Overall looks really good Dave! A few thoughts:
- I like the way you've embedded the rocks in the hillsides
- The boulders at the base of the hills look a bit uniform - might want to sprinkle in a few smaller 'fragment' types among them.
- The S-curve in the track seems kinda sharp from a high angle, but looks OK from low angles.
- You might want to consider adding some kind of static grass or Silflor-type weed clusters in the foreground side of the track
- For the track, you might want to take off some of the ballast on the sides of the rails, and consider a dusting of a dark gray or brown to weather it.
- I like the way you did the timber grade crossing. You might want to consider adding a 'Stop' or 'RR crossing' sign.
Ed