RCW 46.61.135: One-way roadways and rotary traffic islands.

(1) The state department of transportation and the local authorities with respect to highways under their respective jurisdictions may designate any highway, roadway, part of a roadway, or specific lanes upon which vehicular traffic shall proceed in one direction at all or such times as shall be indicated by official traffic control devices.

(2) Upon a roadway so designated for one-way traffic, a vehicle shall be driven only in the direction designated at all or such times as shall be indicated by official traffic control devices.

(3) A vehicle passing around a rotary traffic island shall be driven only to the right of such island.