COG/TPB staff, working with consultant assistance, develop, maintain, apply, and improve the TPB’s family of regional travel demand forecasting models, which are used for regional, long-range transportation planning in the metropolitan Washington region. In 2018, COG/TPB staff set out to develop a next-generation travel demand model. The project team, consisting of RSG and Baseline Mobility Group, recommended that COG transition from its current aggregate, trip-based travel demand model (i.e., Gen2 Model) to a simplified activity-based model (ABM) implemented in the open-source ActivitySim software platform. The new ABM would be known as the Generation 3, or Gen3, Travel Model. Development of the
ActivitySim software is governed by the ActivitySim
consortium.
The development of the Gen3 Model was divided into two phases. Phase 1 development, which was completed in February 2022, created a prototype model that can be tested by the COG/TPB staff. The ongoing Phase 2 development aims to implement a production-use model that can be used for regional planning work, such as the air quality conformity analysis, by the end of CY 2023. The purpose of this phased approach to model development is to use the initial deployment and calibration efforts to inform the scope of final model development and calibration/validation tasks, rather than scope the entire model development project at the project initiation. This allows the project team to learn from the initial deployment and prioritize resource allocation in Phase 2, to ensure that the final delivered Gen3 Model meets the needs of COG/TPB, partner agencies, and decision-makers.
Tasks completed in Phase 1 included deployment of a population synthesizer and creation of base-year and future-year synthetic populations, coding and expansion of household travel survey data, implementation of ActivitySim with MWCOG population, land-use data, and level-of-service skims and integration with Bentley Cube software, estimation of key model components including tour mode choice, mandatory tour destination location choice, and non-mandatory tour destination choice, model calibration and validation, and sensitivity testing. A range of documents have been created by the project team to document the various Phase 1 work activities.
The development of Gen3, Phase 1, Model is considered a milestone during this significant model development effort that will last over three years. As noted on COG’s
Data Requests webpage, “It is against staff policy to transmit developmental travel models or land activity forecasts since these have generally not been thoroughly vetted by staff and are not considered finished products.” However, given the relatively long development time, the project team decided to share the main documents of the Gen3, Phase 1, Model, at the end of this webpage, for the following two purposes:
1. To facilitate the engagement of regional stakeholders in the learning, testing and future applications of the Gen3 Model in support of various regional transportation planning activities.
2. To solicit the scrutiny of the ongoing Gen3 Model development in the regional community of travel model users.
As noted above, it is against COG/TPB staff policy to distribute developmental models, including the Gen3, Phase 1, Model, despite the sharing of the Gen3, Phase 1, Model documentation. It should also be noted that COG/TPB staff may not have the time and resources to provide clarifications or other “help desk” services on the shared documentation because they are developmental in nature.
Gen3, Phase 1, Model Documentation
RSG. Gen3 Data Development. Washington, D.C.: Metropolitan Washington Council of Governments, National Capital Region Transportation Planning Board, December 29, 2021
Gen3, Phase 2, Model Documentation
Page updated 6/6/2024.