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Anyone modelling LMS signalling in Britain?

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An interesting poster for ex-LNWR signalling. Also looks like they are all lower quadrant, which was the norm at the time, until the introduction of upper quadrant.

Lower quadrant had the problem of if snow or if ice froze the signal arm in the clear position a driver would think the line ahead was clear, but as we all know some railway accidents happen because of this and the railway companies via a kick in the backside by the government review (pre H&S) where told to replace all lower quadrant signalling ASAP, the fact that in some places this is still the case up to the 1980’s I thing in some parts of the UK, not sure about Ireland.    

Colin R

Edited by Colin R
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Apparently a number of LNWR signals in the North Wall Holyhead Yard survived the closure of the LNWR North Wall station in the 1920s and were in use at least until the re-modelling of the yard as a container terminal in the 1970s.

The risk of a lower quadrant signal failing to return to danger if a signal wire breaks or because of snow or ice is a myth otherwise the Railway Inspectorates would have had to force the railways to phase out lower quadrant signals within a specific time frame rather than the UK Railway Inspectorate advising the railways to phase out lower quadrant signals as part of their signal renewal programme.

The myth probably originated with the Abbots Ripton disaster in the 1870s when the arm of a slotted signal froze within the signal post and and failed to return to danger despite the signal mans best efforts. Originally slotted signals may have operated in a similar manner to American 3 position semaphore signals, with horizontal danger or Stop, 45° as Caution or Approach and vertical as Clear. The signal at Abbotts Ripton was set at clear with the arm vertical within the post and not visible to the driver of an approaching train.


Early semaphore do not appear to have been "fail to safe" in that Clear may have been the normal position and the signal wire had to be pulled rather than released return the arm to the Danger position as the signal arm may not have been balanced by a heavy weight.

In current British and Irish practice both lower and upper quadrant semaphore signals return to danger by gravity by a balance weight as a fail safe when the signaller returns the signal lever to it normal position in the frame or in the event of a signal wire breaking. The actual metal signal arms used by Irish Rail are extremely light in comparison with the weight of the spectacle plate and balance weight and sometimes a lower quadrant arm will bounce against the stop when a signaler returns a signal to danger.

The main advantage of the semaphore is probably less effort for a signaller in "pulling" an upper quadrant arm into the off position and less wear and tear on the signalling system because of the lighter balance weight compared with a lower quadrant signal.

Edited by Mayner
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3 hours ago, Galteemore said:

Very informative, Mayner. And at least no Irish lines were employing slotted signals into the 1950s.....😉

The Sligo Leitrim had at least one to the end, and I’ve an idea (need to check) there was also one on the Donegal.

Edited by jhb171achill
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