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Post by tut on Mar 23, 2021 19:07:52 GMT
Thread split from here. It means that the train in the platform is signalled to depart the station, information provided for station staff as the driver receives this in the cab. On sub surface stock the white lights are on the train with the door indicator lights. The Central Line uses a different system, the white aspect displayed on signal heads advises that the next section is occupied but movement into that section is possible in ATO. Sequence would be red, white, green. I can only find a photo of a signal post showing a danger aspect, without white, which is unhelpful to commuter White signals can also be passed in Coded Manual, so long as you have codes, you can proceed obeying them. A white signal is only a stop aspect in Restricted Manual mode. Now of course, you'd only be in RM out there on the main line during a failure or degraded working in the first place and a fundamental part of passing a signal at danger with authority is switching to RM, so as far as I can tell white aspects are only really of relevance when applying 'the Rule', though I am by no means an expert on 'the Rule' on the Central line
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Post by brigham on Mar 26, 2021 12:44:40 GMT
Are these white lights something new, or are they a survival from the 'white for clear' days?
The only white signal I can remember on the 'main line' was what looked like a flashing car headlamp just in rear of an automated level crossing.
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Post by principlesdesigner on Mar 26, 2021 16:39:42 GMT
They have been there ever since ATP/ATO operation was commissioned in the mid 90s. The white signal on the mainline indicates to the driver that the crossing is in order
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Post by tut on Mar 26, 2021 18:38:16 GMT
Are these white lights something new, or are they a survival from the 'white for clear' days? The only white signal I can remember on the 'main line' was what looked like a flashing car headlamp just in rear of an automated level crossing.
The Vic had white signals as well in its original system, but no I shouldn't have thought they're a survival.
Yes for locally monitored level crossings, AOCLs (Automatic Open Crossing Locally Monitored) and ABCLs (Automatic Barrier Crossing Locally Monitored). The flashing white light repeats the red road lights and indicates that the crossing is in order. If the light is out or a red light (steady or flashing) is shown the driver must bring their train to a stand before reaching the crossing and then proceed as long as it is safe to do so, sounding the horn continuously until the front of the train is on the crossing. During darkness or poor visibility only passenger or ECS trains with interior lights lit may pass over the crossing when no flashing white light is displayed unless arrangements have been made to prevent road traffic passing over the crossing. Also if there are barriers trains may pass over the crossing during darkness/poor visibility if the barriers are down and the lights on the barriers are lit
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Post by tut on Mar 26, 2021 19:36:44 GMT
The only white signal I can remember on the 'main line' was what looked like a flashing car headlamp just in rear of an automated level crossing. A couple more are the two white lights that give an off indication at a position light shunt or subsidiary signal (plus the red and white on indication of the old-fashioned type of ground position light signals) and some semaphore subsidiary signals can show a white light at night when in the on position. |
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Tom
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Post by Tom on Mar 26, 2021 20:27:40 GMT
The Vic had white signals as well in its original system, but no I shouldn't have thought they're a survival. Some of them did; the white aspect on the corner signals was used at some places (Victoria SB is one) as a kind of 'off' indicator to platform staff, as the signal itself is in the tunnel and hard to see. |
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Post by tut on Mar 26, 2021 20:40:01 GMT
The Vic had white signals as well in its original system, but no I shouldn't have thought they're a survival. Some of them did; the white aspect on the corner signals was used at some places (Victoria SB is one) as a kind of 'off' indicator to platform staff, as the signal itself is in the tunnel and hard to see. My apologies if your post wasn't intended to imply otherwise but there were quite a few white aspects on the Victoria Line and by no means limited to platform starting signals (although again I don't know if that's what you meant to imply). And indeed there were plenty of platform starting signals without the white aspects. I always thought the corner signals were originally the only signals and meant for the train operator as much as anyone else, but it was found they were a bit difficult to see from the cab, so co-acters were added in the tunnels later. But maybe that's one of those things you hear that isn't actually true. ^ The last paragraph above is essentially true. I just took the trouble to check the yellow peril for the opening of Stage 1:
But again, I don't assume you didn't already know that!
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North End
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Post by North End on Mar 26, 2021 21:21:15 GMT
Some of them did; the white aspect on the corner signals was used at some places (Victoria SB is one) as a kind of 'off' indicator to platform staff, as the signal itself is in the tunnel and hard to see. My apologies if your post wasn't intended to imply otherwise but there were quite a few white aspects on the Victoria Line and by no means limited to platform starting signals (although again I don't know if that's what you meant to imply). And indeed there were plenty of platform starting signals without the white aspects. I always thought the corner signals were originally the only signals and meant for the train operator as much as anyone else, but it was found they were a bit difficult to see from the cab, so co-acters were added in the tunnels later. But maybe that's one of those things you hear that isn't actually true. ^ The last paragraph above is essentially true. I just took the trouble to check the yellow peril for the opening of Stage 1:
But again, I don't assume you didn't already know that!
