...
Is this an operational restriction or a physical one? If its the former
surely some special operational plan could be put into force?

It's both. The signalling was not designed to allow it to happen, so you
could only do it by working (and securing) the points manually.

The diagram below shows the area [1]. To reverse from south-to-north the
following would have to happen:-
1. Train runs in to southbound platform (no problem)
2. PG4 clear for shunt in to siding (no problem)
3. 6 points reversed/secured and train authorized out of siding (past PG10
at danger)
(problem - no protection from a train approaching from the south - PG1
is too close to the platform to do this, all other signals before that are
automatic).
4. 6 points normalized/unsecured and PG2 cleared

6
----------------------------------------------------------------------------------------------------------------
N/B to Cockfosters
|o PG1 ############## |oo PG2/3 \ PG10 o|
--------------------------------------
############## |oPG4 /
----------------------------------------------------------------------------------------------------------------
S/B from Cockfosters
PG11o| 7 PG12co| PG12bo|
PG12ao|

The problems basically are securing the points and authorizing the train out
of the siding. It could well require the power to be taken off (further
complicated as you might have to involve the sections for both directions
because the siding is in the middle, plus the gaps with the next section to
the north happen to be at 6 points), and would take a lot of time.

There is a fixed red lamp at the southern end of the northbound platform,
however it probably doesn't have a trainstop, so some kind of additional
protection would be necessary. I suppose the problem of northbound trains
could be dealt with by holding the Turnpike Lane stating signal at danger
and renumbering it as an "X" signal, but then you lose the ability to
transfer trains from Northfields to Cockfosters via the northbound line (has
this been happening, or vice versa?) or to run (engineers?) trains out of
the bomb site.



[1] Layout is correct, but doing it from memory so certain numbers might be
wrong. Also, referring to north and south for convenience - I'm sure someone
would have be along to remind everyone that the Picc is considered to run
from east to west!