A proposed development typically impacts traffic patterns in the vicinity (i.e., generates new or additional traffic). A Traffic Impact Analysis (TIA) is a review of existing traffic conditions and volumes, development traffic volumes and conditions, and the latter's impact on the existing and future roadway network.

Gloucester County requested research to establish some criteria for when a Traffic Impact Analysis should be required in response to a request for rezoning or a conditional use permit, e.g., number of trips threshold, current conditions of the roadway, etc. The county currently relies on VDOT to identify when a traffic study is required during its review process. Research was desired on national, state, and local guidance.

HRTPO staff comprehensively reviewed the criteria for requiring a TIA, including:

• Transportation Research Board (TRB) for national guidelines on TIA
• VDOT on state guidelines for TIA
• Local governments in the Hampton Roads region
• Other local governments in Virginia

The takeaway from this review is that most Hampton Roads localities have criteria that will trigger TIA and several localities use VDOT's criteria. While there are exceptions, the criteria for most Hampton Roads localities for requiring TIA is the number of daily trips, ranging from 50 to 5,000 daily trips. Other local governments in Virginia use the number of daily trips, ranging from 380 to 5,000, as criteria for requiring TIA.

Gloucester County officials can use this comprehensive review of criteria to develop their criteria for TIA, and other localities can use this study to review their existing criteria. The full version of the report can be accessed HERE.