The traffic authority shall have the exclusive power and duty to place and maintain or cause to be placed and maintained official traffic-control devices when and as required under this title. The traffic authority may place and maintain such additional traffic-control devices as he may deem necessary to regulate traffic under this title or under state law, or to guide or warn traffic. The city council does hereby delegate the right, power and authority to the traffic authority, in those instances where he deems such action necessary on his part, to place and erect with the approval of the city council expressed by resolution duly adopted by the city council and of record in the minutes of its meetings, additional traffic-control devices as defined in this title. When so erected, such traffic-control devices shall for all intents and purposes be deemed to be official traffic-control devices within the meaning of this title, and when such devices are so in place it shall be unlawful for any person to, and no person shall, disobey the directions or controls established by, shown on or indicated by the same or any of them. The traffic authority shall likewise, with the consent of the city council expressed by resolution duly adopted by it and of record in the minutes of its meetings, have the right and authority to remove any traffic-control device placed under the authority of this section, and upon such removal, the directions or controls established by, shown on or indicated by such traffic-control devices shall no longer apply at such location.
(Prior code § 16-58; Code 1959 § 11.41)
The traffic authority is hereby authorized:
(1) 
Traffic Signals at Intersections, etc. To install and maintain official traffic signals at such intersections and other places as he may deem necessary for the regulation of traffic.
(2) 
Establishment of Safety Zones. To establish safety zones at such places as he may deem necessary for the protection of pedestrians.
(3) 
Marking Traffic Lanes. To mark lanes for traffic on street pavements at such places as he may deem advisable, consistent with the State Vehicle Code and traffic ordinances of the city.
(4) 
Determination of Location and Extent of Street Markings. To determine the locations and extent of all distinctive street or roadway markings within the city, and to cause such markings to be placed and indicated upon such streets and roadways. Signs shall not be required in connection with the distinctive street or roadway markings.
(Prior code § 16-59; Code 1959 § 11.42)
The driver of any vehicle and the person in charge of any animal shall obey the instructions of any official traffic-control device applicable thereto placed in accordance with this title, unless otherwise directed by a police officer, subject to the exemptions granted by this title.
(Prior code § 16-60; Code 1959 § 11.43)
The driver of any vehicle or the person in charge of any animal shall obey the instructions of any barrier or street sign erected by any of the public departments of the city or public utilities in the city, or by any other person pursuant to law.
(Prior code § 16-61; Code 1959 § 11.20)
No provision of this title for which signs or markings are required shall be enforced against an alleged violator, if, at the time and place of the alleged violation, an official sign or marking was not in place and sufficiently legible and visible to be seen by an ordinarily observant person.
(Prior code § 16-62; Code 1959 § 11.44)
Whenever traffic is controlled by traffic-control signals exhibiting the words "GO," "CAUTION" or "STOP," or exhibiting different colored lights successively one at a time, the following colors only shall be used, and the terms and lights shall indicate as follows:
(1) 
Signal Showing Green. Green alone or "GO":
(a) 
Vehicular traffic facing the signal shall proceed either straight through or turn right or left, unless a sign at such place prohibits either such turn, except that vehicular traffic shall yield the right-of-way to other vehicles and to pedestrians lawfully within the intersection or adjacent crosswalks at the time such signal is exhibited.
(b) 
Pedestrians facing the signal may proceed across the roadway within any marked or unmarked crosswalk.
(2) 
Signal Showing Yellow. Yellow alone, or with green or "CAUTION," when shown following the green or "GO" signal:
(a) 
Vehicular traffic facing the signal shall stop before entering the nearest crosswalk at the intersection, but if such stop cannot be made in safety a vehicle may be driven cautiously through the intersection.
(b) 
No pedestrian facing such signal shall enter the roadway until green or "GO" is shown alone.
(3) 
Signal Showing Red. Red alone or "STOP":
(a) 
Vehicular traffic facing the signal shall stop before entering the nearest intersection or crosswalk, or crossing the nearest clearly indicated limit line, and, except in the case of red flashing signals only, shall remain standing until green or "GO" is shown alone, or flashing amber is shown alone, except as provided in subsection (3)(b) of this section.
(b) 
Local authorities may designate any intersection by appropriate signs thereat where the driver of a vehicle which is stopped as close as practicable at the entrance to the crosswalk on the near side of the intersection or, if none, then at the entrance to the intersection in obedience to a red or "STOP" signal, may make a right turn, but shall yield the right-of-way to pedestrians and other traffic proceeding as directed by the signal at the intersection.
(c) 
No pedestrian facing such signal shall enter the roadway until green or "GO" is shown alone.
(4) 
Bells Ringing in Connection with Traffic Signal. The ringing of a bell in connection with any official traffic signal shall indicate that a change is taking place or is to take place in the traffic signal. However, all traffic shall be required to obey the direction of the signal itself; the ringing of a bell is to be construed merely as a warning to traffic of a change in signal.
(5) 
Disobeying Directions of Section. No person shall disobey the directions of this section except when it is necessary to stop for the purpose of avoiding an accident or in case of other emergency or when otherwise directed by police official.
(Prior code § 16-63; Code 1959 § 11.45)
(1) 
Flashing Red (Stop Signal). When a red lens is illuminated by rapid intermittent flashes, drivers of vehicles shall stop before entering the nearest crosswalk at an intersection or at a limit line when marked, and the right to proceed shall be subject to the rules applicable after making a stop at a stop sign. A flashing red signal shall not be used except at a place where a stop sign is located.
(2) 
Flashing Yellow (Caution Signal). When a yellow lens is illuminated with rapid intermittent flashes, drivers of vehicles may proceed through the intersection or past such signal only with caution.
(Prior code § 16-64; Code 1959 §§ 11.46, 11.47)
The traffic authority is authorized to determine those intersections within any business or residence district at which drivers of vehicles shall not make a right turn against a red or stop signal and shall erect proper signs giving notice of such prohibition. No driver of a vehicle shall disobey the directions of any such sign.
(Prior code § 16-66; Code 1959 § 11.49)
It shall be unlawful for any person to tamper with, deface, remove or cause to be removed, without authority of the traffic authority so to do, any signs or markings, or traffic-control devices erected under or pursuant to the provisions of this title.
(Prior code § 16-67; Code 1959 § 11.50)
The traffic authority may erect or place and maintain signs at any intersection prohibiting the making of left turns by drivers of vehicles, wherever the traffic authority determines that such left turns would cause traffic congestion or traffic hazard, and during the time such signs are so erected or placed, no left-hand turns shall be permitted at such designated intersections, and it shall be unlawful for the operator of any vehicle to make any left-hand turn in such intersection at such times.
(Prior code § 16-71; Code 1959 § 11.54)