Below are some questions frequently asked by subregions and local jurisdictions:


SCAG SPM is to assist local jurisdictions in land use planning and sketch level analysis by providing easy access to spatial data resources and estimated fiscal, environmental, transportation, and public health impacts of alternative land and policy choices.

We intend to use SPM as: (1) a spatial data portal to provide local jurisdictions with free access to SCAG’s spatial data resources; (2) a platform to share, review, update, and disseminate data between SCAG and local jurisdictions while maintaining data consistency and integrity; (3) a scenario planning and visualization tool with sketch level analysis capability to assist local jurisdictions in estimating the potential benefits of future land use and policy choices; and (4) a conduit to key SCAG models which will be used for the analysis of plan performances by providing accurate local level data.

SPM estimates the magnitude of potential benefits of different future scenarios and policy assumptions using Scenario Planning Zone (SPZ, aka super parcel) as a minimum unit of analysis. That being said, caveats of SPM include:

  1. while local jurisdictions can edit at the parcel level if they choose so to create a scenario, outputs will be at the level of SPZ or higher;
  2. SPM is not to predict the future or to provide specific answers, but rather to allow consideration of alternative views of the future by estimating potential impacts;
  3. and thus SPM is to assist in policy decision making by helping decision makers to anticipate potential impacts of their choices and is not to direct or determine future policies.

We understand that the model can never be successful if it does not deliver what end users like you may need without adding extra burdens to utilize it. So what we’d expect from you first is to tell us what your expectations or needs are as we develop our model. You can do this by participating in a working group.

Once SCAG SPM is ready, we’d expect you to adopt the model by utilizing it to review and update local data and to create land use scenarios in the preparation of regional plans and further. 

SCAG SPM will use three different geographic levels depending on data type and purpose. For socioeconomic data such as population, employment, and household, SPM uses Transportation Analysis Zone (TAZ), Tier 2/3 geography for review and display. So you will be able to review your total POP, HH, and EMP at this level and make necessary changes. For land use data such as existing condition, zoning, and General Plan land use, SPM uses parcel geography to review and edit. You will be able not only to review and make changes at this level, but also to create a scenario by editing parcel level information.

Once edits occur, the edited information will be disaggregated (in case for SED) or aggregated (in case for land use) to a Scenario Planning Zone (SPZ) for analysis. For public display purpose, TAZ geography will be used for the both data types including land use scenarios. More detailed information will be released only to local jurisdictions per request.

SCAG SPM will be a web-based tool hosted on SCAG server which means that once you make changes, you can push your edits to SCAG when you are satisfied. Through user permission, data review and editing will be limited to its own jurisdictions.