Hi Everyone –

I bet you have a lot of questions about CTPP using the first 3 years of ACS and TAZs, but unfortunately, I can’t answer them yet!


Given the current uncertainty of the next CTPP (“custom tabulation”) using the ACS, we are moving forward to develop products using standard ACS products.  Some of you will recall that we created a series using the first 2005 ACS data products.  They are posted on both the FHWA web  http://www.fhwa.dot.gov/planning/census/2005tpoverview.htm  and  on the AASHTO web



On December 9, 2008, the Census Bureau plans to release the first 3-year ACS products (surveys completed in 2005, 2006 and 2007).  The minimum population threshold is 20,000 for the 3-year products, compared to 65,000 population for the ACS 1-year products.  So, while the data is still “swiss cheese,” that is, geographic coverage has holes,  a lot more geographic units will be available.  The results are still subject to the Census Bureau rules of “collapsing and filtering” which means that sometimes the data have been suppressed and you will see an "N". 


We are now designing new profile sheets, in which we plan to include data from 2000 (using Census Summary File 3 and CTPP2000) and from 2005-2007 ACS.   Please let me know if you have any recommendations for specific tables to include (the data must be available in both 2000 and from the 2005-2007 ACS).    One recommendation from Nathan Erlbaum (NYS DOT)  is to create a spreadsheet macro that will sum up multiple geographic units and re-calculate the Margin of Error (using the materials on Page 96-98 in NCHRP Report 588).   


Also, I am wondering if there is any interest in an updated “Journey to Work Trends” report to include the 2005-2007 ACS results.  http://www.fhwa.dot.gov/ctpp/jtw/index.htm This report was limited to metropolitan areas with population over 1 million, but had trend data including 1960, 1980, 1990 and 2000.  Because of  redefinitions of metropolitan areas by OMB, the data need to be accumulated from county records for historical comparability, which makes for quite a bit of work.   The last report used the 1999 definition, but the 2005-2007  ACS data will be reported using the 2007 OMB definitions (I think).  My question for you is:  is this report useful enough to spend time and resources on?   


Thanks in advance for your opinions.

Elaine Murakami

FHWA Office of Planning (Wash DC)

206-220-4460 (in Seattle)