Traffic Analysis Zone (TAZ) Program

August 2010

Census Transportation Planning
Products (CTPP) AASHTO Update
Penelope Weinberger, AASHTO,
Pweinberger@aashto.org
CTPP Three-Year ACS Data Products
The Census Bureau has delivered the CTPP
three-year data (2006 to 2008) to AASHTO and
FHWA. AASHTO has delivered the data to
Beyond 20/20 to be imported into the CTPP
Access Software.
CTPP Access Software
Access software for the CTPP based on ACS
three-year data (2006 to 2008) is under development. Software developers Beyond 20/20 and
Citygate have delivered a first prototype version
of the software which is being reviewed. It is
expected to be ready in fall 2010. (More information below.)
CTPP Oversight Board Meeting
The CTPP Oversight Board met on May 4,
chaired by new Oversight Board Chair Jennifer
Finch, Colorado DOT. Jennifer Finch is the
Director of the Division of Transportation
Management and Planning at the Colorado
DOT. She brings a wealth of knowledge and
new energy to the CTPP Program and we welcome her! During the meeting the budget and
work plan were approved. The next Oversight
Board meeting is scheduled for August 25-26.
CTPP Training
The training subcommittee has sponsored and
held a number of webinars and workshops. Two
of the webinars are archived and accessible on
the AASHTO CTPP webpage: Urbanized Areas
(June 11, 2010) and Introduction to CTPP (June
18, 2010). The subcommittee also has developed a framework for e-learning modules for

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

Plan for TAZ delineation in
Spring/Summer 2011
If you are an MPO or State DOT and want
the 2006-2010 CTPP to include tabulations
for Transportation Analysis Zone (TAZ)
and Transportation Analysis District
(TAD), you need to include a TAZ
delineation task in your 2011 work plan.
TAZ delineation software developed by
Caliper will be a GIS-based application and
will not require purchase or license any
additional software. It will be a blockequivalency program.
The TAZ field work will occur in Spring
2011with submissions to the Census Bureau
due in Summer 2011. There will be a
software training session before the field
work starts.
CTPP and AASHTO signed a contract with
MultiMedia for development. E-learning modules are expected beginning in the fall.
CTPP Five-Year ACS Data Products
The first CTPP using ACS with small area
tabulation will use ACS records from 2006 to
2010. AASHTO has been working with the user
community to develop a table request.
AASHTO is now working with Westat (the
contractor for the NCHRP Project 08-79,
“Producing Transportation Data Products from
the American Community Survey that Comply
with Disclosure Rules” to generate a final
request. The data are expected to be released in
2012.
(continued on page 2)

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August 2010

Census Transportation Planning Products (CTPP) AASHTO Update
(continued)
CTPP Web Site:
http://ctpp.transportation.org
CTPP is now on Facebook!
(http://www.facebook.com/pages/CensusTransportation-Planning-ProductsCTPP/114473021912735) While we are excited
about our foray into social networking, we recognize that it is not a substitute for the CTPP

listserv. Some future directions for the CTPP
web site include a searchable, thread-based, user
forum and wiki. Additionally, the web site will
continue to be updated with webinars, files,
tables, articles, e-learning, and eventually the
data and data access software for the CTPP
based on three-year ACS (2006 to 2008).

CTPP Data Access Software
Paul Agnello, Virginia Department of Transportation, paul.agnello@vdot.virginia.gov
AASHTO has contracted with Beyond 20/20
and Citygate for the development and production of the access software for the next CTPP
using American Community Survey (ACS) 2006
to 2008 data. The vendors currently are in the
process of finalizing the software by linking the
browser to CTPP tabulations. The final data
access software with embedded CTPP data will
be released in fall 2010.

The software is primarily a web-based solution,
with a desktop solution using Beyond 20/20
Professional Browser. The software web site
has four essential components, including Quick
Tour, Session Editor, Go to My Session, and Go
to Public Folders (Figure 1).

Figure 1. The Screenshot of the Software Home Page

The Quick Tour provides a lot of valuable information and gives users basic guidance about the software.