The extra signal heads appeared as part of the preparation for the 09 stock. Presumably for sighting reasons. |
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Tom
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Post by Tom on Mar 26, 2021 22:52:03 GMT
Indeed they did; I actually had the chance to go to the VLU project to do all the design work for the Co-Acting signals, and turned the opportunity down. I ended up working on the Waterloo and City line train wash signalling alterations instead.
I should have clarified that some of the white aspects in the corner signal units were retained as an 'off' indicator after resignalling.
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Post by jimbo on Mar 27, 2021 0:19:01 GMT
Surely the signal aspects appear in the cab, so the traditional line-side signals are only used if the cab system fails?
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Post by tut on Mar 27, 2021 0:33:14 GMT
Surely the signal aspects appear in the cab, so the traditional line-side signals are only used if the cab system fails? I don't think LU has ever had a system where signal aspects appear in the cab. On the Central Line target speed is displayed in the cab and the fixed signals are sort of supplementary. They have definite value and degraded working is one but not the only. However the automatic colour lights that are provided between stations on plain line sections on the Central have always interested me somewhat. I love fixed signals and hate and loathe their removal so I'm not complaining but I've never been quite sure on the stated purpose of their retention after ATP was rolled out. I have read things that suggested there were originally some ideas which were later dropped about perhaps allowing trains without ATP to run on the line as well and the fixed signals were intended for them (I'm talking about the automatic signals between stations specifically) but I dunno really, I suspect they were probably retained for degraded working. The original Victoria Line system had a way of displaying the current code in the cab but the problem was that was all it could display. What it couldn't tell you was that the code was gonna come down before it did. I believe that's why the 67s were limited to 25 mph in Coded. Because the problem was if not you'd be going along at full speed with your 420 code completely fine, then suddenly the train would receive a 180 code and it'd trip. And there was nothing you could do about that so 25 it was.
I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. |
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Post by superteacher on Mar 27, 2021 9:45:23 GMT
Surely the signal aspects appear in the cab, so the traditional line-side signals are only used if the cab system fails? I don't think LU has ever had a system where signal aspects appear in the cab. On the Central Line target speed is displayed in the cab and the fixed signals are sort of supplementary. They have definite value and degraded working is one but not the only. However the automatic colour lights that are provided between stations on plain line sections on the Central have always interested me somewhat. I love fixed signals and hate and loathe their removal so I'm not complaining but I've never been quite sure on the stated purpose of their retention after ATP was rolled out. I have read things that suggested there were originally some ideas which were later dropped about perhaps allowing trains without ATP to run on the line as well and the fixed signals were intended for them (I'm talking about the automatic signals between stations specifically) but I dunno really, I suspect they were probably retained for degraded working. The original Victoria Line system had a way of displaying the current code in the cab but the problem was that was all it could display. What it couldn't tell you was that the code was gonna come down before it did. I believe that's why the 67s were limited to 25 mph in Coded. Because the problem was if not you'd be going along at full speed with your 420 code completely fine, then suddenly the train would receive a 180 code and it'd trip. And there was nothing you could do about that so 25 it was.
I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. |
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North End
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Post by North End on Mar 27, 2021 12:16:06 GMT
I don't think LU has ever had a system where signal aspects appear in the cab. On the Central Line target speed is displayed in the cab and the fixed signals are sort of supplementary. They have definite value and degraded working is one but not the only. However the automatic colour lights that are provided between stations on plain line sections on the Central have always interested me somewhat. I love fixed signals and hate and loathe their removal so I'm not complaining but I've never been quite sure on the stated purpose of their retention after ATP was rolled out. I have read things that suggested there were originally some ideas which were later dropped about perhaps allowing trains without ATP to run on the line as well and the fixed signals were intended for them (I'm talking about the automatic signals between stations specifically) but I dunno really, I suspect they were probably retained for degraded working. The original Victoria Line system had a way of displaying the current code in the cab but the problem was that was all it could display. What it couldn't tell you was that the code was gonna come down before it did. I believe that's why the 67s were limited to 25 mph in Coded. Because the problem was if not you'd be going along at full speed with your 420 code completely fine, then suddenly the train would receive a 180 code and it'd trip. And there was nothing you could do about that so 25 it was.
