Traffic Impact Assessment:Purpose of Tool:
The purpose of Traffic Impact Assessment (TIA) is to establish uniform guidelines for conducting studies to analyze the potential transportation impacts resulting from the construction of a new development, or from redevelopment of an existing property. TIAs are used to identify potential issues, such as safety, congestion, and access that may arise from the construction of a new or expanded development, as well as determining the necessary improvements to mitigate those impacts. Some local TIA programs may also include a cost sharing analysis element that identifies the portion of the mitigation costs to be borne by the developer versus that of the jurisdiction that owns and maintains the impacted transportation facilities.
Benefits of Using Tool:
The benefits of TIAs include helping communities to:
Steps Involved to Use Tool:
The basic four steps involved with completion of a TIA are as follows:
Special Requirements to Use Tool:
In many communities, traffic impact assessments are a standard part of the development review process. Thresholds that trigger a TIA process and quality of service or level of service standards are often established by ordinance. For example, the Institute of Traffic Engineers (ITE) recommends traffic impact studies for any development generating more than 100 new daily trips, or for developments that are located in sensitive areas with respect to transportation system operations or safety. Local governments will need to establish a standard TIA process for the development community which may include thresholds for developments that require TIAs, study area boundaries, standards for performance of the transportation system with the forecast traffic from developments, and required fees or mitigation measures associated with impacts on the transportation system.
Specials Resources Needed to Use Tool:
Resources may be necessary to collect or develop the information for conducting TIAs. This information includes a quantitative description of proposed development (or redevelopment) projects, historic and current traffic data, safety/crash data, traffic operational information (such as signal timing plans), and information on planned and programmed transportation projects. Much of the data needed may be available from the local departments of public works, transportation departments, Metropolitan Planning Organizations, and/or state Departments of Transportation. Staff time to forecast future traffic within the study area, review programmed improvements, and review TIA studies provided by developers may be necessary, depending on the TIA requirements.
Communities / Agencies that Have Used Tool:
Many local jurisdictions in Texas require traffic impact analysis. In the Greater Houston Region, a TIA is required in the cities of Pearland, Missouri City, Sugar Land, and Harris County. Other cities in Texas such as Round Rock, Grand Prairie, Plano, Arlington, Fort Worth, El Paso, Austin, and San Antonio require TIAs. Two specific examples are:
City of Fort Worth
Director of Planning and Development
City Hall, Lower Level
1000 Throckmorton St.
Fort Worth, TX 76102
City of Fort Worth Transportation Impact Fee Manager
P.O. Box 727
Florence, AZ 85232
Metrics to Use to Monitor Tool Effectiveness:
TIAs are used to project the current and future traffic impact that a development may have on a particular area. Measures of effectiveness may include roadway level of service, as well as multimodal level of service maintained after developments occur. A case study was completed in Eugene, Oregon for Barger Crossing Shopping Center, which was built in 1996, to determine the accuracy of the original TIA. The study found that the original TIA under-predicted the number of peak hour trips in 2007 by 57%.
List of Resources to Obtain Additional Info: