40-6-72.
   
  (a) Preferential right of way may be indicated by stop signs or
  yield signs as authorized in Code Section 32-6-50.
   
  (b) Except when directed to proceed by a police officer, every
  driver of a vehicle approaching a stop sign shall stop at a clearly
  marked stop line or, if there is no stop line, before entering the
  crosswalk on the near side of the intersection or, if there is no
  crosswalk, at the point nearest the intersecting roadway where the
  driver has a view of approaching traffic on the intersecting roadway
  before entering it. After stopping, the driver shall yield the right
  of way to any vehicle in the intersection or approaching on another
  roadway so closely as to constitute an immediate hazard during the
  time when such driver is moving across or within the intersection or
  junction of roadways.
   
  (c) The driver of a vehicle approaching a yield sign shall, in
  obedience to such sign, slow down to a speed reasonable for the
  existing conditions and, if required for safety to stop, shall stop
  at a clearly marked stop line or, if there is no stop line, before
  entering the crosswalk on the near side of the intersection or, if
  there is no crosswalk, at the point nearest the intersecting roadway
  where the driver has a view of approaching traffic on the
  intersecting roadway before entering it. After slowing or stopping,
  the driver shall yield the right of way to any vehicle in the
  intersection or approaching on another roadway so closely as to
  constitute an immediate hazard during the time such driver is moving
  across or within the intersection or junction of roadways. If such a
  driver is involved in a collision with a vehicle in the intersection
  after driving past a yield sign without stopping, such collision
  shall be deemed prima-facie evidence of his failure to yield the
  right of way.