Thank you.

 

 

Hi Mark –

1.        The Census Bureau Geography Division will need a block equivalency file.  Perhaps the CB geo staff can answer the question of whether the TAZ Instruction will include a FILE LAYOUT for the output files.  If so, then it seems to me that you SHOULD be able to do the TAZ delineation OUTSIDE of the MTPS TAZ module software, but it would NOT be the PREFERRED method.    The software has checking features, e.g.  completeness, contiguity, etc, such that if you make your own file using the new TIGER files, it will not have the same quality control features. 

2.       What other purposes of  “Census TAZs and TADs”.  The current CTPP is funded to include the 3-year (2006-2008) tabulation and the 5-year (2006-2010) tabulation, but depending on how things go, future 3-year and/or 5-year CTPP tabulations are possible if someone wants to pay for them.  We think that the Census Bureau should have made a consistent geographic tabulation unit for the 20,000 population threshold (for the 3-year ACS), so that there could be complete coverage, instead of the “swiss cheese” coverage using counties and places, but they didn’t and haven’t.  So, this is OUR opportunity to do something about it, and maybe we can convince the CB that these units could be an ACS 3-year tabulation geography in the future.  The PUMAs (100,000 population threshold) provide a consistent geographic tabulation unit for the 1-year ACS, but how they have been defined has not always been useful to transportation planners.    As you know, PUMAs were not designed to be tabulation units, but have become tabulation geographic units in the ACS. 

3.       No one is required to define Census TAZs.  If you think that defining Census TAZs is too much work for the value you will get from CTPP, you can just say to use census tracts, or block groups for CTPP.  However, we still would recommend that you define TADs, by combining tracts, for the reason listed above.

 

Elaine

 

Is there anything to prevent an MPO from creating their own shape files for Census TAZ or Census TAD boundary/ Block Equivalencies assuming they have already obtained 2010 TIGER boundary sets?

 

Also, we am planning a Census TAZ delineation workshop on February 7^th to discuss issues associated with nesting model TAZs within Census TAZs given the relatively low populations of most of our MPO model TAZs.  I had hoped to acquaint people with the software environment prior to the training sessions at the end of the month but understand that we are not a testing state.   I also expect a discussion of the complexities of obtaining CTPP special tabulation data then needing to reallocate the data to model TAZ geographies.  Is there anything you can share with us to assist in these areas?  I have also received a question of what other uses (besides the one-time use of obtaining CTPP data) the census TAZ and TAD geographies have beyond the census year.  LEHD On the Map comes to mind… other uses?

 

Thank you.

 

 

As you know, TAZ delineation by State DOTs and MPOs will occur very soon, with software distribution in March/early April and files returned to the CB by mid-July.   The software is being tested by volunteer State DOTs and MPOs starting from Friday, Jan 14 thru Feb 2.  Thank you to all the volunteers!  We do not need any additional software testers. 

We have two web training events scheduled.  REGISTRATION IS REQUIRED.   Please make sure that you capture the full http:// address, in case the listserv breaks it up.   You need the address including webconfid=22433, or webconfid=21975

I have reserved 300 spaces for each day, so there should be enough room for everyone.  If you are unavailable on those days, the sessions will be recorded and available for later viewing.   The same training will occur on each day, so please sign up for only one.

The web meeting software has been upgraded, therefore, the email with the confirmation of your registration will have a link to check the functionality on your computer. 

Friday, 2/25/2011, from 10 a.m. – noon EASTERN:

Registration URL:  https://www.nhi.fhwa.dot.gov/resources/webconference/web_conf_learner_reg.aspx?webconfid=22433

Monday, 2/28/2011, from 2  - 4 p.m. EASTERN:

Registration URL:  https://www.nhi.fhwa.dot.gov/resources/webconference/web_conf_learner_reg.aspx?webconfid=21975

Question:  why is the time to do this only 3 months?

Answer:  For the TAZ and TAD delineation, it is important to be able to use the TIGER files with the 2010 geography and 2010 population counts.  The 2010 population counts will be released to the public on a flow basis starting in March 2011, so we have to wait until these data are available to begin TAZ and TAD delineation.  If the 5-year CTPP using 2006-2010 ACS records will be tabulated for TAZs and TADs, the TAZ and TAD delineations need to be completed quickly and returned to the CB Geography Division (GEO) 3 months after the agencies receive their files (no later than July 2011).

This provides GEO with sufficient time to QC the submissions, produce the necessary files so that ACS records will get TAZ/TAD identifiers, and create TIGER/Line shapefiles for TAZ/TAD geography.   If the TAZs and TADs

are not delineated within this time frame, the CTPP tabulation could be delayed for another year, that is, Fall 2013.

Question:  are there strict thresholds on either residential population or workplace population?

Answer:  No.  The software will give a warning message, but will still allow you to define TAZs below the recommended “threshold.”  (The FAQ will include more discussion about this topic.)

We are working on an FAQ document on TAZs and will post it on the AASHTO CTPP page.

http://ctpp.transportation.org/Pages/taz.aspx

Elaine Murakami

FHWA Office of Planning

206-220-4460