Wash. Rev. Code § 36.75.120
When the true location, course, or width of a county road, which was prior thereto uncertain, has been reported by the examining engineer, the board shall file an action in the superior court of such county for the determination thereof. All persons affected by the determination of the true location, course, or width insofar as the same may vary from the originally established location, course, or width shall be made parties defendant in such action and service had and return made as in the case of civil actions. Upon the hearing the court shall consider the survey, maps, and all data with reference to the investigation of the examining engineer and may demand such further examination as it may deem necessary and any objection of any party defendant may be heard and considered. The court shall determine the true location, course, and width of the road and may in its discretion assess the cost of such action against the county to be paid from the county road fund.
RCW 36.75.120