Btw - for easier comparison - here is Marc's layout plans:
"Duluth Urban industries 1":

"Duluth Urban Industries 2":
The part I like the least is the length of the tail track on the right hand side (inside the factory) - it looks to be so short that you can only take one car at a time up to or down from the factories/warehouses along the rear end of the layout.
I would have tried to be able to move at least cuts of 2 and 2 cars, and tried hard to avoid having to use the track in front of one industry as a switchback to reach another industry.
Couldn't help it - had to make a sketch to see what could be done in 18" x 6 feet. Here is one possible solution to this issue:
both tail tracks (upper left hand corner and right end below carfloat) hold two cars + loco, runaround hold two cars, there is one holding track in the lower right hand corner (to hold inbound or outbound cars while you are swapping outbounds for inbounds), and each industry can be switched without touching cars in front of other industries:
Smile,
Stein