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Changing from semaphore to colour light signals. - Signals & Signalling. - The Prototype Photograph Archive. - Your Model Railway Club
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 Posted: Wed Nov 23rd, 2022 02:16 pm
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longie
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When BR were changing to colour light signals I seem to remember seeing some sort of big cross on the colour light signals to show that they weren’t operational yet. Does any one have any photos or details of these crosses please?



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 Posted: Mon Nov 28th, 2022 08:33 pm
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longie wrote: When BR were changing to colour light signals I seem to remember seeing some sort of big cross on the colour light signals to show that they weren’t operational yet. Does any one have any photos or details of these crosses please?Copyright image at this link https://sdjr.co.uk/the-signalling-project

A white cross, usually of wood, is affixed to any signal not in use and therefore not to be observed by train crew or other staff.  In colour-light signal areas a large black vinyl hood is normally placed over the signal head with a white cross stitched or painted onto it facing oncoming trains.  

The white cross might be required in cases where signalling is being changed over with the new erected but not in use whilst the old remains to be observed; on the day of change-over the old ones will gain white crosses instead until the signalling equipment is removed.

They are sometimes quite crudely made but others are "professional" jobs.  The meaning is the same.  Quite simply "This signal / device is not in use and its indication must be ignored." 



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 Posted: Mon Nov 28th, 2022 09:16 pm
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longie
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Thanks Rick, that is what I sort of remember.



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 Posted: Tue Nov 29th, 2022 12:36 pm
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Black bag with white diagonal stripes (X) to show out of  use. Used when converting a line from semaphore to lights.

Nigel



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 Posted: Tue Nov 29th, 2022 02:48 pm
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longie
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Thanks Nigel, have to get my thinking head on to see how to make one of those!



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 Posted: Tue Nov 29th, 2022 06:34 pm
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Barry Miltenburg
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Just out of interest, does anyone know how the interlocking was got around?  Surely, until the signals had been pulled, the frame would not have allowed subsequent levers to be pulled so if the signals were not pulled off (because they were out of use), what happened?  Was it only the signals that were locked in rotation?  No real interest for us modellers, but it would be interesting to know

Barry



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 Posted: Tue Nov 29th, 2022 09:13 pm
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Signals and points which were out of use were locked out at the frame.  Typically, on a manual lever frame, by padlocking the lever or by inserting a plate into the lever slot preventing it from being moved.  There could also be adjustments made to the locking.  For more modern panels the electronics were isolated and the relevant details covered over on the line diagrams often by sticking paper across redundant signals or points.

A signal is taken out of use for one of several reasons.  

Where the line or area is being re-signalled in its entirety there is usually a shut-down (currently of multiple days for large areas but formerly across a weekend for a single manual box was the norm) during which signals are de-commissioned, the locking and diagrams altered accordingly and new signals brought into use.  Old levers or panel buttons can be connected to new signals or points as required.  

For re-signalling the new signals will be covered with hoods carrying the white cross until the changeover at which time those covers are removed and placed over the now-redundant signals (if colour-light) or simple white crosses fixed to semaphore arms until the signalling equipment is physically removed.  That can be weeks or months later - and exceptionally it isn't removed at all but simply left there.  

Where, for example, a siding is taken out of use its points are clipped and locked to the position which will remain available - usually "normal" - and associated signals disconnected with the white cross placed over them.  Controlling levers or buttons at the frame or panel are locked out and the line diagram updated.  

I cannot think of a situation where a redundant signal would need to be cleared in order to pass traffic along the line so Barry's question is largely academic.  Signal sections are sometimes altered to insert additional signals or to remove others creating or removing block sections.  But at no time does a "crossed" signal need to be pulled off or cleared for movement to take place.  

An example: 

Signalbox B, located between signalboxes A and C, is to be abolished and the line re-signalled from semaphores to colour lights.  The new signals are erected some time ahead of the changeover with the hoods over them.  They may or may not be in the same locations as those they are to replace and in this instance they are to be located in different places altogether.  Signalbox B is no longer essential to the running of the line so can be closed, its signals "crossed" and disconnected and the interlocking altered so that A links to C rather than A to B then B to C.  When Signalman A clears his section signal (known as the Advanced Starter in some areas) this will then admit a train to the line as far as C's home signal because all of B's signals are out of use and can be disregarded.  A cannot clear his distant until C, rather than B, has cleared all signals through his section; A's distant will therefore have its interlocking with B changed to interlock with C instead.  

When the change-over to colour-light signalling occurs all of A and C semaphores will also be crossed out of use but unless the signalboxes are also being replaced - for example by a remote signalling centre - then their levers are connected to the new signals or, in some cases, a new miniature electronic panel is installed and the lever frame becomes redundant. A traditional lever connected to a colour-light will "pull off" very easily; I know because I have done it.  However it is more typical to replace all the signals with a remote electronic system these days and close the signalboxes entirely.  Such electronic systems are usually semi-automatic and only require remote supervision at a computer screen with manual intervention as and when required such as to set a route other than that programmed or for unscheduled traffic which isn't in the database.  

What the observer sees at the lineside is that the signals are probably more evenly spaced than before giving better line capacity despite the closure of Signalbox B.  The concept of the Block Section remains fundamental to safe operation but it isn't quite the Absolute Block of 100+ years ago upon which semaphore signalling is based.  Successive signals may not match the traditional pattern of Distant - Home - Starter - Section; there may be one or more Intermediate Block Signals in an otherwise long section which can be used to break it up into smaller sections when required.  That is very similar to the old concept of "switching-in" a normally-closed signalbox to pass extra traffic at peak times.  The principle is the same however in that only one train is allowed in each section (special arrangements excepted) and the option to display advance cautions (double-yellow aspect) means speeds can be better managed.  

In another example a bay platform is to be closed and taken out of use.  Trains approaching the station come to the home signal which could be in one of several formats.  If it is a "splitting" semaphore then the main arm which will remain in use is unaffected but the subsidiary arm reading into the closed bay will be "crossed" and taken out of use at the frame by locking its lever.  If the home signal, be it semaphore or colour-light, is equipped with a junction indicator then the electronics which control this will be altered accordingly; either the "feathers" - white lights above the aspect to indicate a divergence - will be switched off and may have a cross or hood placed over them, if a "theatre" type of indicator is used which can illuminate one or more letters to show which route is cleared the relevant one will be disabled and if it is one of the roller-blind type then the panel appropriate to the closed route will have a blank display replacing the letter or number indicator.  The point will also be clipped and padlocked and its lever or control switch locked out or isolated.  

In due course the signalling engineer will come along and remove all the old signalling but this isn't always done at the same time as a change-over simply because of the time taken.  The need is always to re-open the railway to traffic as soon as possible.



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 Posted: Tue Nov 29th, 2022 10:36 pm
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Barry Miltenburg
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Thanks Rick - interesting and useful

Barry



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 Posted: Wed Nov 30th, 2022 09:55 am
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longie
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I knew I had seen a picture somewhere!!!Thanks to all who helped.






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