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Post by djlynch on Sept 1, 2011 2:22:04 GMT
There was a mention on the thread about the recent Circle line closures that part of that area has sequential signalling, and I'm not familiar with the term. What makes it different from conventional signalling and why is it needed?
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Post by Harsig on Sept 1, 2011 4:33:12 GMT
In simple terms sequential signalling provides a check that track circuits have operated in the correct sequence as a train passes through the section before allowing signals to clear for the following train. This provides an additional level of protection where there is or was a perceived risk of the track circuits showing a false clear when there is a train in section. In the case of the section of line through Notting Hill this risk arose from the poor drainage on that section of line.
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Post by abe on Sept 1, 2011 8:50:06 GMT
I understand that sequential signalling can be switched on north of Rickmansworth. It is used during leaf-fall season, when track circuits are more likely to 'lose' trains due to the insulating layer of leaf mulch that builds up on the rails.
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Post by programmes1 on Sept 1, 2011 9:25:08 GMT
I think it's known as GYR circuit.
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mrfs42
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Post by mrfs42 on Sept 1, 2011 11:50:16 GMT
That would make eminent sense as 'Y' means disengaging.
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Deleted
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Post by Deleted on Sept 1, 2011 18:07:35 GMT
I think it's known as GYR circuit. You are correct it is known as a GYR it also provides a single line (olympia has it) protection. Bayswater has it due to the tunnel getting abit wet at times  |
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Deleted
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Post by Deleted on Sept 1, 2011 18:07:40 GMT
I think it's known as GYR circuit. Green-Yellow-Red? ;D |
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metman
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Post by metman on Sept 1, 2011 18:44:27 GMT
But YGYR on some parts of the Met! ;D
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mrfs42
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Post by mrfs42 on Sept 1, 2011 19:00:43 GMT
Signal Disengaging Relay
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Post by railtechnician on Sept 10, 2011 3:36:05 GMT
I believe the Bakerloo was resignalled with GYR circuitry in the late 1980s resignalling. At the time my involvement was with rewiring tunnel telephones, commissioning SPTs and renewing the original Storno train radio cabling and I can't ever recall having seen GYR ciruitry as it didn't exist where I worked as a signal lineman in later years. An example would be interesting if there are any around. |
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Tom
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Post by Tom on Sept 10, 2011 22:12:16 GMT
Yes, the Bakerloo has GYR circuitry throughout (and it was developed for the Bakerloo line).
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