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| Welwyn tunnels down line 04/01/2011 at 12:28 #2194 | |
hornby0729
33 posts |
Hi could someone with the correct knowledge help please. On this photo I can see two four aspect signals for the down line both at red, I assume that they are both the same signal just in different positions for different amounts of visability. Can anyone please explain the set up here. Or has anyone got any better pictures of the section of track and signals in the area between the two tunnels that shows other things? Thanks in advance. Log in to reply |
| Welwyn tunnels down line 04/01/2011 at 12:28 #13077 | |
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hornby0729
33 posts |
Hi could someone with the correct knowledge help please. On this photo I can see two four aspect signals for the down line both at red, I assume that they are both the same signal just in different positions for different amounts of visability. Can anyone please explain the set up here. Or has anyone got any better pictures of the section of track and signals in the area between the two tunnels that shows other things? Thanks in advance. Log in to reply |
| Welwyn tunnels down line 04/01/2011 at 13:24 #13078 | |
GeoffM
6287 posts 
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They're showing yellow and are coacting signals - in other words show the same aspect. Usually the lamps in both signals have to be proved alight before the preceding signal will show a proceed aspect.
SimSig Boss Log in to reply |
| Welwyn tunnels down line 04/01/2011 at 13:58 #13080 | |
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clive
2738 posts |
Both signals between the tunnels, and (IIRC) the down signal after the north tunnel, are co-acting pairs. The signal on the ground (red at the top) is easily seen through the tunnels. The signal on the gantry (red at the bottom) is easier to see when the train is stopped at it, and is the original 1976 signal. Being co-acting, both show the same aspect (including flashing).
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| Welwyn tunnels down line 04/01/2011 at 23:31 #13087 | |
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UKTrainMan
1803 posts |
clive said:and (IIRC) the down signal after the north tunnel, are co-acting pairs.Correct. I can't recall if the signals between the two tunnels also flashes, but I know for certain that the pair at country end of Welwyn North tunnel does flash. Any views and / or opinions expressed by myself are from me personally and do not represent those of any company I either work for or am a consultant for. Log in to reply |
| Welwyn tunnels down line 05/01/2011 at 00:49 #13088 | |
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lpeters
160 posts |
You know travelling through those tunnels they seem to be reasonably long from my experience of being on 365s on CBG/PBO fast/semi-fast (Finsbury Park then Stevenage) but when you look at those photos they are actually much shorter than they feel when in an actual train. Slightly off-topic but as an on-topic comment, If one of those signals fails, are both considered failed or would they still show proceed aspects?
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| Welwyn tunnels down line 05/01/2011 at 06:55 #13090 | |
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clive
2738 posts |
Yes, the signals between the tunnels flash. If you think through the aspect sequences, you'll see that they have to (or just set up the routes on SimSig KX). The south tunnel is 446 yards and the north tunnel 1046 yards. The latter is beaten by Potters Bar tunnel, at 1214 yards. Log in to reply |
| Welwyn tunnels down line 05/01/2011 at 09:33 #13091 | |
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Firefly
521 posts |
Luke Both Signals are driven by the same relay so they will always show the same aspect as each other. It's possible that one could become black (display no aspect) in which case the signal in rear would be held at danger. The other signal would continue to show the correct aspect. FF Log in to reply |
| Welwyn tunnels down line 05/01/2011 at 22:29 #13102 | |
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UKTrainMan
1803 posts |
clive said:The south tunnel is 446 yards and the north tunnel 1046 yards. The latter is beaten by Potters Bar tunnel, at 1214 yards.Yet they're all trumped by Ponsbourne Tunnel on the Hertford Loop being roughly 2640 yards long (1[sup]1[/sup]/[sub]2[/sub] miles). Any views and / or opinions expressed by myself are from me personally and do not represent those of any company I either work for or am a consultant for. Log in to reply |