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Regional Models


Models are the principal tools used for alternatives analysis, and they provide planners and decision makers with information to help them equitably allocate scarce resources.

Modeling Overview

SANDAG deals with many complex mobility issues facing the San Diego region, including the development of a long-range Regional Transportation Plan (RTP). Transportation and land use models perform a very basic yet vital set of functions. Models are the principal tools used for alternatives analysis, and they provide planners and decision makers with information to help them equitably allocate scarce resources.

SANDAG has produced forecasts of demographic and economic growth in the region since 1971. Transportation forecasting at SANDAG began in 1981. The SANDAG forecasts are used by policymakers and the general public, as well as by public and private agencies throughout the region. For example, SANDAG uses the forecasts to develop the Regional Transportation Plan (RTP), the Regional Comprehensive Plan (RCP), and the Air Quality Conformity Plan. Local jurisdictions use the forecasts for general plan updates and capital facilities planning, including environmental impact reports (EIR), as well as for local transportation planning. Other agencies, such as the San Diego County Water Authority and the San Diego Regional Energy Office, use aspects of the SANDAG forecasts to develop plans for providing these essential services.

Transportation Modeling

SANDAG completed the transition from an enhanced four-step transportation model to an activity-based model (ABM1) in 2013 and applied ABM1 in the 2015 Regional Plan. SANDAG has since completed the development of ABM2 and applied it in the 2019 Federal Regional Transportation Plan. SANDAG is currently deploying ABM2+ to support the 2021 Regional Plan, also known as the 5 Big Moves.

More information about Transportation Modeling and the Activity Based Model

Demographic, Economic, and Land Use Models

The currently adopted Regional Growth Forecast (referred to as the Series 14 Regional Growth Forecast) uses a collection of models that consists of two main components: (1) the San Diego Demographic and Economic model (SanDE), the region-wide forecasting model, and; (2) the Integrated Land Use, Demographic, and Economic Model (iLUDEM), the subregional allocation model. SANDAG continually refines and evaluates these models to incorporate updated techniques and information as necessary. The Series 14 Regional Growth Forecast was used in conjunction with ABM2+ to support the development of the 2021 Regional Plan. Outputs from the subregional allocation model were used as inputs to ABM2+ at the Master Geographic Reference Area (MGRA) level, SANDAG's custom unit of geography. A high-level overview of the modeling workflow is shown below.

More information on the Demographic, Economic, and Land Use Models

 

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