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Thurston Regional Planning Council (TRPC) Travel Model Peer Review Report

4.0 TRPC Model Improvement Plan

TRPC has a clear vision for the functions needed in its updated travel model. This section describes the draft TRPC work plan for acquiring the necessary data and carrying out the model updates. Much of this section of the report is taken from the TRPC presentation to the review panel[3] and its RFQ for consultant support for model development.[4]

4.1 Thurston Regional Planning Council Priorities for Model

TRPC has been careful to link its modeling needs to its planning business needs. Its vision is to create a model that both addresses its fundamental planning mandates (e.g. long range plan update analysis, and air quality conformity determination) and helps to answer the following major planning questions:

In light of these key planning issues TRPC staff proposed a list of topics for the panel to consider with the understanding that while the agency is fortunate to have model development resources they are finite. The peers' understanding of that list's priorities (below) framed their discussion and structured their suggestions (the latter appear in Sections 6 and 7 below).

4.2 Summary of Model Update and Data Acquisition Plan

TRPC tentatively plans to execute its overall model update in four main phases, each of which consists of several tasks. TRPC proposes to support these model updates with a comprehensive data collection effort. The centerpiece of new data will be a new household travel survey to be conducted in the fall of 2012. The plan, including data collection, can be summarized as follows:[5]

  1. Update Model Structure (June 2012 - December 2012)
    1. Revise current internal TAZ structure to accommodate zonal refinements
    2. Expand model boundary to the north up to SR512: Add zones and network detail
    3. Revise network attributes: lanes, speeds and capacities
    4. Transit network: add walk and bike access, auto access, park and ride lots, and review transit routes
    5. Refresh existing screenlines
    6. Revise trip distribution criteria of current truck model and external model
    7. Develop a new district system for model validation
  2. Data Collection and Analysis (June 2012 - January 2013)
    1. Design and administer a new household travel survey
    2. Form a regionwide database of traffic counts
    3. Obtain transit ridership data from Intercity Transit
    4. Collect additional traffic and network data such as travel times, speeds, intersection geometry, signal timing, intersection queues and other pertinent information, in key strategic traffic corridors to support detailed DTA modeling.
  3. Model Calibration and Forecasts (January 2013 - December 2013)
    1. Estimate new model coefficients in all stages of the model
    2. Move from current peak hour trip assignments to peak period modeling
    3. Update external trip distribution models using recent Origin & Destination data
    4. Work with the Puget Sound Regional Council to develop interregional trip tables for consistency in the two models
    5. Conduct base year model validation
    6. Develop 2040 forecast year model
  4. Develop 2010 and 2017 DTA Models (August 2013 - January 2014)
    1. Identify priority corridors for which the DTA model will be built
    2. Refine the model network on priority corridors: add intersection geometry, traffic control, and signal timing data
    3. Calibrate the DTA model assignments on priority corridors using travel time, speed, and intersection queue data.

[3] TRPC. Travel Model Improvement Program (TMIP) Peer Review Meeting--Review of Proposed TRPC Model Improvements. Presentation for the Peer Review. June 11, 2012

[4] REQUEST FOR QUALIFICATIONS #2 - TRAVEL DEMAND MODEL CONSULTANT Thurston Regional Planning Council (TRPC) Travel Demand Model Enhancements April, 2012

[5] TRPC. Travel Model Improvement Program (TMIP) Peer Review Meeting--Review of Proposed TRPC Model Improvements. Presentation for the Peer Review. June 11, 2012. Slides 74-77.

Updated: 3/25/2014
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