The contractor just follows the plans devised by the local engineering entity in charge. I supplied road materials for state, county, and city projects for almost 40 years and many times I could see from the engineering specs the material wouldn't last more than a few years. Numerous times I got the "That's the way they do it in Europe." explanation from the inspectors in charge. "This ain't Europe!" :lol:was usually my response. Every now and then they would come up with some engineering that would actually improve the products and I had no problem with complying. But some of their experiments, Oy Vey :BangHead:.