20-09-2012, 04:22 PM
Haven't got access right now to my plan, so will respond later re detail.
However the treadles needed for an AHBC are:
1. For the outer strike in, which as you say could need to be inhibited if there is a signal within this area that then could require to have delayed clearance applied.
2. To detect a SPAD (to back-up the TC occupation) at such a signal
3. Treadles either side of the road crossing in order to determine directionality of the train and to rasie the crossing afterwards
4. Strike-in for a "wrong direction" train (as per 1 but generally placed at lesser distance to reflect the lower speed for moves in the abnormal direction)
However the treadles needed for an AHBC are:
1. For the outer strike in, which as you say could need to be inhibited if there is a signal within this area that then could require to have delayed clearance applied.
2. To detect a SPAD (to back-up the TC occupation) at such a signal
3. Treadles either side of the road crossing in order to determine directionality of the train and to rasie the crossing afterwards
4. Strike-in for a "wrong direction" train (as per 1 but generally placed at lesser distance to reflect the lower speed for moves in the abnormal direction)
(20-09-2012, 12:56 PM)savitha kandasamy Wrote: Hi PJW,
with reference to your 2002 solved layout, I have one query. For upbranch, AHBC has a treadle placed near to SIP(40 sec).. My understanding is that, if a signal happens to be placed within the striking distance, the signal is approach released (delayed clearance control). But I am not able to understand the need for one more treadle near signal G38. Kindly clarify.
PJW