August 2010

Page 3

Figure 2. The Screenshot of the Quick Tour

Session Editor connects to the site being developed by Citygate GIS. It is a mapping interface
to allow users to select the geographies and
tables for a new session or edit the contents of
an existing session.
Go to My Sessions opens the data viewing tool
for the user’s personal folders where their session are stored and Go to Public Folders opens
the data viewing tool to the main folder view of

Figure 3. The Screenshot of the Folder View

the site where the user can navigate the Part 1, 2,
and 3 folders to a specific table or perform a
general search of the tables.
The picture below is the screenshot of the folder
view. The folder view lists the themes and subthemes on the left pane. Click on a folder name
to display the contents of the folder in the right
pane. The search function helps users get specific tables quickly by typing the keywords.

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August 2010

The picture below is the table view which identifies the component parts of a report.

Figure 4. The Screenshot of the Table View

New NCHRP Synthesis Project on ACS PUMS
Ed Christopher, FHWA Resource Center Planning Team, edc@berwyned.com
In May 2009, NCHRP synthesis project committee selected 12 new topics under the 41-00
series, among which Topic 42-02, The Use and
Application of the Census Bureau’s Public Use
Microdata Sample by States and Metropolitan
Planning Organizations was initiated. The purpose of this synthesis is to discover who in the
transportation community is using the PUMS

data, what, why and how they are using it, and
identify any data issues encountered. In July,
TRB solicited letters of interest for the synthesis
topics. Later in August, the Project panel will
meet, and a contractor will be selected. For
more information please go to: http://
144.171.11.40/cmsfeed/TRBNetProjectDisplay.
asp?ProjectID=2938.

August 2010

Page 5

Important Dates for 2010 Census
Liang Long, Cambridge Systematics, Inc., liang.long@dot.gov
The 2010 Census count is now complete. The 2010
Census national participation rate by mail was
about 72 percent – the same rate achieved in
Census 2000 and 48 million nonresponse follow-up
(NRFU) households were visited as of July 7,
2010.1

Table 1 shows the important dates for Census
2010 products.2

Table 1. Census 2010 Data Product Release Schedule

Planned
Release Date

Lowest-Level
Geography

Data Product

Data Product Explanation

February 2011March 2011

Census Redistricting Data
(P.L.94-171) Summary File

Population counts for race and Hispanic or
Latino categories; housing unit counts by
occupancy status.

March 2011February 2012

2010 Census Briefs

Topics based on 2010 Census questions;
similar to the Census 2000 Briefs series.

May 2011

Demographic Profiles

Selected population and housing
characteristics.

June 2011June 2013

2010 Census
Special Reports

Detailed analysis of topics, including
graphs, tables, and maps; similar to the
Census 2000 Special Report series.

Largest Places

June 2011August 2011

Summary File 1 (SF 1):
state files released on a
rolling basis from June to
August 2011

Population counts for many detailed race
and Hispanic or Latino categories, and
American Indian and Alaska Native tribes;
selected population and housing
characteristics; similar to the Census 2000
SF1.

Blocks/
Census Tracts

December 2011April 2012

Summary File 2 (SF 2):
state files released on a
rolling basis from December
2011 to April 2012

Population and housing characteristics
iterated for many detailed race and
Hispanic or Latino categories, and
American Indian and Alaska Native tribes.

Census Tracts

To be determined

Public Use Microdata
Sample (PUMS) Files

Includes age, sex, race, Hispanic or Latino
origin, household type and relationship,
and tenure data with identifying
information removed.

PUMAs of 100,000+
Population

1 U.S. Census Bureau: http://2010.census.gov/2010census/take10map/.
2 U.S. Census Bureau: http://www.census.gov/population/www/cen2010/glance/index.html.

