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Traffic Impact Studies


What are they?

A traffic impact study assesses the adequacy of existing or future transportation infrastructure to accommodate proposed land development, redevelopment, or rezoning. These studies can vary widely in detail and complexity depending on the type, size, and location of the proposed development. Traffic impact studies are important tools used by public agencies to assist in making land use and planning decisions. These studies are used to help evaluate whether the proposed development is appropriate for a given location and what type of transportation infrastructure improvements may be needed in order to maintain adequate traffic flow.

Traffic impact studies are conducted in order to…

  • Forecast additional traffic that would accommodate new developments. 
  • Determine any improvements that are needed to accommodate a new development. 
  • Assist in land use decisions. 
  • Identify any problems that proposed development may face, ultimately influencing development decisions. 
  • Allow communities to assess the impacts of a proposed development. 
  • Ensure safe traffic conditions on streets after a development is completed. 
  • Reduce the negative impacts created by the development by helping ensure transportation infrastructure can accommodate the new development. 
  • Recommend alignment or operational improvements to roadways to promote traffic flow.

What does an impact study entail?

Components of a traffic study could potentially include:

  • Proposed development land uses and sizes
  • Study locations, particularly intersections
  • Existing traffic counts (including turning movements counts, pedestrian, and bike activity)
  • Times of day or day of the week
  • Expected growth in the area without development 
  • Crash history 

What is included in the final report?

Considerations that are included in the final report typically include:

  • Existing congestion areas 
  • Existing queue lengths (how many vehicles are stopped per lane, delay of queues)
  • Forecasted congestion and queue lengths
  • And any alternatives for addressing the congestion and crash problems in the area, such as:
    • Added lanes
    • Signs
    • Pavement Marking
    • Traffic Signals
    • Roundabouts
    • Sidewalks
    • Bike Paths
    • Sight Distance Improvements
    • Lighting