CTPP August 2009

ctpp@listserv.transportation.org

22 participants
19 discussions

[CTPP] Re: ctpp-news Digest, Vol 66, Issue 4

by Jorge Argote

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

15 years, 12 months

[CTPP] RE: ctpp-news Digest, Vol 66, Issue 1

by Ali Bonakdar

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 _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news

15 years, 12 months

[CTPP] Neil R Wiggins/STLS/FRS is out of the office.

by Neil.R.Wiggins＠stls.frb.org

I will be out of the office starting 08/05/2009 and will not return until 08/11/2009. I will respond to your message when I return.

15 years, 12 months

[CTPP] RE: ctpp-news Digest, Vol 66, Issue 2

by Kyeongsu Kim

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.net http://www.chrispy.net/mailman/listinfo/ctpp-news

15 years, 12 months

[CTPP] RE: ctpp-news Digest, Vol 66, Issue 2

by Patricia Tice

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

15 years, 12 months

[CTPP] Liang Long is out of the office.

by Liang Long

I will be out of the office starting Wed 07/29/2009 and will not return until Mon 10/05/2009. I will respond to your message when I return. Please contact with Pramoda Gode (pgode(a)camsys.com) for any CTPP related questions.

15 years, 12 months

Re: [CTPP] TAZ Development

by Sam.Granato＠dot.state.oh.us

Mr. Paddock: It's safe to say that one set of TAZs will not be able to cover both these needs for you. There's been discussion here before about developing two or more sets of TAZs just for different levels of disclosure problems with 2010 CTPP (ACS) data alone. You'll need at least one more set for traffic modeling, where you can geocode the address-based, Census block and other small area data not subject to these disclosure problems and than from there aggregate to the level needed for the model. Sam Granato Ohio DOT, Office of Multi-Modal Planning 1980 W. Broad Street, Columbus, OH 43223 Phone: 614-644-6796, Fax: 614-466-0822 "It's all very well in practice, but it will never work in theory." - French proverb 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

15 years, 12 months

[CTPP] RE: ctpp-news Digest, Vol 66, Issue 1

by Patricia Tice

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

15 years, 12 months

Re: [CTPP] TAZ Development

by pmission＠srpedd.org

I will be on Vacation until August 11th.

15 years, 12 months

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CTPP August 2009