Transportation Models

Transportation Model

SCAG develops and maintains state-of-the-art transportation models to support SCAG’s planning program. These models include:



These models are applied by SCAG to forecast transportation conditions and resulting air quality.

Trip-Based Model (Existing Travel Demand Model)

The Regional Travel Demand Model provides travel forecasting capabilities for the analysis of SCAG’s plans and programs. The trip-based model was Peer Reviewed in May 2011 and found consistent with the state-of-the-practice.

Activity-Based Model

The Activity-Based Model (ABM) is a new generation of travel demand model. The AMB simulates daily activities and travel patterns of all individuals in the region, as affected by transportation system level of service. This new modeling system is designed to meet or exceed federal regulations and state laws/requirements.

Subregional Modeling Tool

The new Subregional Modeling Tool (SMT) greatly simplifies the creation of subregional models. The SMT fully automates the development of all aspects of a subregional model. The Tool is used by transportation commissions, counties, subregions, and cities wishing to create subregional models based on SCAG’s new Regional Model. The new Tool promotes model consistency between the Region’s various model agencies and greatly reduces the cost and effort required to create subregional models.

Heavy-Duty Truck Model

Southern California Association of Governments (SCAG) developed the Heavy Duty Truck (HDT) model to evaluate important policy choices and investment decisions. The HDT model is a primary analysis tool to support the goods movement policy decisions made by SCAG and regional stakeholders.

Air Quality Model

EMFAC2007 is an emission factors model developed by the Air Resources Board (ARB) for calculating emission inventories for vehicles in California. This is the emission model approved by the Environmental Protection Agency (EPA) for calculating vehicle emissions for conformity purposes in California.