Regional Model

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Why We Maintain a Model

As the federally designated Metropolitan Planning Organization (MPO) and the Washington State designated Regional Transportation Planning Organization (RTPO) for Thurston County, TRPC is responsible for developing, maintaining, and running the Regional Travel Demand Model. We are committed to working with our member jurisdictions to provide the highest quality data to support both local and regional modeling needs.

Our regional travel demand model is a traditional 4-step model developed in the Emme platform. The base model update was completed in 2015. In 2017 the model was expanded to include all of Lewis County. The regional model includes a 2015 and 2040 baseline forecast scenario. The 4-steps of estimating the region’s transportation choices are:

  • How many trips and for what purpose do each household produce?
  • What are their destination choices?
  • What mode of travel do they use for each trip?
  • What is the route they take for each trip?

The regional model is used to make objective, judicious and informed decisions on transportation infrastructure investments. In addition, the model provides a platform to assess future transportation issues, to identify potential solutions, and to evaluate the efficiency of such solutions.

More specifically, the Thurston region uses the regional travel demand model to support programs like:

  • Major transportation system investment studies and funding applications
  • Regional land use and transportation policy evaluation
  • Regional transportation planning
  • State Commute Trip Reduction (CTR) law
  • Traffic impact studies
  • Travel Demand Management (TDM)
  • Air quality analyses

How the Model is Used in Transportation Planning

Identifying a unified transportation vision for the region involves coordinated planning effort with regional partners. Usually, this planning process leads to exploring transportation issues and opportunities, and evaluating the alternative options to achieve that unified transportation vision.

Travel demand models play an important role in this planning process. They provide an objective and unbiased approach to look at the transportation system and help policy-makers, planners, and engineers make informed transportation investment decisions.