No person shall place, maintain or display upon or in view of any street or highway any unauthorized sign, signal, marking or device which purports to be or is an imitation of or resembles an official traffic control device which attempts to or interferes with the effectiveness of any official traffic control device; and no person shall place or maintain, nor shall any public authority permit, upon any street any traffic sign or signal bearing thereon any commercial advertising. This shall not be deemed to prohibit the erection on private property adjacent to highways of signs giving useful directional information and of a type that cannot be mistaken for official signs. Every such prohibited sign, signal or marking is hereby declared to be a public nuisance and the street department is hereby empowered to remove the same, or cause it to be removed without notice. Business or professional signs in established places of business or professions are authorized. (1985 Code ch. 20 § 2-3)