I will be out of the office starting 08/07/2009 and will not return until
08/24/2009.
If you need immediate assistance please see one of the following people
during my absence.
August 7
Melissa Chiu 7H484F 3-2421.
August 10 -August 14
Kin Koerber 7H486E 3-7620
August 17-August 21
Melissa Chiu 7H484F 3-2421
For all CTPP-related matters please see Melissa Chiu.
I am out of the office until 08/17/2009.
I will respond to your message when I return.
Note: This is an automated response to your message "RE: [CTPP] TAZ
Development" sent on 8/11/2009 9:28:39 AM.
This is the only notification you will receive while this person is
away.
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(a)metc.state.mn.us
651 / 602-1340
I will be on vacation from August 10 through Sept 3, 2009.
If you need immediate help please contact:
Tanya Rodriguez at 212-383-2516 (trodriguez(a)dot.state.ny.us)
Munnesh Patel at 212-383-2528 (mpatel(a)dot.state.ny.us)
Jorge Argote, P.E.
Manager, Travel Surveys Unit
Technical Group
NY Metropolitan Transportation Council
199 Water Street, New York, NY 10038
Tel: (212) 383-2527; Fax: (212) 383-2418
jargote(a)dot.state.ny.us
I will be on vacation from August 10 through Sept 3, 2009.
If you need immediate help please contact:
Tanya Rodriguez at 212-383-2516 (trodriguez(a)dot.state.ny.us)
Munnesh Patel at 212-383-2528 (mpatel(a)dot.state.ny.us)
Jorge Argote, P.E.
Manager, Travel Surveys Unit
Technical Group
NY Metropolitan Transportation Council
199 Water Street, New York, NY 10038
Tel: (212) 383-2527; Fax: (212) 383-2418
jargote(a)dot.state.ny.us
As I recall my old modeling lessons, sometimes you need to create "dummy TAZs" Whether you would get Census data for it or not that is a different issue.
Ali Bonakdar, AICP
Director
Corvallis Area Metropolitan Planning Organization
301 SW. 4th Street, #140
Corvallis, OR 97333
Ph: (541) 758-1911
Fax: (541) 758-3127
Email: abonakda(a)ocwcog.org
Web: www.corvallisareampo.org
-----Original Message-----
From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Mike LeBlanc
Sent: Wednesday, August 05, 2009 6:42 AM
To: 'ctpp-news(a)chrispy.net'
Subject: [CTPP] RE: ctpp-news Digest, Vol 66, Issue 1
Hello:
We have several TAZ's that have zero population and zero employment because we are modeling areas that are entirely agricultural. One area is about 2 square miles. We also have some TAZ's in central portion of the modeling areas (industrial) that are distinct in terms of the surrounding land use (residential). For us, the issue has always been getting TAZ's are similar in landuse and are defined by access to the transportation network rather than population.
Last Census we split everal TAZ's that were developed before we did a revision to our model and it was a real complex problem to split TAZ's in terms of creating matrixes and balancing the network. I would advise against that procedure unless absolutely necessary.
Is the Census Bureau going to enforce this rule of 1200 (employment + population) for Taz's as part of the 2010 census?
Mike LeBlanc, AICP
Planning Manager, Special Projects Division
Rosa Parks Transportation Center
Lafayette Consolidated Government
Department of Traffic and Transportation
P.O. Box 4017-C
101 East Cypress Street
Lafayette, LA 70502
Ph: 337-291-7179
Fx: 337-291-8458
Planning for the 21st Century
-----Original Message-----
From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Patricia Tice
Sent: Wednesday, August 05, 2009 7:02 AM
To: ctpp-news(a)chrispy.net
Subject: [CTPP] RE: ctpp-news Digest, Vol 66, Issue 1
The seminar I went to two years ago seemed to indicate minimum TAZ size in the range of 1200 people (again, pop or employment or combination). The issue is that in most areas transit accounts for 0.5-1.5% of the mode split and if you want to keep from having that data suppressed you will need to have that many people in it. I was told that suppression usually will occur when the real value is 3 or less, but true integer value reporting doesn't start until the real value is more than 10 (I think...it's been 2 years). The problem then becomes that area totals over several TAZ's are way off because you are adding "rounded" numbers rather than real numbers.
I suspect that the real question will have to do with which data set you are going to use. If you are going to try to use the ACS 1 year aggregate you really need large TAZ's. They say they are not going to suppress as much in the 3 year aggregate and may not suppress anything in the 5 year (at least for category totals).
As a modeler, this drives me completely crazy. To get the network to load well, you need to have the TAZ size and connections that are appropriate relative to the geography and roadway network. If you're dealing with a subdivision with 500 houses and one or two driveways the 1200 people limit is fine. If you're dealing with a city block with single family units, you've got a real problem.
One way to get around this (thinking out loud) is to take an area with a relatively uniform density and report that area as a whole as a census TAZ. Then when you get the data back, you can split that TAZ proportionately for your model's sake. Most travel demand models are only accurate enough to get you lane calls anyway so making some internal estimates from the Census data will keep you away from suppression issues and not adversely impact your accuracy. It will take a little data massaging on the back end but it may be worth it, especially in areas with dense roadway network connections.
Patricia C. Tice, PE, AICP, LEED AP
Glatting Jackson Kercher Anglin, Inc.
120 N. Orange Ave
Orlando, FL 34787
407-284-4753
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I recently had a chance to talk with a Census Bureau staff and was told
that the 3 (not 5) year average of CTPP like product will be available
in fall 2010.
Kyeongsu Kim
Census & Travel Survey Specialist
NY Metropolitan Transportation Council
199 Water St, 22nd fl.
New York, NY 10038
kkim(a)dot.state.ny.us
1-212-383-7233
>>> ptice(a)Glatting.com 8/5/2009 11:56 AM >>>
If the information that I received two years ago is correct, the ACS
will be the only thing available. Unless something has changed, ACS
replaces "long form" and it will not be used in the 2010 census.
However, 2010 will see the first publishing of the 5 year running
summary from the ACS. I assume a CTPP like product will be (or at least
could be) generated from this 5 year summary.
Again, if someone more who is more up to date, I would love to know
where this stands.
Patricia C. Tice, PE, AICP, LEED AP
Glatting Jackson Kercher Anglin, Inc.
120 N. Orange Ave
Orlando, FL 34787
407-284-4753
_______________________________________________
ctpp-news mailing list
ctpp-news(a)chrispy.nethttp://www.chrispy.net/mailman/listinfo/ctpp-news
If the information that I received two years ago is correct, the ACS will be the only thing available. Unless something has changed, ACS replaces "long form" and it will not be used in the 2010 census. However, 2010 will see the first publishing of the 5 year running summary from the ACS. I assume a CTPP like product will be (or at least could be) generated from this 5 year summary.
Again, if someone more who is more up to date, I would love to know where this stands.
Patricia C. Tice, PE, AICP, LEED AP
Glatting Jackson Kercher Anglin, Inc.
120 N. Orange Ave
Orlando, FL 34787
407-284-4753
