The department of transportation may make and enter into agreements with the federal government or any state or group of states or agencies thereof, or any nonprofit association, on a joint or cooperative basis, to study, analyze, or test the effects of weight on highway construction. The studies or tests may be made either by designating existing highways or the construction of test strips including natural resource roads to the end that a proper solution of the many problems connected with the imposition on highways of motor vehicle weights may be determined.
The studies may include the determination of values to be assigned various highway-user groups according to their gross weight or use.
RCW 46.44.049