Oregon Revised Statutes Oregon Vehicle Code § 810.120

(a) Determine where overtaking or passing or driving to the left of the center of the roadway would be especially hazardous; and

(b) Establish zones on the roadway where overtaking or passing or driving to the left of the center of the roadway are prohibited because such would be especially hazardous.

(a) Determine that a need for a zone exists in accordance with standards and procedures adopted by the Department of Transportation.

(b) Mark the zone by appropriate signs or by a yellow unbroken line on the pavement of the right-hand side of and adjacent to the center line or a lane line of the roadway to indicate the beginning and end of the zone.