We looked at county commuting patterns from 1980 to 2000 for Northern NJ (including to NY), and once tried to use trends to establish new forecasts, the problem we ran into was the growth in inter-county trips was so high in many cases, that if you just extrapolated the trends you wound up with non-sensical intra-county commuting trips, to the point that some counties had only 20% or 25% of their work trips intracounty. WE had to modify this on a case by case basis, and established a floor below which intracounty commuting would not fall below. That was using 1980-2000 as a basis. I really think this is a case by case analyis based on each metropolitan area. In my opnion you really need to look at results and not wholly use trends, and going back to 1970 may not make sense given it was so different and pre 1973 with oil prices. -----Original Message----- From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Ed Christopher Sent: Thursday, April 27, 2006 12:27 PM To: ctpp-news maillist Cc: Mary Luebbers Subject: [CTPP] Re: Commuting Patterns Projections I am passing this question I got on to the CTPP listserve in case anyone can add to discussion. I hope Mary does not mind--its an important question. Mary Luebbers wrote: Mary--I have not seen any but that does not mean that someone hasn't done it. Personally, I could think of a hundred reasons to pick at any projections especially if I didn't like the look of the numbers but that does not mean that the flow history wouldn't be able to add some insights and dimension to any projections. Projections always flow better when they appear tied to some historical context, but I digress.. .While these are not exactly projections they are some examples of how I have seen county flows presented: Anyone others out there? Chicago Area Commuting Patterns and Trends by Ed Christopher and Siim Soot (March 2003) http://www.berwyned.com/papers/co2cochgo.pdf Example of County-to-County Flow Maps for North Carolina prepared by Todd Steiss (August 2003) http://www.TRBcensus.com/articles/nc_flowmaps.pdf Web page on County-to-County Worker Flows in Bay Area and Northern California (Data Released: March 6, 2003). (Updated: March 12, 2003) http://www.mtc.ca.gov/maps_and_data/datamart/census/county2county/ -- Ed Christopher 708-283-3534 (V) 708-574-8131 (cell) FHWA RC-TST-PLN 19900 Governors Dr Olympia Fields, IL 60461 _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news