TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference

Developing And Updating A Subregional Model Tool For The Southern California Association Of Governments

Corresponding Author: hao cheng, Southern California Association of Governments

Presented By: Jim Lam, Caliper Corporation


The Southern California Association of Governments (SCAG) Regional Travel Demand Model is a large model encompassing almost 12,000 zones and over 100,000 network links. Many smaller subregions within the SCAG modeling area have a desire to develop smaller subregional focused models. The work of creating focused models and datasets for subregions is typically labor intensive and can be costly, especially when model integration and calibration/validation issues are taken into account, and is multiplied by the number of subregion models. This presentation details the development and application of a Subregional Model Development Tool for SCAG that automates the creation and modeling of focused subarea models. The objectives of the tool were to dramatically decrease the time and effort required to develop sub-regional models, and to standardize these models within the SCAG region.

The tool uses Regional Model datasets as a starting point, along with additional inputs such as highly detailed TAZ definitions for all subregions, detailed demographics, and detailed networks within the subregion. The user interactively chooses the subregion area by city, county, or other designation. The tool uses these inputs to automatically create focused TAZ, network, and auxiliary model datasets that are extracted from Regional Model inputs and outputs. These datasets provide the necessary detail within the subregion but also aggregate outside of the subregion to both improve model run times. To maintain consistency with the Regional Model, model outputs and flows that are outside and not connected to the subregion are directly used from the Regional Model once aggregated.

The tool was applied to various areas in the SCAG region, including San Bernardino, Riverside, Imperial, and Ventura Counties. This presentation details the development and application of the tool and the issues encountered during application.


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