Below are some questions frequently asked by subregions and local
WHAT’S THE INTENDED USE OF SPM FOR SCAG AND FOR LOCAL
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
We intend to use SPM as:
A spatial data portal to provide local jurisdictions with
free access to SCAG’s spatial data resources
A platform to share, review, update, and disseminate data
between SCAG and local jurisdictions while maintaining data
consistency and integrity
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
A conduit to key SCAG models which will be used for the
analysis of plan performances by providing accurate local
WHAT ARE CAVEATS OF SPM?
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:
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.
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.
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
WHAT WOULD SCAG EXPECT FROM LOCAL JURISDICTIONS?
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.
WHAT GEOGRAPHIC LEVEL WILL SCAG SPM USE? AND WHAT LEVEL WILL
LOCAL JURISDICTIONS NEED TO WORK WITH TO REVIEW AND UPDATE?
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.
HOW WOULD SCAG SPM ENSURE THAT THE INTEGRITY OF INFORMATION THAT
LOCAL JURISDICTIONS PROVIDE IS MAINTAINED?
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.