What is a Traffic Impact Analysis and Why is it Important?
A Traffic Impact Analysis, or TIA, is an engineering study conducted by traffic engineers for new developments that may generate significant vehicle trips throughout the day or during the morning or afternoon peak travel periods, when congestion is highest. The goal of a TIA is to determine what consequences will result from the new development and what should be done to mitigate any negative impact to the roadway network or operations. A TIA will provide recommendations such as additional turn lanes, modification of traffic signals, and installation of pedestrian crossings.
Who Reviews the TIAs?
The group responsible for the review of TIAs includes members of the WMPO, NCDOT, and the local jurisdiction’s staff in which the development is proposed. This group is comprised of traffic engineers, civil engineers, and planners. The WMPO and NCDOT share the review and approval for roadway improvements, which are endorsed by the jurisdiction (city, town or county) of record.
When is a TIA Needed?
TIAs are required when a development generates site trips at one of the following thresholds:
- 3,000 Daily Trips
- 100 AM Peak Hour Trips, 7-9AM
- 100 PM Peak Hour Trips, 4-6PM
Some agencies may also be required at the discretion of the local jurisdiction if the development is near or within an area of concern.
What Factors are Considered in a TIA?
TIAs review existing traffic congestion and then predict the future condition due to a proposed development. Further, the TIA will identify mitigation measures to offset any negative consequences of the additional traffic. It is important to identify specific traffic issues and concerns during the initial scoping stage of the TIA process so the applicant and reviewing agencies agree on the scope of the study.
Some of the factors that are incorporated into the TIA are:
- Local concerns identified by planning and transportation staff who are familiar with the area
- Adjacent intersections and roadways which will serve to access the development
- Surrounding developments that may add to the rate of growth in the area
- A traffic model showing the existing and future anticipated operations of the road network
- Planned infrastructure improvements which may change the future conditions or operations
- Acceptance of traffic count data, and site characteristics, such as site trips or roadway capacity
WMPO Traffic Impact Analysis (TIA) Projects
This web application below shows the currently approved Traffic Impact Analysis (TIA) within the Wilmington Urban Area Metropolitan Planning Organization’s (WMPO) jurisdiction.
For any questions, please contact the WMPO’s transportation planning engineer.