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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

CTPP Status Report

January 2005

CTPP 2000 Release (almost) Complete

CTPP 2000 data release is 99 percent complete. Final versions of Part 1 (Place of Residence) and Part 2 (Place of Work) data were mailed to State DOTs and MPOs in 2004. Part 3 (Journey-to-Work Flow) data in flat ASCII file formats were released in May 2004. The Part 3 data in IVT format and software are close to completion, and should be in the mail in the next two weeks.

The CTPP Access Tool (CAT) is a user-friendly software that allows you to easily find, browse, thematically map, and export CTPP 2000 data to various formats including DBASE, MS Excel Spreadsheet, ASCII text, and ESRI Shapefile formats. The data CD-ROMs are packaged with this software. Page 7 of this status report provides more information on the CAT. Additional copies can be ordered online for free from the BTS Bookstore at

The Bureau of Transportation Statistics (BTS) has developed an FTP site at their TranStats portal to host data for all three parts in flat ASCII format. These files are separate from the data on the CD-ROM, which come in proprietary IVT format. SAS programs are available along with the documentation to read these ASCII files. BTS staff are also working to post the data on their TranStats web-based data retrieval system, which will allow users to query specific geographies, tables, and cells, and download them in CSV format. To access data online, please visit click on FHWA and on CTPP 2000.

For easy access to key characteristics, two-page profiles for place of residence, and place of work are posted on the AASHTO website at

CTPP 2000 Related Activity at the 84th TRB Annual Meeting

(January 11-15, 2004 Washington DC)

We hope to see many of you at the TRB Annual Meeting. The following sessions/meetingsare scheduled. In addition, staff will also be present at the CTPP Booth at the Marriott Wardman Park Hotel from January 9 - January 12, 2005.

Travel Data Users Forum

Hilton, Monday, January 10, 2005, 10:15 AM-12:00 PM

Urban Transportation Data and Information Systems Committee (ABJ30) Meeting

Hilton, Monday, January 10, 2005, 1:30 PM-5:30 PM

Census for Transportation Planning Subcommittee (ABJ30(1)) Meeting

Hilton, Monday, January 10, 2005, 7:30 -9:30 PM

American Community Survey: Challenges and More Challenges (Session)

Hilton, Tuesday, January 11, 2005, 1:30 PM-3:15 PM

TRB Conference on Decennial Census and ACS Data for Transportation Planning, May 11-13, Irvine, California

The TRB conference on Decennial Census and ACS Data for Transportation Planning is scheduled for May 11-13, 2005 in Irvine, California. The conference will provide a forum for the transportation community to meet, discuss and provide feedback on the decennial census and the American Community Survey.

While the benefits and problems with Census 2000 and CTPP 2000 will be discussed, the conference will be forward looking as the Census Bureau has now begun the full implementation of the American Community Survey. Participatory workshops will be a key component of the conference. For more information, please visit

Call For Posters

Posters are sought for the conference on the applications of Census 2000, CTPP 2000, and the ACS. Proposals are due on January 21, 2005 to

Qualifying public-sector posters are eligible for limited travel support to the conference.

U.S. Census, CTPP, And NHTS Data Used in the Des Moines Area MPO's Travel Demand Model

By Adam Noelting, Des Moines Area MPO


The Des Moines Area Metropolitan Planning Organization (MPO) serves a Planning Area population of 395,174, from fifteen member cities and portions of three member counties. In 2000, the Des Moines Metropolitan Statistical Area (MSA) consisted of three central Iowa counties: Dallas, Polk, and Warren. The release of the 2000 U.S. Census data revealed that two additional counties would join the classification of the Des Moines MSA: Madison and Guthrie.

