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Percy and the signal. But what signal?

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EM2

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If you're familiar with the Thomas The Tank Engine stories, you will probably know this one.

To pay Percy back for playing tricks on them, Gordon and James tell him about 'backing' signals. When he's out on the line, Percy comes to a semaphore signal which is 'on', i.e. the arm is horizontal. On Sodor, the signals are lower quadrant; the arm lowers to mean 'proceed'.
In this case, the arm goes up, and Percy interprets this as 'go back'. His driver explains what it really means, and Percy feels rather silly.

But...the Rev. Awdry never explains in the book what it *does* mean. I've come across three-position semaphores, where horizontal is 'on', angled up is 'caution', and vertical is 'clear', but never a combined lower and upper quadrant (which is what is described, in effect).
As the Rev was adamant that all the incidents on the books are based on real life incidents, what exactly could this signal be, and what would its indications mean?
 
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Ianno87

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No, I think in the story Percy is simply confused as it is a standard Upper Quadrant, rather than the Lower Quadrants he is used to seeing. This, combined with James's teasing about non-existant 'backing signals' leads Percy to put 2 and 2 together and wrongly make 5.

He needs a route knowledge refresher, I think.
 

krus_aragon

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To give a specific example, most railway companes switched from lower quadrant to upper quadrant in the early 20th century (for failsafe reasons), but the GWR kept to the lower quadrant ones. So working on the fringes of the GWR, you might encounter the odd upper quadrant, as Percy clearly did.
 

TheEdge

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To give a specific example, most railway companes switched from lower quadrant to upper quadrant in the early 20th century (for failsafe reasons), but the GWR kept to the lower quadrant ones. So working on the fringes of the GWR, you might encounter the odd upper quadrant, as Percy clearly did.

Out of interest did the early lower quadrants fail dangerously? Did anyone at that time even care? And when they clearly did start to care and move towards upper quadrant did the GWR do anything to make theirs fail safe, clever weighting of the arm for example? Or did they still fail dangerously?
 

krus_aragon

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The concept of fail-safe signalling is something that developed gradually along with the railways. In the very early days, it was felt that displaying one aspect would be sufficient. "Red for Danger" illustrates this development (in response to disasters) well.

A famous example is the first ever signal on the GWR (1840), which was a ball that could be hoisted up a pole. The regulations stated: "A Signal Ball will be seen at the entrance to Reading Station when the Line is right for the Train to go in. If the Ball is not visible the Train must not pass it." (But if you can't see it, how will you know if you've passed it or not?)

The problem with (conventional) lower quadrant signals was that cable tension was used to lift the signal to danger, and the tension was released to clear the signal. The danger was that if the cable became slack or broken, the signal arm could sag or drop. In such a case the signalbox lever could be set to danger, but the signal would still appear to indicate clear to the driver.

I'm afraid I can't name any particular examples of this happening offhand.
 

30907

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Out of interest did the early lower quadrants fail dangerously? Did anyone at that time even care? And when they clearly did start to care and move towards upper quadrant did the GWR do anything to make theirs fail safe, clever weighting of the arm for example? Or did they still fail dangerously?
Yes they did, in various ways.
Signals in a slot in the post seemed a good idea until they got jammed by snow - after a nasty accident at Abbots Ripton the GNR opted for a centre- balanced "somersault" signal that was well clear of the post.
The GW and others used a heavy spectacle plate to balance the arm, until they realised the upper quadrant was more efficient.
 

6Gman

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To give a specific example, most railway companes switched from lower quadrant to upper quadrant in the early 20th century (for failsafe reasons), but the GWR kept to the lower quadrant ones. So working on the fringes of the GWR, you might encounter the odd upper quadrant, as Percy clearly did.

There is, of course, at least one location where you can still encounter lower quadrant, upper quadrant and colour lights alongside each other. A mere 70 years after the demise of the GWR and 50 years after the location moved to the LMR!
 

MarkyT

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The GW and others used a heavy spectacle plate to balance the arm, until they realised the upper quadrant was more efficient.
The GWR never 'realised' there was anything wrong with their version of the lower quadrant form, actually continuing to use it until nationalisation, then BR(W) and it's successors continued the tradition for renewals until the present day as they have always argued that upper and lower forms shouldn't be mixed in the same control area. BR(M), when they gained control of some former Western areas such as Shrewsbury and Banbury, had no such qualms. I think in reality, all common semaphore signal designs used by the big four in later days were equally reliable and safe, whether upper or lower quadrant.
 

Right Away

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Yeovil Pen Mill was originally a GWR station so was equipped with lower quadrant semaphores. In BR days, the route transferred to the Southern region, and is subsequently part of the Wessex Route of Network Rail. When the signals in the down direction were replaced, they were replaced with new upper quadrant semaphores. The up direction signals remained as lower quadrants. You now have the situation where 'the signals go up in the down direction and down in the up direction.' The up direction section signal is a colour light to complete the set!
 

theageofthetra

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Yes they did, in various ways.
Signals in a slot in the post seemed a good idea until they got jammed by snow - after a nasty accident at Abbots Ripton the GNR opted for a centre- balanced "somersault" signal that was well clear of the post.
The GW and others used a heavy spectacle plate to balance the arm, until they realised the upper quadrant was more efficient.
I seem to remember seeing something like this on a preserved line in South Australia. To be fair though snow or even frost wouldn't be an issue there.
 

