Curt:
I hope my jumping in here doesn’t cross with similar responses
from others. I am on the CTPP subcommittee putting together this set of “business
rules,” aka “software requirements.”
What Census will need from MPOs, DOTs, and any consultants
working in their behalf, is which Census 2010 blocks belong in which TAZs –
hence the correspondence table. Any who want CTPP data for their TAZs
will need to delineate them, but it may be that not every MPO wishes to
delineate TAZs for the CTPP dataset, so that is optional. Some MPOs/DOTs
may want to continue to use the same TAZs they had in 2000, and that would be
fine too.
The reference to 600 minimum is there because TAZs with fewer
residents or workers may be subject to a margin of error that is large enough
to be of concern. This will simply be a guideline rather than a minimum
allowed, because many TAZs need to be small in order to meet local modeling
needs. About half of all TAZs nationwide are actually below 600 in
size. Employment center TAZs may have few or no residents (here in
Olympia, the State Capitol Campus has thousands of workers but only one
residence), and residential neighborhood TAZs may have few or no workers.
That is how it should be for modeling purposes. You will be able to
define TAZs to meet your needs.
The software will be very similar to PSAP. There will be
some added capabilities, such as the ability to import your own datasets
connected to the geography – e.g., if you have current employment
estimates by TAZ to substitute for 2000 vintage ones. Unlike PSAP, the
software will limit us to using aggregations of 2010 Census blocks to form
TAZs. If I remember correctly, PSAP allowed creating boundaries for Census
Designated Places that didn’t necessarily follow the firm rules that
govern Census Blocks (i.e., must be able to see it on the ground, such as
streets, rivers, power lines, etc.). I don’t remember if PSAP
allowed other examples of varying from Census Blocks, since I tried to create a
set of proposed Tract and Block Group boundaries that would avoid raising
issues at Census.
Pete Swensson, Senior Planner
Thurston Regional Planning Council
2424 Heritage Ct. SW
Olympia, WA 98502
(360) 741-2530 (direct line)
(360) 956-7575 (main desk)
(360) 956-7815 (fax)
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From:
ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On
Behalf Of Curt Hutchings
Sent: Thursday, December 03, 2009 12:19 PM
To: ctpp-news@chrispy.net
Subject: [CTPP] RE: Memo to Census Bureau regarding delineation
businessrules
Penelope,
Thank you for the opportunity to comment on the draft
rules.
Section I. Purpose seems to
be contradictory to Section III. TAZ in that Section I. says “In support of the Census Transportation
Planning Products (CTPP) the U.S. DOT and the U.S. Census Bureau will obtain census 2010 block equivalencies for Traffic
Analysis Zones (TAZs) from Metropolitan Planning Organizations (MPOs)
and State Departments of Transportation in 2011.” While
Section III. says in the second paragraph under ‘B’ that “MPOs are not required to define
TAZs;…”
Also,
We at the Dixie MPO in the St. George Utah area have used the
services of consultants to help us with modeling and most recently with TAZ
delineation. As others have mentioned the draft states that there is a
guideline minimum of 600 resident worker population. Though it is a
guideline it may be somewhat difficult for us to adhere to because we have such
a large population of ‘Seniors’ that have moved to the area to
retire. Therefore a large tract or development catering to
‘Seniors’ may actually have very few resident workers.
I participated in a similar process with PSAP a few months
ago. Will this process be similar and what is the best way to tie both
processes together?
Thanks,
From:
ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On
Behalf Of Weinberger, Penelope
Sent: Wednesday, December 02, 2009 12:28 PM
To: ctpp-news@chrispy.net
Subject: [CTPP] Memo to Census Bureau regarding delineation business
rules
Hi
All,
The
Census Bureau asked us to refine this document to help them with their software
development effort. There was a three step process and this is step
two. Step three will be the formal version of the attached memo, due to
Census Bureau in early 2010. At this time we are seeking input on this
memo for the formal version. Please reply directly to me with your
comments.
Please
reply by January 8th, 2010
Thanks!
Penelope
Weinberger
CTPP
Program Manager
AASHTO
202-624-3556
http://ctpp.transportation.org/home/default.htm
It's
just as bad to not make a plan as to blindly follow the one you already have.