Office of Planning, Environment, & Realty (HEP)
E-mail firstname.lastname@example.org or call 301-763-1099 and ask for help from the GEO TAZ Team
The TAZ project officially began on March 18th and all invitation e-mails were sent out by March 29th . TAZ participants are reminded that their delineations are due back 90 business days from the date on which they received the initial invitation e-mail. This means all deadlines are between June 17th and June 30th, depending on the date of the original e-mail. This deadline is a strict one due to the tight schedule the Census Bureau has for getting these updates into the fall benchmark TIGER file.
FHWA and the Census Bureau conducted two web-based software TAZ participant training sessions (webinars) on February 25th and 28th. The webinars were recorded and are available with their supporting material on the AAHSTO CTPP TAZ page: http://ctpp.transportation.org/Pages/taz.aspx
The TAZ program is a voluntary program. Agencies are not required to delineate TAZs or TADs for the CTPP. If an agency chooses not to delineate TAZs for a county, the 2010 census tracts will become the default 2010 TAZs for that county. If an agency wishes to delineate neither TAZs nor TADs in a county, AASHTO will delineate TADs for that county using 2010 census tracts or block groups as building blocks. Note that if a participant drops out of the program, that participant will have no opportunity to review the TAD work done by AASHTO for their area. Agencies that wish to completely drop out of the program (i.e. not delineate TAZs or TADs) should contact the Census Bureau as soon as possible, so that AASHTO can begin their TAD delineation work for the area.
Several agencies have inquired about whether they can keep their 2000 TAZ plan as-is for 2010. The answer is "yes" with one caveat. The 2000 TAZs do not match the new 2010 block geography perfectly. Participants who want to maintain their 2000 TAZs for 2010 will still have to review their TAZ geography in the MAF/TIGER Partnership Software (MTPS), run the validations, and clean up areas where the Census Bureau could not assign a 2000 TAZ code to a 2010 block. The cleaned-up TAZs will then have to be reported back to the Census Bureau using the standard MTPS "Report Changes" function.
The 2006-2008 CTPP data are currently available at the AASHTO page with on-line access software (http://ctpp.transportation.org/Pages/3yrdas.aspx). This article introduces two basic functions of the software and walks through important icons available in the software. These features will be most helpful to you when manipulating the data. A CTPP on-line tutorial is also available at http://data.ctpp.transportation.org/CTPP/Common/Help/help.aspx
After logging in to the software, you will see a page similar to Figure 1. This is the software main page, which is the "Reports" tab. Under "Reports" tab, users can explore the data within the "CTPP Full Data Release" folder or create/edit their own sessions. The session is defined as a set of tabulations which have a common geography.
Figure 1. The Software "Reports" Tab View
Under "Table" tab, users are given rights to customize tables including switching table dimensions, creating custom groups and calculating percentages.
Figure 2. The software "Table" Tab View - Example of Household Income by Means of Transportation table
Figure 3 lists important icons that are available for customizing tables. For example, if you hit "Set Dimension Order," it will lead you to a page similar to Figure 4. You can use arrows shown in Figure 4 to change row and column dimensions for a specific table. Clicking "Select items to view" will bring you to the item selection page (Figure 5). The dimension, HOUSEHOLD INCOME, appears shaded in the list on the left to show that it is the active dimension. The list area on the right shows all the possible item selections. In the default view of this report, everything is selected. You can remove or add items in the item selection page. You can also create custom groups by hitting the icon in the tool bar.
