The track arrangement in Casper:
The Mainline from Glenrock comes in nearest the aisle, then progresses alongside the yard; after turning back on itself (skirting the roundhouse), the mainline leads to Powder River along the wall, at the left side of this diagram. Keep in mind - the mainline is yellow.
To the left of the roundhouse, which represents the West end of Casper, is an industrial area holding a few local industries. The Standard Oil refinery's loading rack and some small part of the refinery is above that. Standard's refinery used to operate on that end of town. The Standard refinery was shut down several years ago. There was another refinery, Conoco, I think, on the east end of town, but this one has been omitted from the layout (you can't reproduce everything, and with a second, almost fully modeled refinery at Cody, I decided a third large refinery, even if only loading racks, would be one too many. Sorry, Conoco!).
Near the top left of the diagram is the large refer icing facility that was located in Casper. The icing tracks will hold ten or eleven cars each, for a total of about twenty.
The other industries in Casper are under development, and as research progresses I'll flesh out more details.
The classification tracks, if completely full, will hold around one hundred cars (give or take a few). I'm gonna need an awful lot of cars on this layout! Those tracks will never be full, of course - a clogged yard can't do its job.
The wreck train track will also be used to store other MOW equipment such as a snowplow, and may also serve to store the odd passenger car, though there will never be more than one or two of those in the yard at a time (despite being the sometimes largest city in Wyoming, Casper was always just a stop on the line, and not a major passenger terminus).
Casper is on the lower level.
Construction at Casper never really got started before the layout came down. All I ever got done in that area was installing wall studs and the backdrop support frame.