@Adriatic, many thanks! I fully understand conceptually. My problem is figuring how to do elevations in SCARM (tried for the first time Wedneday night). Everything that is yellow or green is flat and on the first level. Everything that is pink is flat and on the second level. I want to minimize the elevation of the second limit due to the grades. All the portals but one have the lower track at "sea level" passing under the flat second level. The exception is the down grade where orange passes under pink. That will be the tightest vertical clearance. I envision the plane of the first level being exactly 4.5" (3 x 1.5" layers) below the lower plane of the top layer of foam board (1" thick). Minus the track thickness leaves me about 4.25" from the top of the lower level rails to the portal. Where orange passes under pink, I'll have about 3.75" of clearance. That means about 8' (96") of run to drop 5" of elevation making this downward grade a tad over 5 degrees. The worry is what will happen to the PolEx when it reaches the yellow 42" switch (on the left). Any thoughts?
The SCARM file is just above if anyone can lend a hand there! :-)