The Police Department shall enforce the street traffic regulations of this city and all state vehicle laws applicable to street traffic in this city, to make arrests for traffic violations, to investigate all traffic accidents and to cooperate with the Board of Public Works and Safety and other offices of the city in the administration of the street traffic laws and in developing ways and means to improve traffic conditions and to carry out those duties specially imposed by this traffic code and the ordinances of the city.
('71 Code, § 70.10)