a product of the CTPP Planning Group firstname.lastname@example.org
Maricopa Association of
Adds to Its Look and Feel
Message from the
TAZ Delineation Status
Once the Census 2000 TAZs are submitted, they will be reviewed and integrated into the TIGER/Line 1999 files along with all the other proposed geographies. The Census Bureau will then give the TIGER/Line 1999 files back to the TAZ-UP participants early in 2000. Participants will then be asked to review their TAZs and submit any final revisions at that time.
Those working with the TAZ-UP CDs are reminded that the CD includes the software, a tutorial, and user manual. Included in the manual (page 1-7) are the phone numbers for technical support and assistance. If you are having difficulty, are unsure of something, or just got stuck, make that call for help. You do not want to put this off too long because the Census and CTPP 2000 may go on without you.
Another item added to the look and feel is a single phone number for all CTPP inquiries. The phone number is maintained by U.S. DOT and has an automatic call director to route callers to the most responsible individual for the issue at hand. The new phone number is 202-366-5000. Similarly, an easy to remember email address has been created: email@example.com
While the TRB subcommittee on Census Data for Transportation Planning can not "with a wave of the hand" magically complete all this work for us, it can help by providing a forum for information exchange. Information exchange is important because we are not alone in these tasks. What each one of us is doing is being replicated hundreds of times across the country. To help build a better CTPP 2000 product, streamline our work, and maximize our productivity, the Subcommittee needs to hear from you. The Subcommittee maintains an electronic mailing list and welcomes any questions, comments, or issues you may have. Look below for information on how to learn about our mailing list.
One area of increasing importance to the subcommittee concerns the developments and activities surrounding the American Community Survey (ACS). The ACS uses a continuous measurement methodology and is currently being tested in several counties throughout the country. The ACS is important because it is slated to replace the long form. While the ACS holds a lot of promise for the transportation planning community, it also brings with it a great deal of uncertainty. Not only will the ACS bring a methodological change, it also brings a change in the content of the data.
To be ready for this change, it is imperative that the transportation planning community focus on two fronts. First, each one of us must begin to understand what the ACS is, its methodologies, and our uses of census long-form data. Some of us may even be interested is examining current ACS data, which is available by contacting Ken Bryson of the ACS analytic staff at (301) 457-3606, or the ACS website: http://www.census.gov/acs/www. The second and more pressing issue is that we need to begin to articulate our questions about the ACS. These questions can range from "what is the ACS?" to "how do I report transit usage from Census data when it is a moving average"? Over the next few months the subcommittee will compile our questions concerning the ACS. Once that is done, we can we begin to develop a well orchestrated program to systematically evaluate its full implication.
Again the electronic mailing list is an excellent place to begin posting your questions. To sign up or learn more about the mailing list visit http://www.TRBcensus.com/maillist.html
On a totally separate note, I am currently on a leave of absence from the Chicago Area Transportation Study and working in Washington D.C. as a consultant to the Bureau of Transportation Statistics. My phone number is 202-366-0412, and I welcome your calls.
TRB Census Subcommittee Chair [Top]
The 2000 Census Transportation Planning Package (CTPP) will follow a
process similar to that used in 1990 Census. The production of CTPP
2000 for all States and MPOs are being sponsored by the State Departments
of Transportation, under a pooled fund arrangement with AASHTO.
The approval of the resolution by the AASHTO Board of Directors authorizes AASHTO to enter into a contract with the Census Bureau to acquire and utilize the data, to solicit all State departments of transportation as to their interest in taking advantage of the pooled funded project, to invoice those departments wanting to participate for their share of the costs, and to collect and administer the funds to carry out the project. Each state's share of the cost of the CTPP 2000 program will be 1.1 cents per person residing in the state based on the Census Bureau's 2000 Population projections.
Federal Highway Administration State planning and research and metropolitan planning funds may be used by the States, and MPOs without match for the State contribution. Discussions are also underway with the Federal Transit Administration (FTA) to use Statewide and Metropolitan Planning Funds, more information will be provide as it becomes available.
AASHTO has mailed CTPP Funding Commitment Forms to the State Departments of Transportation. The signed commitment forms are due back to AASHTO by June 25, 1999. After receiving the signed forms, AASHTO will prepare and send an invoice to each participating member department for its respective amount. Once the CTTP Commitment Forms have been signed, AASHTO will then enter into a contract with the Bureau of the Census for the scope of the work for the 2000 Census Transportation Planning Package.
For more information on the State Sponsored CTPP Pooled Fund Project please contact Deborah Buchacz or Dave Clawson at AASHTO at (202) 624-5800.
Difficulties in Geocoding
There are several reasons why geocoding workplace data from the decennial census is so difficult. These include:
Employer Database from infoUSA
The Census Bureau has purchased a license for an employer file from infoUSA. This file is a nationwide database including names, addresses, number of employees, etc. The Geography Division of the Census Bureau will geocode this file to TIGER98.
