Ms. Muradami just mentioned the TAZ population thresholds, which got me thinking.

My MPO (Metroplan in Little Rock) just had a meeting yesterday in which the subject of TAZs for the approaching 2010 CTPP came up. I told the group that, to the best of my memory (based on a conversation with Nanda Srinivasan a couple of years ago), a TAZ for future CTPPs could have a minimum of 1,000, either in total population OR total employment. Your statement that the preferred population for a TAZ should be "at least 1,200" partially contradicted this. But I may have remembered wrongly. Could you please clarify what a good standard would be for TAZ's? Can employment be used as a minimum instead? Would anyone else like to comment on TAZ sizes?

Jonathan Lupton
Metroplan
501-372-3300




Murakami, Elaine wrote:
We are planning to have 5-year ACS data accumulated for small area
tabulation.  "Small area" means census tracts, or TAZs, as defined by
MPOs.  We are planning that this would be 2006 thru 2010 ACS data, so
that 2010 Census geography and sample weighting adjustments can be
incorporated.  This data would be available approximately 2012.  

To summarize: 
Base TAZs  (Census would prefer at least 1,200 population)
Medium TAZs -- at least 20,000 population
Large TAZs -- at least 65,000 population

The Medium and Large TAZs would be used for annual and 3-year ACS
tabulations.  The Base TAZs require 5 years of ACS data. 

Elaine Murakami
FHWA Office of Planning
206-220-4460 

-----Original Message-----
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Bill Moore
Sent: Thursday, June 12, 2008 11:21 AM
To: 'ctpp-news@chrispy.net'
Subject: RE: [CTPP] CTPP Update

Ed:

>From a small (~135,000 pop) MPO perspective, the implications of these
super-TAZs for travel demand modeling are devastating.  If 65K, we would
have two TAZs; if 20K, we would have six or seven.  Fortunately, we are
also an attainment area and are not mandated to do modeling at all;
however a new TMA with population of 200,000 would be so mandated and
would have a total of three or 10, respectively, so it would become
virtually impossible to do modeling for AQ conformity.

The four MPOs (howdy, Larry) along the Front Range are trying to develop
an integrated model for a population of ~3.5 million, so at 65K would
have only 54 TAZs, or at 20K only 175.  The latter number is far less
than we now have (306) in the Pueblo MPO - the smallest of the four.

Bill Moore, MPO Administrator
PACOG MPO/TPR


-----Original Message-----
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net]On Behalf Of Ed Christopher
Sent: Wednesday, June 11, 2008 3:33 PM
To: ctpp-news@chrispy.net
Subject: Re: [CTPP] CTPP Update


Larry--Yes, when we creat 20,000 and 65,000 TAZs our goal is to get
tablulations for these areas.  Or course the DRB would have to approve
any tables.  The current problem with the ACS 1 and 3-year data (due out
at the end of the year) that the Census releases is that your data
coverage in like swiss cheese.  You get data for some areas and not
others.  Our plan is to have complete coverage to eliminate this problem
with any tables paid for with CTPP dollars. Who knows maybe we can get
the Census Bureau to see the light and adopt the concept of having zonal
coverage consistent with the data release thresholds for their data
products as well.

Larry Mugler wrote:
  
If we create "super" tazs with populations of 20,000 and/or 65,000,
would we be able to get tabulations for such areas?

Larry G. Mugler, AICP - Planning Services Manager
303-480-6759 - Customer Resource and Support
Denver Regional Council of Governments

-----Original Message-----
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Murakami, Elaine
Sent: Wednesday, June 11, 2008 12:43 PM
To: ctpp-news@chrispy.net
Subject: RE: [CTPP] CTPP Update

Re:  poverty and Income comparisons between Census 2000 Long Form and
ACS:
The only report I am familiar with is:
http://www.census.gov/acs/www/Downloads/Report05.pdf
Pages 34-37 discuss county-level comparisons.  These are comparisons
between the Census 2000 Long Form (aka sample) and the ACS "C2SS", and
18 of the test ACS counties.  They found that the C2SS results
consistently had lower incomes than the Census 2000 sample, and
therefore, a higher poverty ratio.   They found that income allocation
occurs 30 percent in the Census 2000 sample, and 24% in the C2SS.

