This came out very well. I like it, I've seen variations of this, you found a newness to it. Well done composition.
There are a few detail things that you can look to include in your next diorama. One thing I like to see is a 'touched up' base. Add a small piece of 1/4 round molding to the edge and stain it. Or even fill in the edge with household spackle, sand and paint. It sets it off really nicely as a display piece.
I like that you've added track ruts, a pile of dirt for the tunnel, and other details sometimes left out.
Nice job.