We know that the infoUSA file is not fully complete or accurate for the entire nation. We also believe that there is no perfect file at the national level. MPOs may have their own file, either that they maintain themselves, or have licensed from another vendor and to which they have made improvements. The software discussed below will have the ability to bring in another file to be used in conjunction with the infoUSA file, so that improvements can be made to the file submitted to the Census Bureau.
The Census Bureau Population Division will be developing a GIS-based software program to allow MPOs to evaluate the employer data for their area. Our goal is for a user-friendly system, which will be simpler than the 1990 process and allow the MPOs more say in the final product they ultimately receive. The amount of time and effort MPOs put into these procedures will directly affect the quality of the final CTPP for their area.
We are trying to provide as much flexibility as possible with the LREF program. LREF will include:
LREF will allow MPOs to choose either a database approach or a spatial approach to reviewing the employer file. Any employers that the user deems to be incorrect will need to be corrected. This includes either changing the address, moving the map spot, or deleting the record. Any changes will be flagged and deletes will be saved to a delete file to be sent back to Census Population Division.
Existing records can be modified in two ways:
At this point, we plan to ship LREF in August, 1999. As with TAZ-UP, MPOs will have about six months to work on verifying and correcting the employer file. The MPOs will send the file to the Census Bureau Geography Division to be used for place of work block coding.
|"Surf's Up" Web Sites to Remember|
MAG desired that the Sketch Plan Model to be a quick and simple tool that could be easily applied to many rail lines using existing demographic and land use information. The model is conceptually basic. Establish a set of Trip Rate Factors based on the number of households and the percent of regional jobs within set geographic distances from urban rail stations. These factors can then be applied to the known number of households and job ratios for comparable geographic distances to estimate rail boardings that might be expected at each station for an assumed rail line. The Trip Rate Factors are generalized estimates, based on information gathered from on-board travel data from three similar (to Phoenix) communities: Portland, Oregon, Sacramento and San Diego, California.
The Sketch Plan Model has three specific purposes. One purpose is to serve as an independent check of the values produced by a mode choice component of the regional travel forecasting model. The model uses analogous data from existing light rail systems, so it implicitly reflects various attributes that influence transit use, such as vehicle ownership, transit service levels of roadway congestion, parking supply/cost characteristics, etc…. As long as the general demographic and transportation attributes of the community applying the model are similar to those communities from which the base data is drawn, the Sketch Plan Model can be used to independently validate the results of other travel forecasting tools.
Another purpose of the Sketch Plan Model is to provide a quick and simple method of estimating potential rail ridership. To reach this goal the model uses basic demographic information available either through the Census Bureau or recorded in Transportation Analysis Zones (TAZ) data. Specifically the model uses the total number of households and total number of jobs by TAZ located within specified radial distances from proposed rail stations.
The third purpose is to define in a mathematical form the relationship between station locations and the distribution of trip ends by ranges of travel distance to and from stations. This relationship can be used to help transportation planners in generally locating rail stations relative to residential densities and job densities.
MAG will continued to use its existing four step modeling process to forecast rail ridership. This approach requires substantial “model setup”, i.e. establishment of networks, linkages, and operating assumptions to produce ridership estimates. However the four step model is much more sensitive to changes in system variables. Thus it is more useful for design purposes and answering the many detailed question that arise in the process of planing a light rail system. In addition, the amount of time for model setup is insignificant in relation to the cost of building a light rail transit system.
The CTPP provided readily available demographic data and allowed MAG to achieve its goal of creating a tool that was easily operated, simple, quick, and produces reasonable system wide ridership estimates.
|Ed Christopher (Census Subcommittee Chair)
|Chuck Purvis (Urban Data Committee Chair)
|Ed Limoges (Census Subcommittee Secretary)
|Ron Tweedie (State Data Committee Chair)
Census Population Division (JTW questions)
Census Geography Division (for TAZ update questions)
BTS FTA AASHTO
(See under TRB Committees)
Kudos to Elaine Murakami (FHWA) and Clara Reschovsky (Census) for the content and Kevin Cross (BTS) for the production as well as the CTPP Planning Group for its review efforts.
The second document is the technical manual for the TAZ-UP software
and process. It can also be found on the TAZ-UP software CD-ROM.
The document is in PDF format and was prepared by Election Data Services,
the consultant who designed the TAZ-UP software. The document can
found through the TRB Census Subcommittee’s web site or downloaded directly from http://members.xoom.com/berwyned/ctpp/tazupdoc.pdf (note: it is 6.5 megabytes.)
Should there be a problem with the direct links check the Subcommittee's web site under the “Committee Notes and Articles” button at http://www.TRBcensus.com/notes.html
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