Data Used

Decennial Census

CTPP 2000 Table 1-063: Household Size by Vehicles available, Table 2-002: Sex by Mode to Work

Summary File 1 Table Number P015001: Total Households

NHTS 2001

Trips by Trip Purpose, Trip length distribution

Third Quarter 2000 Iowa Workforce Development (IWD) ES202 database

The Des Moines Area MPO began the process of updating the long-range transportation plan to Year 2030. This update necessitated the need for a new travel demand model. The Year 2000 was selected as the calibrated model base year largely due to the release of the 2000 U.S. Census data, the 2000 Census Transportation Planning Package (CTPP), and the Des Moines Area MPO's purchase of an add-on survey to the 2001 National Household Travel Survey (NHTS).

Trip Generation

Trip generation is the travel demand modeling step involving locating zones where trips are generated and, in turn, locating zones where generated trips are attracted. This process is often completed by identifying places of residence and places of employment, commonly expressed as socioeconomic data, and assigning those places to a geographic location.

Socioeconomic data was assembled and assigned to Traffic Analysis Zones (TAZ) using population and household data from the 2000 U.S. Census Summary File 1 (SF 1) at the census block geographic level. The census blocks were aggregated into TAZs and summed to establish Base Year 2000 total population and total number of households for each individual TAZ within the Des Moines metropolitan area.

Another vital piece of the socioeconomic data was employment. TAZ level data for Base Year 2000 total employment was obtained from the Third Quarter 2000 Iowa Workforce Development (IWD) ES202 database. Using the CTPP Part 2: Data by Place of Work allowed for the comparison of the ES202 data to the CTPP 2000 Part 2's estimate of total number of workers by place of work.

The CTPP 2000 Part 2 data were not available in time to be used during the socioeconomic data assignment to TAZs. As observed in previous CTPP Status Reports, Workers-at-work counts obtained from CTPP are usually smaller than total employment. In the Des Moines metropolitan area, the CTPP 2000 Part 2 workers-at-work counts were lower than data provided by the Third Quarter IWD ES202 database by nearly five-percent.

In early 2000, the opportunity to participate as an add-on to the 2001 National Household Travel Survey (NHTS) arose. Household Travel data had not been collected since the 1960's. To update the data, the Des Moines Area MPO chose to purchase 1,200 of the 2001 NHTS Add-on surveys for a four-county area including, Polk, Dallas, Warren, and Madison Counties. Data from 1,231 households were collected.

The Des Moines Area MPO's cross-classification is based on household size (1, 2, or 3+) and number of automobiles available (1, 2, or 3+). These cross-classified households then were analyzed to determine updated cross-classification trip production rates.

The CTPP 2000 Part 1 Data by Place of Residence, Table 1-063 was used to determine the estimated number of households in each category. The estimated number of households were conjoined with the updated cross-classification trip production rates to calculate the total number of productions for each TAZ. Data from the 2000 CTPP Part 1 Table Number 1-063 was extracted at the TAZ level.

Table 1-063: 4-County Totals in Des Moines Area

Households by Vehicles Available in Households
Household Size 0-veh 1-veh 2-veh 3+ Veh
1-person 7,485 34,5206,160 1,475
2-person 2,210 13,360 37,495 10,010
3+ Persons 1,640 10,560 35,290 24,730

A frequency distribution diagram of trip lenghts. The picture shows model percent, survey percent, and survey trend line.

CTPP 2000, Table 1-063, and 2000 U.S. Census SF 1 Table Number P015001 for households were used with trip production rates to determine the total number of trips for each TAZ. The total number of NHB, HBO, and HBW trips then were compared to the weighted results from the 2001 NHTS Add-on.

Trip Distribution

Trip Distribution is the travel demand modeling step by which the production trips for each zone are linked to the attraction trips for each zone. The production and the attraction trips are balanced and are distributed among TAZs based on distance and on travel times.

The 2001 NHTS Add-on data was used during the trip distribution step to replicate the reported trip lengths. The 2001 NHTS Add-on trips were tabulated by trip purpose and graphed, to create a trip length frequency distribution. Friction factors were created using the trip length frequency distribution and applied to the travel demand network to attempt to replicate the trip lengths reported in the 2001 NHTS Add-on. Modeled results closely matched the 2001 NHTS Add-on results.

