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Traffic Signals Brochure - How is it Determined if a Traffic Signal is Needed?

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How is it Determined if a Traffic Signal is Needed?

Study 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.

Important Considerations.

This study considers a number of important factors, including the following:

  • Intersection design
  • Crash 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 wise 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