All traffic-control signs, signals, devices, and markings placed or erected prior to the adoption of this code by the police department and in use for the purpose of regulating, warning or guiding traffic are hereby affirmed, ratified and declared to be official traffic-control devices, provided such traffic-control devices are not inconsistent with the provisions of this chapter or state law.
(1981 Code, sec. 18.87)
All traffic-control signs, signals and devices shall conform to the manual and specifications approved by the state department of transportation. All signs and signals required under this chapter for a particular purpose shall, so far as practicable, be uniform as to type and location throughout the city. All traffic-control devices so erected and not inconsistent with the provisions of state law or this chapter shall be official traffic-control devices.
(1981 Code, sec. 18.78)
The chief of police shall place and maintain traffic-control signs, signals and devices when and as required under this chapter to make effective the provisions of this chapter, and may place and maintain such additional traffic-control devices as he may deem necessary to regulate traffic under this chapter or under state law, or to guide or warn traffic. It shall be the duty of the chief of police to supervise the installation and proper timing and maintenance of traffic-control devices.
(1981 Code, sec. 18.79)
The chief of police is hereby authorized:
(1) 
To designate and maintain, by appropriate devices, marks or lines upon the surface of the roadway, crosswalks at any intersection where, in his opinion, there is a particular danger to pedestrians crossing the roadway, and at such other places as he may deem necessary.
(2) 
To establish safety zones of such kind and character and at such places as he may deem necessary for the protection of pedestrians.
(3) 
The mark lanes for traffic on street pavements at such places as he may deem advisable, consistent with this chapter and other traffic ordinances of the city.
(1981 Code, sec. 18.80)
The driver of any vehicle shall obey the instructions of any official traffic-control device applicable thereto placed in accordance with this chapter and other traffic ordinances of the city, unless otherwise directed by a police officer, subject to the exceptions granted the driver of an authorized emergency vehicle.
(1981 Code, sec. 18.81)
No provision of this chapter for which signs are required shall be enforced against an alleged violator if, at the time and place of the alleged violation, an official sign is not in proper position and sufficiently legible to be seen by an ordinarily observant person. Whenever a particular section does not state that signs are required, such section shall be effective even though no signs are erected or in place.
(1981 Code, sec. 18.82)
(a) 
No person shall place, maintain or display upon or in view of any road, 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 or railroad sign or signal, or which attempts to direct the movement of traffic, or which hides from view or interferes with the effectiveness of any official traffic-control device or any railroad signal or sign, and no person shall place or maintain nor shall any public authority permit upon any highway or street any traffic signal or sign bearing thereon any commercial advertising. This shall not be deemed to prohibit the erection, upon private property adjacent to streets or highways, of signs giving useful directional information and of a type that cannot be mistaken for official signals.
(b) 
Every such prohibited sign, signal or marking is hereby declared to be a public nuisance and the city is hereby empowered to remove the same or cause them to be removed without notice.
(1981 Code, sec. 18.88)
No person shall, without lawful authority, attempt to or in fact alter, deface, injure, knock down or remove any official traffic-control device or any inscription, shield or insignia thereon or any part thereof.
(1981 Code, sec. 18.89)
The chief of police, as authorized by the city council from time to time, shall designate intersections at which traffic shall be controlled by electric traffic-control signals or lights and shall cause such signals or lights to be installed and maintained at such intersections.
(1981 Code, sec. 18.83)