03-09-2012, 01:18 PM
Dear Murugesan
Thanks for your posting - here are some comments.
Track circuit dead locking - good, both foul track circuits identified.
Calling and locking by routes (except swinging overlap conditions)
Good. One omission is that the points also need to be called and locked reverse by routes 214A(M) & B(S) for flank protection. this is easy to miss, but you did identify this for 347A(M) & ©.
Swinging Overlap conditions
The additional track circuit clear + points set or free conditions have been correctly specificied
What you've missed (and it's very unpleasant to even think about, let alone write down..!) is the fact that track circuit FZ is also an area where there can be a directly opposing swinging overlap used by routes up to 347 or 349 signals. To express this, you would an extra control to 139 N to R controls as follows:
Requires
All routes up to 212 and SRL normal OR
[(all routes up to 347 and SRL normal Or 132 R (S or F) or (134N,133N S or F) AND
(all routes up to 349 and SRL Normal or 133N (SorF) or 135R (SorF)) ]
where SRL = Sectional Route Locking
SorF = set or free
This set of extra conditions prove that there is either no opposing overlap set up to FZ, or that it is free to swing to another non-conflicting lie.
It should be noted that this horrendous piece of login doesn't have a set of contro, table columns to write it in, but you can create it either by joining enties together with brackets, dashes & OR statements, or writing it out separately on a continuation page
Overall, a good attempt; the points I have corrected are unlikely to lose many marks
Reuben
Thanks for your posting - here are some comments.
Track circuit dead locking - good, both foul track circuits identified.
Calling and locking by routes (except swinging overlap conditions)
Good. One omission is that the points also need to be called and locked reverse by routes 214A(M) & B(S) for flank protection. this is easy to miss, but you did identify this for 347A(M) & ©.
Swinging Overlap conditions
The additional track circuit clear + points set or free conditions have been correctly specificied
What you've missed (and it's very unpleasant to even think about, let alone write down..!) is the fact that track circuit FZ is also an area where there can be a directly opposing swinging overlap used by routes up to 347 or 349 signals. To express this, you would an extra control to 139 N to R controls as follows:
Requires
All routes up to 212 and SRL normal OR
[(all routes up to 347 and SRL normal Or 132 R (S or F) or (134N,133N S or F) AND
(all routes up to 349 and SRL Normal or 133N (SorF) or 135R (SorF)) ]
where SRL = Sectional Route Locking
SorF = set or free
This set of extra conditions prove that there is either no opposing overlap set up to FZ, or that it is free to swing to another non-conflicting lie.
It should be noted that this horrendous piece of login doesn't have a set of contro, table columns to write it in, but you can create it either by joining enties together with brackets, dashes & OR statements, or writing it out separately on a continuation page
Overall, a good attempt; the points I have corrected are unlikely to lose many marks
Reuben