I do not know if the Census Bureau has pursued other research on how
    
ACS
  
respondents answer the income questions.

Elaine

-----Original Message-----
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Ed Christopher
Sent: Wednesday, June 11, 2008 9:50 AM
To: ctpp-news maillist
Subject: [CTPP] CTPP Update

On May 21 and June 4 members of the CTPP team conducted a series of
webinars to help bring our community up-to-speed on several of the
    
CTPP
  
activities.  The slides from these presentations can be downloaded
    
from
  
our webinar room at http://fhwa.acrobat.com/ctpp1 (enter as a guest)
    
and
  
the responses to many of the questions asked during the meetings are
presented below.  If folks have additional questions please feel free
    
to
  
post them to the list serve and someone on the CTPP team will attempt
    
to
  
answer them.

CTPP Webinar - Questions and Answers

Question: Will the 3-year CTPP data product based on ACS include
    
tables
  
by race and household income?
Response:  Yes but the best source for information on race will still
    
be
  
the Census Bureau's standard ACS tabulations found on American
FactFinder (http://factfinder.census.gov/).  The 3-year CTPP proposed
tables for parts 1 and 2 include a few tables with the variable
"minority status." Also, there are various tables with the variables -
Income, Poverty Status and Worker Earnings that will be available.
Please note that Poverty Status is a calculated variable based on
household income, family size, number of children and number of family
members over the age of 65.

Question: Since the new CTPP products will be based on data collected
over 3 years (or 5 years), to which year will the income be adjusted?
Response:  Income will be adjusted to the last year of the survey
period.   For the first 3-year product all incomes will adjusted to
2007.

Question: Is there data available on zero car households? If yes, what
geography level is it available?
Response:  Yes, there will be information available for zero car
households in both the 3-year CTPP data product and as part of the
standard Census products.  The data will be available for geographic
areas greater than 20,000 residents.

Question: Slides 6 & 7 of the DRB presentation show different
percentages of data lost due to DRB rules, why is that?
Response:  Slide 6 showed the number of workers lost while slide 7
showed the number of origin-destination pairs lost.  The point is that
when thresholds were applied to CTPP Part 3 data as was the case with
the 2000 data, many folks looked at the loss of workers as being
significant but more surprising was actual loss of individual O-D
pairs.  All in all table thresholds devastated the part 3 flow data.

Question: 2005 ACS data doesn't have information on Group Quarters,
    
but
  
the 2006 and 2007 do.  How is this being handled in the 3-year 2007
    
ACS
  
products?
Response:  The Group Quarter data available for 2 years (2006 and
    
2007)
  
will be reweighed to account for the missing year.

Question: Will the variable - Means of Transportation to Work have
    
walk
  
and bike modes combined? Also, what about taxi, bus and other?
Response:  Regarding the 3-year CTPP data product there are multiple
category lists for the variable - Means of Transportation to Work.
There are a few tables all 17 modes plus the total are shown
    
separately
  
but then there are many others where walk and bike have been collapsed
together.  A great deal of the detail on the mode variable is in the
hands of the Census Bureau's disclosure Review Board.  Currently they
have proposed some very tight restrictions on the proposed 3-year CTPP
tables.  Please see http://trbcensus.com/drb/ for more

Question: Do you have anything on the TAZ definition timeframe that
    
you
  
can share with the group?
Response:  Please see our Status Report newsletter for the latest
http://www.TRBcensus.com/newsltr/sr052008.pdf.

