In this diagram From the shunt signal at A I can signal a train onto road 1 via a shunt signal at B how then do I signal a move via A to road 2 or road 3. Can a shunt signal have feathers or a theatre indicator?

Whilst the question may appear to be simple the answer is not necessarily so as it depends on the era and whether we are talking about power signalling or mechanical signalling. In either case the points at B and C would normally be hand worked and the signal at A would just read into the yard without any indication of the route. The "route indication" would be given by the Shunter depending on how he had set the points. In power signalling the signal at A would simply be a position light shunt signal without any route indication and in mechanical signalling it would be a semaphore disc signal, assuming there is no route back along the main line.

If, for some reason, it was deemed necessary to provide full signalling to each siding then the signal at A would either be position light shunt signal with a stencil route indicator or three semaphore signals one on top of the other.

What is missing from this layout in real life is that there would have to be a set of trap points at the exit from the yard between B and A to prevent anything running out of the yard onto the passenger line. (I am assuming it is a passenger line as a platform is shown.) There would, therefore also be a signal at the toe of the trap points to control movements leaving the yard. This would normally be a position light shunt signal with a red aspect or a semaphore disc signal with a red band. However the red aspect/band could be yellow if there was a shunt neck to which movements could be made past the signal at danger without the Signaller's permission.

I hope this helps if you are trying to create an accurate model. However,In N Gauge modelling trap points and detailed signal aspects are often too difficult so Rule 1 applies (make up your own rules) and if it was me, just to be representative, I would just provide the two signals but then I haven't got round to providing any signals yet on my layout.

Ron

I stand to be corrected on this but I believe that you only need to signal into or out of a yard, not within it - so you would need a signal at A reading into the yard or out onto the main line, and a signal at B reading the other way for exit from the yard.

This is a bit of a pain as you would have to signal each shunting move onto the headshunt as it is also a platform road - if you had a separate headshunt you could shunt all day without needing a signal!

If you need shunt signals reading for various routes for e.g. "bang road" moves they would be stacked vertically, top to bottom reading left to right in the olden days, or now with colour lights they would have "theatre box" indications with a letter indicating the route.  I think this is what you would have at "A"

As I say - others may know with more certainty, but at least a starter! 

Cheers   Jon