Deleted
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Post by Deleted on Aug 29, 2014 14:37:49 GMT
I notice on the JLE there are a number of signals that look like draw up signals, but seem to be a variant on the theme.
For example, let's take Southwark to London Bridge.
The station starter at Southwark eastbound was TP1 and then we had: TJ158/TJ100, TJ1, [the crossover is here] R154/1, R154/2, A154 and A151 - the station starter at London Bridge eastbound.
Going in the other direction from Bermondsey to Southwark we have:
The station starter at Bermondsey westbound was TR1 and then we had: RTJX155, RTJ157/RTJ800, TJX155, TJ157/TJ800, TJ8 - the station starter at London Bridge westbound - [the crossover is here], R159, A159 and A161 - the station starter at Southwark westbound.
The signals in bold appear from the diagram to be three aspect signals and they look like draw up signals. The thing is, though, I cannot understand the numbering of them and they are also located well outside the platform.
Can anybody help me out here?
Are there anymore signals like this across the network?
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North End
Beneath Newington Causeway
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Post by North End on Aug 30, 2014 13:20:53 GMT
I notice on the JLE there are a number of signals that look like draw up signals, but seem to be a variant on the theme. For example, let's take Southwark to London Bridge. The station starter at Southwark eastbound was TP1 and then we had: TJ158/TJ100, TJ1, [the crossover is here] R154/1, R154/2, A154 and A151 - the station starter at London Bridge eastbound. Going in the other direction from Bermondsey to Southwark we have: The station starter at Bermondsey westbound was TR1 and then we had: RTJX155, RTJ157/RTJ800, TJX155, TJ157/TJ800, TJ8 - the station starter at London Bridge westbound - [the crossover is here], R159, A159 and A161 - the station starter at Southwark westbound. The signals in bold appear from the diagram to be three aspect signals and they look like draw up signals. The thing is, though, I cannot understand the numbering of them and they are also located well outside the platform. Can anybody help me out here? Are there anymore signals like this across the network? According to the Traffic Circular supplements issued when the signals were first installed, some of these signals were intended to be part of the abortive moving-block signalling, which meant they weren't ideally located for the supposedly temporary conventional system which was actually installed. During the years after installation many of these signals were modified in order to gain extra train throughput, and in some cases renumbered. Like many signals on the JLE, their operation was comparatively complex, and it's not possible to give a simple answer as to how they collectively worked. If there are any particular ones where more information is required, it can be quoted off the relevant notices. As an aside, why the westbound starter at London Bridge was numbered A151 (odd number in an otherwise even sequence of autos) is something I've never been clear on. The Northern had some similar anomolies around Golders Green and Camden Town, however these could be explained as being part of a much older numbering sequence. |
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Post by Deleted on Aug 30, 2014 14:34:49 GMT
Thanks for the info  |
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Tom
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Post by Tom on Aug 30, 2014 22:55:01 GMT
From the numbering the nearest equivalents I can think of are in the Baker Street area, MB16/170, and MB16/171, which care cleared either by virtue of clearing MB17, by operating a timing section, or by calling MB16 route, depending on what else is going on.
In the cases mentioned it sounds like they either operate as an auto (hence the auto numbering sequence) or a draw up, depending on what was going on ahead at the time. Of course, they have always been given a controlled code to make it clear that they must be treated as controlled signals under the rules.
What sounds odd is that RTJ157/RTJ800 doesn't also repeat TJX155. As a general rule if an additional running signal is located between a signal and it's repeater, the repeater should also repeat the signal in the middle - not necessarily for sighting purposes but more to keep the aspect sequence logical.
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Deleted
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Post by Deleted on Aug 30, 2014 23:09:54 GMT
Funny you should mention Baker Street, I was just pondering over it myself. Ta very much, that would make some sense I suppose, although - as North End has mentioned - the positioning of TJ157/TJ800 seems a little hard to fathom. I can only imagine it's TJX155 which would be used to hold a westbound train short for a train reversing east to west. Or, in actual fact, would it be TJ157/TJ800 that would hold it as the reversing train entered the platform and reversed? TJ157/TJ800 could then presumably clear to yellow - and then green, given sufficient time - as the reversing train departed, improving capacity? Obviously, when a train is reversing east to west, I suppose the signal operates as TJ800 and when everything's fine and dandy it operates as TJ157, which is essentially akin to an X signal? Or am I just completely wrong?  |
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Tom
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Post by Tom on Aug 30, 2014 23:33:53 GMT
Without reviewing the scale plans and design details, I wouldn't be able to say!
North End is right that the JLE signalling arrangements were comparatively complex; one of the benefits (or drawbacks, depending on your view) of being able to have the logic in software rather than wires. The temporary nature of the signalling and the many mods to improve things also meant that not everything followed conventional logic...
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Deleted
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Post by Deleted on Aug 30, 2014 23:40:29 GMT
Without reviewing the scale plans and design details, I wouldn't be able to say! North End is right that the JLE signalling arrangements were comparatively complex; one of the benefits (or drawbacks, depending on your view) of being able to have the logic in software rather than wires. The temporary nature of the signalling and the many mods to improve things also meant that not everything followed conventional logic... Okey dokey well thanks for the information both of you. Oh, and congratulations on post 2,500. (I like round numbers ) |
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North End
Beneath Newington Causeway
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Post by North End on Aug 31, 2014 17:20:23 GMT
From the numbering the nearest equivalents I can think of are in the Baker Street area, MB16/170, and MB16/171, which care cleared either by virtue of clearing MB17, by operating a timing section, or by calling MB16 route, depending on what else is going on. In the cases mentioned it sounds like they either operate as an auto (hence the auto numbering sequence) or a draw up, depending on what was going on ahead at the time. Of course, they have always been given a controlled code to make it clear that they must be treated as controlled signals under the rules. What sounds odd is that RTJ157/RTJ800 doesn't also repeat TJX155. As a general rule if an additional running signal is located between a signal and it's repeater, the repeater should also repeat the signal in the middle - not necessarily for sighting purposes but more to keep the aspect sequence logical. I don't have any of the relevant documentation to hand at the moment, however *from memory* TJ157/TJ800 was originally just TJ800. I'm sure I remember at some stage a modification was made and the renumbering occurred. Certainly some of these signals seem to work in strange ways, for example clearing to straight yellow (with no speed control) if the associated signal route has been *selected*. I'm sure in another case the signal simply cleared at the same time as the associated signal. The signal clearance diagrams are probably the most accessible source of information on these signals. Thinking back, another anomoly was some of the starting signals at the east end of the line - TUA101. Auto or semi? In case of any doubt one would (should) err on the side of caution and treat as a semi, and authority would always be required to apply the rule at a station starter, but why just at Canning Town and West Ham, and why not TU101 instead of TUA101? On another note, there was some very discontinuous numbering in the Baker Street to Finchley Road section as well, although without looking in detail I presume this was to avoid duplicating numbers used elsewhere - but then why not use a complete fresh sequence? |
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