Question: Can you talk about the difference in income between ACS and
Long Form?
Response:  In Census 2000, the question was asked during April for the
previous year, 1999.  Because April is so close to IRS annual return
data it was felt that "good" income data was being collected because
    
it
  
was fresh in people's minds.  However, for the ACS the same questions
are asked, but the respondent could be getting the survey during any
month of year (depending on when she/he received the form).  This
reported income is then adjusted to the current year (year of
tabulation) based on CPI.  There are several issues with this with the
largest being that at anytime during the year most people do not how
much money they made in the last 12 months.  Needless to say the
    
income
  
question is messy.

Question: Poverty rates seem discontinuous, higher. Any ideas why?
Response:  Yes, they are discontinuous.  Hopefully they will look
    
better
  
with the 3-year ACS data products.

Question: If the DRB is so strict with its rules then why bother with
new TAZs?
Response:  We hope that the DRB will relax its rules but having TAZs
that correspond to the ACS data release products (65,000 pop TAZs,
20,000 pop TAZs and small TAZs) will help us in the future all sorts
    
of
  
data products.  Having geography match the data release seems to make
good sense so that we can at least get complete coverage
    
(wall-to-wall)
  
within a region.

Question: What are the implications of rising fuel prices on travel
choices on mode to work?  Has anybody thought about it, especially
    
with
  
aggregating 3 years worth of data?  Since the ACS asks about "usual"
mode, it could still miss modes used only part of the time.
Response:  The 3 year ACS trend data might look a lot different than
    
the
  
2000 data. This might be a good research question.

Question: Is the category list for the variable - occupation being
consolidated?
Response:  No, DRB has not asked us to collapse the variables -
    
industry
  
or occupation.

Question: Is anybody planning to write to Congress about the DRB
    
issue?
  
Response: AASHTO SCOP is sending a letter to the Census Bureau to
    
appeal
  
the DRB decision.  As FHWA staff, we cannot contact Congress directly
but we know that many regional agencies do talk with their
    
Congressional
  
delegations.  It is somewhat ironic but many of the congressionally
mandated analysis like the FTA New Starts program and environmental
justice analysis all need data at a smaller geography level which will
be difficult to obtain with the DRB's current rules.
Question: We are relatively a new MPO and I have a CTPP 101 question.
As an MPO do we need to provide you any information, and what are our
sources of information regarding CTPP specifically regarding TAZs?
Response: The CTPP listserve is a good place for information regarding
ongoing CTPP related activities. The TAZ definition process is planned
for March/April of 2009 and it is recommended that MPO's allocate some
budget when preparing their work plans for FY 2009, especially for new
MPOs. The CTPP Status Report is also a good source of information.  If
you have any particular questions please do not hesitate to contact
anyone one of us on the CTPP team.

Question:  Somewhere it was noted the first CTPP ACS product would be
available in 2009 for areas of 20,000 or more for places and counties.
Response: Yes that is correct.  We are still in the negotiation stage
regarding some DRB issues but this is our GOAL.  This first CTPP
    
product
  
would use 3 years of ACS
data.

Question:  There was also a mention of TAZ level data also for 20,000
population threshold.  However, I am not sure if this is included in
    
the
  
first 3 year product for 2009, or whether the first TAZ level report
will not be available until 2012 with a 5 year product.
Response: To get "small" area geography like a TAZ or a census tract,
the census requires 5 years of ACS data. So, we are planning to wait
    
for
  
2006 thru 2010 ACS data to incorporate 2010 Census geography and
weights, which we hope would be tabulated by 2012.   This will likely
require some data synthesis before release.  Because of the
    
probability
  
that the data will be synthetic, we do not anticipate any population
threshold.

--
Ed Christopher
Resource Center Planning Team
Federal Highway Administration
19900 Governors Drive
Olympia Fields, Illinois  60461
708-283-3534 (V)  708-574-8131 (cell)
708-283-3501 (F)

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--
Ed Christopher
Resource Center Planning Team
Federal Highway Administration
19900 Governors Drive
Olympia Fields, Illinois  60461
708-283-3534 (V)  708-574-8131 (cell)
708-283-3501 (F)
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