(A)   (1)   The State Department of Highways, as regards to state and federal highways, and the City Manager, as regards all other streets, are hereby authorized to determine those portions of a highway where overtaking and passing or driving to the left of the roadway would be especially hazardous and shall by appropriate signs or markings on the roadway have the beginning and end of the zones indicated.
      (2)   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 thereof.
   (B)   Where signs or markings are in place to define a no passing zone as set forth in division (A) above, no driver shall at any time drive to the left side of the roadway within the no passing zone or on the left side of any pavement striping designed to mark the no passing zone throughout its length.
(47 O.S. § 11-307)  (`90 Code, § 20-40)