|Table Tools||Does this...|
|Set Dimention Order||Switch row and column positions for currrent table|
|Select items to view||Select a table dimension and go to item selection page|
|Global settings||Activate global settings (will be applied to current table and any others that you open), deactivate global settings (no effect on current table, but will not be applied to others you open) or delete global settings.|
|Reset Default view||Go back to default table view, which is how it was last saved (when session created, or when public report was published).|
|Download||Download selected tables to your local drive|
|Custom Groups||Create compound group or calculated group|
Figure 3. Table Toolbox List
Figure 4. Set Dimension Order
Figure 5. Item Selection Page
|Many analysts already have tools and databases for analyzing data. If you are equipped with such tools, you may wish to receive all the data of interest in Comma-separated Value (CSV) files so you can easily load it into your tools. The data has been packaged by state and by part so that you can download it in a single operation. The data can be found in the data access software in the "Source Files by State" folder within the "CTPP Full Data Release" folder (Figure 6). There is a separate folder for each state, and within each folder, there are three files, one for each part. The files for download are in compressed data folders (Zip files), so you can expand these on your own machine. Within each Zip file, there is a separate file for each table and each table contains entries for each geography with the state. There is also a labels file that contains the label associated with each GEOID in the files. At this time, there is no published documentation on how to parse these files, but they are relatively simple and self-explanatory once you view them.||
Figure 6. Raw Data in the Software
Since AASHTO released the 2006-2008 CTPP data product access software in January 2011, there has been an increased demand for CTPP training. In response, Ed Christopher and Liang Long have conducted several one-day hands-on training sessions. The one-day training is specifically designed for transportation planners and modelers from state DOTs and MPOs. To date, three sessions have been held. For the state of Michigan, the training focused on Census data and CTPP related data issues. For Arizona and Florida, the classes focused on the 3-year CTPP data product, its online access software and the TAZ delineation software.
For in-person CTPP training including computer exercises, a minimum of 1.5 days is recommended.
AASHTO and FHWA are also participating in several conferences and conducting workshops on CTPP.
On-line training in basic use of the CTPP Data Access Software is available. These one-hour "webinar" sessions are offered for live inter-active participation and recorded for viewing. CTPP Basic, a basic introduction to the CTPP software, including how to create a user profile, and how to access and manipulate data will be offered several times a month on a first come, first served registration basis. A recorded session of CTPP Basic is now available at: http://ctpp.transportation.org/Pages/webinardirectory.aspx.
The next live webinars for CTPP Basic are
Notice of available registration will be made by message to the CTPP and TMIP list serves, or e-mail Penelope Weinberger at email@example.com to receive notification. Additionally, the CTPP program is working hard to develop an intermediate to advanced CTPP Software Webinar course. Users should attend the basic course and/or submit a transportation analysis problem as preparation. Both webinars will be offered until demand is met.
Five webinars are archived and accessible on the AASHTO CTPP webpage: http://ctpp.transportation.org/Pages/webinardirectory.aspx. Five eLearning modules are under development and will be made available at: http://ctpp.transportation.org/Pages/elearningmodules.aspx.
The five eLearning topics are:
The CTPP program team is always interested in increasing data users' capacity to use CTPP products. Please contact Penelope Weinberger to discuss your training needs.
In 2010, the Indian Nations Council of Governments, the MPO for the Tulsa, Oklahoma urbanized area, started an update of their regional travel model for application in a transit system plan and eventually, New Starts Alternative analysis. Many of the data underpinning the model were built on data released as part of the 2000 Census including the origin / destination of workers. The question arose during the model review process as to how much the travel patterns of workers had changed over the previous decade. It is a simple enough question but not one that is readily answered without a more contemporary dataset.
In early 2011, the 2006-2008 CTPP web-based tool was released by AASHTO1. This provided the first and most obvious way to see what changes had occurred in the region and how those changes may validate or invalidate the assumptions regarding the stability of travel patterns in the region. A further benefit of this comparison is that, though the CTPP 2000 and 2006-2008 CTPP use very different methods to "fill in the blanks," understanding the resulting differences in reported travel could provide some insight into the suitability of the ACS-based CTPP as a basis to update key model parameters, if necessary.
