(a) Hazardous zones, commonly called "no passing zones," shall consist of an auxiliary yellow line marked on the roadway pavement and placed parallel to the normal center line or marked lane line. When the auxiliary yellow line appears on the left side in the driver's lane of travel and to the right of the normal center line or marked lane line, no driver shall drive across the auxiliary yellow line to overtake and pass another vehicle proceeding in the same direction. When auxiliary yellow lines appear on both sides of the normal center line or marked lane line, drivers proceeding in either direction shall not drive across such auxiliary yellow lines to overtake and pass another vehicle proceeding in the same direction. No driver shall, at any other time, drive across the yellow auxiliary line when it appears in the driver's lane of travel, except to make a lawfully permitted left-hand turn under the rules governing such movement. No passing signs may also be erected facing traffic to indicate the beginning and end of each no passing zone.
When appropriate signs or markings indicating hazardous or no passing zones are in place and clearly visible, every operator of a vehicle shall obey the directions of the signs or markings, notwithstanding the distance set out in Section 331.06.
(b) Subsection (a) of this section does not apply when all of the following apply:
(1) The slower vehicle is proceeding at less than half the speed of the speed limit applicable to that location.
(2) The faster vehicle is capable of overtaking and passing the slower vehicle without exceeding the speed limit.
(3) There is sufficient clear sight distance to the left of the center or center line of the roadway to meet the overtaking and passing provisions of Section 432.05, considering the speed of the slower vehicle.