The pavement structure of SR 12 between Montesano and Elma, Washington was evaluated for the proposed heavy loads associated with construction of the Satsop power plant. Information used in evaluating SR 12 resulted from two sources which included field studies conducted by the Washington State Department of Transportation and development of various material strength parameters by the University of Washington. These data were used to model the pavement structure as a layered elastic system. By use of this analysis procedure, the stresses, strains and deflections were estimated for the expected range of loading conditions. The results indicate that the most probable amount of damage (fatigue and rutting) expected for the non-cement treated base structural sections is less than one to two percent of available pavement life for the "expected" loading condition. An increase in either or both the trailer wheel load and pavement temperature will act to produce greater losses in pavement life. It is estimated that the tensile stresses in the cement treated base may exceed the tensile strength of this material.