A few comments. I like the overall flow, but I'm concerned about the 48" width of the sections on the sides. 48" is too far to reach the tracks near the wall on the left and the bottom corner on the right. Aside from that, the yard is going to be difficult to navigate. It appears the sidings are too short to hold many cars and it looks cumbersome to move cars/engines to the 2 upper sidings. At a minimum, and assuming you don't care about the long reach, I would change it as shown below. This would allow trains to enter the yard from the left and then back into a storage track. If going in the opposite direction, you could still back in from the right, it would just tied up a little more track initially.
