At our monthly CTPP Technical meeting last week, April
Avnayim of the Census Bureau Geography Division, gave us an update on the TAZ
delineation software schedule.
November 2010: agencies verify contact names by
reviewing file at Cambridge Systematics ftp site, and report any changes to
Liang Long.
December 2010: final delivery of software by Caliper
to CB
February 2011: web-based training coordinated with FHWA
January thru March 2011: delivery of software and Census
2010 data and geographic files on a rolling basis.
Each state will get 3 – 4 months to delineate their
TAZ and TADs and return the files to the Census Bureau.
July 2011: all files MUST be returned to CB Geography
Division.
Please note: TAZs for CTPP tabulation do not
necessarily match the TAZs for your travel demand model. Because the ACS
sample is small, some agencies are planning to make the TAZs for CTPP LARGER
than their model TAZs, e.g. combining their model TAZs together. Also, TAZs for
CTPP are census block equivalencies. You will NOT be able to modify the
TIGER segments (which was possible in the CTPP2000). Finally,
agencies are NOT required to define TAZs or TADs. If you do not define
TAZs, then census tracts will be used as the default geography for CTPP (2006-2010)
tabulation. However, even if you do not define TAZs, we recommend
that you create TADs (population threshold of 20,000) by combining census
tracts together.
The TAZ business rules are posted on the FHWA webpage: http://www.fhwa.dot.gov/ctpp/tazddbrules.htm