Subregional Modeling

Subregional Modeling Thumbnail Image
Primary Purpose

The goal of the Subregional Modeling Program is to provide modeling support and services to SCAG member agencies, transportation commissions, subregions, and Caltrans. SCAG recently developed the Subregional Modeling Tool (SMT) to enhance modeling support to member agencies. The new Tool streamlines the development of models for agencies wishing to create subregional models based on SCAG’s Regional Transportation Model. The new SMT promotes model consistency between the Region’s various modeling agencies and greatly reduces the cost and effort required to create subregional models.

About Subregional Modeling Tool

The resulting model provides subregions a consistent tool to evaluate their plans and to provide SCAG input into the RTP process based on a common set of assumptions and analytical methods. Currently three subregional models were built using the Subregional Modeling Tool including:

  • North Los AngHeading 5eles Model
  • San Bernardino County Model
  • Imperial County Model

In addition, several city level models and corridor studies were developed using the SMT.


The SMT fully automates the development of all aspects of a subregional model and includes the following features:

  • User friendly model interface;
  • Automated routines for assisting model developers to create new sub-area models;
  • Sub-routines to automatically create key model inputs; and
  • The model interface allows the modeler to run only the needed portion of the modeling code, which significantly reduces model run times.


The Subregional Modeling Tool is built directly on top of SCAG’s Regional Model’s computer code. The SMT uses the same basic model components as the Regional Model, with custom sub-routines to automate the development of the subregional model inputs. This ensures that model methods and results are consistent. In addition, the common model and data structure encourages sharing of model input data between agencies.

Documents & Resources

Final Report for the SCAG Subregional Model in TransCAD 5.0
​User’s Guide for the SCAG Subregional Planning Model in TransCAD 6.0