The middle of the three sections has been installed on the vertical spacers. I attached it using small wood screws that were counter-sunk.



I could now commence the construction of the subroadbed for the lower-level track. Since a gentle curve is needed to connect the center section of the layout with this new piece of plywood on the right-hand side of the layout, a spline subroadbed seems to be the best solution. Using the table saw, I cut a one-inch (2.54cm) wide strip of 1/8"-Masonite hardboard. I left its length the full length of the sheet, i.e. 8 feet (244cm). What the photo below shows is the piece clamped to the two areas of the layout that are to be connected by this spline subroadbed. A vertical spacer is temporarily clamped to the back side of the layout using the orange-handled spring clamp. This prevents the spline subroadbed from sticking out the back of the layout.



I wanted the Masonite spline to be level with the plywood subroadbed of the center section of the layout. I carefully clamped it in place using two C-clamps.



On the other end I let the piece extend however far it needed to. I rested it on top of the new plywood sheet and clamped it down.



I wanted to inset the end of the spline into the new piece of plywood for support and to make sure the top of the spline was level with the top of the plywood. I marked off how long the spline piece needed to be and cut it while it was still clamped to the layout. I then marked off on the plywood where the spline inset was to be. I used a deep-throat fret saw to cut the groove by hand. A block of wood glued to the layout structure provided the support for the spline to keep it level at the top with the plywood. I then glued the spline to the plywood.



With all that glue dried, I then glued the other end of the spline to the plywood subroadbed. I also cut vertical spacers to make sure the rest of the spline was supported. Those are being glued to the layout structure in the next photo.