Eligibility
To be eligible for evaluation and study, a traffic signal or left-turn arrow request must be:
- Within Phoenix city limits.
- (Traffic signal only.) At least one-quarter mile from an existing signal. There may be cases where installation of a new traffic signal within one-quarter of mile is recommended.
- More than three years since the location was last evaluated/studied. If a location was evaluated or studied within the past three years, it will not be re-evaluated unless there has been or there will be a significant change to the previous traffic, e.g., a new, large multifamily development or shopping center opens in the area, or a documented history of serious crashes.
Signal Warrant Analysis (SIGWAR) Overview and Traffic Signal Installation Process
Prior to construction, the potential location for a new traffic signal is evaluated and studied to ensure its placement is appropriate. The Signal Warrant Analysis (SIGWAR) is a process designed to conform with all standards, guidelines, and warrants established by the Federal Highway Administration in the Manual on Uniform Traffic Control Devices (MUTCD), while incorporating additional factors such as proximity to schools, intersection spacing for synchronization, traffic speeds, and other relevant conditions and/or data.
SIGWAR generates a priority ranking for signal installation based on the nine warrants in the MUTCD and other factors. Meeting a MUTCD signal warrant suggests that further study for traffic signal control may be warranted. The SIGWAR data is reviewed, and engineering judgment is applied to assess whether the signal warrants are met to justify installation. If the study recommends a traffic signal, that location is added to the SIGWAR list. The final decision to install a traffic signal is based on engineering judgment, which considers both MUTCD criteria and the unique characteristics of the location. The priority ranking generated by SIGWAR helps determine which signals should be prioritized within available budgetary constraints. As funding is identified, traffic signals from this list may be designed and constructed. As of 2024, traffic signals typically cost anywhere from $600,000 to $700,000 to construct, and, in some cases, over $1 million.
Phoenix Left-Turn Arrow Warrant System (LTWAR)
The City of Phoenix has developed a Left-Turn Arrow Warrant System (LTWAR) that evaluates the following factors for left-turn signal installation:
- Number of left-turn lanes
- Number of opposing lanes
- Crash history
- Posted speed limits
- Geometric factors (sight distance, storage length, etc.)
- Conflict factors
- Available funding
Engineering judgment plays a crucial role in determining which improvements should be prioritized and installed.
