Deleted
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Post by Deleted on Jul 19, 2014 18:13:09 GMT
I was up on the Northern end of the Met today and I noticed that the fog repeaters on that part of the line do not seem to display a green aspect, but instead the light is quite a bright white colour. I don't know if the fog repeaters have recently been changed or if they've been like that for a while. Is it just me, or is this a new type of fog repeater? I thought fog repeaters showed green or yellow like ordinary repeaters.
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Post by revupminster on Jul 19, 2014 18:30:22 GMT
This is because it is a four aspect signal area GYYR . You cannot show a green aspect if the associated signal is showing double yellow or single yellow. Tis was the reason for the last 80 odd years. As a side issue fog repeaters never used to be permanently illuminated but were switched on when required and Station Supervisors had to test them periodically by travelling on a train. So they would not be treated as danger signals (signal not illuminated) the aspects were surrounded by a white plate. The same white plate only triangular was used for rail gap indicators that normally displayed no aspect.
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Deleted
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Post by Deleted on Jul 19, 2014 18:40:04 GMT
Ah thank you!  I was momentarily slightly worried about my colour vision there... Speaking of not-permanently-illuminated signals, the wrong road starter at Northwood northbound did not illuminate until a train arrived from Northwood siding. Is it approach lit? |
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Post by Harsig on Jul 19, 2014 18:46:08 GMT
Speaking of not-permanently-illuminated signals, the wrong road starter at Northwood northbound did not illuminate until a train arrived from Northwood siding. Is it approach lit? Yes |
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Deleted
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Post by Deleted on Jul 19, 2014 18:52:54 GMT
Speaking of not-permanently-illuminated signals, the wrong road starter at Northwood northbound did not illuminate until a train arrived from Northwood siding. Is it approach lit? Yes Ta |
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Ben
fotopic... whats that?
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Post by Ben on Jul 19, 2014 19:35:27 GMT
Are fog signals permanently lit now?
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Post by Deleted on Jul 19, 2014 19:39:39 GMT
Yes
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Post by metrailway on Jul 20, 2014 7:55:28 GMT
Are fog signals permanently lit now? Yes for SPAD mitigation purposes |
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Deleted
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Post by Deleted on Jul 21, 2014 12:30:30 GMT
Are fog signals permanently lit now? Yes for SPAD mitigation purposes I'd noticed that. Can anyone tell me how long this has been the case please? |
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Rich32
Staff Emeritus
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Post by Rich32 on Jul 21, 2014 12:33:52 GMT
I'm not sure exactly how long, but it's been around four/five years.
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Post by Harsig on Jul 21, 2014 14:03:40 GMT
I'm not sure exactly how long, but it's been around four/five years. And the rest. I'm certain the change was made in the late 1990s. I became a signalman in 1996 and I'm sure the change was made very soon after that as I remember the change being made but have no recollection prior to that, of ever having to switch fog repeaters on or off or making arrangements for this to be done where they were controlled from a station rather than a signal cabin. |
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Deleted
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Post by Deleted on Jul 21, 2014 15:01:11 GMT
Fog Repeaters left on - It was from June 2001 - Traffic Circular 25/01.
The wrong road starter at Northwood has always been approach-lit (since 4-tracking). There are a small few other approach-lit signals around the system as well.
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Deleted
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Post by Deleted on Jul 21, 2014 15:08:28 GMT
The wrong road starter at Northwood has always been approach-lit (since 4-tracking). There are a small few other approach-lit signals around the system as well. Thanks What are they for, I mean, why have them? |
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North End
Beneath Newington Causeway
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Post by North End on Jul 21, 2014 16:45:29 GMT
The wrong road starter at Northwood has always been approach-lit (since 4-tracking). There are a small few other approach-lit signals around the system as well. Thanks What are they for, I mean, why have them? The normal reason is if the aspect could cause confusion to a driver on another line. I suspect the reason for the Northwood signal is because it could cause confusion to a driver on the southbound Main. Another cause is in long straight sections of Tube tunnel. Drivers will be able to tell you that sometimes red signals can appear much closer than they actually are. Therefore a small number of signals have been made approach-lit for the red aspect only in order to prevent drivers slowing down too early and therefore reducing the headway. An example of this is A.382 on the T4 Loop, which is on a long straight section. I think this may be the only one now, there were a few on the Jubilee which obviously have now all gone. In reality, once drivers get familiar with the arrangement, seeing the absence of an aspect tends to lead to drivers starting to slow down anyway, defeating the object - this could be avoided by making both aspects approach-lit, but I don't think it has ever been done this way. |
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Post by metrailway on Jul 21, 2014 16:46:07 GMT
The wrong road starter at Northwood has always been approach-lit (since 4-tracking). There are a small few other approach-lit signals around the system as well. Thanks What are they for, I mean, why have them? Not sure why the one in Northwood is approach lit. In the old days many signals were approach lit to conserve battery power and/or prolong bulb life. There is also one approach lit signal at Rickmansworth. Apart from one in Gloucester, the Ricky example is the only approach lit signal on a line used by mainline services in England. There are still quite a few examples dotted around in Scotland. |
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Deleted
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Post by Deleted on Jul 21, 2014 16:52:49 GMT
Thank you both - very interesting I was fascinated to hear about the approach-lit signals on the T4 loop. Any idea which signal at Ricky is approach-lit? The only thing I would say is that, given the protective wall that separates the northbound local platform from the southbound main, I'd be very surprised if you could see the wrong-road starter (JF 21, I believe) from the southbound main. Possibly right at the last moment? |
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Post by Deleted on Jul 21, 2014 19:02:30 GMT
Also the outlet signal in the siding at Hammersmith (D&P) at the Hammersmith end memory serves me right WD30a. That is also approch lit its to stop the picc W/B drivers getting confused, when someone is new in the area it is always reported as no red aspect.
There is also normal repeaters dotted around the place which have surpressed lighting which are switched over points.
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Deleted
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Post by Deleted on Jul 23, 2014 10:42:45 GMT
there were a few on the Jubilee which obviously have now all gone To the best of my knowledge there was: JM7 (between Neasden and Wembley Park NB (provided for wrong-road move SB, I believe)) A214 (between St. John's Wood and Swiss Cottage NB) A224 (between Baker Street and St. John's Wood NB) A261 (between St. John's Wood and Baker Street SB) R154/1, R154/2, A154 (between Southwark and London Bridge EB) TMX118 North Greenwich platform 2 inner home (from Canary Wharf EB) RTW2300.RTW22/1 (between West Ham and Stratford EB) RTW22/2, TW22 (between West Ham and Stratford. Provided on WB line for trains proceeding east towards Stratford) RTW5.RTW6/1 (between West Ham and Stratford EB) TW26 (between West Ham and Stratford EB, provided for trains proceeding wrong-road, although I don't fully understand this signal as it appears to me that the signal cannot display green, although it has a route indicator which may have been disabled. Presumably it is lit only when a train is approaching, bound for Statford Market Depot (I believe the two roads in question may be the 'holding roads'). Such a train would, I think, nevertheless be cleared by the shunt signal.) RTU21 (between Stratford and West Ham WB) |
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I was momentarily slightly worried about my colour vision there...
