A great deal of time is consumed during the NEPA process on the determination of the cost of impacts to Section 106 4f properties.  Most of this debate centers around the inpact of the proposed transportation project on historic properties of questionable historic value to the commuity or region.  Many times this lengthy process ends up in costly mitications that are founded on nothing more than a guess or an opinion as to the cost of the impact.  A more systimatic approach would result in less cost to project and more focused mitigation to valuable historic resources.