Oregon Revised Statutes Highways, Roads, Bridges and Ferries § 366.487

(1) If a roadside rest area adjacent to or within the right of way of a state highway does not have a separate rest room facility for persons with disabilities of both sexes, a person with a disability and a person of the opposite sex who is accompanying a person with a disability for the purpose of assisting the person with a disability in using the rest room may enter any existing rest room. Prior to entering the rest room, the assisting person shall receive permission from anyone who is in the rest room.

(2) A sign shall be posted outside all rest room facilities subject to the provisions of subsection (1) of this section stating that attendants of the opposite sex may accompany or be accompanied by persons with disabilities into any rest room. The sign shall include appropriate graphics.