ctpp-news

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2560 discussions

Documentation on using LEHD OnTheMap files

by Elaine.Murakami＠dot.gov

We (the royal "we") are interested in personal travel patterns, for a variety of transportation planning applications. The CTPP program will provide home-to-work origin-destination tables using multiple years of surveys from the American Community Survey. But, other data sources should be examined for their potential to augment the CTPP, for small area origin-destination matrices. For example, many of you are aware of my interest in using multi-day GPS. Each data source, including ACS and the CTPP, has its own benefits and limitations. One of the datasets of interest is the LEHD OntheMap "home-to-work" flows. We would like to encourage more analysis and evaluation of the LEHD OnTheMap data. While the LEHD OnTheMap interface is a user-friendly web-based software http://lehd.did.census.gov/led/ , we believe that transportation planners will be more interested in the potential of the synthetic block data records (10 implicates are created in the data synthesis process) to examine the origin/destination flow results. These data are available for download on the Cornell University Virtual Data Center. I asked Laura McWethy at Cambridge Systematics to prepare some documentation on the files, to make it easier for others to examine this data. It is attached. Caveats: The files are large since they represent block-to-block pairs. The data are synthetic. This is the first synthetic data product approved by the Census Bureau's Disclosure Review Board. Data synthesis is used to protect individual confidentiality. The universe of workers (workers covered by unemployment insurance) differs from "all workers" You should take the time to understand the data sources and synthetic data processes used to generate these results. We are interested in your tests of the LEHD OnTheMap block level data. I hope that Nathan Erlbaum and Aaron Westcott of New York State DOT will share the results of their work on county-to-county flows. Introductory material on LEHD OnTheMap is available through a recorded presentation from the TRB Planning Applications conference in Houston http://teachamerica.com/APP09/ (go to the Sunday session and look for DATA), and also at the LEHD OnTheMap home page http://lehd.did.census.gov/led/ . Elaine Murakami FHWA Office of Planning (Wash DC) 206-220-4460 (in Seattle)

15 years, 4 months

automated response

by Douglas Bell

I will be out of the office until Monday, August 31. I will reply to your message when I return.

15 years, 4 months

Tools of the Trade 2010 Call for Abstracts

by Everett, Jerry D

Hello all (Please forgive me if you have already received this information from another source.) Attached is a Call for Abstracts for the next Tools of the Trade Conference. The Conference focuses on transportation planning topics and tools for small and medium-sized areas. The conference will be held in September 2010, in historic Williamsburg, VA. Please review the topics listed in the Call and consider submitting an abstract about work conducted in your area or by your agency that would be of interest to others across the country. In addition, please forward this Call to anyone that you think might be interested in submitting an abstract or in attending the conference. Our committee website has additional information and can be accessed at the following link: http://www.trbtoolsofthetrade.org/conference.html. Jerry Everett Research Director Center for Transportation Research Suite 309 Conference Building 600 Henley Street University of Tennessee Knoxville, TN 37996 (865) 974-8275

15 years, 4 months

Alison K Fields/POP/HQ/BOC is out of the office.

by alison.k.fields＠census.gov

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.

15 years, 5 months

RE: ctpp-news Digest, Vol 66, Issue 7

by Patricia Tice

The full white paper on TAZ guidelines from the FDOT systems planning office is here: http://www.fsutmsonline.net/images/uploads/reports/FDOT_TAZ_White_Paper.pdf A power point presentation based on this is here: http://www.google.com/url?sa=t&source=web&ct=res&cd=1&url=http%3A%2F%2Fwww.… Patricia C. Tice, PE, AICP, LEED AP Glatting Jackson Kercher Anglin, Inc.

15 years, 5 months

AUTO: Harvey Michaels (returning 08/17/2009)

by Michaels.Harvey＠epamail.epa.gov

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.

15 years, 5 months

TAZ Development

by Paddock, Bob

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

15 years, 5 months

Re: ctpp-news Digest, Vol 66, Issue 5

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, 5 months

Re: ctpp-news Digest, Vol 66, Issue 4

by Jorge Argote

15 years, 5 months

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, 5 months

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