The Triangle Regional Model (TRM) is a state of the practice regional transportation planning model, also known as a regional travel demand model. The TRM is developed and maintained by the Triangle Regional Model Service Bureau (TRMSB) within the Systems Planning and Analysis Group at ITRE and four stakeholder sponsors: NC Department of Transportation, Durham-Chapel Hill-Carrboro Metropolitan Planning Organization, Capital Area Metropolitan Planning Organization, and GoTriangle. In addition to ITRE TRMSB team members, travel modelers from the sponsoring agencies also support work activities related to the TRM. Together this group forms the TRM Team.

Official Model Triangle Regional Model

The current official model is the TRMv6 2045 MTP 2nd Amendment.

Requests for the official model to support work conducted for one of the TRM sponsoring agencies can be made by sending an email request to
TRM v6 Technical Documentation
TRM v6 User Guide

What is it?

A transportation planning model is a series of mathematical equations that represent the transportation system and the travel choices that people make as they participate in activities. The transportation system is represented by roadway and transit networks. The TRM includes all major roads in the region and transit services provided by Chapel Hill Transit, Duke Transit, Go Cary, Go Durham, Go Raleigh, Go Triangle, and Wolfline.

In addition to transportation supply, travel choices are also influenced by demographic and land activity data within each transportation analysis zone (TAZ). A TAZ is a geographic unit similar to a Census Block, though often bigger than a Census Block and smaller than a Census Block Group. The TAZs for the TRM cover all of Wake, Durham and Orange counties, and portions of Chatham, Franklin, Granville, Harnett, Johnston, Nash, and Person counties. This area covers 3,379 square miles, including all or part of 40 jurisdictions. The area is divided into 2,857 TAZs , that include a total of 1,040,972 jobs and 1,997,445 people (2020). For a detailed exploration of our demographic and land use data, please see our data dashboard . The modeled transportation system includes 5,640 miles of roadway and 215 transit routes operated by 7 transit systems and encompassing 60,000 service miles.

The travel demand resulting from travel choices is developed using a series of mathematical models that capture choices related to the number and types of trips people make, the mode they use to travel, the choice of destination, and the highway or transit routes used to reach that destination.

The TRM is the principal analytical tool used by transportation agencies in our region to develop and evaluate transportation strategies that support the mobility, accessibility, economic health and quality of life for the Triangle region.

Training and Outreach

TRM User Forum

The TRMSB administers a TRM User Forum intended to create a space where model users (consultants and agency staff) can share ideas and views related to the TRM. The benefits of a TRM Users Forum include:

  • Improved customer service between the TRMSB and member agencies and/or the consultants that support their work program.
  • Increased trust through enhanced transparency by providing a platform where members can share constructive suggestions and praise.
  • Increased TRMSB program success through knowledge sharing and identification of resolutions to common problems.
  • Driving model enhancement ideation though an open discussion of big ideas, next best things, and improved model features or capabilities.
  • Removing barriers between the TRMSB and end users by providing a stronger presence in the Triangle modeling community.

The format of the User Forum varies from meeting to meeting, and may include elements such as panel discussions, lightning round presentations on modeling topics, a focused presentation around a small number of recent TRM applications along with lessons learned and suggested improvements, or a facilitated conversation around a specific question or topic.

To be added to the list of invitees, please send an email to

Scheduled Training

There is currently no TRM related training scheduled. The development of the second generation of the TRM (TRMG2) is underway. Training opportunities for TRMG2 will be provided once this model becomes the official model for the region.

TRM Data Tools and Analytics

The TRM Team uses available data and tools to describe travel and travel metrics in the Triangle region in a way that provides useful insights for informing the public and transportation planners, guiding future actions, or informing future decisions. This work may result in interactive data visualizations that are posted to the TRM Data Dashboard or in graphics driven fact sheets that are shared with sponsoring partners and the public through the TRM website.

Fact Sheets

Interactive Visualizations

TRM Data Dashboard
TRM VMT and Delay Metrics

Innovations and Investigations

Being housed within a university research center provides a unique opportunity to leverage the TRM as a laboratory for model innovations intended to improve existing model components or processes, and model investigations intended to provide insight into future model enhancements.

Current Innovations

The TRM Team is currently working to develop a tighter integration between the TRM and CommunityViz, the model used to allocate future land use for the TRM. The expected products from this effort are recommendations and procedures for using CommunityViz place types and regions to inform the development of key demographic variables related to household size, income and workers, and a streamlined process for converting CommunityViz outputs to TRM inputs.

Current Investigations

Emerging Issues

Travel demand models are important analytical tools that support the planning programs for MPOs, DOTs, and transit agencies, but as a macroscopic model they have limited utility for understanding the dynamics of traffic assignment and the associated performance measures, for example bottlenecks, queuing, and operational vs. planning level capacity. To overcome this limitation, many agencies are exploring the integration of microscopic models, such as TransModeler, with their macroscopic models, such as TransCAD, to improve their analytical power.

The TRM Team is currently investigating the benefits and challenges of an integrated system for macroscopic and microscopic models in the Triangle. This investigation includes conversations with peer agencies, conversations with model providers, and the identification of data and resource needs. The expected product from this effort is a draft action plan for the possible development of a mesoscopic or microscopic model for the Triangle region. A microscopic model simulates the movement of individual vehicles based on the principles of traffic flow theory. A mesoscopic model is one that includes properties of both macroscopic and microscopic models.


The increased demand for home deliveries for all types of goods and services is increasing the freight and commercial vehicle traffic on our transportation system in ways that we may not have previously expected. While the TRMG2 will reflect an improvement in the way trucks and commercial vehicles are modeled, there is still room for improvement. The TRM Team is working with professors and students from NC State to research and propose an enhanced freight component that could be considered for future inclusion in the TRM. Inasmuch as Automated Vehicles (AV) may prove to be part of the solution identified, the incorporation of AVs into the TRMG2 environment will be part of this research. Expected products from this effort include a literature review, assessment of possible enhancements to the TRMG2, and research findings.


Leta Huntsinger, Ph.D, P.E.
919-515-8625 |