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Post by antharro on Jun 30, 2010 12:57:24 GMT
The last few times I've been at Piccadilly Circus (Bakerloo), I've made a point of standing at the northbound end of the southbound platform when getting a train going south.
Signal A1000, at the northbound end of the northbound platform, would appear to be for northbound trains, but I've never seen it used. Is it used for the crossover?
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mrfs42
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Post by mrfs42 on Jun 30, 2010 13:09:07 GMT
ISTR that it is connected with checking the speed of trains going through the crossover - is it still approach lit?
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Oracle
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Post by Oracle on Jun 30, 2010 14:30:23 GMT
Hands up those who recall the scissors crossover, allowing both-directions reversals?
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Post by Deleted on Jun 30, 2010 18:48:21 GMT
My hand is up! Never had the pleasure of using it though.
In fact, in addition to A1000 (which will only illuminate when the NB starter [BP10] from the SB platform is clear - it can only show red or yellow), there is also the NB starting signal BP9 just inside the tunnel, beyond which are three further signals, A9000, A9001 and A9002, all approached controlled. A1000, A9000, A9001 and A9002 were all commissioned from 06.11.2000 to restrict the speed of trains departing NB from the SB platform, the scene of several derailments over the years, some serious and some very serious (i.e. the latter category causing a lot of infrastructure damage - track, cabling and train).
One derailment of a 1959 Stock saw the wheel flanges of the car involved ending up sitting on top of the running rails, rather than being "on the floor".
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Post by antharro on Jun 30, 2010 19:31:26 GMT
And there's the answer. Thanks, all! :-)
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Tom
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Post by Tom on Jun 30, 2010 21:38:39 GMT
My hand is up! Never had the pleasure of using it though. Too old for me, but I did use the existing crossover once, and maintained it more than once. From memory the BP10/A1000/BP9/A900x group of signals are not the easiest to test either... |
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Post by Deleted on Jul 1, 2010 0:04:28 GMT
One derailment of a 1959 Stock saw the wheel flanges of the car involved ending up sitting on top of the running rails, rather than being "on the floor". Wow  Another example of auto numbers repeating themselves across the network, the A1000 that sprung to my mind was (the trainstop-less) A1000 as you come into Chesham. |
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mrfs42
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Post by mrfs42 on Jul 1, 2010 0:20:40 GMT
One derailment of a 1959 Stock saw the wheel flanges of the car involved ending up sitting on top of the running rails, rather than being "on the floor". Wow Another example of auto numbers repeating themselves across the network, the A1000 that sprung to my mind was (the trainstop-less) A1000 as you come into Chesham. H over G, isn't it? You've also got A1001 (nights/carpet shampoo) and A1002 lurking around on the Aldwych branch. |
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Post by Deleted on Jul 1, 2010 12:35:43 GMT
I think there's an A1000 outside Chesham too.
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Post by Deleted on Jul 1, 2010 22:08:06 GMT
When did the scissors-crossover get taken out at Picc Circus? I was a driver on the Bakerloo when they had the Thames Tunnel shut-down in the 90s when all s/b trains reveresed there, and there was no sissor-crossover there then. Why did they remove it? Seems a good idea to have this extra operational capability.
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Tom
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Post by Tom on Jul 1, 2010 23:14:47 GMT
There is an A1000 at Chesham as well. Part of the Terminal Protection signalling was to provide a home signal prior to all terminal stations including those on single lines. The numbering was intended to be:
A1000 Chesham
A1001 Olympia?
A1002 Aldwych
A1003 Ongar
A1004 Mill Hill East
In the end, only the signals at Chesham, Aldwych and Mill Hill East were ever commissioned.
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Tom
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Post by Tom on Jul 1, 2010 23:19:16 GMT
When did the scissors-crossover get taken out at Picc Circus? I was a driver on the Bakerloo when they had the Thames Tunnel shut-down in the 90s when all s/b trains reveresed there, and there was no sissor-crossover there then. Why did they remove it? Seems a good idea to have this extra operational capability. It was removed some time prior to resignalling in 1991 (the exact date I'm sure Reganorak will provide). It was actually more hassle than it was worth, as the starter and southern end of the crossover were sited well into the NB platform. The bracketry was only removed in the last year or so, and the gap in the positive rail for the trainstop still exists. On the occasions when trains did use it, they had to stop in the NB running tunnel south of the station and cut various doors out. |
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Post by Deleted on Jul 1, 2010 23:19:44 GMT
There is an A1000 at Chesham as well. Part of the Terminal Protection signalling was to provide a home signal prior to all terminal stations including those on single lines. The numbering was intended to be: A1000 Chesham A1001 Olympia? A1002 Aldwych A1003 Ongar A1004 Mill Hill East In the end, only the signals at Chesham, Aldwych and Mill Hill East were ever commissioned. The A1000 outside Chesham despite having no trainstop, has an effect on the platform based 'policeman' trainstop entering the platform. Due to a dead end this ties in exactly with what Tom says. If A1000 on the single line is passed at a red aspect, the train will get tripped in the platform. This tube lark is better worked out than most would think ;D ;D ;D ;D ;D |
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mrfs42
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Post by mrfs42 on Jul 1, 2010 23:19:52 GMT
I'm fairly sure that I've seen a reference to A1001 being 'considered' for Olympia.
