[CTPP] TAZ Development

[Krishnan Viswanathan]

You can find the Florida DOT paper that Ed referred to here :
http://www.fsutmsonline.net/images/uploads/reports/FDOT_TAZ_White_Paper.pdf

On Thu, Aug 6, 2009 at 10:44 AM, Ed Christopher <edc at berwyned.com> wrote:

> Watching this discussion on TAZs has been interesting and the size of TAZs
> has been shown to be more of an art than a rule based science. With that
> said I want to toss a few more items on the table when folks are considering
> TAZs.
>
> 1.  TAZs to be used in the production of a CTPP 5-year ACS product will not
> have to be developed until the Summer of 2011.  The process used will be an
> equivalence method where folks will be asked to say which Census Blocks  (in
> their entirety) will be placed in which TAZ.
>
> 2.  There will likely be at least two TAZ sizes.  The regular TAZs that we
> have all come to know and the subject of Bob's question and maybe a larger
> one somewhere in the neighborhood of 20,000 residents.  Just this week the
> AASHTO CTPP Oversight Board established a subcommittee to work out the TAZ
> details.  Guy Rousseau of the Atlanta MPO is chairing the group.
>
> 3.  The TAZs will be developed to support a tabulation of the 5-year ACS
> data using (2006, 07, 08, 09 and 2010) data that is planned to be released
> in the Summer of 2012.  For areas that do not submit TAZs Tracks (and maybe
> Block Groups) will be the default.
>
> 4.  For the CTPP 5-year tabulation there is a NCHRP project (NCHRP 8-79)
> getting underway that, if successful, will take any disclosure issues off
> the table.  The RFP for the project, "Producing Transportation Data Products
> from the American Community Survey that Comply with Disclosure Rules" was
> just finalized and put out on the street two days ago. See
> http://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=2708 to view the
> RFP and details.
>
> 5.  Assuming NCHRP 8-79 is successful, which there is no reason why it
> should not be, TAZ sizes will not be affected by the artificial disclosure
> rules and instead can go back to being determined based on good planning
> practice.  Which doesn't answer Bob's original question but does help put
> the focus where it should be.
>
> 6. Regarding disclosure rules we know from our attempt to get some CTPP
> tables produced from the 3-year ACS that if the same rules for the 3-year
> were extended to the 5-year data the losses would be so devastating that
> there would be no usable 5-year data, which is why we fought for the NCHRP
> project.
>
> 7. In terms of a 3-year CTPP ACS product we hope to have one released in
> the Spring/Summer of 2010 using 2006, 07 and 08 data.  This release will be
> subject to a variety of data suppression and disclosure rules and will only
> be for areas of 20,000 residents or more.  To see the tables that were
> designed for this go to http://trbcensus.com/products/
>
> 8.  In terms of TAZ sizes for planning the Florida DOT through its modeling
> group has published a report on the subject.  I do not have the link to the
> report handy but maybe someone else the list can find it and post it.
>
> I hope this helps clarify a few things
>
> Paddock, Bob wrote:
>
>> I must admit that, of late, I have gotten lost in the woods while trying
>> to see all the trees.  During these past months I have been engaged in
>> developing a new TAZ system for the Minneapolis – St. Paul MPO area that
>> will both serve the needs of travel demand modeling here at the Metropolitan
>> Council *AND* provide us with the information we want from a 2010 CTPP-like
>> product.
>>
>>
>> This new TAZ system is substantially more refined than those of the past
>> and should result in reasonable travel loadings on our arterial roadway
>> network.  However, certain issues have been raising their knobby heads
>> regarding zone size that probably will clash with Census Disclosure Board
>> rules.  Does anyone have a reasonable idea as to what minimum population or
>> household levels a TAZ will need to attain in order to circumvent large
>> numbers of “blank” cells?  I suspect that there is not an easy,
>> uncomplicated answer but would like to hear one nonetheless.
>>
>>
>>
>> *Bob Paddock***
>>
>> Transportation Planning
>>
>> Metropolitan Council
>>
>> Bob.paddock at metc.state.mn.us
>>
>> 651 / 602-1340
>>
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> ctpp-news mailing list
>> ctpp-news at chrispy.net
>> http://www.chrispy.net/mailman/listinfo/ctpp-news
>>
>
> --
> Ed Christopher
> 708-283-3534 (V)
> 708-574-8131 (cell)
>
> FHWA Resource Center Planning Team
> 4749 Lincoln Mall Drive, Suite 600
> Matteson, IL  60443
> _______________________________________________
> ctpp-news mailing list
> ctpp-news at chrispy.net
> http://www.chrispy.net/mailman/listinfo/ctpp-news
>



-- 
Krishnan Viswanathan
1101 High Meadow Dr
Tallahassee FL 32311
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.chrispy.net/pipermail/ctpp-news/attachments/20090806/b20952c7/attachment-0001.html