Started looking at the points; clearly you did not finish 211!
210
Overall pretty good; I accept that you show route locking including the overlap so I don't comment upon that now.
Interested why you showed BC as a conditionally foul TC; personally I wouldn't have done as I'd say that any hand-signalled move over 210R would also be via 211R (indeed historically this is a classic case of point-to-point with 210 being "by 211". Not actually wrong but I think unnecessary. However what is wrong is that when you came to 211 points you didn't show such locking and it is definitely needed there.
Also I note that for 210 you have not considered EM as a conditionally foul track (I suppose depending on where the EM/CN functional joint actually is- always one end or the other in a 6ft crossover, not in the middle as Signalling Plans depict - then it may be clear but the plan does not say and you have not stated an assumption. Again 215 would traditionally have had point-to-point with 210, but this time of the form that 210 locks 215; 215 locks 210 so only one of the points could be reverse at any time.
Therefore you do seem to have been a bit inconsistent.
The reason why it is worth thinking of point-to-point is that this can be a way of ensuring that you catch all the flank point calls and associated route holding. You did get most of it, but didn't include 134A(M). I'd have made this call and lock 210N; first it gives flank to the overlap and secondly it stops locking 210R if that is the way they happen to be should CN becomes occupied and prevent the setting of 127A(M) etc. I have rather lost touch with the latest NR standards; the "making it simple" series of Notice Boards seem to me to be anything but! However I'd still be inclined to make 132A(M) detect 210A Normal in its aspect, to avoid the complications of extra SPAD overrun controls if omitted.
Similarly I think 128A(S) should also set and lock 210N.
Another thing that I'd be thinking of relating to point-to-point is the route holding on 210 after 131A(M); in the traditional world the route locking would always have extended to EM (since if having 215N is a pre-requisite of calling 210R then the locking on 210 might as well extend as far as the locking on 215 would have to). Without point-to-pint potentially 210 could be released earlier on the clearance of CN (as you have depicted)- provided of course that joint is really beyond clearance which takes us back to the earlier consideration of the conditionally foul dead track locking. A good cross check is always see if the route locking on points is consistent with the dead locking and if it is not be sure to analyse if there is a good reason for the discrepancy (there rarely is)
As far as the swinging overlaps are concerned then (at least until the latest "simplification") facing points are typically (i.e. except when there is a "preferred O/L defined etc) left where they happen to lie UNLESS the overlap to which they face is not available. The condition on the call is not therefore the further points being "Set locked and detected"; if the the further points are available to go to the lie compatible with the initial lie of the facing points it is them rather than the facers that are called. The facers are only called to move if the overlap beyond them cannot be set (by definition there must be an available overlap if the facers move because the route which has just set and is doing the calling has previously had to ensure that at least one overlap existed or the signaller's route request would have been rejected.
Hence in the calling column of the CT, the way to express it is of the form:
R>N: 107A(M) w 211N (set & locked only)
and in the corresponding route holding column, the entry would be:
N>R: 107A(M) or 211R (set or free to go).
Of course if 107A(M) set and locked 215N for either of the overlap lies over 210, then it would make the corresponding locking simpler and would not be restrictive; clearly that option would not be sensible to apply in the case of 211 as we have operational need to get 211N with 210N
211
You didn't do much of this and I have commented above about the track locking which it seems you overlooked. Clearly you ran out of time to finish the route calling or start the route locking; given the similarity of the two points then I think concentrating your time on the calling was probably the most sensible use of the last moments of your time.
Similar comment as before re the conditional call by 58B(M) and clearly there were various other overlaps involved- it was a shame that you didn't have the chance to add these at all since you can't get credit for what does not appear at all, yet if you had got all the calls then I think you may have got the lion's share of the marks for this point given the similarity of the route locking with 210.
I'll revisit the route CTs later; I'll look at the points on 2010; after all I have once signed into use an interlocking with no routes at all commissioned but the points available on point switches!
210
Overall pretty good; I accept that you show route locking including the overlap so I don't comment upon that now.