Can't for the life of me remember where
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Tom
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Post by Tom on Jul 1, 2010 23:21:44 GMT
I'm fairly sure that I've seen a reference to A1001 being 'considered' for Olympia. Can't for the life of me remember where I'm having the same problem! I'm sure the signal numbering drawing has some reference to these signals... |
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Post by programmes1 on Jul 2, 2010 7:51:39 GMT
Hands up those who recall the scissors crossover, allowing both-directions reversals? I have to admit using it once in the well it was a long time ago. The cross-over was removed 1970s if the memory is working. The problem reversing S-N via the NB platform was the length of the actual platform it just wasn't long enough so when a train was reversed the driver had to go into the tunnel then wait for the guard to go into the rear cab and check if the signal BP11 I think which was hanging down from the ceiling of the platform well before the headwall, if the signal was clear the driver would reverse yes reverse back into the full length of the platform needless to say a minefield for the H&S brigade. |
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Post by DWS on Jul 2, 2010 8:38:16 GMT
Hands up those who recall the scissors crossover, allowing both-directions reversals? I have to admit using it once in the well it was a long time ago. The cross-over was removed 1970s if the memory is working. The problem reversing S-N via the NB platform was the length of the actual platform it just wasn't long enough so when a train was reversed the driver had to go into the tunnel then wait for the guard to go into the rear cab and check if the signal BP11 I think which was hanging down from the ceiling of the platform well before the headwall, if the signal was clear the driver would reverse yes reverse back into the full length of the platform needless to say a minefield for the H&S brigade. Yes BP11 was just out side the door of the signal cabin on the northbound. Also signal's BPZ14 & BPZ15 on the Piccadilly line used to hold the last trains at night to make passenger connections to and from both lines. |
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Post by North End on Jul 2, 2010 10:25:32 GMT
There is an A1000 at Chesham as well. Part of the Terminal Protection signalling was to provide a home signal prior to all terminal stations including those on single lines. The numbering was intended to be: A1000 Chesham A1001 Olympia? A1002 Aldwych A1003 Ongar A1004 Mill Hill East In the end, only the signals at Chesham, Aldwych and Mill Hill East were ever commissioned. If I remember correctly, there was a fixed yellow signal approaching Ongar, whose ID plate simply read "ONGAR" on a yellow background. Not sure when this was commissioned. |
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Tom
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Post by Tom on Jul 3, 2010 0:24:24 GMT
I believe it was part of the Terminal Protection works. Ongar never got A1003 as planned.
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Post by Deleted on Jul 3, 2010 0:48:30 GMT
I'm fairly sure that I've seen a reference to A1001 being 'considered' for Olympia. Can't for the life of me remember where See Underground News 565 jan 09 where A1001 is considered for holborn. Hope this helps. |
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Post by mrfs42 on Jul 3, 2010 23:44:28 GMT
I'm fairly sure that I've seen a reference to A1001 being 'considered' for Olympia. Can't for the life of me remember where See Underground News 565 jan 09 where A1001 is considered for holborn. Hope this helps. It was and installed. Got the YP somewhere. |
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Post by suncloud on Jul 5, 2010 18:18:48 GMT
I was always bemused by the equivalent signal on the Abbey Flyer...
Well I say signal, it is a sign depicting a 'warning' semaphore.
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Post by chorleywood on Jul 12, 2010 21:48:52 GMT
There is an A1000 at Chesham as well. When the Piccadilly Circus speed controlled scheme was designed, this doppelganger was noted, but it was decided that the risk of confusion was sufficiently low! The decision to include A1000 in the scheme at all was marginal - it's hard to for a train to get up to a speed at which it will actually get tripped by this signal unless the reversing train is short and hence starts from further away after having stopped at the SB platform stop mark. (Is this still true? Were the timing sections adjusted recently when the crossover was replaced?) There's one other signal that was affected by this scheme but which no-one has mentioned! A374 will approach clear for a reversing train when position detector NE indicates that the rear of the train is off the crossover - this prevents a driver going past A9002, seeing a green light and being tempted to regain line speed. Instead the driver gets a green "in their face" when it's time to put the handle round! |
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Tom
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Post by Tom on Jul 13, 2010 20:46:23 GMT
There is an A1000 at Chesham as well. When the Piccadilly Circus speed controlled scheme was designed, this doppelganger was noted, but it was decided that the risk of confusion was sufficiently low! Yes - and you'd know all about that scheme...  They weren't modified AFAIK, but it did happen during my time in exile. I forgot about A374 - just like when the need for a GSR was overlooked! |
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