70 pages?? It takes only one sentence to say zone boundaries need to be based on access to the network being modeled, period. Sam Granato Ohio DOT, Office of Technical Services 1980 W. Broad Street, Columbus, OH 43223 Phone: 614-644-6796, Fax: 614-752-8646 "You will be flogged for being right and flogged for being wrong, but it hurts less when you're right." - Hunter S. Thompson The Florida DOT has just posted a 70 page report discussing TAZs and their construction. While the information is for the model users community in Florida there is a wealth of information in the report that those who think about such things will find of interest. The document is well worth adding to any list of TAZs references that you may have. The report can be found on the Florida Transportation Modeling web site at http://www.fsutmsonline.net/index.php?/site/directory/model_docs The direct link to the report is http://www.fsutmsonline.net/images/uploads/reports/FDOT_TAZ_White_Paper.pdf