Interested why you showed BC as a conditionally foul TC; personally I wouldn't have done as I'd say that any hand-signalled move over 210R would also be via 211R (indeed historically this is a classic case of point-to-point with 210 being "by 211". Not actually wrong but I think unnecessary. However what is wrong is that when you came to 211 points you didn't show such locking and it is definitely needed there.
Also I note that for 210 you have not considered EM as a conditionally foul track (I suppose depending on where the EM/CN functional joint actually is- always one end or the other in a 6ft crossover, not in the middle as Signalling Plans depict - then it may be clear but the plan does not say and you have not stated an assumption. Again 215 would traditionally have had point-to-point with 210, but this time of the form that 210 locks 215; 215 locks 210 so only one of the points could be reverse at any time.
Therefore you do seem to have been a bit inconsistent.
The reason why it is worth thinking of point-to-point is that this can be a way of ensuring that you catch all the flank point calls and associated route holding. You did get most of it, but didn't include 134A(M). I'd have made this call and lock 210N; first it gives flank to the overlap and secondly it stops locking 210R if that is the way they happen to be should CN becomes occupied and prevent the setting of 127A(M) etc. I have rather lost touch with the latest NR standards; the "making it simple" series of Notice Boards seem to me to be anything but! However I'd still be inclined to make 132A(M) detect 210A Normal in its aspect, to avoid the complications of extra SPAD overrun controls if omitted.
Similarly I think 128A(S) should also set and lock 210N.
Another thing that I'd be thinking of relating to point-to-point is the route holding on 210 after 131A(M); in the traditional world the route locking would always have extended to EM (since if having 215N is a pre-requisite of calling 210R then the locking on 210 might as well extend as far as the locking on 215 would have to). Without point-to-pint potentially 210 could be released earlier on the clearance of CN (as you have depicted)- provided of course that joint is really beyond clearance which takes us back to the earlier consideration of the conditionally foul dead track locking. A good cross check is always see if the route locking on points is consistent with the dead locking and if it is not be sure to analyse if there is a good reason for the discrepancy (there rarely is)
As far as the swinging overlaps are concerned then (at least until the latest "simplification") facing points are typically (i.e. except when there is a "preferred O/L defined etc) left where they happen to lie UNLESS the overlap to which they face is not available. The condition on the call is not therefore the further points being "Set locked and detected"; if the the further points are available to go to the lie compatible with the initial lie of the facing points it is them rather than the facers that are called. The facers are only called to move if the overlap beyond them cannot be set (by definition there must be an available overlap if the facers move because the route which has just set and is doing the calling has previously had to ensure that at least one overlap existed or the signaller's route request would have been rejected.
Hence in the calling column of the CT, the way to express it is of the form:
R>N: 107A(M) w 211N (set & locked only)
and in the corresponding route holding column, the entry would be:
N>R: 107A(M) or 211R (set or free to go).
Of course if 107A(M) set and locked 215N for either of the overlap lies over 210, then it would make the corresponding locking simpler and would not be restrictive; clearly that option would not be sensible to apply in the case of 211 as we have operational need to get 211N with 210N
211
You didn't do much of this and I have commented above about the track locking which it seems you overlooked. Clearly you ran out of time to finish the route calling or start the route locking; given the similarity of the two points then I think concentrating your time on the calling was probably the most sensible use of the last moments of your time.
Similar comment as before re the conditional call by 58B(M) and clearly there were various other overlaps involved- it was a shame that you didn't have the chance to add these at all since you can't get credit for what does not appear at all, yet if you had got all the calls then I think you may have got the lion's share of the marks for this point given the similarity of the route locking with 210.
I'll revisit the route CTs later; I'll look at the points on 2010; after all I have once signed into use an interlocking with no routes at all commissioned but the points available on point switches!
(01-09-2013, 01:41 PM)dorothy.pipet Wrote: Did this some time ago, and now can't remember whether I felt I'd finished them!
Unfortunately I've not had access tot he scanner at work so this post was held up.
Anyhow - comments please?
opps, one more.
PJW