[CTPP] RE: A Question - work flow vs. HBW trip rate

Elaine and Ed, Thank you very much for your answers. They are very helpful. One more question on this issue. In Eric's explanation- "Using a factor of 1.5, 1,000 employees would generate 1,500 HBW trips; then you'd need to divide by two to approximate a CTPP-derived home-to-work trip, giving you 750 trips." Does he mean comparing "750 trip" to the "CTPP workers" ? Thanks a lot! Binbin -----Original Message----- From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of ctpp-news-request(a)chrispy.net Sent: Saturday, November 08, 2008 12:00 PM To: ctpp-news(a)chrispy.net Subject: ctpp-news Digest, Vol 57, Issue 2 Send ctpp-news mailing list submissions to ctpp-news(a)chrispy.net To subscribe or unsubscribe via the World Wide Web, visit http://www.chrispy.net/mailman/listinfo/ctpp-news or, via email, send a message with subject or body 'help' to ctpp-news-request(a)chrispy.net You can reach the person managing the list at ctpp-news-owner(a)chrispy.net When replying, please edit your Subject line so it is more specific than "Re: Contents of ctpp-news digest..." Today's Topics: 1. Re: ctpp-news Digest, Vol 57, Issue 1 (Out Of Office Auto Message) (John Posey) 2. RE: A Question - work flow vs. HBW trip rate (Murakami, Elaine) 3. Re: A Question - work flow vs. HBW trip rate (Ed Christopher) 4. Quick TAZ Update (Ed Christopher) 5. Diana Portillo is out of the office. (Diana Portillo) ---------------------------------------------------------------------- Message: 1 Date: Fri, 07 Nov 2008 12:04:59 -0600 From: "John Posey" <john.posey(a)ewgateway.org> Subject: [CTPP] Re: ctpp-news Digest, Vol 57, Issue 1 (Out Of Office Auto Message) To: <ctpp-news(a)chrispy.net> Message-ID: <s9142ef8.080(a)nws-ewg4.ewgateway.org> Content-Type: text/plain; charset=US-ASCII I will be out of the office until November 17. Please contact Hilary Perkins if you need assistance before then. ------------------------------ Message: 2 Date: Fri, 7 Nov 2008 11:27:29 -0800 From: "Murakami, Elaine" <Elaine.Murakami(a)fhwa.dot.gov> Subject: RE: [CTPP] A Question - work flow vs. HBW trip rate To: <ctpp-news(a)chrispy.net> Message-ID: <195CBC4D6D4C1547BFCE1198D7D6633977AA51(a)fhxwa4.fhwa1.fhwa.dot.gov> Content-Type: text/plain; charset="us-ascii" 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@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