Wash. Rev. Code § 46.61.160
The department of transportation may by order, and local authorities may by ordinance or resolution, with respect to any limited access highway under their respective jurisdictions prohibit the use of any such highway by funeral processions, or by parades, pedestrians, bicycles or other nonmotorized traffic, or by any person operating a motor-driven cycle. Bicyclists may use the right shoulder of limited access highways except where prohibited. The department of transportation may by order, and local authorities may by ordinance or resolution, with respect to any limited access highway under their respective jurisdictions prohibit the use of the shoulders of any such highway by bicycles within urban areas or upon other sections of the highway where such use is deemed to be unsafe.
The department of transportation or the local authority adopting any such prohibitory regulation shall erect and maintain official traffic control devices on the limited access roadway on which such regulations are applicable, and when so erected no person may disobey the restrictions stated on such devices.
RCW 46.61.160
Severability-1975 c 62: See note following RCW 36.75.010.