3' x 2' coffee table style layout split across.

The basic idea is the one side is heavy industrial (backscene warehouses etc
including a protruding half relief section), with a bit of street running
and the like while the other is rural and uses big buildings to give a 'big'
feel.

As envisaged the rural track enters top left from a tunnel in the backscene
with perhaps a bit of half relief, and exits the other side under a road
bridge on the backscene (again perhaps half relief) running down to the grain
elevator

The industrial one comes from under the warehouses and exits via the street
running which with the big buildings close each side can probably just be a
hole in the backscene for most view angles.

The siding bottom right could also be used as an exchange siding or similar
and the geometry is such you can add one at the top the same way (off the
start of the curve) to join to another layout.