To NR practice, 212 is in a simple swinging overlap beyond 122. If 212 happen to be lying N then when a route to 122 is set then it will remain N but if it happens initially to be lying R then the route will still set and the points will be left R. Even with that route remaining set then 212 remain free to be swung either on the points individual switch or by setting a route forward from 122.
The overlap is simple in that there are the same aspect controls in either lie- no additional tracks, points or opposing routes to consider for one differently to the other.
The locking that there will be is purely because of how close 212 is to 122 signal; there will be "time of operation" locking to prevent point movement when there is a chance that there could be a SPAD that might then reach the points in mid-stroke. This is symmetrical N to R and R to N; the points are locked upon occupation of DH when there is overlap locking and released once DH has been occupied long enough that the train has been timed to a stand.
The overlap is simple in that there are the same aspect controls in either lie- no additional tracks, points or opposing routes to consider for one differently to the other.
The locking that there will be is purely because of how close 212 is to 122 signal; there will be "time of operation" locking to prevent point movement when there is a chance that there could be a SPAD that might then reach the points in mid-stroke. This is symmetrical N to R and R to N; the points are locked upon occupation of DH when there is overlap locking and released once DH has been occupied long enough that the train has been timed to a stand.
(07-08-2014, 10:34 AM)StrongLifts5x5 Wrote: Hi Folks
Regarding 212 points if the signaller keys 212R he can still set 138A(M)- 132B(M) so do 138A(M),136(B)M, 134B(M), and 132B(M) not also have to be in the R-N train detection clear box?
It would mean you would have both routes in both boxes so I'm not sure if its acceptable, the route boxes say "up main" but there would be nothing to stop a route set to 122 with 212R. With no condition within the aspect level of the signal, then there is no need for "counter conditional" in the point locking.
Or is the assumption that the points always called normal with a Up main route as its a terminal station?
PJW