Trestles are Jim's thing. He has built all of them in the layout. The wood is primarily pine and has been "ripped" to size. Several "jigs" are used to get the dimensions correct and then they are assembled using wood glue and brads. They are then treated with a redwood primer or oil based stain. Once in place in the layout they are cut to the proper height and then they are screwed together with stringers. Because of the severe grade in parts of the layout (why not take chances) the trestles range from 2" to 24" in height.