Wash. Rev. Code § 22.09.850
Any railroad delivering commodities covered by this chapter in cars at designated inspection points shall provide convenient and suitable side tracks at such places as the department may approve. All cars billed for inspection shall be placed on such side tracks and the department shall be notified by the railroad in accordance with department regulations. Such railroad company shall provide suitable track scales for weighing cars of commodities upon the request of interested persons. Upon request, the department may weigh, or supervise the weighing of all cars of commodities received over the line of such railroad. Such weighing shall be conditioned upon the weighing of such cars after unloading to determine the actual weight of commodities delivered.
RCW 22.09.850