Blocks

Largest Places
Places/Functioning
Minor Civil Divisions

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August 2010

NCHRP 08-79: Current Research Efforts to Minimize Effects of Disclosure in
the CTPP
Tom Krenzke, Westat, krenzkt1@westat.com
The NCHRP 08-79 research project is entitled
“Producing Transportation Data Products from
the American Community Survey (ACS) that
Comply with Disclosure Rules.” The goal is to
develop a practical approach to perturb ACS
data to allow for small area CTPP tabulations.
The results must satisfy the disclosure rules set
by the Census Bureau’s Disclosure Review
Board (DRB). The main disclosure avoidance
practice that has been used on certain CTPP
tabulations was cell suppression. It is clear that
the data loss at finer geographic areas, such as
planned Transportation Analysis Zones (TAZ)
will be substantial on five-year ACS data if the
same disclosure avoidance rules are applied,
because there are fewer underlying data records
than in the Census 2000 long-form data. For
this reason, efforts are now focused on ways to
generate a complete set of data consisting of
perturbed values that strive to retain the usability
of the CTPP tabulations.
The project began in January 2010 and is to be
completed by July 2011. We began the research
by holding discussions with transportation planners, as well as the Census DRB, and Census
operations staff. These discussions resulted in
an initial set of research tables and variables,
involvement of Metropolitan Planning
Organizations (MPO) as test sites, clarification
on DRB disclosure threshold rules, and identification of source data, including ACS imputation
flags, and swapping flags and other data needs.
After reviewing several data perturbation
approaches, three techniques were selected for
testing. The three approaches include parametric unit-level modeling, semiparametric modelassisted approach, and controlled random
swapping.
In our work so far, we now recommend splitting
the set of CTPP tables into two. The Set A
tables are tables that do not have DRB threshold
rules and will be constructed using the ACS
weights and variables, and the usual rounding

rules will apply to the cell estimates. The Set B
tables are tables where DRB threshold rules
apply and will be constructed using CTPP
adjusted weights (from this research’s weight
adjustment procedure) and the perturbed
variables. Since the Set B tables use the disclosure protected microdata, the current plan is that
the DRB threshold rules will be lifted.
An initial risk assessment has identified records
and variables at most risk of disclosure. The
risk analysis shows that for some variables
(those involved in cell means or aggregates, and
those in Part 3 flow tables), about 40 to 50 percent of records would be impacted by a violation
of a DRB rule. The perturbation approaches will
target records and variables identified as being at
most risk.
Currently, we are in the development and evaluation phase. We are testing the process in four
locations: Atlanta, Iowa, Madison, and
St. Louis. The tests include two different
amounts of perturbation: full replacement of all
data values, and partial replacement. The
resulting perturbed datasets will be compared to
the ACS data for cell means, standard errors,
weighted counts in two-way tables, and multivariate associations. We are requesting travel
demand model data from the MPO and state
DOT test sites. Once collected, a comparison
will be done on the perturbed and ACS data with
travel model outputs. Also, to balance data utility with disclosure risk, plans for disclosure risk
measures have been developed. The evaluation
results will be used to determine the best
approach for moving forward.
This fall, the selected approach will undergo a
validation phase, where it will be processed
using preliminary five-year ACS data on four
new test sites. Once the validation is completed,
work will begin to prepare for the full nationwide implementation on the ACS 2006 to 2010
data.

August 2010

Page 7

Urban Areas
Ed Christopher, FHWA Resource Center Planning Team, edc@berwyned.com
The areas designated as Urban by the Census
Bureau are important to the transportation community for several reasons. First, they set the
population count for many of the Federally
funded programs. Second, they set the population count for determining which areas will need
to designate a Metropolitan Planning
Organization (MPO) and which areas will be
designated Transportation Management Areas
(TMA). An MPO must be designated for each
urban area with a population of more than
50,000 people. The MPO boundary must
include the urbanized area as a minimum, plus
the area that is expected to be urbanized in the
20-year (minimum) horizon. A TMA is an area
designated by the Secretary of Transportation,
having an urbanized area population of over
200,000, or upon special request from the
Governor and the MPO designated for the area.
For more information on what the Census
Defined Urban Area boundary means to the
transportation community refer to http://
www.fhwa.dot.gov/planning/census/
faqa2cdt.htm.
Urban Areas are defined by the Census Bureau
based on population density. The term Urban
Area (UA) refers collectively to the Urbanized
Areas (UZA), areas over 50,000 people, and
Urban Clusters (UC) with a population between
2,500 and 49,999 people. The Census Bureau
will redefine the Urban Areas using the 2010
decennial Census. A Federal Register notice
soliciting comments on the criteria is expected in
August 2010. The Census Bureau will define
Urban Areas starting in spring 2011 and publish
them in spring 2012.
On June 12, 2010, FHWA Resource Center and
CTPP team hosted a webinar on “CTPP –
Census Bureau’s Planning for Urbanized
Areas.” The webinar featured a presentation and
discussion on the Census Bureau’s plans for the
delineation of 2010 Urban Area (UA) boundaries as well as staff from FHWA who brought
the transportation perspective. The recorded
webinars and Q and As are posted on the
AASHTO CTPP web site:
http://ctpp.transportation.org/pages/
webinars.aspx.

