One conceptual idea I liked about screw assembly of spline was that allows easy adjustment; splines can be dissassembled, adjusted or reused in an other place easily.
In this quot;Beforequot; photo, the roadbed climbing away from the staging level runs along the front edge of the benchwork from right to left, then re-enters the scene along the wall as it climbs to next level. I decided to switch this so that it exited the scene on the left along the wall, and completed it's climb along the edge of the benchwork. See next photo.