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U.S. Department of Transportation
Federal Highway Administration
Bureau of Transportation Statistics
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AASHTO Standing Committee on Planning
In cooperation with the TRB Census Subcommittee

CTPP Status Report

August 2011


TAZ Delineation for Use in CTPP

Shonin Anacker, Census Bureau Geography, Shonin.Anacker@census.gov

The CTPP 2006-2008 are now available in the BTS Bookstore.

The 2006-2008 CTPP has a one click download button for downloading the raw data (CSV format) and a link directing users to the data access software at AASHTO website. Follow this link to the BTS Bookstore for CTPP data products.

The TAZ program is nearing completion. All participating organizations will have submitted their delineations by August 1st. Participants can be divided into three basic categories: those who delineated TAZs and TADs, those who delineated only TAZs, and those who dropped out of the program, opting to accept the default of Census Tract-based TAZs.

Of the 381 original participants who were originally signed up for the program, 264 (approximately 69%) delineated TAZs and TADs, 58 (15%) delineated only TAZs, and 64 (17%) dropped out and opted for the Census Tract default option.

For the areas where participants did not delineate TADs, AASHTO contracted with Caliper to delineate TADs. As a result, there should be nationwide coverage for TADs.

Many of the submissions required significant rework after review by the Census Bureau. We estimate that 25% of first submissions from participants had to be returned for serious verification failures (such as non-contiguous entities, nesting issues between TAZs and TADs, unassigned area problems, and below-minimum population TADs). Generally, Census Bureau staff was able to work with participants to obtain corrected re-submissions in a timely manner. In almost every case, participants who delineated TADs adhered to the 20,000 minimum population criteria, the only exceptions to this rule being in cases where participants created water-only TADs (or TADs that consisted solely of water and offshore islands). The TAZs and TADs will be added into TIGER so that the 2006-2010 CTPP will include these custom geographic units.


TRB Census Data Conference in October 2011

Jonette Kreideweis, jonette.kreideweis@comcast.net

A TRB Conference on "Using Census Data for Transportation" will be held October 25-27, 2011 at the Beckman Center in Irvine, California. Information on the conference can be found at http://www.cvent.com/events/using-census-data-for-transportation-applications-conference/event-summary-fecf178bb83a468d86c4d85de1a3bcbf.aspx

The conference planning team has fashioned a program to:

Opening sessions will provide background and context on the status of census data planning programs and how they align with transportation planning requirements. In addition, the conference will include breakout discussion sessions for participants to share ideas for improving and sustaining census data programs for transportation planning applications.

Census data are critical inputs for a host of transportation planning applications. They help us understand current conditions and predict future trends. They provide household, workplace, journey-to-work, and flow data for policy and planning studies, travel demand modeling, environmental justice analyses, transit evaluations, and many other work activities.

I hope that those of you who have used census data and have experiences to share will plan to participate in the conference. Early bird registration ends August 24, 2011 and advance registration expires on September 24, 2011.


CTPP Special Tabulation from US Census Bureau American Community Survey Data based on 5-year (2006 – 2010) Data

Penelope Weinberger, AASHTO, Pweinberger@aashto.org

The CTPP and the US Census Bureau are working together on a special tabulation request for the next CTPP data product. The product will be a special tabulation based on ACS 2006 – 2010 5-year data. In many respects the tabulation will be similar to the CTPP data product based on the 3-year 2006 – 2008 ACS data. There are two main differences:

The special CTPP tabulation is expected to be available in early 2013.


2010 Census Summary File 1

Elaine Murakami, FHWA Office of Planning, Elaine.Murakami@dot.gov

As of July 25, the Census Bureau had released the Summary File 1 for 23 states. SF1 release is scheduled to be completed by the end of August.

Why is Summary File 1 of interest to transportation planners?

The Table 1 is a list of tables in 2010 Census Summary File 1 that might be of interest to the transportation community.

Table 1. Selected Table List in the 2010 Census Summary File 1

Table

Table number

Number of cells

Sex by Age

P12

23 age categories

Sex by Age (under age 20)

P14

Single years 0-19

Household size and type by presence of children

P19

19 cells

Household type and Household size

P28

16 cells

Group Quarters by GQ Type (institutional or non-institutional)

P42

10

Housing Units (Occupancy)

H3

3

Average Household Size by Tenure

H12

3

There are at least three ways to access the 2010 Census Summary File 1:

In early July, the Census Bureau released a Microsoft Access Table Shell for use with the Summary File 1 files. This may be because the American FactFinder 2 has been difficult to use. The table shell will provide an easier way to access Summary File 1 information from the Census Bureau's FTP site http://www2.census.gov/census_2010/04-Summary_File_1/. Instructions for how to use the shell and work with the information is included in the .zip file on the FTP site.

You can also access the data using American FactFinder 2. http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml, but you may find it easier to use the Microsoft Access table shell. To get the complete SF1 table list, start with "Topics" (green circled) on the left panel, then select dataset 2010 SF1 (See Figure 1 and Figure 2). But do not click the link that marked red X in Figure 1 as that link is limited to "Quick Tables". You can also try keyword search in the box on the top left of Figure 2. And it might lead to several pages to find the table you want.

Figure 1. American FactFinder 2 Home Page

Screenshot of the Census Bureau American FactFinder 2 home page.

