The Atlanta Regional Commission Travel Demand Model is a technical tool to assist in the development of the Regional Transportation Plan (RTP) and the policy decision making process. The Travel Demand Model utilizes a traditional four-step trip-based model process consisting of trip generation, trip distribution, mode choice and trip assignment for the 20-county non-attainment area.
Visualization examples of the ARC Regional Travel Demand Model, Activity-Based Model, Survey Data, TRANSIMS Model, and VISSIM Model Applications can be found at the ARC Modeling Youtube Channel.
Other Modeling Activities
Beginning in 2010, a dual-track method will be utilized to maintain the four step trip-based model and the implementation of an Activity-Based Model process based on CT-RAMP (Coordinated Travel Regional Activity-Based Modeling Platform). The CT-RAMP Activity-Based model addresses both household-level and person-level travel choices including intra-household interactions between household members, as compared to other more simplified Activity-Based Models where all travel choices are modeled at the person level, independently of choices made by other household members within the household. The Activity-Based Model reflects and responds to detailed demographic information, including household structure, aging, income changes, and other key attributes.
Learn more about the ARC Activity-Based Model and CT-RAMP:
Population Synthesizer (PopSyn)
A population synthesizer was developed to enable proper demographic inputs and land use information into the travel demand model. Through the use of census data and land use model outputs, a detailed synthetic population was developed. A record for each household in the region and a record for each person in the household are included.
Production Exchange Consumption Allocation System (PECAS)
Work is currently underway in the development of the Atlanta region’s population and employment forecast model utilizing PECAS.
Emissions modeling is a requirement of the Clean Air Act in regions in nonattainment for certain human-health impacting compounds, such as ozone and fine particulate matter. Running and non-running mobile source emission inventories are developed with the help of a travel-demand model. Vehicle miles traveled (VMT) estimates from a travel demand model are combined with emission factors from an air quality model to calculate the total transportation sector contribution of pollutants into the atmosphere.
The Atlanta region is currently in nonattainment for both ozone and fine particulates. The maintenance and continued improvement of the regional travel demand model is important for the transportation conformity process.
Peer reviews have been conducted to assess the state of the ARC travel demand model and appropriate modeling practices.