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Line Diagram - an explanation

Posted: Wed Dec 18, 2019 7:13 pm
by yorkiespud

Long time reader first time poster. There are so many knowledgeable people on these forums, I feel a bit like an imposter but here goes.

I have recently bought a couple of line diagram books from the NERA, these are fascinating little things documenting all the features along a track bed. Most of these are obvious but 4 of them have me baffled, can anyone shed light of them:

Pit Fall Post
Super Elevation 6” (with either an up or down pointing arrow) some times S.E. Plate 3” and an arrow
Gangers Layers
Wheel Chock


Re: Line Diagram - an explanation

Posted: Wed Dec 18, 2019 11:37 pm
by richard

Super Elevation is where the track is titled slightly around a curve - a bit like a NASCAR or Indy track (but not F1!) but to a much lesser degree.
Presumably the up or down arrow is on one particular side, so you can work out the amount of super elevation that is applied (eg. west side up 6").

Re: Line Diagram - an explanation

Posted: Thu Dec 19, 2019 10:14 am
by drmditch
Likewise Welcome!
Pitfall posts provide a measure of (suspected) colliery subsidence.

There is a discussion of them

Re: Line Diagram - an explanation

Posted: Thu Dec 19, 2019 10:18 am
by 65447

Cannot answer all but here goes:

Pit Fall Post - a fairly tall post erected near the trackbed, often on an embankment, which was set vertical in both planes. In the event of any subsidence due to the collapse of any underground workings the post will lose its verticality - indicating the occurrence of subsidence and, by the extent of deviation from the vertical, the degree of ground movement. In likely subsidence areas these posts would be erected at regular intervals, much like the snowpoles alongside roads prone to snow drifts and blockage, and the variations in the movement of individual posts would provide useful information about the extent of any area of subsidence.

Superelevation - also known as cant - is as Richard describes. It is applied to the outer rail on a curve and counteracts the tendency of the locomotive and rolling stock to continue in a straight line. It is usually applied gradually and typically matches the rate of change of curvature in the 'transition' from straight to the continuous curved section of track, and then reduced as the track straightens again. The amount of superelevation is related to the line running speed and the sharpness of the curve.

Gangers Layers???

Wheel Chock - what it says on the tin, to chock the wheels of any stationary rolling stock or permanent way equipment to stop it running away.

Re: Line Diagram - an explanation

Posted: Thu Dec 19, 2019 12:29 pm
by thesignalman
Gangers Layers
The term Ganger and Platelayer are pretty interchangeable, maybe this is an indication of a platelayers' hut or something of that ilk?


Re: Line Diagram - an explanation

Posted: Thu Dec 19, 2019 3:32 pm
by richard
Yes "cant" is a good word for super-elevation. I was thinking "roll" which is more of an aeronautical term but it didn't seem right :-)

Occasionally you see people attempt to model super-elevation, but I don't recall ever seeing Pit Fall Posts modelled.

Re: Line Diagram - an explanation

Posted: Fri Dec 20, 2019 11:36 am
by yorkiespud
Hi Gents,

Thanks for the welcomes and explanations

Super elevation - obvious when pointed out.

Pit fall posts - well the ones I can see in this diagram book all occur on branch lines heading towards ironstone mines so the explanation makes a load of sense. The lines are documented up the end of NER responsibility and not beyond.

Gangers Layers. All the ones I have spotted are document as such without a drawn symbol. I can see Platelayer Cabin are documented by the words and a small hut diagram, so I guess that's ruled out. I haven't found any Gangers Huts documented.

Of the 12 lines documented only 1 uses the term. For the remaining 11 lines I have found gangers length and gangers division, both documented in words but without a symbol. I am taking these to mark the end of responsibility for a ganger group. Could Gangers layers be an alternate term for the former two?


Re: Line Diagram - an explanation

Posted: Fri Jan 10, 2020 5:17 pm
by PinzaC55
The wheel chock may have referred to the devices used on the NER which were a baulk of timber hinged horizontally so that it could be swung over the rail and then locked into position to stop wagons running away, rather than a wheel chock in the conventional sense which was a wooden wedge placed under the wagon wheel on top of the rail.