EM2

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So thinking further, why would the Fat Controller, who appears to have overall control of Sodor's railways, use a mixture of signal types?
 

Steamysandy

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I'm certain Victorian Railways in Australia adopted the somersault signal as standard.The gantries at one of the Melbourne terminals were a sight to behold!!
 

Spartacus

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So thinking further, why would the Fat Controller, who appears to have overall control of Sodor's railways, use a mixture of signal types?

He uses a mixture of types and origins of locos and stock, so doing the same for equipment would surely only be natural? He's clearly not a fan of standardisation :smile:

I seem to remember a few LNWR lower quadrant signals hanging on surprisingly long, well after the end of steam.
 

Ken H

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There is, of course, at least one location where you can still encounter lower quadrant, upper quadrant and colour lights alongside each other. A mere 70 years after the demise of the GWR and 50 years after the location moved to the LMR!
Shrewsbury?
 

MarkyT

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No, it was a heavy weight on the end of an arm close(r) to ground level
Even without that weight, the arm will still balance to horizontal but yes the weight is important to return the signal to danger in the event the signal wire breaks. Also, a rod links that lower weighted arm to the signal itself. The signal wire doesn't go all the way up the post.
 

MarkyT

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Some inspection being carried out on a BR(W) lower quadrant example at Bishops Lideard, West Somerset Railway, illustrating the various components.
 

Ken H

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Even without that weight, the arm will still balance to horizontal but yes the weight is important to return the signal to danger in the event the signal wire breaks. Also, a rod links that lower weighted arm to the signal itself. The signal wire doesn't go all the way up the post.


There is the wire from the lever frame to the counterweight at the bottom of the signal post. If that wire breaks the signal will go to danger becuase of that weight. From that weight to the actual signal there is a wire or rod. If that breaks then I assume the signal will still go to danger.
here is a pic of a signal at Worcester. You can see the counterweight I am talking about at the bracket level

lower-quadrant-stop-and-distant-semaphore-signals-at-worcester-shrub-EM2019.jpg
 

Ianno87

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Of course, in the Thomas series, Henry has a serious accident* in The Flying Kipper, caused by the unfortunate combination of frozen points and a lower quadrant forced down by snow and ice. This suggests Sodor's signals are not counter-weighted to be fail-safe (or not that particular signal at least).

*It's OK - he gets sent to Crewe for repair, returning with a more efficient firebox/boiler so not needing special (expensive) Welsh coal any morem
 

randyrippley

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To give a specific example, most railway companes switched from lower quadrant to upper quadrant in the early 20th century (for failsafe reasons), but the GWR kept to the lower quadrant ones. So working on the fringes of the GWR, you might encounter the odd upper quadrant, as Percy clearly did.

Barrow-in-Furness is rather beyond the fringes of the GWR.........
 

MarkyT

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Of course, in the Thomas series, Henry has a serious accident* in The Flying Kipper, caused by the unfortunate combination of frozen points and a lower quadrant forced down by snow and ice. This suggests Sodor's signals are not counter-weighted to be fail-safe (or not that particular signal at least).

*It's OK - he gets sent to Crewe for repair, returning with a more efficient firebox/boiler so not needing special (expensive) Welsh coal any morem

Although in original form he had a Gresley-style wide firebox over a rear pony truck rather than a narrow Crewe style Belpaire arrangement. While GWR engines with similar boilers performed excellently on the the superior Welsh coal, they possibly may not have coped so well on variable quality stuff from the north, which is why the LNER plumped for enormous wide fireboxes on their larger engines, like Henry. Again it doesn't compute for me and I'm getting doubts over the bona fides of this Reverend fella!
 

etr221

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To give a specific example, most railway companes switched from lower quadrant to upper quadrant in the early 20th century (for failsafe reasons), but the GWR kept to the lower quadrant ones. So working on the fringes of the GWR, you might encounter the odd upper quadrant, as Percy clearly did.
Upper quadrant two position signals were only introduced as a standard just after the grouping (before then, upper quadrant was only (IIRC) used for the few three position semaphore installations; the change corresponded to the introduction of daylight colour light signals when three or more aspects were required). And then the change was - even on the 'big three' that adopted them - a relatively slow process, pre-grouping lq signals were commonplace well into the BR era.

And every driver of that era must have had his first encounter with an uq signal...
 

krus_aragon

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Barrow-in-Furness is rather beyond the fringes of the GWR.........
You wouldn't think it, from the variety of rolling stock used there... ;)

I think Percy is a Bristolian engine, which could explain why he'd only be familiar with lower quadrant signals. That's no excuse for his driver, though.
 

edwin_m

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There has been at least one accident where upper quadrant signals have remained in the clear position.
http://www.railwaysarchive.co.uk/documents/MoT_Chinley1958.pdf
The failure to keep the signal wires free from contact with the rising clay also contributed to the accident, and I have no doubt that closer attention will he given to this aspect of maintenance work in future.
However this alone would not have caused the accident. There were several signaller errors, in particular the failure to observe the arm returning to danger. Other parts of the report mention that this was required where the signal was within sight of the box, and arm repeaters would be provided for non-visible signals. It also mentions that the detonator placer was frozen, although this had no bearing on the accident.
 
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