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| Signal 424 Approach Locking (Bug or Interlocking) 26/06/2014 at 05:39 #62064 | |
CTCThiago
232 posts |
Good Morning all, I found some strange situation on my last time on West Hampstead (it was 10 minutes ago), I have a train (6M92-2009TT) crossing from Upper Holloway to Carlton Road Jn. The signal 424 was Yellow, and i replaced to red, until here, ok, but the signal entered in emergency (Flashing Red 120 seconds) and i got the message (box) of 120 seconds approach locking on signal 424. I don't know if it is a bug, I have an attachment: Note: When Track circuit T195 is occupied, signal 424 (if replaced to red) enters in emergency.   Anyone can clarify for me? Regards, Thiago. Post has attachments. Log in to view them. Log in to reply |
| Signal 424 Approach Locking (Bug or Interlocking) 26/06/2014 at 11:40 #62077 | |
Jay_G
54 posts |
I wouldn't call it 'emergency', it's just holding the route for a set amount of time INCASE a train is approaching. Some installations don't have "comprehensive approach locking release" as it's quite expensive and complicated to do, so some will just time out regardless if a train is coming or not. Whether that's the case here or not I don't know! Log in to reply |
| Signal 424 Approach Locking (Bug or Interlocking) 26/06/2014 at 12:25 #62080 | |
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Stephen Fulcher
2078 posts 
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That is working correctly. Even though the train going away is not going to pass that signal anyway, the track circuit that is occupied is between it and the previous signal, therefore the interlocking "sees" within the approach locking distance for the signal that was replaced, hence it has to time out. This would be the case whether it has comprehensive approach locking or not - the train is within the approach locking distance so comprehensive locking would have to time out, and if it was non-comprehensive then the positions of any trains or track circuit failures would be irrelevant. Jay, it is sort of an emergency provision in that the whole purpose of approach locking is to hold points and crossings in the same position until a train can be reasonably expected to have come to a stand at a signal. If a SPAD occurs then the route is still held. In SimSig, this will not be relevant as SPADs do not happen, but in reality it is not uncommon. Once the signal has been passed then the route is held irrespective of whether it has timed out or not. Log in to reply The following user said thank you: CTCThiago |
| Signal 424 Approach Locking (Bug or Interlocking) 26/06/2014 at 13:47 #62085 | |
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CTCThiago
232 posts |
Thanks for the excellent answer stephen, I understood 100%. " said: That is working correctly.:cheer: Thiago. Log in to reply |