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Question on signalling

Posted: Wed Apr 19, 2006 6:38 pm
by TimMeese
I'm currrently working on signalling. Now, I think I've got a grasp of the basics, and perhaps a bit more, but here is the situation I'm puzzeling over. I jave a four track main line with a shed, goods yard, and station bay to the left outside the main line. To the right, inside the main line there is a single track branch line. A line crosses from the shed area to the branch line with diamond crossings over the inner fast lines and scissor junctions on the two outer slow lines. Anyway, my uncertainty concerns the signalling from the shed complex onto the main line.

As we all know, on bracket or split junction signals the taller doll is for the major route. The signal controling the junction from the shed will have two dolls. But which should be short and which should be tall? The one controling the main line is the obvious choice for a tall doll, but for my conditions, most of the traffic will be sent down the branch line, so perhaps that is the major route. Alternatiively, both routes might be considered to be equally important, in which case the two dolls would be of equal height (my currently preferred option). I'm wondering whether there is a definitive answer when it comes to main lines and branch lines (as opposed to a splitting secondary route for example, where I think two dolls of equal height would be fine).

Arguably, each of the 3 routes from the shed complex should receive its own junctions signal, but as all three are in clear sight of the main line junction, I thought I could use a single junction signal, and then ground signals for the routes up to that point. Seems reasonable, but I'm not sure whether it is proptypical.

Also, I remain a little uncertain about the difference between using split and bracket signals at junctions. I'm thinking it probably has more to do with local conditions, traditions and railways companies rather than anything of operational significance.