2006 Part A Q2 POINTS

[PJW]

Hello YLP, Peter,

Looking again at 122A(M) with the exit signal at 134, Point 222 being a facing point is a swinging overlap. As long as the point is detected either in Normal or Reverse, the overlap for the 122A(M) can be in either lie - one AD, AE, the other BM, BN. However for the overlap on track circuit BN, 225 must be in a Normal position. It is reflected as a overlap locking timed to a stand on AC before exit signal 134.

I'll give more full comments later but overall the latest attempt for 225 was pretty damn good- there were just a few issues with the overlaps but considering the complexity you did well to get most.
Looking specifically at YLP's comment re the O/L of 122A(M) he is right. What you wrote above is also basically true (NB the "other overlap is AD, BM, BN) but is worded rather more re the aspect controls for 122 than the point locking- though of course for swinging overlaps these are indeed related.

So in the set by column you should have put:
[122A(M) w 222R]- with the "w" standing for "when" (reflecting it is only needs to be called sometimes, dependent upon the point lie of the facers)

Conversely the locking after 122A(M) which you have recorded only applies in the situation that 222 ar not free to swing away from directing the O/L onto the Up Main. Hence this should be written:
[122A(M) AD,BM,BJ,BK,AB, (AC ---- or AC -- for 30) ----- or 222N$28]
with the extra condition re 222N being written in the Remarks column linked by dashes and the square brackets holding the entire expression spread across 5 separate columns all together as clearly one item. You'd need to define the $28 (or just choose any # note if you don't want to remember the standard note) as "set or free to move"
You'll note that in the list of tracks I have also added the overlap track sections prior to the dead locking track BN as the overlap locking also needs to hold the points- they effectively have to be added at the front (out of logical running order) to ensure that they don't get muddled up with the time out condition re AC occupancy- if you really want to then you can write underneath the other tracks and link by a dashed line to be "after" the bracket; however this gets messy and takes up extra space so isn't often done.

You'll find there are other cases of such overlap conditions on some of the other routes; also what about 175A(M) and 122D(M)?
Conversely I don't think I'd make 122C(S) call N as there is an alternative overlap the other way; indeed it is a better one so I might even be tempted to make 122C(S) soft call 225R.....

Hope that addresses the issues that both Alex and YLP had; respond if need more assistance