(a) Members of the Police Department and Special Police assigned to traffic duty, are hereby authorized to direct all traffic in accordance with the provisions of this Chapter, or in emergencies as public safety or convenience may require.
(b) No person shall wilfully fail or refuse to comply with any lawful order or direction of any police officer invested by law with the authority to direct, control, or regulate traffic.
(c) Except in the case of emergency no person not authorized by law shall direct or attempt to direct traffic. (M.C. 1963, 20.102.)