When finished the roadbed is probably glued to the risers but to be sure there is a stable base I screwed the spline to the risers. Start with a small drill hole slightly smaller than the screw and drill a countersink hole so the head of the screw finishes below the top to the spline roadbed.
You can see in the picture above that I used spline spacers on some areas.
The next stage is to sand the top of the splines ready to attach the cork roadbed. Sanding is difficult. No matter how careful I was to align the splines as I glued and clamped them the top of the spline roadbed is far from even. A plane did not work. Hand sanding was slow and laborious. I used a flat sheet planner but wished I had access to a planner.
Anyway the top was levelled and the cork roadbed attached with white glue as on the rest of the layout. Once dry the cork was sanded and checked for levels across the run of track. When happy i bevelled the cork edges and painted the cork before laying track.
Track was laid on the cork using coloured caulk spread thinly. Prior to caulking I laid out the track and drilled holes for the feeder wires / track connections to the bus. Remember I attach feeder wires to every section of track on the underside so there is no visible connection once installed.
Here are some shots of the first trains testing out the spline section.