Mr. Paddock: It's safe to say that one set of TAZs will not be able to cover both these needs for you. There's been discussion here before about developing two or more sets of TAZs just for different levels of disclosure problems with 2010 CTPP (ACS) data alone. You'll need at least one more set for traffic modeling, where you can geocode the address-based, Census block and other small area data not subject to these disclosure problems and than from there aggregate to the level needed for the model. Sam Granato Ohio DOT, Office of Multi-Modal Planning 1980 W. Broad Street, Columbus, OH 43223 Phone: 614-644-6796, Fax: 614-466-0822 "It's all very well in practice, but it will never work in theory." - French proverb I must admit that, of late, I have gotten lost in the woods while trying to see all the trees. During these past months I have been engaged in developing a new TAZ system for the Minneapolis - St. Paul MPO area that will both serve the needs of travel demand modeling here at the Metropolitan Council AND provide us with the information we want from a 2010 CTPP-like product. This new TAZ system is substantially more refined than those of the past and should result in reasonable travel loadings on our arterial roadway network. However, certain issues have been raising their knobby heads regarding zone size that probably will clash with Census Disclosure Board rules. Does anyone have a reasonable idea as to what minimum population or household levels a TAZ will need to attain in order to circumvent large numbers of "blank" cells? I suspect that there is not an easy, uncomplicated answer but would like to hear one nonetheless. Bob Paddock Transportation Planning Metropolitan Council