The spline method starts with a single strip of material. Normally, the strip would be mounted to the rest of the benchwork, but I don't want to commit myself to that yet, so I am clamping it to the bookcase upon which this layout will rest.

Where the orange-handled clamp is in the photo below is where the two Masonite strips are butted against each other. The two other clamps hold the strips down to the top of the workbench.

Another clamp holds the center strip in place on the left side of the layout.

And now the fun begins. In the photo below, I am gluing the second row of strips to the first strip. The joints are going to be staggered by one foot. The strips are glued with Elmers' Yellow Carpenters glue, and just about all the small clamps we own! The beauty of the spline method of constructing the roadbed is that the wood automatically makes for smooth curves, a natural easement. I used a straight-edge to keep the first part of the roadbed as straight as possible, clamping it to the wood as the glue is drying.

When the two 8-foot long strips were dry (glued to the center strip), I cut the remaining 12 inches off the one end and glued it in place at the beginning, as shown in this photo.

And now it is just a matter of gluing all ten strips to each other to form the subroadbed. My intention was to make the two curves with about an 18-inch radius, but they turned out to be about 21 inches, which is good enough.