alexgoei Wrote:Hello Peter,
Gone through your review comments for this year's paper and have some questions.
Your suggestion to show this under Points N > R or R > N is only possible if the routes called/locked always have the point-to-point in the same throw. However this is not the case as my answers show.
Thank you and Regards
Think about 310 and 311.
a) 310N, 311N is a valid combination- parallel moves along the various running lines
b) 310R, 311N is a valid combination- e.g. 109B simultaneously with 118A
c) 310R, 311R is a valid combination- e.g. 118C
d) 310N, 311R is not useful as any move over 311R must also want 310R. Had there been a move in the opposite direction along the same path (imagine 109 reading to a LOS at the DH/DJ joint) then whilst that train on DG 311 would have to be locked R but 310 could be normalised thus allowing traffic on the Branch.
The point-to-point that could be provided is
a) the requirement for 311 to ensure that 310 already R before 311 could go R
b) the requirement for 310 to ensure that 311 already N before 310 could go N
since never want 311R without 310R. Such point-to-point would lead to slightly excessive locking on 310 had there been a move to the imagined LOS (but we'd have lived with this) but without any such a move existing then it is not restrictive (other than effect on the event of a detection fault).
From a route calling of points perspective (i.e. pseudo point-to-point) then the thing that you need to see that you should do is "any route that calls 310N should also call 311N". So if doing 311's CT, it is a prompt to look at routes such as those from 112 that you might otherwise have forgotten about; hey presto you get the marks for recognising that 311 provides flank protection.
You were right in what you were saying- what that was telling you was that you were attempting to place inappropriate point-to-point!
Does the above clarify?