Figure 2. American FactFinder 2 Census 2010 Summary File 1 Selection

Illustrates how to select a dataset in the American FactFinder 2.

Another way to access the 2010 Census Summary File , is by using the Missouri Census Data Center (Figure 3 and Figure 4). http://mcdc.missouri.edu/cgi-bin/uexplore?/pub/data/sf12010

For more information on which states have been released, please see: http://www.census.gov/2010census/news/press-kits/summary-file-1.html

Figure 3. Missouri Census Data Center Home Page

Screenshot of the Missouri Census Data Center home page.

Figure 4. Missouri Census Data Center Website

Illustrates how to select 2010 Census Summary File 1 tables in the Missouri Census Data Center.


Using 2006-2008 CTPP in Planning for San Juan Light Rail Transit Study

Robert G. Schiffer, AICP, Principal, Cambridge Systematics, Inc.

Planning has been underway for several years on a proposed light rail transit corridor connecting Old San Juan with the region's existing heavy rail system, Tren Urbano. Over the past three years, planning for Tren Liviano, as the light rail corridor is called, has passed from preliminary feasibility through Alternatives Analysis and into the Draft Environmental Impact Study (DEIS) phase. While Tren Livinao is not being proposed for FTA New Starts funding, accurate estimates of potential ridership are critical to receiving local funding and gaining the attention of potential private constructors in a design, build, operate, and maintain project proposal. Data from the CTPP 2006-2008 has been a critical component in quantifying the performance of the regional travel demand model being used for the DEIS.

The regional model being used to forecast ridership had been inherited from a similar study being done on another corridor project within the greater San Juan area. This model had been validated in the absence of recent household travel diary surveys (the last one was conducted in the early 1990s). A series of onboard transit surveys have been conducted recently to quantify model assumptions on transit riders but the CTPP 2006-2008 was the only recent available travel characteristics information on the automobile mode. There were essentially three key areas in which the CTPP was used in refining the San Juan travel demand forecasting model.

First, the CTPP was used as a source for model validation benchmarks on the following statistics:

The above statistics from the model were compared against the same statistics from the CTPP as a part of validation and reasonableness checking.

The second use of CTPP in the San Juan model was related to calibration of trip distribution. In addition to the earlier benchmark statistics, the CTPP was used to check trip distribution performance at a finer level of detail:

Finally, CTPP was useful in developing mode choice calibration targets for an effort focused on adjusting logit model constants to best match HBW mode splits against CTPP observed mode splits. The CTPP targets complimented those from the onboard transit surveys and some generalized statistics from the 1990s era household travel survey.

Below are a few visuals based on comparisons between CTPP and modeled HBW trips.

Travel Time (minutes)

Travel Time (minutes)

Figure 5. Trip Length Frequency Distribution in Minutes

Two line graphs for CTPP Original Data Plot and Smoothed Plot. Click image for source data.

Table 2. Percent Difference Trips between CTPP and Model Output

Percent Difference Trips betwen CTPP vs Model Output

Workplace Total

Percent Destination

Aguas Buenas Municipio

-15%

-7%

Aibonito Municipio

-16%

-8%

Barranquitas Municipio

5%

15%

Bayamõn Municipio

-3%

7%

Caguas Municipio

-11%

-2%

Canõvanas Municipio

-28%

-21%

Carolina Municipio

-17%

-9%

Cataño Municipio

32%

44%

Cayey Municipio

-20%

-12%


CTPP Hotline - 202/366-5000
Email: ctpp@dot.gov
CTPP Listserv:http://www.chrispy.net/mailman/listinfo/ctpp-news
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

AASHTO
Penelope Weinberger
PH: 202/624-3556
Email: pweinberger@aashto.org

Jennifer Toth, AZDOT
Chair, CTPP Oversight Board
PH: 602-712-8143
E-mail: jennifer.toth@azdot.gov

Susan Gorski, MI DOT
Vice Chair, CTPP Oversight Board
PH: 651/366-3854
Email: Gorskis@michigan.gov

Census Bureau: Housing and Household Economic Statistics Division
Alison Fields
PH: 301/763-2456
Email: alison.k.fields@census.gov

Brian McKenzie
PH: 301/763-6532
Email: brian.mckenzie@census.gov

FTA
Ken Cervenka
PH: 202/493-0512
Email: ken.cervenka@dot.gov

BTS
Li Leung
PH: 202/366-0634
Email: li.leung@dot.gov

FHWA
Elaine Murakami
PH: 206/220-4460
Email: elaine.murakami@dot.gov

Ed Christopher
PH: 708/283-3534
Email: edc@berwyned.com

Liang Long
PH: 202/366-6971
Email: liang.long@dot.gov

TRB Committees
Catherine Lawson
Urban Data Committee Chair
PH: 518/442-4773
Email: lawsonc@albany.edu

Clara Reschovsky
Census Subcommittee Co-Chair
PH: 202/962-3332
Email: creschovsky@mwcog.org

Kristen Rohanna
Census Subcommittee Co-Chair
PH: 619/699-6918
Email: kroh@sandag.org

CTPP Listserv

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.


1 The trip lengths were grouped into five minute increments and this was his attempt to smooth out the distribution.

Updated: 04/02/2014
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