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Census Transportation Planning Products

Results from the CTPP User Survey (AASHTO), October 2005

1. Introduction

The CTPP User Survey was conducted by AASHTO from September 1 - September 15, 2005. This survey was about customer use and level of satisfaction with CTPP 2000. In addition, users were asked their expectations and concerns as we transition from using decennial Census "Long Form" data to using the ACS data. The survey is available at

81 staff from various organizations responded to the survey. The breakdown of the survey respondents by type of organization is shown in Table 1:

Table 1. Response by Type of Organization (Total = 81)

[Not Answered]
Other (please specify
State DOT
Small MPO (Serving 50,000 to 199,999 people)
Large MPO (Serving 500,000 or more people)
Medium MPO (Serving 200,000 to 499,999 people)
Transit Operator
Local government (city/town)

A majority of the respondents (73 percent) had considerable previous experience (5 or more years of experience) with Census data (Table 2).

Table 2. Number of Years of Using Census Data

Years of experience Number
[Not Answered]
2 to 4 years
5 to 9 years
10 or more years
Less than 2 years

A majority of the users used Census products such as Summary File 1, Summary File 3, and CTPP (Table 3). Over half the respondents seemed unaware of the redistricting file, the Public Use Microdata Sample (PUMS) file, or any of the CTPP profiles, and publications.

Table 3. Users of Census Related Products

Product Number of Users Percent
Summary File 1
Summary File 3
CTPP Part 1, Place of Residence Data
CTPP Part 2, Place of Work Data
CTPP Part 3, Journey-to-Work Flow Data
County-to-County Worker Flows
CTPP Place of Residence Profiles
P.L 94-171 (redistricting) Data File
CTPP Place of Work Profiles
Journey-to-Work Trends Report
Public Use Microdata Samples (PUMS)

2. Poor Ratings on timeliness, and Disclosure Issues

A clear majority of the respondents felt that data was delivered late by the Census Bureau, and that rounding and threshold issues constrain the use of the data (Table 4). Although many respondents expressed dissatisfaction with TAZ-UP, and the CTPP browser, a majority of the respondents liked these programs. Other data issues such as worker counts, and accuracy of workplace geocoding, had relatively higher percent of respondents with complaints, compared to respondents who were satisfied.

Table 4. Issues where respondents were most dissatisfied

Q Title % Satisfied % No opinion % Not Satisfied
6a Timeliness of delivery of CTPP tables by the Census Bureau
11a Rounding (to nearest 5 for most cells)
11b Thresholds (requirement for 3 unweighted records for most Part 3 flow tables)
10a TAZ-UP for defining Traffic Analysis Zones into TIGER/Line
11c Worker Counts
11d Accuracy of Workplace Geocoding
5b Viewing (browsing) the table
5a Finding appropriate table
5c Mapping
5d Exporting

3. Good Ratings for Communication, Table content, Website access, and Training

Many users rated CTPP content, website access, and communications issues highly (Table 5). The CTPP Status Report, Listserve, and technical support by e-mail are all clearly well liked by the users.

Table 5. Issues where respondents were mostly satisfied

Q Title % Satisfied % No opinion % Not Satisfied
9d CTPP Status Report
9c CTPP listserv
9a Technical assistance by email
7a Variables used
7c Variable categories
5b Viewing (browsing) the table
7b Cross-tabulations
8 Geographic Detail (often called "Summary levels") in CTPP 2000
5a Finding appropriate table
5d Exporting
6b Ease of TranStats website for access to CTPP 2000 data
9f Hands-on computer workshops
10a TAZ-UP for defining Traffic Analysis Zones into TIGER/Line
9b Technical assistance by telephone
9e CTPP Electronic Guidebook
6d Ease of ordering CTPP 2000 CD-ROMs using the BTS/RITA Bookstore (web)
9g Conference presentations

4. Opinions

Among the opinion issues, most users fully support another CTPP-like product based on ACS (Table 6). A majority of the users solely depend on the journey-to-work flow for their home-to-work flow matrices. A number of respondents are yet to use ACS data, and expressed concern about the quality of ACS data.

Table 6. Opinions on ACS, CTPP, and Small area employment data

Q Title Agree No Opinion Disagree
12c I fully support another CTPP-like product based on ACS
12a I know about and understand the basics of the American Community Survey (ACS)
12b I have yet to use any data from the ACS
12e The Census data are my only source for home-to-work flow matrices
12g I need more training on ACS
12j I have time to analyze the Census data and use them for planning activities
12i I have sufficient staff resources to use Census data for analytic purposes
12h I have other sources of small area employment data
12d I think the ACS will meet my planning data needs as well as the long form did
12f I rarely use the small area (TAZ) workplace data from the CTPP

Many respondents wrote their general issues in a write-in box. These comments are shown in Appendix A.

Appendix A

Question 13: Add-In Comments

Have sufficient detail and accuracy in the Part3 flows by mode at the TAZ level - as in 1990, but not in 2000.

