Great Model, it is amazing what you have done. I hope to do about the same in HO. Now I am pumped to do mine, thanks for the inspiration.
I have been experimenting with a small radius in the corners to keep the start stop burn from building up in the corner. Seems to work, reducing the dimension of the radius to see what the min. will be.
This the prototype of my old west bridge finished. These two parts measure ~210 feet in HO scale made from birch.
Once totally completed it will be made out Basswood and the deck will be made from individual ties on top of long wooden rails along the outside of the trestles and the rails will be hand laid by the customer.
Watch out for the basswood. Basswood absorbs water (even from the paint) causing thin pieces to warp. You can usually straighten them out but it does add the extra work. Same thing happens with laserboard. I usually use thin birch plywoods to a suitable scale for the bents which I make in several layers and then sandwich them together to obtain a 3D effect.