What is this ground shunt signal for?

[edwin_m]

Thingley would have been on the "old" Swindon panel which went only a few years ago, as no doubt discussed elsewhere on that link, and I expect the GF would have been replaced during that re-signalling. The economics of ground frames seems to have tilted back and forth over the years, depending on whether someone thought it was cheaper to provide the kit for local control or the extra circuits back to the main interlocking.

Maybe that "someone" or some other "someone" has now decided that a hand signal isn't good enough to authorize a train movement past a ground frame. Or for some reason the signaler might want to prevent a train entering or leaving the siding after they'd released the frame. I'd have though that having blocked the main line by doing that, they would want the move completing as quickly as possible.

 

[Merle Haggard]

A Pictorial record of LNWR Signalling includes the following passage, which I have quoted in full - it repeats what has already been said, I know, but provides some interesting amplification.

'The idea of using yellow arms and lights in ground signals to signify that the signal could be passed during shunting was introduced in July 1929. This situation occurred when the move was made past the signal along a route to which it did not read. An example would be a ground signal controlling movement from a siding to the main line but where shunting could continue safely into a headshunt. This system was widely applied during LMS times. Prior to 1929, drivers were expected to know to which routes the signals applied and under what circumstances they could be passed.'

Like ChiefPlanner I coveted the LNWR ground signals at Harrow & W. Don't know what happened to them, but I did acquire at auction a single (red) arm one a couple of years ago, and subsequently a yellow arm one, now awaiting collection. They are scaled down full size signals and much easier to display, but as an aside their acquisition has prompted some research on my part. The miniature semaphore design was only introduced 'just before WW1', rotating (in the horizontal plane) discs were used before. And you'll notice that yellow arms were introduced about 6 years after the LNW ceased to exist, but yellow LNW pattern arms existed. The design of the arm (which was stove enamelled) was changed in LMS days, with a thicker white surround, giving me the common dilemma of choice between a tatty but genuine LNW arm and an immaculate but LMS one (I've bought a couple of spare arms).

 

[John Webb]

There was a mechanical groundframe but it is now electrically operated. I'm not sure when it was converted as I didn't move to this side of the country until after that photograph was taken, but I'm wondering if it was around the same time as there appears to be temporary fencing around the cabinet in the background (which houses the control panel), the rail looks fairly new, and the yellow clamplock covers are very clean and unfaded. Images of the control panel are available here: https://photos.swindonpanel.org.uk/picture.php?/539/category/21

That site also has an album of images from Swindon Down Yard showing another example of a yellow GPL worked from a mechanical groundframe (still in situ): https://photos.swindonpanel.org.uk/index.php?/category/48

Thanks very much - that's the first instance I've come across of an 'electric' ground frame - hadn't appreciated Swindon PSB covered that far! (Still haven't visited Didcot to see the preserved Swindon panel, although I contributed a number of interface boards towards it's revitalisation.)

 

[edwin_m]

Thanks very much - that's the first instance I've come across of an 'electric' ground frame - hadn't appreciated Swindon PSB covered that far! (Still haven't visited Didcot to see the preserved Swindon panel, although I contributed a number of interface boards towards it's revitalisation.)

They've been around for a while. There's one at Blackburn that would date from the Preston scheme, and I think I read somewhere others on the northern WCML are similar.

 

[alxndr]

Thingley would have been on the "old" Swindon panel which went only a few years ago, as no doubt discussed elsewhere on that link, and I expect the GF would have been replaced during that re-signalling.

The control panel has been replaced at some point, possibly during resignalling, but it is in essence exactly the same other than that the door opens the other way.

Thanks very much - that's the first instance I've come across of an 'electric' ground frame - hadn't appreciated Swindon PSB covered that far! (Still haven't visited Didcot to see the preserved Swindon panel, although I contributed a number of interface boards towards it's revitalisation.)

TVSC Swindon workstation (the successor to Swindon PSB) covers all the way down to Corsham on the mainline. Even so, there's also an older electrically operated groundframe at Wootton Bassett Junction (photos also available on that site) but no yellow GPL so straying a touch off topic there.

 

[Peter C]

I think there used to be one of these such signals at Moreton-in-Marsh, Cotswold Line:

Adrian the Rock - Signals at Moreton-in-Marsh

(scroll down to " A view of the down platform with the down inner home, and yellow disc, clearly visible" or use CTRL+F on that phrase)

-Peter

 

[30907]

I think there used to be one of these such signals at Moreton-in-Marsh, Cotswold Line:

Adrian the Rock - Signals at Moreton-in-Marsh

(scroll down to " A view of the down platform with the down inner home, and yellow disc, clearly visible" or use CTRL+F on that phrase)

-Peter

Interestingly, that was a modern yellow-on-black version, and going by the old box diagram https://www.s-r-s.org.uk/html/gws/S2578.htm
replaced a normal red disc - given the short length of the dock siding, providing a yellow disc to access it looks excessive.

 

[edwin_m]

Interestingly, that was a modern yellow-on-black version, and going by the old box diagram https://www.s-r-s.org.uk/html/gws/S2578.htm
replaced a normal red disc - given the short length of the dock siding, providing a yellow disc to access it looks excessive.

Strictly speaking it would be prohibited to put anything into the dock if it was a red disc with the only route being to the main line. Which would be something of a nonsense if the dock was actually needed for loading things rather than just being a glorified trap point.

 

[Ashley Hill]

The GF at Bridgewater is an electronic push button variety.

 

[LOM]

The GF at Bridgewater is an electronic push button variety.

These are called ground switch panels (GSP)

 

[Peter C]

Interestingly, that was a modern yellow-on-black version, and going by the old box diagram https://www.s-r-s.org.uk/html/gws/S2578.htm
replaced a normal red disc - given the short length of the dock siding, providing a yellow disc to access it looks excessive.

That's cool. As @edwin_m says - having a disc to control such a short dock is a bit odd.

-Peter

 

[30907]

Strictly speaking it would be prohibited to put anything into the dock if it was a red disc with the only route being to the main line. Which would be something of a nonsense if the dock was actually needed for loading things rather than just being a glorified trap point.

Agree - green handsignal from the box (if there's anyone in authority about)?

 

[Belperpete]

To be honest I'm now even more confused, wondering what the situation is that requires a slot on a yellow shunt from a ground frame.

On the Southern, where I started my career, ground-frames were almost exclusively used where siding points would be too far from the signalbox to be worked direct by rodding. As such, they tended to be outside junction areas, and so require little in the way of signal controls, moves being handsignalled in and out of the siding by the ground-frame operator.

When I moved to the Western, I was a bit taken aback by their propensity for putting them in the middle of junctions and station throats, where all the adjacent points were worked from the signalbox. As a move leaving the siding would almost immediately be passing over a set of points worked from the box, and possibly in contra-direction to signals worked from the box, it was necessary for the box to have some control over moves leaving the siding. When I asked why the siding points weren't just worked direct from the signalbox like all the other points, I was told that the freight people wouldn't pay for that. It seemed madness to me.

 

[edwin_m]

I guess the Southern, being busier, would have more concern about the delay and possible disruption caused when completing a move was reliant on a bloke pulling levers on a frame. Some residue of that regional difference might explain why Thingley has a ground frame and a yellow shunt even after recent re-signaling.

 

[Ashley Hill]

I haven't seen anything stabled in Thingley yard for a long time,not even track machines. Although not shown OOU is it still technically available?

 

[alxndr]

I haven't seen anything stabled in Thingley yard for a long time,not even track machines. Although not shown OOU is it still technically available?

I'm not aware of any reason why you couldn't put something in there if you wished, although there's much less track than there used to be. Unlikely that anything would ever pass the yellow GPL at yellow though as the headshunt has been severely cut back to make way for the substation.

 

[iantommo]

There was a yellow armed semaphore shunt signal at Skiers Spring (between Elsecar and Chapeltown) on the Sheffield?Barnsley line up to the nearby colliery closing around 1976

 

[36270k]

In the 1970's There was a yellow shunt signal of this type at Redhill A Box.
When on it led to the shunt neck.
When off it led over the crossover to the up main.
Probably disappeared when Redhill was resignalled.