The purpose of this posting is to alert interested parties to the current status of the expected timeline related to the creation of Traffic Analysis Zones (TAZs) for CTPP products. Based on the Census Bureau's (CB) timelines we should be working on TAZ definition for CTPP by February 2009. Therefore, work plans should include sufficient staff time for this task. Below are some things to consider. Census timeline and PSAP To prepare for the 2010 census and other CB data products there is an opportunity to update the geography and zones. Very soon the CB will be posting the final criteria on defining tracts and block groups etc. This will come out in the Federal Register. Coinciding with this the CB is fine tuning its list of primary PSAP contacts. PSAP is the program under which regions can define the tracts, block groups and other geography for their areas. For more on PSAP and what it is, see http://www.census.gov/geo/www/psap2010/psap2010_main.html How do TAZs tie in? According to the PSAP schedule, regions will be defining their tracts, block groups, etc. during the summer and fall of this year (2008). Dovetailing on the tract process the states and MPOs will be asked to work on their TAZ submittal. This will occur around this time next year which means it is not too early to begin planning your resources and thinking about TAZs. TAZ development process The details of the process are in various stages of discussion. Two more central issues to the process include, what software will be used for defining TAZs and how many different TAZs layers will there be? For the software, we are awaiting the installation of the AASHTO CTPP Policy Board and finalizing some on-going discussions with the CB Geography Division. For the latest update on the AASHTO front see the "CTPP Status Report" newsletter article "CTPP Consolidated Purchase" at http://www.trbcensus.com/newsltr/sr0108.pdf For TAZ sizes and the number of different geographic layers that CTPP data products will come in, there have not been any firm decisions made yet. Will there be one, two, three or even four different zonal layers? For now, suffice it to say that one can build a good case for any or all of these scenarios especially when considering the ACS and how the CB will be releasing the data. Look for further discussions on this topic on the "CTPP-news" list serve. If you are getting this posting and you are not part of the "CTPP-news" list serve you can join by visiting http://www.trbcensus.com/maillist.html and subscribing. -- Ed Christopher 708-283-3534 (V) 708-574-8131 (cell) FHWA RC-TST-PLN 19900 Governors Dr Olympia Fields, IL 60461