Ok then, if your running a depot then what's the maximum length of fiddle yard you realistically need?, one, two or three locos, I'd not think any more, other than perhaps twin 20's or 25's there not much over 70' that would enter that yard other than say a 31 or 37 with two or four TTAs for fuel oil.
So from that lets add two boards each end at 1200x450 that gives another 12sq feet and leaves you 3 square feet left over which will easily allow you to expand the width to 24". In fact if you lost that track top right, though it'd be a shame to do so as it adds interest to that corner, you could reduce your left hand fiddle board to about 12" to cover the two tracks at bottom left.
I'm with pugsley on the cramped layout, or more correctly, overly complicated, depots are simple affair and track costs money, one thing you'll rarely find are double slips, I'd suggest you wouldn't get that link from the inner shed road to the head shunt up by the signal box. I don't think there would also be a double cross over to the left, one set would suffice in reality, but I've no idea what you have planned for those two roads?
Or, retain that link line and remove the other one that runs through the double slip but take the DS out (see Tinslet Servicing image below), I'm with you on the shed theme and currently running research myself and gathering info on the likes of Colchester, Tinsley servicing, Rotherwood, Wath, Frodingham, Ripple Lane, Shirebrook etc, all outside the 33 challenge (which I can't enter as I've missed the deadline for registering interest by a country mile).
Sadly depots are not designed for operational interest, just get locos in and out as fast as possible or to store locos over the weekend.
Have a look at the attached, it's very close to your design and I'll personally use the fiddle yard to hold freight trains that can run along that track the 76 is on, as per prototype, note just in front of the 56 coming off shed the points are set wrong, high chance these are sprung to aid loco release. I've a track plan for this but not a signalling one but this depots offers a huge range of locos that can visit, as can Wath.
Copyright unknown.
Even a small depot like that will cover a large area if scaled correctly so some selective compression would be needed. Colchester is a little smaller and looks like it has a pit outside for servicing the odd steam engine, or it could be a jet wash spray down pit ready for locos to go on shed. Also of note in these two images is the width between tracks inside the shed, far wider than normal twin tracks on a main line.
Copyright Irwell Press, BRILL.
Anyway just some off the wall ideas thrown into the pot, I think I see where your going and with a few tweaks to match real life you'll have a cracker of a depot layout
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