I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. I definitely recall this as well. They were certainly used in this way for the Central Centenarian tour in 2000. I forget what the actual arrangements were for that, however it was certainly running under signals. There must have been some serious work gone into the planning for that one. |
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Post by superteacher on Mar 28, 2021 11:25:37 GMT
I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. I definitely recall this as well. They were certainly used in this way for the Central Centenarian tour in 2000. I forget what the actual arrangements were for that, however it was certainly running under signals. There must have been some serious work gone into the planning for that one. I have no recollection of that tour - do you remember the itinerary? |
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Post by Dstock7080 on Mar 28, 2021 11:36:47 GMT
I have no recollection of that tour - do you remember the itinerary? 1960 Stock 3906-4927-3907 operating after normal traffic hours, as not fitted with ATP: West Ruislip d.0130 North Acton d.0151 Ealing Bdwy d.0202 Epping d.0332 Woodford d.0356 Hainault d.0415 Leytonstone d.0433 West Ruislip a.0531. |
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Post by goldenarrow on Mar 28, 2021 18:21:28 GMT
I seem to recall this too - maybe for engineers' train or special workings. In the end, the engineers' trains were fitted with ATP, so the colour light signals are somewhat pointless. I definitely recall this as well. They were certainly used in this way for the Central Centenarian tour in 2000. I forget what the actual arrangements were for that, however it was certainly running under signals. There must have been some serious work gone into the planning for that one. I seem to recall reading somewhere that a Whole Line Possession was taken for the Central line that night in order to facilitate the rail tour running. This I’m assuming would be a modern equivalent of the “One Engine in Steam” principle. |
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Post by tut on Mar 28, 2021 19:27:26 GMT
One engine in steam is, I have always been led to believe, an older name for what is usually referred to today as "one-train working". It is a method of working single lines, generally single-track branch lines ending in buffer stops or perhaps a small yard, but it can also be used on single track sections between passing places. Only one train is permitted to be on the line at the time. This can be enforced by providing a unique physical staff (generally a nice wooden staff engraved with the details of the line to which it applies, although I have heard rumours a set of bicycle handlebars once acted as a staff) which a driver must be in possession of before allowing the train onto the line (one-train working with staff), or by continuous track circuiting or axle counters or an arrangement of track circuits and treadles (one-train working without staff). I believe the staff and ticket system is considered a type of one-train working today but may have been considered a separate system to true one engine in steam working in the past. Not really sure about that. Home, section and distant signals governing entry to and exit from the single line may be provided, or fixed distants and stop boards may be all you get. You can get points on the single line, leading off to sidings and yards, and these are released by the staff if one is provided. Not too sure about one-train working lines without staffs. Generally you wouldn't really have much other signalling. The point of all that being that, yeah, definitely, the one engine in steam principle achieves its objective of preventing collisions by permitting only one train to be on the line at a time. But in fairness where you've got a double track railway with fully signalled junctions, several interlockings, etc. etc. being temporarily taken wholly under possession with just the one train being allowed to work on it, although 'one train working' seems the obvious name for that, I don't think 'the modern equivalent of that principle' is quite the way to put it  That I suppose would be using axle counters. |
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North End
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Post by North End on Mar 28, 2021 20:15:43 GMT
I definitely recall this as well. They were certainly used in this way for the Central Centenarian tour in 2000. I forget what the actual arrangements were for that, however it was certainly running under signals. There must have been some serious work gone into the planning for that one. I seem to recall reading somewhere that a Whole Line Possession was taken for the Central line that night in order to facilitate the rail tour running. This I’m assuming would be a modern equivalent of the “One Engine in Steam” principle. I’d love to know how they came up with a method to ensure the train ran at safe speeds, given that the Central Line no longer has speed limits published or displayed trackside. There must have been some serious thought put into the planning. A very memorable night, though, especially the stop at Wood Lane. |
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rincew1nd
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Post by rincew1nd on Mar 28, 2021 21:36:06 GMT
One engine in steam is, I have always been led to believe, an older name for what is usually referred to today as "one-train working". It is a method of working single lines, generally single-track branch lines ending in buffer stops or perhaps a small yard, but it can also be used on single track sections between passing places. Only one train is permitted to be on the line at the time. This can be enforced by providing a unique physical staff (generally a nice wooden staff engraved with the details of the line to which it applies, although I have heard rumours a set of bicycle handlebars once acted as a staff) which a driver must be in possession of before allowing the train onto the line (one-train working with staff), or by continuous track circuiting or axle counters or an arrangement of track circuits and treadles (one-train working without staff). I believe the staff and ticket system is considered a type of one-train working today but may have been considered a separate system to true one engine in steam