Mode Choice

Mode Choice is the travel demand modeling step to determine what mode of transportation will be utilized for each trip. Mode choice or mode split modeling is commonly used to determine the percent of trips by means of public or alternative transportation.

The 2001 NHTS Add-on survey also was analyzed to determine amount of alternative transportation usage. The 2001 NHTS Add-on results indicated alternative transportation usage accounted for less than one-percent of all trips. Data from the CTPP 2000 Part 2 Table Number 2-002 also was analyzed to determine alternative transportation percentage for work trips. Four different modes of transportation were examined: automobile, bus, bicycle, and walking. The extracted data from Part 2 estimated alternative transportation accounted for less than five-percent of all work trips in the Des Moines metropolitan area. Part 2 Table Number 2-002 showed that bus trips made up less than two-percent of all work trips. The table also showed that walking and bicycle trips combined for two-percent of all work trips. Results from the CTPP 2000 Part 2 were similar to findings from the 2001 NHTS Add-on.


The Des Moines Area MPO found the 2000 U.S. Census, CTPP 2000, and the 2001 NHTS Add-on datasets and tabulations very useful in calibrating and validating its travel demand model and in describing travel in the Des Moines metropolitan area. Datasets and tabulations from the 2000 U.S. Census and the CTPP 2000 permitted assignment of socioeconomic data within each TAZ, cross-classification of socioeconomic data within each TAZ, and calculation of productions and attractions within each TAZ.

To continue monitoring the travel patterns of the Des Moines metropolitan area and improve the travel demand model, the Des Moines Area MPO hopes to participate in the next NHTS as an Add-on, and looks forward to future Census Bureau data releases.

Use of 2000 Decennial Census Data in Transportation Planning

Nanda Srinivasan, Cambridge Systematics Inc.

Census 2000 data are used for many diverse planning applications. A search on the Internet revealed several.

Corridor development and Environmental Justice (EJ) Analyses

The Missouri DOT has a Socio-economic Indicator Resource system that is a user-friendly interface for several profiles including race and Hispanic origin, age, gender, poverty status and income, rent and housing value, mode to work and vehicle availability, and a few others. These profiles can easily be used for Environmental Justice analyses. A complete listing of Missouri DOTs use of Census data is compiled in Lance R. Huntley et. al, 2003. [1]

The Missouri DOT has also used census data for corridor studies. The Missouri DOT analyzed the corridor along Highway 65 running from Buffalo, Missouri to the Arkansas and Missouri border. The route was buffered in 5,10, 20 and 30-mile increments.[2] Detailed socio-economic data (same variables as listed above) for Census Block Groups was aggregated for these buffers in a GIS environment. Thus, an estimate of households in poverty, or other variables, along the corridor was easily captured and displayed.

Long Range Plans and Comprehensive Plans

Many MPOs use Census data for understanding demographic growth and changes. Census data are commonly used as baseline values for forecasts which are used in long range transportation plans, transportation improvement plans, comprehensive plans, and regional pedestrian and bicycle plans. Some examples include Northwestern Indiana Regional Planning Commission's "Connections 2030 - Regional Transportation Plan", Johnson City (Tennessee) MPO Long Range Transportation Plan, and the "Broward County Comprehensive Plan". [3] ,[4] ,[5]

While the location of population growth is one concern, changes in the demographic characteristics of neighborhoods over time, and how these changes influence travel demand are also relevant to planners. For example, a new suburban development might attract many young families, and older suburbs may have fewer children, with larger proportions of older, retired couples or older people living alone. Often in travel demand models, these are reflected by household size combined with number of workers as demographic characteristics.

Trend Analysis

One of the advantages of Census data is that it has been available consistently over many decades. Trend analyses include examination of mode to work, county-to-county flows, as well as smaller area flow patterns, and changes in commute travel time. The Puget Sound Regional Council in Seattle regularly issues "Puget Sound Trends" which often includes Census data. For example, in the Seattle region, the transit share to the Bellevue CBD increased from 4.7 percent in 1980 to 8.0 percent in 2000.

