I like the road plan. A train traveling the cloverleaf through the town will be really entertaining to view. Painting the road will keep with the 40's/50's style. You could texture the foam for road cracks and potholes and such. Scuff it sandpaper and then some clever slits and gouges will make the paint pop.
I would be tempted to go more modern with the canyon. Glue the stacked foam and shape and hack it with tools and then paint it. 4 1/2" grinder with a cutting wheel, a rasp, the big kitchen knife, a pencil for detail cracks. Latex paint covers it wells and you can blend the varying shades while it is all wet. Take the pieces to the garage or shop. here's a result from forum member frizzinbee 7/31/18, 8/7/18 he found that heat gun does a nice finish after the shaping and hacking.
