Correction: The track isn't too narrow, the ships are scaled to big. I told zero to use the same scale on the ship and track: If the track is scaled 10x, the ship has to be scaled 10x with a variation of 10% because Unity misreads the actual size of the object if the export units are incorrect. On the 1:1 ratio the track is 3 ships wide (13.5 meters).
I made some changes on the terrain so I can delete some unnecessary polys and added the tree walls:
Attachment 2862
It's starting to look a lot like blue ridge, lol...