In Utah, commutes of 45 minutes or longer increased from 7.3 percent of commutes in 1990, to 9.6 percent of commutes in 2000. These changes in travel time were examined in context with the county-to-county flow patterns, showing increases in commute trips outside of one's residence county. [6] ,[7]

Model development

The VA DOT Statewide Transportation model took the Census Journey to Work worker flows and adjusted them to represent HBW trips. The Virginia State Wide model documentation is available at:

Several other examples of the use of CTPP in model development are shown in this issue of the status report.

Transit Planning

Many transit agencies combine Census (CTPP) with attitudinal data from household surveys to better understand their transit markets. For example, the Utah Transit Authority combined attitudinal data from a household survey with small area Census 2000 data to create the market segments/clusters to better understand their different markets of transit users. [8] These clusters were used to study potential transit markets, and generate profiles of transit users.

Cambridge Systematics (CS) used similar approaches in structural equations modeling work performed for the San Diego Association of Governments (SANDAG ), SamTrans Strategic Plan, I-580 BART study, and the San Francisco Water Transit Authority. In the case of the San Francisco Water Transit Authority, the clusters were used to analyze the potential for a new ferry service.[9]

What should I do when I get my CTPP CD?

By Ed Christopher, FHWA Resource Center

With the Part 3 flow tabulations coming out; users of the CTPP Access Tool (CAT) software will need to update the CAT browser "viewer software" that they have been using. The new viewer due out with Part 3 works with all three parts and should replace the earlier versions. While loading the new browser software and adding the Part 3 data, it would be a good time to look at your CTPP directory structures and file organization. Here are a few things I did to keep things organized.

When you put the CTPP CD-ROM in your drive, the screen shown below should appear. If it does not, it means your "autorun" is not turned on, so you need to find the 'start.exe' file on the CD and run it.

I highly recommend that you go through the tutorial and read the documentation and "About CTPP2000", but you might want to experiment with the viewer first.

To load the "viewer software" just click on it. I recommend letting it load by accepting all its defaults. This is the application software and it runs best if it resides with all your other program files on the C:/ drive. If you run your operating system software off a different drive letter, for example, in a network situation, you will have to make a change in your registry file assuming a Windows installation. Since this is application software, you may have to get rights to load it on to your computer.

Looking at the opening "blue" screen, the next task would be to click on the "Install Database" area. DON'T DO IT! It will only end up installing the CTPP tables that you select. I will show you what I did.

Picture of the front screen of the CTPP Access Tool

Organizing the files

It is at this juncture where the real organization comes in. After loading the application software on my C:/ drive I next went to my separate data drive which I call G:/ and created a folder for my "ctpp data" with 5 sub folders underneath it--One for Part 1, one for Part 2, Part 3 and one for the documentation and most importantly, one for the sessions that I will be creating with the CTPP data. After creating these subfolders it became a simple task of going to CTPP CD that I wanted and dragging the state directory over for a specific part.

For quick one time uses, keeping the original data on the CD might be best, but moving the data to your hard drive can be extremely useful if you plan to have repeated use across all parts. It will also make it easier when working in multi-state regions.

A word on file structures

When looking at the files on the CTPP CD for a particular state you will notice there are tables and a subfolder called shapes. "Shapes" contains the geographic layers or coverages used by the software. Although it looks to be duplicative that each Part contains shape files, I learned the hard way that you need to keep the Part 1 shape files with Part 1, Part 2 shape files with Part 2, and Part 3 shape files with Part 3. While there is a great deal of commonality between the parts, there are summary levels that are unique to each part. For example, PUMA level data are published in Part 1, but not in Part 2.

For further help or guidance with your CTPP data feel free to give Nandu Srinivasan a call at 202-366-5021 or drop us an email at

Picture of Ed's file folder contents

Use of Census Transportation Planning Package (CTPP) Data To Update the Kentucky Statewide Traffic Model

By Scott Walker, Wilbur Smith Associates, and Amy Thomas, Kentucky Tranportation Cabinet

In early 2003, the Kentucky Transportation Cabinet (KYTC) contracted Wilbur Smith Associates (WSA) to update the Kentucky Statewide Traffic Model (KYSTM). The model, currently under development, uses Census Summary File 1, and Census Transportation Planning Package (CTPP) data, as well as other data sources.


