Traffic Impact Analysis

A Traffic Impact Analysis (TIA) develops public/private partnerships to coordinate land use and transportation facility development.  Both the City of Plano and the land developer share in the responsibility to consider all reasonable solutions to identified transportation problems.

The TIA study looks at development size and use and determines the effect of that use on the existing roadway system.  This process fosters a roadway system that accommodates the proposed land use and may recommend mitigation measures to foster efficient traffic flow around the proposed site.

When are Traffic Impact Analysis studies prepared?
Plano requires that a Traffic Impact Analysis (TIA) study be done for zoning revisions and  preliminary site plans. Both types of TIA's, share the goal of identifying the relationship between land use and transportation needs.  TIA's are required whenever the additional site-generated Average Daily Traffic (ADT) is more than or equal to 8,000.

Who prepares the Traffic Impact Analysis?
Traffic Impact Analysis studies shall be performed by a consultant qualified to practice Transportation Engineering in the State of Texas. Requirements for mitigating negative traffic impacts shall apply to all zoning cases and site plans.  The applicant or developer shall provide the consultant services.

What information and issues are addressed by a Traffic Impact Analysis?
A pre-submission consultation with the Development Review and Transportation Engineering Division staff is required to verify the need and content for a Traffic Impact Analysis (TIA).  Following that meeting, typical procedures shall be followed in preparing traffic impact studies submitted to the City of Plano. Currently, two types of TIA's may be required for development in Plano: a Zoning TIA and/or a Site Plan TIA (the most common).

1. Zoning Traffic Impact Analysis Content
The Traffic Impact Analysis (TIA), done at the time of a zoning change request, determines the traffic loading that the proposed zoning will impose on the thoroughfare system in a future design year. The study also evaluates if  the impacted road system, as planned, can handle the traffic loading at Level of Service (LOS) D or better in the peak hour.  The study area shall be a one mile radius for less than 10,000 trips per day.  A larger radius may be considered for more than 10,000 trips per day. The following elements should be included in the Zoning TIA document submitted to the City:

  • Study Area Maps
  • Proposed Trip Generation
  • Existing Zoning
  • Net Increased Trip Generation and Distribution
  • Proposed Zoning
  • Level of Service Analysis
  • Thoroughfare Network
  • Conclusions
  • Existing Traffic Volumes

2. Site plan Traffic Impact Analysis Content
A Traffic Impact Analysis, at the time of site plan approval, defines the immediate traffic impacts of the proposed development and proposes transportation improvements (public or private) to foster satisfactory levels of service on affected roads.  Traffic levels exceeding Level of Service D, where the development is contributing five percent or more of the total trips, should be mitigated.   

The detail of a Site Plan Traffic Impact Analysis study is greater than TIA's prepared for Zoning cases.  The study area shall be a minimum of a one mile radius at the discretion of the City’s Traffic Engineer.  The following elements should be included in the Site Plan TIA document submitted to the City:                                       

  • Study Area Maps
  • Trip Distribution and Assignment
  • Existing Zoning and Development
  • Level of Service Analysis
  • Proposed Development Zoning
  • Conclusions
  • Thoroughfare Network
  • Mitigation
  • Proposed Trip Generation

How will the results of the Traffic Impact Analysis be used?
The Transportation Engineering staff reports to the Planning & Zoning Commission on all Traffic Impact Analysis (TIA) studies. The Planning & Zoning Commission considers the staff recommendation in conjunction with requests for review of site plans and rezoning. 

On a zoning or site plan TIA, the Planning & Zoning Commission may make a recommendation for approval, modification or denial of the zoning case or site plan based on other planning factors in addition to its review of a TIA.

The applicant or their representative should be available to answer questions that may arise during the Planning & Zoning meetings or City Council meetings.

Other Sources

ITE. Trip Generation (Manual). latest edition.
"Traffic Impact Analysis", Section 3-1400, Zoning Ordinance