Coalorsdale - signalling help / advice wanted.

[The Stationmaster]

On 07/02/2021 at 14:38, TheSignalEngineer said:

 

This would generally be enforced by the interlocking requiring the points in advance of the second home signal being locked normal by pulling the lever for the outermost signal.

 

Although it is quite possible with Western locking practice that the signal in rear of the tunnel would also be interlocked with the points in advance of the Inner Home (second) Signal

[TheSignalEngineer]

14 minutes ago, The Stationmaster said:

Although it is quite possible with Western locking practice that the signal in rear of the tunnel would also be interlocked with the points in advance of the Inner Home (second) Signal

Thanks Mike, think I got most of it right. It must be about 25 years since I had to fathom out the locking on WR frames and the inter-relationship with electrical controls when I was involved in the early work on Radyr and Valleys Lines signalling jobs. 

[Horsehay Railway Modeller]

Looking at sand drags... 

 

Does it make more sense to have a seperate sand drag leading to an L shaped retaining wall cut into the embankment...

 

Or the sand drag along the track like the one at Didcot, with the retaining wall just to make space? 

 

 

[The Stationmaster]

15 hours ago, Horsehay Railway Modeller said:

Looking at sand drags... 

 

Does it make more sense to have a seperate sand drag leading to an L shaped retaining wall cut into the embankment...

 

Or the sand drag along the track like the one at Didcot, with the retaining wall just to make space? 

 

 

As the distance is limited I would go for the arrangement in your top photo.  The one in your lower photos won't be anything as like effective in stopping a runaway from fouling the main line.

[The Stationmaster]

18 hours ago, TheSignalEngineer said:

Thanks Mike, think I got most of it right. It must be about 25 years since I had to fathom out the locking on WR frames and the inter-relationship with electrical controls when I was involved in the early work on Radyr and Valleys Lines signalling jobs. 

It must have been quite interesting trying to get your head round the somewhat strange (in safety terms) Western interlinking between the block and a Home Signal berth track circuit as well as the one pull (sort of) control on Section Signals which very definitely came into the 'sort of' category when compared with full Welwyn Control.    The shortened frame at Pontypridd also had some interesting interlocking and controls which made it very easy to tie yourself in knots but some locks could be (legitimately) 'lifted' mechanically via FPL levers.

 

Sorry to digress

[bécasse]

I agree with Mike that the full run-off siding would be needed in this case. In similar situations that I was familiar with, the sand drag in front of the buffer stop extended the full width of the permanent way and fully covered the rails (although not by too much, there was apparently a fine margin between having enough sand to help bring an errant vehicle to a stand without doing too much damage, and having too much causing the errant vehicle take off like a plane).

 I suspect that the example illustrated where the sand was confined closely to the rails was a special case because there was insufficient space to provide a proper run-off track, but perhaps Mike might like to confirm that this wasn't yet another example of the GWR doing things differently to everyone else.

[Horsehay Railway Modeller]

at the moment i plan to add a seperate siding covered in sand.

 

would it be okay to ignore the frog crossing the running rail as seen here?

[Horsehay Railway Modeller]

My attempt so far. 

[RailWest]

As this trap would be normally 'open' and worked in conjunction with the facing point on the main line, why not just use an ordinary point?

[Horsehay Railway Modeller]

As this is on a curve I would have to modify a point anyway for it to be Electrofrog (it's tighter radius than the Electrofrog curved points.

 

Also as I am a student I thought I'd save the expense of a point and motor. 

 

I don't need it operational. I just want some resemblence of the prototype. 

 

 

[The Stationmaster]

21 hours ago, bécasse said:

I agree with Mike that the full run-off siding would be needed in this case. In similar situations that I was familiar with, the sand drag in front of the buffer stop extended the full width of the permanent way and fully covered the rails (although not by too much, there was apparently a fine margin between having enough sand to help bring an errant vehicle to a stand without doing too much damage, and having too much causing the errant vehicle take off like a plane).

 I suspect that the example illustrated where the sand was confined closely to the rails was a special case because there was insufficient space to provide a proper run-off track, but perhaps Mike might like to confirm that this wasn't yet another example of the GWR doing things differently to everyone else.

Generally from the Western run-offs I have seen over many years the use of troughs of sand around the run-off rails was unusual and only happened where there was no real alternative to having the rails partly in the four foot (the one at Abercynon was an good example of this but it was very long).  Otherwise where full two rail trapping was used and depending very much on the situation both rails ran clear and into a sand drag but sand drags were not over common - it all depended on the situation.

 

There was for example one at N&B Jcn, near Neath, but it was no more than 3 or 4 wagons long and it did absolutely nothing to stop a serious runaway.  In a b nasty incident what stopped the train was the embankment of the South Wales main line which lay at the end of the sand drag) and the train piled up against that in quite a large heap.   We had a passenger train run off a trap at Old Oak Common coming off the Victoria Branch and what stopped that, apart from the late breaking, was the Class 47 at the head of it running out of rails and turning its bogies into ploughs.  But the application of the brake did by far the most of the stopping, albeit too late.