Kentucky took advantage of the TAZ-UP program to define TAZs to be easily used in urban models for MPO areas and small urban areas (SUA) (48 counties in KY). In addition, the KYSTM TAZs were defined for an additional 72 rural Kentucky counties. In 2002, the Census Bureau provided an option to define an additional level of geography in the MPO and SUA counties called "Combined Zones". Kentucky was one of the few states to take advantage of the Combined Zones effort, and defined KYSTM TAZs using Combined Zones in the 48 MPO and SUA counties. There were two (2) major goals for the Combined Zones project:

  1. Refine TAZs for the KYSTM to provide more detail through Kentucky; and,
  2. Re-define census geography for CTPP to match the KYSTM TAZ system.

As part of the current update to the KYSTM, a much more detailed GIS network was created. To account for the improved detail, smaller TAZs were defined particularly in the transitional areas between an urban area and a rural area.

Population / Household Data

Census level population and household data were obtained through use of Census 2000 Summary File 1 data at the CTPP TAZ or Census block level. These smaller levels of geography were then aggregated as necessary to obtain population and household totals for each of the new 3,644 KYSTM TAZs within Kentucky. Household data was used to estimate the number of home-based other (HBO) and non-home based (NHB) trips within Kentucky.

CTPP Review

As part of the update to the KYSTM, WSA reviewed the CTPP data for Parts 1 (residence), Part 2 (workplace), and Part 3 (flow between home and work). Initially, the Part 3 data did not include the Combined Zone information established for Kentucky but this was resolved by working with CTPP staff at the Census Bureau and FHWA.

Journey-to-Work Data

CTPP worker data were used to establish a home-based work (HBW) trip table for the KYSTM. The difference between a statewide model and an urban model is that urban models often use HBW trip rates for trip generation. However, in the case of the KYSTM, all HBW trips were based on CTPP worker counts. Factors were applied to the CTPP data to convert it to a HBW format.

The CTPP Part 3 data, in flat ASCII format, were downloaded from the Bureau of Transportation Statistics website ( For the KYSTM, Part 3 data was obtained for the entire state of Kentucky including all worker flows that either originate or terminate in Kentucky, or both.

Part 3 data for 2 different summary levels were used: Summary Level 140, at the census tract level, and Summary Level 944, at the Combined Zone geographic level. Geographic regions outside of the state were represented at the census tract level.

Correspondence tables were created in order to match data from the CTPP Combined Zone geography level into the new zone system defined for KYSTM.


As noted, the update to the KYSTM is not yet complete. However, the CTPP data has been an important component in updating the KYSTM, and it will continue to be an important component in all model efforts in Kentucky in the future.

Use of CTPP data in the Cook-DuPage Corridor Study

By Krishnan Kasturirangan and Kimon Proussagloglou, Cambridge Systematics Inc.

The Cook-DuPage Travel Market Analysis is the first of three phases of the Cook-DuPage Corridor Study. The primary objective of this phase is to understand the transportation users in the corridor, their current and projected travel patterns, and the constraints and deficiencies of the corridor transportation system in serving travel needs. The study is for the Regional Transportation Authority (RTA). Several local agencies and more than 50 local governments are key partners in this effort. Cambridge Systematics (CS) has been contracted to complete the work.

The Travel Market Analysis will identify, analyze and quantify travel demand and transportation supply within this corridor. The study will guide the identification and selection of priority markets for mobility improvements within the corridor.

The analysis first examines who uses the transportation system focusing on historical changes in both population and employment and summarizes the expected growth patterns. The existing transportation system in the corridor is examined from a multimodal perspective by reviewing the existing highways and major arterials, commuter rail, rapid transit, fixed bus routes, paratransit services and bicycle facilities. To examine the planned transportation system, the Region's Transportation Plan for 2030 is then reviewed.

