The DDD Track is made 100% of wood with outdoor glue and nails. Enamel paint protects the wood. In our case, we bought 3/4" - 4' by 8' high quality plywood. It was ripped in three equal 8' parts. When purchasing the plywood, the store will do this for you. The cut is critical because the track sections must be equal in width or the cars will hit the protruding sides. Should you have some that are narrower, you cna use them for the side 3" strips, or at the top of the track. Cars will not hit protruding walls if the part sticking out is after the narrower section.
The side rails are 3" strips of 8' plywood. They are glued and nailed on the outside of the track.
We made 18 - 8' sections for a total of 144' of track. Each section has a male and female end that enterlock to provide a secure joint.
The first 4 sections we used a 3/4" strip of pine glued and nailed to the surface to act as lane side rails. Refer the pictures at this site. After these middle lanes end, full contact between the cars is possible.
Below is a spreadsheet showing how the tract was designed. I must admit it is not totally clear but as volunteers, we do our best.