Backdrop ?

[MasonJar]

Actually, come to think of it, you could make it double sided, but not have any industries on the left side. The track could be "unhidden" and just run past a backdrop of flats that represent the backs of buildings, such as you see in almost every major city. If you went this route (so to speak) you'd only need to set it in from the left edge a few inches - just enough to clear that track. The reverse side could still be a conventional backdrop for the buildings on the right, or it could be as Art Curren suggested.

Andrew