County-to-county travel patterns obtained from the U.S. Census dating back to 1970 provide a broad-brush picture of how people travel to and from different areas in the corridor. The six counties in the analysis area included Cook, DuPage, Lake, McHenry, Kane, and Will Counties. From the large geographic perspective of county-to-county flows, the focus then shifts to a finer geographic detail.

1990 CTPP, and CTPP 2000 Part 3 data have been used by both CS and RTA staffs to analyze the journey-to-work patterns of resident commuters in the 6-Counties. Urban CTPP data at the traffic analysis zone (TAZ) level were used to analyze the journey-to-work travel patterns. Then, these data were aggregated to the CATS MPO planning zone system for comparisons with non-work travel data. Travel flow tables at different geographic levels were made for both the corridor and for the region as a whole.

Using this method, key travel patterns were identified representing:

One benefit of the CTPP data was the ability to look at the origin-destinations flows in combination with the mode use.

In addition to the Census data, other data on the current use of the multimodal network include traffic data, including volume, travel time and speed by direction and time of day, the extent of highway congestion. For the transit system, local data on ridership, level of service and on-board transit surveys were used to provide a profile of commuter rail, rapid transit, and bus transit.

Finally, population, employment and travel trends and regional projections were examined to help assess the future demand on the transportation system. Outputs from the NIPC socioeconomic forecasts and the CATS regional travel model for the forecast year 2030 are used to help evaluate future travel patterns.

These analyses set the stage for identifying the characteristics of potential transportation improvements needed throughout the corridor. These findings will be used as input into Phase 2 of the Cook-DuPage Corridor Study that will focus on establishing a short list of feasible options.

[1] Lance R. Huntley, M.S., Tracy Dranginis, Ph.D., and Ernie Perry, M.S. "Development and Use of Social and Economic Data at MoDOT." Missouri Department Of Transportation, Research, Development And Technology, August 2003, posted online at

[2] See, January 29, 2003

[3] Johnson City MPO Long Range Transportation Plan, "Chapter 2: Growth and Regional Change." Available online at (August 15, 2001)

[4] Available online at (November 8, 2004)

[5] (September 28, 2004)

[6] Puget Sound Regional Council, "Puget Sound Trends" See Nos. T1, T18 and T22.

[7] Perlich, P., 2003, "Commuting Patterns in Utah: County Trends for 1980, 1990, and 2000." Utah Economic and Business Review.

[8] Cambridge Systematics Inc., "Attitudinal-Based Market Research." Prepared for Utah Transportation Authority, December 2003.

[9] Personal Correspondence with Chris Wornum, Cambridge Systematics Inc.

CTPP Hotline -202-366-5000

CTPP Website:
TRB Sub-committee on census data:
FHWA Website for Census issues:
CTPP for 1990 and 2000 downloadable via Transtats:
CTPP Place of Residence Profiles: http://www.transportation.orglctpp/homeldefault.htrn
Order CTPP 2000 CD-ROM with Software:

Elaine Murakami
PH: 206-220-4460 (in Seattle)
Dave Clawson
PH: 202-624-5807

Nanda Srinivasan
PH: 202-366-5021

Census Population Division
Phil Salopek
PH: 301-763-2454
Ed Christopher (Urban Data Committee Chair)
PH: 708-283-3534

Clara Reschovsky
PH: 301-763-2454

Eric Pihl
PH: 202-366-6048
TRB Committees
Ed Christopher (Urban Data Committee Chair)
See under FHW A
Pheny Smith
PH: 202-366-2817
Email: pheny
Bob Sicko (Census Subcommittee Chair)
Mirai Associates
PH : 425-415-0905

CTPP Listserve

The CTPP Listserve serves as a web-forum for posting quesitons, and sharing information on Census data. Currently, over 700 users are subscribed to the listserve.

To subscribe, please register by filling a form posted at:

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.

For questions on the listserve, please e-mail Ed Christopher at

Updated: 04/02/2014
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