Keep mode categories consistent across all Census products, especially grouping of bike/walk and transit/taxi/motorcycle. More categories, the better.

similar to current CTPP products

zip-code based data

"Two issues: a public file and one only for the purpose of going into the models. The public file should only include summary levels which will hold up statistically.

I use CTPP data to get characteristics of workers at their place of work. "

We will need zone-to-zone worker flows at the smallest level possible.

Compatibility between the census Summary files and the CTPP is important for economic studies.

dont get rid of town level data

"1. We would strongly oppose a CTPP flow product that has the same thresholds as CTPP2000. These thresholds will kill an AASHTO pooled-fund project.

2. Part 1 and 2 CTPP data are, for the most part, being handled as ""standard products"" by the Census Bureau's ACS plans. This is great. This means that AASHTO and others can focus on the development of meaningful and useful CTPP worker flow products. What we don't know, however, is what kind of small area (tract, zone, block group) tabulations will be provided as standard ACS tabulations."

More user friendly and more options with the mapping.

Need small area geographic data! This is most important for getting source data for modeling and benchmarking our locally developed intercensal estimates. We look forward to it each decade and need to understand how to find a similar set of this data for major jurisdictions in the next decade. We look to ASHTO to help aggregate our refforts, even if they are the State level official and we are more local/regional.

If data suppression is a necessary evil, I would like to see hybrid summary levels in the part 3 dataset, such as county subdivision of residence to census tract of employment and tract of residence to county subdivision of employment. This would avoid a good deal of suppression.

I would suggest that it have components similar to the CTPP, ie home end, work end and origin-destination tabulations. It should have reliably accurate information at the small-area, e.g. TAZ.

Make it more user friendly. The current CTPP seemed very user un-friendly, and at times it seemed like "hocus-pocus" and hope to pull out the right answer or table. Also, make the information headings appropriate. Many times I would query on one item such as "households", and my answer would appear with the heading "persons". This made using the data and interpreting it quite confusing. Also, make all the past CTPP data compatible with the latest version of CTPP to come out. Make the first CTPP browser released able to read all the data types, past, present, and future. Where I work it takes months to get approvals to load the software, and then actually get it loaded. Not having to load newer versions of the CTPP browser would have made things much more seamless, as it is easier to use updated data on CD-Roms, than to have to wait to get the updated browser loaded.

The most lacking factor in CTPP is non-user friendly browser..and non user friendly data structures

I need to do POP distribution by TAZ - I need CTPP to include the age of housing variable

Place of work and journey to work are important tools only avaible from CTPP. Losing this source of data would make life more difficult for those running transportation models.

"Please fix errors in compatability with Windows XP

Include help or tutorial feature with each release (missing from Part 3 CDROM)"

I recommend the formation of a committee consisting of members from the CB, FHWA, FTA, MPOs, AASHTO, and universities to review and evalute the existing census data tables, including CTPP and select the data tables needed for transportation planning.

Handle the disclosure problem through rounding, or the TAZ definition criteria, or thresholds, but not all three! Couple the disclosure avoidance techniques with the distribution schedule, and the product is almost useless before we even receive it.

To make the data like it used to be. You could find info by the file (data) type such as Population, Dwelling, Ages, etc.

Include non-work characteristics (number of daily work and non-work trips, time of day for work and non-work, purpose (if not work).

Why can't the State DOTS pay for the NHTS add-on programs for the MPOs.

Make the data available quicker. It's almost out of date before we get it. Part 3 has been totally useless to us because of the delay.

The sample size needs to be large enough to estimate home to work flow matrices with some degree of accuracy. To my knowledge, the ACS will not provide an acceptable level of accuracy.

"1. Minimize the margin of errors from present level.

2. Improved granularity of the data aggregation at the higher density levels.

3. Data availibity years should tie to the MPO's long-range-plan update cycles (once in 3 years). Need further review on this subject matther."

We do not want to lose worker flows. We do not have the staff to analyze this in house, but are using a researcher to look at the worker flows in our state. We are concerned with sample size and losing geographic detail in the rural areas and outside of major metropolitan areas.

We need detailed travel behavior data on work trips and other trips coded to the TAZ level by mode without rounding or supression. ACS will not work because the sample is too small for any single time period and an average over multiple years is useless for planning.

Timliness. Do not believe data access tool is worthwhile, whould prefer more support for use of CTPP data in ACCESS and EXCEL.

make the release of data more timely.

comparability to 2000 CTPP

(1) Timely delivery of data. Five years is too late as many have lost interest in previous Census data. (2) More secondary mode details. More and more people are using multiple modes during a typical week. Just reporting on the primary mode way undercounts transit, shared-ride and non-motorized travel. (3) Need more data on seconary jobs -- place and mode(s). Many people are working two jobs and only getting travel data on one job does not yield a good work trip data set. (4) Tour based model are becoming the primary modeling method. So, we need to have details on how many stops are made going to work and returning home.

Automatic mailing to MPOs and local governments for use.(I know this would require more subsidy by the MPOs and DOTs, but it is very useful data.

I use the PUMS directly and would like the Census to keep that product.

