Building a Helix

My helix will consist out of 8 pieces of 4mm thick plywood , that together form an octagon, much easier to saw then round pieces with almost no waste of wood.
Using the first piece as a jig I'm making 58 pieces to make 7 1/4 loops.
First loop with the ramp starting on the right side , each loop will climb 6,5 cm in about 260 cm of length making a gradient of 2,5% , with a radius of 16 inches , in total climbing 18 inches. Almost all my engines , except for maybe a UP Big Boy and Challenger should be able to cope with this.
The loops still missing a straight piece in between to connect them , after that is done I will begin with the risers.
First loop done.
Ready to caulk down track.
Second loop with track weighted down while drying.
Slowly but surely to the top.
A schematic of the Helix , both levels have track going to a staging area. Lower level has track to east and west of the layout , upper level only to east.
Helix is finished , now to figure out where I need auto-reversers.
I tested the helix with 3 different sized and motorized engines , some small problems at first but a couple of hours of adjusting and fiddling did the trick.