R.I. Gen. Laws § 31-15-8: Posting of no passing zones.

The state traffic commission is authorized to determine those portions of any highway where overtaking and passing or driving to the left of the roadway would be especially hazardous and may by appropriate signs or markings on the roadway indicate the beginning and end of the zones. When the signs or markings are in place and clearly visible to an ordinarily observant person every driver of a vehicle shall obey the directions given by them. Violations of this section are subject to fines enumerated in § 31-41.1-4.