Yes, the CTPP 2000 uses the Census 2000 and provides a count of WORKERS AT WORK. Workers at work is generally at least 10 percent lower than employment or jobs. Also, the Census 2000 allows a response for only 1 job per worker. http://www.fhwa.dot.gov/ctpp/ctppatwork.htm NCHRP 365 used results from regional household travel surveys AND the 1990 NPTS. (Page 23) You might want to take a look at the NHTS transferability project that FHWA completed a few years ago. http://nhts.ornl.gov/tools.shtml The work was done by Oak Ridge National Labs and uses the 2001 NHTS data, and estimates total person trips, total vehicle trips, and trips by purpose at the tract level. You need to understand how trip purpose is coded. I glanced at results for census tracts in one county in Washington State and HBW were about 12% of total trips. Let's say that the overall average number of household trips is 9 or 10, then 12% would be 1.1 to 1.2. The transferability project provides trips rates by household size and vehicle availability. However, it is very important to understand that a trip from WORK to SHOP, and then SHOP to HOME, would not be included as a WORK to HOME (with 1 stop) in the count of HBW trips. This is why, using the concept of TOURS and TRIP CHAINING has become increasingly used in travel demand models. The links below are to Nancy McGuckin's papers (2001 NHTS and 1995 NPTS) on trip chaining: http://www.travelbehavior.us/projects_files/Trip%20Chaining%20Trends%20i n%20the%20US%20TRB%20paper%2005-1716%20(2).pdf http://nhts.ornl.gov/1995/Doc/Chain2.pdf Hope this helps. Elaine Murakami FHWA Office of Planning _____ From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Binbin Chen Sent: Thursday, November 06, 2008 2:18 PM To: ctpp-news(a)chrispy.net Subject: [CTPP] A Question - work flow vs. HBW trip rate Hi, I'm new in using CTPP data, and am a little confused about the work flow CTPP provided and work trip. Basically, CTPP counts workers, not trip. Then can it be used to compute HBW trip per household? For example, assume 1.5 trips/worker (NCHRP#365), HBW trip/HH = 1.5*workers/household numbers ? And How can CTPP work flow compare to NHTS HBW trip rate? I highly appreciate your help! Best, Binbin