working in the past. Not really sure about that. Home, section and distant signals governing entry to and exit from the single line may be provided, or fixed distants and stop boards may be all you get. You can get points on the single line, leading off to sidings and yards, and these are released by the staff if one is provided. Not too sure about one-train working lines without staffs. Generally you wouldn't really have much other signalling. The point of all that being that, yeah, definitely, the one engine in steam principle achieves its objective of preventing collisions by permitting only one train to be on the line at a time. But in fairness where you've got a double track railway with fully signalled junctions, several interlockings, etc. etc. being temporarily taken wholly under possession with just the one train being allowed to work on it, although 'one train working' seems the obvious name for that, I don't think 'the modern equivalent of that principle' is quite the way to put it That I suppose would be using axle counters. One engine in steam has it's origin in exactly what it says. On a small line unconnected to any other, there would only every be one engine in steam at a time. |
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Tom
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Post by Tom on Mar 28, 2021 22:08:48 GMT
The point of all that being that, yeah, definitely, the one engine in steam principle achieves its objective of preventing collisions by permitting only one train to be on the line at a time. But in fairness where you've got a double track railway with fully signalled junctions, several interlockings, etc. etc. being temporarily taken wholly under possession with just the one train being allowed to work on it, although 'one train working' seems the obvious name for that, I don't think 'the modern equivalent of that principle' is quite the way to put it That I suppose would be using axle counters. The 2020 equivalent would be 'Cancelled Engineering Hours' with the train operating under an Incompatible Train Movements Procedure. One of the requirements would undoubtedly be that all other trains must be stabled, and more than likely with certain signals maintained at danger to prevent the incompatible train from going where it shouldn't or other trains coming away from their stabling locations onto the main line. Where we have bi-directional section of single line, e.g. the Chesham Branch, you're correct that there is an axle counter and latched relay arrangement - once a train is detected going on to the single line, the latched relay operates to lock the single line out to other trains. When the train is detected coming off the branch, the reverse happens. From memory, the axle counter is a secondary backup. |
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Post by joshua on Mar 14, 2022 16:42:52 GMT
The point of all that being that, yeah, definitely, the one engine in steam principle achieves its objective of preventing collisions by permitting only one train to be on the line at a time. But in fairness where you've got a double track railway with fully signalled junctions, several interlockings, etc. etc. being temporarily taken wholly under possession with just the one train being allowed to work on it, although 'one train working' seems the obvious name for that, I don't think 'the modern equivalent of that principle' is quite the way to put it  That I suppose would be using axle counters. The 2020 equivalent would be 'Cancelled Engineering Hours' with the train operating under an Incompatible Train Movements Procedure. One of the requirements would undoubtedly be that all other trains must be stabled, and more than likely with certain signals maintained at danger to prevent the incompatible train from going where it shouldn't or other trains coming away from their stabling locations onto the main line. Where we have bi-directional section of single line, e.g. the Chesham Branch, you're correct that there is an axle counter and latched relay arrangement - once a train is detected going on to the single line, the latched relay operates to lock the single line out to other trains. When the train is detected coming off the branch, the reverse happens. From memory, the axle counter is a secondary backup. So does the Northern Line Mill Hill East Branch operate in a similar way as the Chesham Branch? |
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metman
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Post by metman on Mar 15, 2022 20:18:09 GMT
Not sure, it is of course an ATO (Automatic Train Operation) line so there will be an equivalent method of allowing only one train on the single line section but axle counters wouldn’t be used I’m sure of it!
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Post by Deleted on Mar 15, 2022 21:06:33 GMT
Axle Counters would be used on the branch for Mill Hill East plus its still run by TBTC
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Tom
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Post by Tom on Mar 15, 2022 21:21:00 GMT
So does the Northern Line Mill Hill East Branch operate in a similar way as the Chesham Branch? Similar in principle, that once one train is on the branch you can't get another on it, but totally different in the way that is achieved in practice. |
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Post by joshua on Mar 15, 2022 21:39:57 GMT
Axle Counters would be used on the branch for Mill Hill East plus its still run by TBTC What does TBTC stand for? |
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Post by Chris M on Mar 15, 2022 23:29:29 GMT
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Post by spsmiler on Aug 6, 2022 14:45:17 GMT
I recall this thread from last year and recently noted that there is no photo showing a signal with a white aspect - so have published one on Flickr which shows this. The train's doors are closed because it has just arrived - its better this way as it also means that there are no arriving passengers blocking the view!  Platform3a-Stratford-Station-White-Signal-P1690137 |
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It means that the train in the platform is signalled to depart the station, information provided for station staff as the driver receives this in the cab.
That I suppose would be using axle counters.
That I suppose would be using axle counters.
