How is it Determined if a Traffic Signal is Needed?
Unless a study has recently been completed, an agency typically will respond to a request for a traffic signal and complaints about an intersection by conducting a special traffic engineering study to obtain and analyze the pertinent information.
This study considers a number of important factors, including the following:
- Intersection design
- Accident history and potential
- Vehicle traffic volumes and gaps in traffic approaching the intersection
- Turning traffic and pedestrian crossings
- Approach speeds and sight distances
- Locations of nearby signals
- Characteristics of the area and adjacent land use
- Projected and planned growth
Digesting the facts.
With the facts in hand, engineers look to determine what actions, if any, will yield the best results with the least adverse side-effects. When considering the possibility of a traffic signal, the engineers must, by State and federal law, consider the guidelines for signal installation set forth in the national Manual on Uniform Traffic Control Devices, which embodies time-tested recommended practices developed to ensure that signals are used where, but only where, they are justified by comprehensive, objective criteria.
What are the Alternatives to a Traffic Signal?
Are there alternatives?
Where a problem is documented, experience has shown that other improvements, alone or in combination, may work better than a new traffic signal to enhance the operation of an intersection. They often can alleviate the problem without the adverse side effects that a signal may cause. Alternatives to a traffic signal can include:
- Improving the line of sight along the intersection approaches
- Installing flashing signals (beacons)
- Adding turn lanes
- Constructing curbs and pedestrian safety islands
- Revising traffic controls, measures, and regulations
- Installing/revising traffic signing and marking
- Rerouting crossing traffic to safer locations
- Retiming nearby signals
- Installing intersection lighting
- Constructing a roundabout
- Making other roadway improvements