NOTES ON CTPP 2000 PROFILES

Darft 1: EM (October 28, 2002)

Draft 2 (NS – October 29, 2002 at 1:20 am)

Draft 3:  EM  Oct 29

 

 

The first data product of the Census Transportation Planning Package 2000 (CTPP2000) is now available.  The Census Bureau has prepared profile sheets for States and Counties, which are posted on the AASHTO web page at http://ctpp.transportation.org/ in both html format and pdf format.  The html format can be read easily into a spreadsheet.  One convenience of these profile sheets is that they include data from both 1990 and 2000 for some basic characteristics such as household size, vehicle availability, means of transportation to work, and travel time to work. 

 

Notes for the CTPP profiles:

 

1. GEOGRAPHIC LEVEL REPORTED:  Data are limited in most cases to State and County totals.  In six states, (Maine, Vermont, New Hampshire, Massachusetts, Rhode Island, and Connecticut), MCDs are included.

 

2. DATA ROUNDING:  In CTPP 2000 and other special tabulations from Census 2000, figures that do not duplicate data released in standard census products are being rounded.  Therefore, certain tables in the CTPP profile sheets contain rounded numbers.  In these tables values from 1 through 7 have been rounded to 4, and values greater than or equal to 8 have been rounded to the nearest multiple of 5.

 

3. DATA SOURCE IS DECENNIAL CENSUS LONG FORM:  All of the data in the CTPP Profile is from the “long form.”  The data will not match the short form (100% count) data exactly.   

 

4. MICROSOFT EXCEL 97 PROBLEM:  There is a display problem when the CTPP2000 profiles in html format are opened in Microsoft Excel 97.  The problem is that the second column (column B) of the spreadsheet is hidden from view.  To display column B, right-click the mouse over either the column A or column C header, and choose Unhide from the pop-up menu.  This problem appears to be corrected in later versions of Microsoft Excel.

 

5. MEANS OF TRANSPORTATION TO WORK:  Public transportation includes bus or trolley bus, streetcar or trolley car, subway or elevated, railroad, ferryboat, and taxicab.  In subsequent CTPP2000 tabulations, taxicab will generally be included in the “other means” category.  However, in the CTPP profiles taxicab has been included in public transportation, similar to aggregations used in the Census 2000 demographic profiles.

 

6. TRAVEL TIME TO WORK:  In the 1990 Census (including the CTPP data), the maximum travel time assigned to any worker was 99 minutes.  Workers who reported travel times of 100 minutes or more were coded to 99 minutes in 1990.  The maximum travel time was increased to 200 minutes for Census 2000, thus the 2000 data are more accurate because they include the actual value for these long trips.  The impact of this coding change is that increases in travel time between 1990 and 2000 are somewhat over-stated.  At the national level, the Census Bureau estimates that about 29% (0.9 minutes) of the 3.1-minute increase in average travel time is attributable to the coding change.   

 

7. HOUSEHOLD INCOME IN 1999:  In a small number of cases, the mean household income and median household income figures shown in the CTPP2000 profiles differ from those published in other Census 2000 products.  These differences of one dollar are the result of software rounding differences and hardware numeric precision differences between the two platforms used to create the products.

 

8. VEHICLES AVAILABLE:  The data in CTPP2000 on vehicles available are tabulated for households.  This is different than in standard census products, where data on vehicles available are tabulated for housing units.  Although the estimates are usually quite close, the number of housing units is not always equal to the number of households, because the Census Bureau calculates weights differently for housing units and households.  Therefore, the distribution of vehicles available shown in CTPP2000 will not exactly match the distribution presented in standard census products.

 

 

A data CD will be sent to State DOTs and MPOs, however, we expect that most users will be able to get everything they need from the AASHTO web page.

 

We expect CTPP Part 1 to begin data release by the end of November, and run through December.  CTPP Part 1 will include many more details of geographic reporting, including places, census tracts and Traffic Analysis Zones.  Similar to Summary File 3, the data is limited to residential geography only, but the tables are designed specifically for transportation planning purposes.  For a complete list of tables, please see

http://www.fhwa.dot.gov/ctpp/content.htm

 

Although no official release date has been set yet, the Census Bureau hopes to release county-to-county flow data (count of workers) by the end of calendar year 2002.  The first workplace data and flow data to be released from CTPP 2000 is not expected until April 2003.