Bob,
The beauty of the spline system is you don’t have to rely on the basic snap track method of old. You create any radius you want with great transitions.
I use a little different method of spline. I use 1/4" strips of redwood 1-1/2" wide. I draw center lines on a sheet of plywood for the diameter I want with transitions into straights or anyhing else. I then use 1-1/2" closet rod, 2" tall, and screw them down 6" apart over the lines. I take the first strip of wood, bend it to the jig, and clamp it to the dowels. I take my blocks and glue & 1/4" staple them to the strip of wood between each dowel. Then I glue and staple the other strip of wood to the other side of the blocks. After this sets, I glue and staple another strip of wood on both sides. After everything is dry, I remove the screws from the dowels, remove the dowels from the spline, and paint the section. To install the section, I place it on the layout, drive 2"x 2" stakes into the ground between the spline, level it where I want it with screws through the spline into the stakes, and cut-off the left over stake. I am now ready to bend my rail to fit the spline.
This system may sound like it takes a lot of time, but it really does’nt. I can fabricate 16’ long section in one evening, remove it from the jig the next day and install it.
Currently I have over 400 feet of spline installed with all but 20’ of track completed. This spline has been in the ground for over three years with no movement or twisting, and very level track.
Chuck