As I said, drawing to come. Here is my current sketch.
Lets start with getting to the staging area(s). There is a track right next to the wall on the left hand side of the shed at the rear corner that enters the OUTSIDE curve of the track helix. It begins its descent inside the shed just after it crosses over that last major bracket supporting the main level deck. By the time it reaches the 9 o’clock position on the helix it is at a -1.5”. It subsequently drops 1” for each quarter turn around the helix, ending up at -7.5” at the 3 o'clock position, and subsequently -8” at the 3-way turnout at the entrance to the 3 area staging. That is a little less than a 2% grade (1.8% I believe).
Now it can branch out into 3 directions, ...5 tracks on either side, and an undetermined number down under the straight peninsula. At the head of each side track(s) there are 4 Peco medium radius turnouts that feed 5 tracks that ALL make the same 24” inch radius turn into the straight sections of the staging.
Those 10 straight sections (5 each side) of staging make turns at their 'tails', and can either dead end at the bracket that is located to either side of the big door, OR there will be a lift-out bridge provide that could connect the 5 tracks continuously. The radius’s on those staging track tails are progressively built in 24”, 26.5”, 29”, 31.5”, and 34” so as to maintain a 2,5” centerline between themselves. Other than in the 4 corners of the layout, the shelf depth required for these generously spaced staging tracks is only 14” from the wall.
The staging level deck will be constructed of the same 3/4” plywood I purchased for the main level deck, and will be supported every 24” by a combination of metal brackets fashioned from the same 2” square, and 1.5” angle iron I am planing on using for the main deck above it. That is probably 'overkill', and the staging areas may just utilize the angle iron material.
Not yet shown in this dwg is a central spine support down the peninsula built of the 2” square tubing to be very minimalistic yet strong.
The helix itself will be 'housed' in a trapezoidal shaped box formed on four sides using some 1.5” square alum sections I salvaged from some screened in porch/pool structure here in Florida. They will intersect with some 64” steel circles I am having bent up from 1.5” angle iron. Those two steel circles (one top, one bottom) will be joined by 12 vertical post made up from 1” square alum sections I salvaged elsewhere. It should be strong, and rigid.
Alum siding will be attached to the outer perimeters of the framing and the top cover. There will be some sort of trap door in the bottom to keep pest out.