Updated 7/8/2019:
Today I added the vertical supports for the sub-roadbed. They will also hold up the masonite sections that support the foam.
By the way, the drawing is out of date. The track centers along the straight segment are not 4 5/8" apart - they are 4.25".
Here are the vertical supports. The first one is closest to the Stone Arch (just off camera to the left).
The second photo is of this same vertical support from below.
In order to give them maximum strength, I used 3" screws to attach the vertical 2"x2" from above and below as well as wood glue. Finally, I marked them done.
I guess you could say the were glued, screwed, and tattooed.
More when I know it.
George