Each year, the City receives many inquiries concerning the installation of new traffic signals or left turn arrows. Engineering studies are done to determine where new devices are needed.
Our review may include an examination of:
- The amount of vehicular and pedestrian traffic.
- Special conditions such as hills and curves.
- The incident history at the intersection.
- Spacing of adjacent traffic signals.
- The proximity of schools.
How To Ask For A New Signal
Traffic signals and other traffic calming devices can be requested through the Traffic Engineering Division. Contact us at (520) 791-4259.
A list of requested improvements is compiled during the year. Signal and arrow studies generally begin after the first of each year and take several months to complete. Studies are done during this time of the year because that is when traffic conditions are generally busiest.
Steps may include the following:
Traffic crews conduct an engineering study to see if the location meets the State and Federal warranting criteria. This engineering study is an information gathering process. For new traffic signals, traffic volume, the speed that traffic is flowing, the amount of pedestrian activity, accident history and the distance the proposed new signal location is away from adjacent signals is gathered.
For left turn arrow requests at existing signals, turning and opposing volumes are counted during peak hours, the delay per turning vehicle is calculated, total turning delay is determined and accident history is reviewed.
- If the location passes the engineering study, the proposed improvement goes on a priority list and is ranked by traffic volume figures and accident history.
- Each year, based on funding, the City of Tucson starts at the top of the priority list with the goal of constructing as many warranted improvements as the budget will allow.
Note: The Federal Manual on Uniform Traffic Control Devices (MUTCD) states: "The satisfaction of a traffic signal warrant or warrants shall not in itself require the installation of a traffic control signal."
Advantages of Traffic Signals
Traffic control signals are not the solution to every traffic problem. When properly used, traffic control signals are valuable devices for the control of vehicular and pedestrian traffic. They assign the right-of-way to the various traffic movements and thereby profoundly influence traffic flow.
Traffic control signals that are properly designed, located, operated, and maintained will have one or more of the following advantages:
- They provide for the orderly movement of traffic.
- They increase the traffic handling capacity of the intersection if proper physical layouts and control measures are used, and if the signal timing is reviewed and updated on a regular basis to ensure that it satisfies current traffic demands.
- They reduce the frequency and severity of certain types of crashes, especially right angle collisions.
- They are coordinated to provide for continuous or nearly continuous movement of traffic at a definite speed along a given route under favorable conditions.
- They are used to interrupt heavy traffic at intervals to permit other traffic, vehicular or pedestrian, to cross.
Disadvantages of Traffic Signals
Traffic control signals are often considered a panacea for all traffic problems at intersections. This belief has led to traffic control signals being installed at many locations where they are not needed, adversely affecting the safety and efficiency of vehicular, bicycle, and pedestrian traffic.
Improper or unjustified traffic control signals can result in one or more of the following disadvantages:
- Excessive delay.
- Excessive disobedience of the signal indications.
- Increased use of less adequate routes as road users attempt to avoid the traffic control signals.
- Significant increases in the frequency of collisions (especially rear-end collisions).