by Sabula, Julianne Ruth (Engineering-Const Planner II)
I am passing on a question from one of our strategic planners. "Where
can I find data on Mode of transportation for work trips by county,
travel time to work by county, number of commuters by community/city,
and carpool commuter activity by community/city?" If anyone knows where
to find this information (state of Utah), please let me know.
Utah Transit Authority
Engineering and Construction Planner II
669 West 200 South
Salt Lake City, UT 84101
w. (801) 237-1973
c. (801) 867-5203
Thanks Elaine. I haven't actually used OnTheMap other than to explore the web application and try some downloads but I thought that I would forward the caveats that I have run across.
Re: Version 3 OTM...(see: http://www.vrdc.cornell.edu/onthemap/data/v3/notes-otm-v3.0.pdf )
•QWI numbers are drawn from QWI release R2008Q2. Stable jobs and statistics related to 'stable jobs' have a bug which has been fixed in QWI release R2008Q4. An update to the data is expected later this year. Consult the LEHD site for more details.
•Current QWI numbers are considered experimental. Since they are computed using the same confidentiality protection technology as the general QWI numbers, but using much finer geographic cells, there are more suppressions (more smaller numbers to protect). Users should be aware that when aggregating numbers to levels that are comparable to the general QWI data, the numbers they generate will be systematically lower.
•Only one implicate has been released at this point. Future updates should be counted (and used) as additional implicates. Additional implicates may be released in the future as well.
•WAC, OD, and QWI files are only available for states participating in the LEHD program. RAC files are available for all states, even those not actively participating in the LEHD program, but coverage is limited. For example, a worker of a NJ company (NJ participates in LEHD) may live in NY (which not yet been integrated). Thus, a residence area for this and other workers is defined, and available here for download. However, the residence area information will NOT include information on workers of NY companies, since that information was not available at the time that OnTheMap v3.0 was created. (This applies for v3.0 to: CT, DC, MA, NY, NY, OH, PR, VI). These RAC files can be accessed through the links in the OD AUX files of states where these workers are tabulated.
It appears that only one implicate has been released in Version 3.
Version 2 documentation from section 1.2.3 at http://www.vrdc.cornell.edu/onthemap/doc/otm_public_master.pdf indicates that three implicates were available and adds the following warning:
This version of the data provides 3 implicates (independent draws in the synthesizing algorithm) for the OD matrix and the Residence Area Characteristics (RAC) files. This is reflected in the filenames, see Sections 1.4.3 and 1.4.4. For further information on how to properly analyze multiply synthesized or imputed datasets, see Raghunathan et al. (2003); Reiter (2004b) and Reiter (2004a), or consult Sessions 8a and 8b of the online INFO 747 class at Cornell University's CISER at http://vrdc.ciser.cornell.edu/info747/. A note of warning is in order, though: It is statistically incorrect to use the average of the 3 implicates unless the aggregator function is strictly linear. Adding geographic areas is linear, and forming ratios from two linearly aggregated quantities (earnings over employment, for example) can be done correctly as long as the numerator and the denominator are averaged separately.
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
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.
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
FHWA Office of Planning (Wash DC)
206-220-4460 (in Seattle)
(Please forgive me if you have already received this information from
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
Center for Transportation Research
Suite 309 Conference Building
600 Henley Street
University of Tennessee
Knoxville, TN 37996
I will be out of the office starting 08/07/2009 and will not return until
If you need immediate assistance please see one of the following people
during my absence.
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
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.
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
NY Metropolitan Transportation Council
199 Water Street, New York, NY 10038
Tel: (212) 383-2527; Fax: (212) 383-2418