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| Phantom Overlaps 13/05/2017 at 19:11 #95070 | |
Giantray
347 posts |
Can someone with a technical background explain Phantom Overlaps please. I understand why they are used, but I am having trouble understanding how the interlocking knows the overlap is clear to the POL and not the standard overlap which could be occupied?
Professionalism mean nothing around a bunch of Amateur wannabees! Log in to reply |
| Phantom Overlaps 13/05/2017 at 19:22 #95071 | |
JamesN
1607 posts |
Giantray in post 95070 said:Can someone with a technical background explain Phantom Overlaps please. I understand why they are used, but I am having trouble understanding how the interlocking knows the overlap is clear to the POL and not the standard overlap which could be occupied?They tend to be found where trailing points are within the POL. Conditions on the signal would be along the lines of Txxx clear OR points Pyyy reverse/normal as appropriate. Last edited: 13/05/2017 at 19:23 by JamesN Reason: None given Log in to reply |
| Phantom Overlaps 13/05/2017 at 20:25 #95074 | |
GeoffM
6376 posts 
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JamesN in post 95071 said:Giantray in post 95070 said:I don't think it matters if it's facing points or trailing points beyond the POL. The track circuit is longer than it needs to be so the POL is "at" the correct distance usually, with the points beyond (there may still be locked points before the POL). Since the points are beyond the overlap, they don't need to be in any specific position so are neither called nor detected. However, the TC still needs to be clear. I suppose you could consider the POL marker as the distance beyond which no more locking/checking is in effect.Can someone with a technical background explain Phantom Overlaps please. I understand why they are used, but I am having trouble understanding how the interlocking knows the overlap is clear to the POL and not the standard overlap which could be occupied?They tend to be found where trailing points are within the POL. Conditions on the signal would be along the lines of Txxx clear OR points Pyyy reverse/normal as appropriate. SimSig Boss Last edited: 13/05/2017 at 20:41 by GeoffM Reason: None given Log in to reply The following user said thank you: Giantray |
| Phantom Overlaps 13/05/2017 at 20:40 #95075 | |
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Hawk777
386 posts |
GeoffM in post 95074 said:The ones I've seen tend to be facing points in the overlap. The track circuit is longer than it needs to be so the POL is "at" the correct distance usually, with the facing points beyond. Since the points are beyond the overlap, they don't need to be in any specific position so are neither called nor detected. However, the TC still needs to be clear. I suppose you could consider the POL marker as the distance beyond which no more locking/checking is in effect.Jumping in here a bit, but this is quite interesting to me. What would be the advantage of a phantom overlap ending in rear of the points, in contrast to a swingable overlap including the points? In both cases you would be able to move the points with a route set to the protecting signal. Log in to reply |
| Phantom Overlaps 13/05/2017 at 21:01 #95076 | |
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Stephen Fulcher
2078 posts
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Saves money. One track circuit and associated Interlocking instead of two.
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| Phantom Overlaps 16/05/2017 at 13:45 #95132 | |
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Giantray
347 posts |
GeoffM in post 95074 said:Thank you Geoff, I knew someone would explain it simply. Explains why they are used and are going to be used in the London Bridge Platforms 6,7,8 & 9. If the full overlap needed to be locked by points, certain moves would not be possible on adjacent lines, but by allowing certain points to be free of the overlap, this would free up other moves. Professionalism mean nothing around a bunch of Amateur wannabees! Log in to reply |
| Phantom Overlaps 16/05/2017 at 13:48 #95133 | |
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Giantray
347 posts |
Stephen Fulcher in post 95076 said:Saves money. One track circuit and associated Interlocking instead of two.Not entirely true. It maybe that by providing the additional track circuits, they may not be long enough to be allowed as there is a minimum length a track circuit can be. Professionalism mean nothing around a bunch of Amateur wannabees! Last edited: 16/05/2017 at 13:48 by Giantray Reason: None given Log in to reply |