Eight foot 2x4s are screwed at 14 inch intervals spacing the four ribs apart at 31 inches each .
Three full length 2x6s are screwed to the bottom of the form. These will sit on the supporting beams that straddle the stream temporarily while the bridge is built. A couple of braces are screwed in place diagonally to stop the form leaning sideways with all the weight of the stones. The form is still quite light. The rest of the wood can be added later.
Ready and loaded on the trailer.
Delivered to the site.