No person other than an officer of the Police Department or member of the Fire Department or a person authorized by the Police Chief or a person authorized by law shall direct or attempt to direct traffic by voice, hand or other signal, except that persons may operate, when and as herein provided, any mechanical push-button signal erected by order of the City Traffic Engineer. (Ord. 1030 § 2(8), 2018; Ord. 526 § 1 (part), 1975)