“State of Metropolitan America”
Report by Brookings Institution
http://www.brookings.edu/metro/StateOfMet
roAmerica.aspx.
Brookings Institution released their report of
“State of Metropolitan America,” which
focuses on the 100 largest metropolitan
areas. One chapter is devoted to commuting.
Driving alone remains the primary
commuting mode in America, representing
75.5 percent of all commuters. For the first
time in 40 years, transit increased as a share,
from 4.6 percent in 2000 to 5.0 percent in
2008. Carpooling continued to decline, and
walking also continued to decline. Given all
these trends, the incremental changes in
commuting patterns evident in the 2000s
means more must be done to reach any
meaningful reductions in carbon emissions.
Only 14 metro areas have transit commuting
rates higher than the national rate of five
percent. Both the New York-Newark, New
York-New Jersey-Pennsylvania, and the
Washington-Arlington-Alexandria, D.C.Virginia-Maryland-West Virginia
metropolitan areas had an increase of over
two percent in the share of workers
commuting by public transit between 2000
and 2008.
The report also points out that regional
differences distinguish metropolitan
commuting modes, and residents of cities
and older, high-density suburbs are more
likely to use transit than commuters in other
parts of metro areas. Foreign-born workers
are very likely to use public transit whether
they live in primary cities or in suburbs.
Areas with large Hispanic population,
continue to report the highest carpooling
rates. As carpooling declined nationally in
the 2000s, only Dayton, Ohio among the 100
largest metro areas showed an increase of
two percent in carpooling.

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August 2010

CTPP Hotline – 202/366-5000

E-mail: ctpp@dot.gov
CTPP Listserv: http://www.chrispy.net/mailman/listinfo/ctpp-news
CTPP Web Site: http://www.dot.gov/ctpp
FHWA Web Site for Census issues: http://www.fhwa.dot.gov/planning/census
2005 to 2007 ACS Profiles: http://ctpp.transportation.org/profiles_2005-2007/ctpp_profiles.html
AASHTO Web Site 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
E-mail: pweinberger@aashto.org

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

Jennifer Finch,
Chair, CTPP Oversight Board
PH: 303/757-9525
E-mail: jennifer.finch@dot.state.co.us

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

Jonette Kreideweis, MN DOT
Vice Chair, CTPP Oversight Board
PH: 651/366-3854
E-mail: jonette.kreideweis@dot.state.mn.us
Census Bureau: Housing and Household
Economic Statistics Division
Alison Fields
PH: 301/763-2456
E-mail: alison.k.fields@census.gov
Brian McKenzie
PH: 301/763-6532
E-mail: brian.mckenzie@census.gov
FTA
Ken Cervenka
PH: 202/493-0512
E-mail: ken.cervenka@dot.gov

Liang Long
PH: 202/366-6971
E-mail: liang.long@dot.gov
TRB Committees
Catherine Lawson
Urban Data Committee Chair
PH: 518/442-4773
E-mail: lawsonc@albany.edu
Clara Reschovsky
Census Subcommittee Co-Chair
PH: 202/962-3332
E-mail: creschovsky@mwcog.org
Kristen Rohanna
Census Subcommittee Co-Chair
PH: 619/699-6918
E-mail: 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 website also
includes an archive of past e-mails posted to the listserv.