(A) No person shall drive a motor vehicle at such a slow speed as to impede or block the normal and reasonable movement of traffic except when reduced speed is necessary for safe operation of his vehicle or in compliance with law.
(B) The speed limits established by this chapter do not apply to ambulances or to an authorized emergency vehicle in motion when responding to an emergency call and when the driver thereof sounds an audible signal by bell, siren or exhaust whistle, as may be necessary; provided, that the vehicle is equipped with and has in operation at least one lighted lamp displaying an oscillating, rotating or flashing red beam. An authorized emergency fire department vehicle may be equipped with and have in operation a triple eight moving white beam light visible under normal atmospheric conditions from a distance of five hundred feet (500') to the front of such vehicle, in lieu of, or in addition to, a rotating or flashing red beam in order to be exempt from the speed limits established by this chapter. However, this provision does not relieve the driver of an authorized emergency vehicle from the duty to drive with due regard for the safety of all persons using the street, nor does it protect the driver of any such vehicle from the consequence of a reckless disregard of the safety of others. (1972 Code)