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
and its RFQ for consultant support for model development.
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:
- What is the future travel demand between the TRPC region and the PSRC region to the north, and what are the resultant impacts both on the TRPC region as a whole and on key facilities such as I-5? A corollary question is: how will the presence and growth of Joint Base Lewis-McChord (JBLM) affect these travel patterns?
- How can the TRPC region absorb its projected future growth and provide good transport services while achieving its environmental and land use goals? The latter, for example, include a policy of capping arterial cross-sections at four travel lanes plus a center left turn lane.
- What specific strategies for managing demand and maximizing system efficiency (e.g. congestion pricing, managed lanes, and increased vanpooling.) would be effective for the TRPC region given its goals and values?
What are likely daily congestion patterns across all modes as the region grows?
- How can the region's particular transit services best respond to future growth in light of regional goals and values?
- Where and how will freight be moving within, into, and out of the TRPC region?
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).
- Highest TRPC Priorities
- Meaningfully modeling interregional travel to and from the Puget Sound Regional Council planning area on the north, especially along I-5.
- Incorporating sensitivity to managed lane, priced managed lane, and general congestion pricing strategies.
- Identifying survey techniques or ways to appropriately borrow and apply existing surveys (e.g. the PSRC 2006 household travel survey) to TRPC needs, especially the interregional travel analysis.
- Better modeling of peak spreading and other congestion responses.
- Other TRPC Priorities
- Better treatment of transit in general but especially of carpooling and vanpooling, and the use by those modes of park-and-ride (PNR) facilities.
- Deciding how best to model bicycle and walk access to transit, and how to efficiently obtain transit data necessary for routine model calibration and base year updates.
- Expanding the existing TRPC Dynamic Traffic Assignment (DTA) model spatial coverage to key additional subareas as well as enhancing the existing model with the necessary detail in several strategic corridors within the existing spatial boundary, and setting up the most efficient relationships and data exchanges between the DTA and travel demand models.
- Deciding how and in what model (demand or DTA) to capture responses to detailed network/operational strategies such as two way left turn lanes, auxiliary lanes, and hard shoulder running.
- Better modeling of regional freight movements, particularly existing and emerging freight distribution centers within the region.
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:
- Update Model Structure (June 2012 - December 2012)
- Revise current internal TAZ structure to accommodate zonal refinements
- Expand model boundary to the north up to SR512: Add zones and network detail
- Revise network attributes: lanes, speeds and capacities
- Transit network: add walk and bike access, auto access, park and ride lots, and review transit routes
- Refresh existing screenlines
- Revise trip distribution criteria of current truck model and external model
- Develop a new district system for model validation
- Data Collection and Analysis (June 2012 - January 2013)
- Design and administer a new household travel survey
- Form a regionwide database of traffic counts
- Obtain transit ridership data from Intercity Transit
- 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.
- Model Calibration and Forecasts (January 2013 - December 2013)
- Estimate new model coefficients in all stages of the model
- Move from current peak hour trip assignments to peak period modeling
- Update external trip distribution models using recent Origin & Destination data
- Work with the Puget Sound Regional Council to develop interregional trip tables for consistency in the two models
- Conduct base year model validation
- Develop 2040 forecast year model
- Develop 2010 and 2017 DTA Models (August 2013 - January 2014)
- Identify priority corridors for which the DTA model will be built
- Refine the model network on priority corridors: add intersection geometry, traffic control, and signal timing data
- Calibrate the DTA model assignments on priority corridors using travel time, speed, and intersection queue data.
TRPC. Travel Model Improvement Program (TMIP) Peer Review Meeting--Review of Proposed TRPC Model Improvements. Presentation for the Peer Review. June 11, 2012
 REQUEST FOR QUALIFICATIONS #2 - TRAVEL DEMAND MODEL CONSULTANT Thurston Regional Planning Council (TRPC) Travel Demand Model Enhancements April, 2012
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.