(a) Officers of the police department or such other persons as are assigned by the chief of police are hereby authorized to direct all traffic by voice, hand or signal in conformance with the provisions of this chapter; provided, that in the event of a fire or other emergency or to expedite traffic or to safeguard pedestrians, officers of the police department may direct traffic as conditions may require notwithstanding the provisions of this chapter.
(b) Officers of the fire department, when at the scene of a fire, may direct or assist the police in directing traffic thereat or in the immediate vicinity.