The driver of a vehicle on a street or highway upon meeting or overtaking from either direction any school bus which has stopped on the highway for the purpose of receiving or discharging any school children shall stop the vehicle before reaching such school bus when there is in operation on the bus a visual signal as required by the statute for operation while the bus is transporting pupils; and said driver shall not proceed until such school bus resumes motion, or is signaled by the school bus driver to proceed, or the visual signals are no longer actuated provided that the driver of a vehicle upon a street or highway of which the roadways for traffic moving in opposite directions are separated by a strip of ground which is not surfaced or suitable for vehicle traffic need not stop his vehicle upon meeting or passing a school bus which is on the opposite roadway. (6-16-61)