High-quality, temporally consistent data backing it up.

Time. We needed place-of-work counts long before they came out. Five years is way too long. If it has to take five years to generate TAZ data, could you at least release county-level and city-level data earlier? Tract data earlier? We could make extrapolations from these levels of geography (especially tracts), which we could cross-check with private data to create preliminary TAZ data.

I would suggest that it be kept in the same general format to which I have become familiar over the years, that is: It is in three parts, place of residence, place of work, origin-destination linkage.

Question 14: Any other comments


Ed Christopher, Nandu Srinivasan, and Elaine Murakami have done an excellent job in promoting, educating, and training me and thousands of others in how to use the CTPP. This hands-on assistance and encouragement is essential to helping the product be used to its potential (ACS or CTPP). I hope that whatever the future holds for CTPP and ACS, it includes these three people!

As you may gather from my responses, I have not actually used the 2000 CTPP, although I do have the CDs. I haven't had a client which neeed those data as yet. That's why I can't comment in detail on the file.

The ACS PUMS file does not identify the City of Chicago with about 3 million people. Confidentiality?

Would like to see more data available for import directly into a GIS program. Either ArcView, or ArcGIS is acceptable.

1. The Census Bureau did a great job in providing usable SAS code to data users. This was a massive time-saver.

We cover some major employers in our Bellevue Kirkland Redmond model area geography and depend on Puget Sound Regional Council data, too. In these areas we have Microsoft and Boeing as major employers, so the magnitude of journey to work on travel and the economy is immensely important.

Small area summary levels (tract, block group) should include county subdivision in the northeast (e.g. state-county-county subdivision-tract-block group).

Now that I have had 3 decades of CTPP experience, I presently lament that there won't be another (now that we've got it down pat!), but I will hold judgement until the ACS makes its debut.

We were designated an MPO in fall of 2002, consequently the CTPP products will not have impact until we are included at the TAZ level sometime after 2008. Our MPO is within only one county and unlikely to include any other county in the future so the county to county data at this point is not very useful. Once we have the data at our TAZ level then the CTPP package becomes more relvant to us. We have been receiving the CD and information, and are looking forward to the products use at that time.

Provide a write up on how these data sets could be used by MPO's and State Transportation agencies. Some agency business units may not be familiar with the aforementioned data sets.

Census data/ACS needs to pay a lot more attention to water usage and wastewater disposal(type, cost and source). Water is going to be much more influential in residential choices of the future.

"TAZ data should be maintained. Rounding procedures used make this data more difficult to use. Part 3 software was never used JTW was processed from the BTS CTPP files. The software used to extract data requires much RAM and processing speed. Once the tables are created the shift into spreadsheets is easy.

Rounding causes many processing problems. Checking work is difficult.

How is population related data going to to match with 100% data. "

"In my opinion, quality and availability of ACS data has been disappointing to date, and not comparable to decennial; concerned about methodology and ability to compare data across time; need to be careful if plan to expand this to CTPP data

Generally, with Census boundaries we'd like to see TIGER updated to reflect real geography"

Keep the long-form questionaire in Census 2010 to obtain accurate zonal data for transportation planning and for evaluating the results of the ACS program.

The CTPP is not only an important data source for our MPO, but for some applications, it is the *only* source. To see the product continue to lose all resemblance to SF1 and SF3 is disappointing at best.

I have had problems with opening tables using the CTPP CD, and have found it easier to use the Census website to download some data.

All questions on the list serve do not have to go the entire list.

The Work-Up task and software was a nightmare, with many bugs in the software. The effort took an enormous amount of staff time, and I am not certain that the level of effort we put into the task paid off. Inaccuracies in the Tiger/Line address ranges were found during the task, but there was no oportunity to fix the errors. This means that the same inaccuracies will be there the next time around. How frustrating!

Need to sync CTPP with CFS (commodity flow survey) survey years, and able to bring combined effects to Transportation (Passenger & Freight) planning activities.

when downloading shape files the attribute titles are changed to fo, f1, f2 etc. need to carry titles with the shape files. This is extremely important, due to the large no of shape files.

Is there a data field that identifies if a particular CTPP origin-destination pair is adjusted to avoid potential disclosure of private information?

rolling ACS every few years, make composite Census-like results every decade and possibly every 5 years instead of 10

Timely delivery of data. Five years is too late as many have lost interest in previous Census data.

Wonderful product.

ASCII data (in CTPP or for any other product) should be packaged in a format that permits easier import into statistical analysis packages. Having to pick columns out of very wide tables is tedious and error-prone; not all of us have SAS.

I fundamentally dislike the CTPP Access Tool. While it has many nice features, I do not find it user-friendly and generally try to export data to better software. I especially dislike having to create a session when all I want is to check for a few quick figures.

There is still a bit of uncertainty as to just how well the ACS will work, how accurate it may be (especially at the smaller-area analysis level). The question of Census Bureau funding also is a concern. It would be nice to see these two issues discussed in the open on the listserve, if possible.

Updated: 10/20/2015
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