The analysis started by summarizing county-level worker flows in the region as described in the 2006-2008 CTPP. This is the first dataset released on the AASHTO website and was selected for ease of use and the hope that a comparison might reflect any impacts from the recent economic downturn experienced nationwide (albeit not witnessed as strongly in the Tulsa region) and highlight differences. While these data are not 100% compatible with INCOG's study area2, they do capture all of the major travel markets that would impact interpretation of the forecasting model's reliability. Using the county-level data as the basis of the initial comparison provides the benefits of a larger dataset (for both the 2006-2008 data as well as the 2000 data), increased reliability and the ability to shed light on how the area is growing outside the "modeled" study area. The summary of the 2006-2008 CTPP dataset is provided in Table 1.The 2006-2008 CTPP data shows that Tulsa County is the largest "attractor" of workers and is a net importer of work trips from other counties in the region with a little more than 280,000 workers residing in Tulsa County and almost 345,000 workers destined for Tulsa County.
|Place of Work|
*source: AASHTO 2006-2008 CTPP Software data (http://ctpp.transportation.org/Pages/3yrdas.aspx)
Next, the analysis focused on summarizing data in the same way but using the CTPP 2000. Shown in Table 2, the CTPP 2000 also reaches a similar conclusion that Tulsa County is a net importer of workers and the largest employment center in the region. This lent credibility to the 2006-2008 datasets and the expansion methodology used at this level of geography. The next question was one of magnitude. Did the new CTPP reflect the appropriate "scale" of workers in the region? Over the decade, despite the economic downturn, the 2006-2008 CTPP shows a net gain of more than 30,000 workers in the region (Table 3) representing a 7.4% increase in total workers (Table 4). This is consistent with local observation and lent additional credibility to the 2006-2008 CTPP data. Further review of the cell-by-cell values in magnitude and ranked importance by county of residence (Table 5 and Table 6) reinforced the conclusion that the 2006-2008 CTPP trip distribution pattern is consistent with expectations and the CTPP 2000 for county-level interchanges greater than 500 workers.
|Place of Work|
*source: CTPP 2000 Data Tables (http://www.bea.gov/regional/reis/jtw/)
|Place of Residence||Place of Work||Total|
|Place of Work|
|Place of Work|
|Place of Work|
While detailed data from the 2006-2008 CTPP are not available at a traffic-analysis zone level, the comparisons between the 2006-2008 CTPP data and the CTPP 2000 provide an early indicator that the county-to-county patterns reflected in the 2006-2008 CTPP data are consistent with those observed in the CTPP 2000. This analysis and comparison process raised no "red flags". Furthermore, as the travel demand model was built on Census 2000 data, including the CTPP, the commonalities and differences between these datasets provide a reliable "high-level" means to identify where changes are "reasonable" and where they are questionable as the travel demand model is updated for use in the transit system plan and subsequent New Starts applications.
With the assurance that the county-to-county flow data observed in the 2006-2008 CTPP are reasonable, subsequent efforts will focus on mining additional variables and comparisons at finer levels of geography to see where differences occur and if those differences are consistent with local observations and other datasets that serve as the foundation of the Tulsa travel forecasting model.
TRB Conference on Census Data in Transportation Planning: October 25-27, 2011
CTPP Hotline - 202/366-5000
CTPP Website: http://www.dot.gov/planning/census_issues/ctpp
FHWA Website for Census issues: http://www.fhwa.dot.gov/planning/census_issues/
2005-2007 ACS Profiles: http://download.ctpp.transportation.org/profiles_2005-2007/ctpp_profiles.html
AASHTO Website for CTPP: http://ctpp.transportation.org
1990 and 2000 CTPP downloadable via Transtats: http://transtats.bts.gov/
TRB Subcommittee on census data: http://www.trbcensus.com
Jonette Kreideweis, MN DOT
Census Bureau: Housing and Household Economic Statistics Division
The CTPP Listserv serves as a web-forum for posting questions, and sharing information on Census and ACS. Currently, over 700 users are subscribed to the listserv. To subscribe, please register by completing a form posted at: http://www.chrispy.net/mailman/listinfo/ctpp-news On the form, you can indicate if you want e-mails to be batched in a daily digest. The web site also includes an archive of past e-mails posted to the listserv.
2 The INCOG travel model area has been expanded since the Census 2000 and includes urbanized portions of Creek, Osage, Rogers and Wagoner Counties in addition to the entirety of Tulsa County.