Where should the junction be?
Cornawall Polbrock Grogley P4 Engine Shed
I've been a little slow in posting a reply to the previous post due to Tredethy Wharf taking up all my spare time but hope this will explain the little dilemma I've had over my fictious Polbrock Engine Shed. This is, where should I place the junction between the up North Cornwall line and the Wadebridge/Padstow Branch?
Ullypug is correct in saying that the scissors crossover might bit extravagant, and that a signal track would be more suitable for this line, but I wonder if this has been seen in the bigger scheme. I have two thoughts about this end of the layout and I hope the following two (very rough) signal diagrams will help to explain.
First is a diagram for a single track through this stretch of line.
When I started to think this one through a question I had was, would the LSWR or SR have kept all four signal boxes on this stretch of line? After all the LSWR did do away with the junction box in 1907/8 and had two parallel running single tracks leaving Wadebridge. These where the up North Cornwall line and the Bodmin line.
So in a thought to simulate this approach and have two parallel lines leaving Grogkey Junction and cut out possibly two Signal boxes I started to draw up plans. I soon realised that Polbock would have needed some way of communicating with Grogley box. Today a telephone might be installed but back in 1907/8 would this have been possible? So I deemed that a Signal box would be required at Polbrock which could also be the junction box. This then created the diagram below;
In both diagrams the grey areas will not be part of the layout but have been included to get a full idea of each signal boes leaver frames.
Hope this goes some way to explain why I've introduced a scissors crossover at Polbrock but I'd welcome any further comments/thoughts about its inclusion. A resultant bonus with the second diagram is helps in the storage sidings by removing possible point work to separate a single line into storage lines.
Please note: these are early thoughts on the signaling for both options and I have a lot to learn so any guidance from learned gentlemen of this parish would be welcome, especially on LSWR signaling practice.