Why pick on the smaller MPOs? >From what I've seen around the country, the most "invalid" models are predominantly in the largest metro areas (with the worst one - in terms of documented traffic assignment error - from the agency in YOUR metro area). Where's the proof that the extensive data collection done in the largest MPOs actually helps?
Sam Granato
Ohio DOT, Office of Technical Services
1980 W. Broad Street, Columbus, OH 43223
Phone: 614-644-6796, Fax: 614-752-8646
"We don't see things as they are, we see them as we are." Anais Nin
Ed Herlihy <ed.herlihy@comcast.net> Sent by: owner-ctpp-news@chrispy.net
06/04/02 06:35 AM
To: ctpp-news@chrispy.net
cc:
Subject: Re: [CTPP] Census JTW
Folks:
As a transportation modeler and one who is constantly looking for good data that will help us better calibrate and validate our forecasting procedures, the early review of the CTPP macro data and the trends are of course interesting and an exciting preview of what is about to come.
What I would hope, however, is that before jumping to lots of conclusions about what has happened and what is most likely to happen in the future, we would continue to organize and plan for the release and use of the data at the TAZ level in our MSA's and provide guidance (and support) to those who maintain the models in these areas on how to use the data to re-validate (and improve) the local forecasting models, especially in smaller MSA's.
I know that there are several superb analysts on this list (and the TMIP list too) and that for many of the larger MSA's, that such a detailed validation plan and process is in place and ready to go. I wonder, in some cases, for some of the smaller or new UA.s and even some of these newer UC's, that when the CTPP detailed data is finally released, whether the time and resources will be spent to look at the data at the community and also the corridor/TAZ level and then to see if the existing forecast models that are up and running need fine tuning, and whether they are demonstrating consistency (validity) in the forecast mode for the Year 2000.
Also, as we all are seeing very clearly, the non-work travel purpose continues to have an increasing impact on our system needs.
So, I am also curious to know if there is has been a defined process in the smaller jurisdictions to improve data collection efforts for these non work travel modes, as well. It is my hope that with the raft of local governmental fiscal constraints that such important and vital data collection efforts were not cut back too much, if at all possible.
Ed Herlihy
Transportation Consultant
Reston VA.
----- Original Message -----
From:Alan E. Pisarski To:Putta, Viplava ; ctpp-news@chrispy.net Sent: Monday, June 03, 2002 4:58 PM
Subject: Re: [CTPP] Census JTW
There is a chart in CIA II that shows that women lag about a 1/2 later than men nationwide on average. It will be interesting to see what has happened to that distrib since. AEP
Yes, carpooling went down drastically from 1980-90 and obviously not as dramatic from 1990-2000. We had over 23% JTW trips by carpool in 1980 Nationwide! 1990 it was down to just over 13% (Nationwide).
I would argue that given the economic condition in 1990 (beaten down) vs. 2000 (just when the .com bubble was to burst but still upbeat) - losses in carpooling and transit are not as significant.
Comparing 1995 NPTS and Census 2000 I have the following to offer:
· Trip chaining (the part that goes with JTW) is up during 1990s (NPTS)
· Huge buy-in in favor of 'flex schedules' during 1990s has essentially marginalized the significance of JTW (there was a drop of more than 5% from 1990 to 1995 in peak hour trip starts in our case)
· Each trip taken by transit would have a front end and a back end trip – (park & ride or ride & walk) – Census asks for only one mode that covered most of the distance (is comparable to 1990) thereby undercounting all other trips;
· Vehicle occupancy rate for HBW is a little bit different from what JTW indicates for the same reason as above – our HBW VOR is less than what census shows (Tulsa)
Another factor – I have noticed with NPTS is – Women as a percent of peak hour commuting public is higher than for men (13.6% men vs. 19.7% women in 1995 for Tulsa). It could be because women tend to keep more regular hours than men. May be 'Rideshare' programs should focus on Women-only carpools as a potential market share.
Whatever it may be, we might notice with CTPP an increase in share of women in commuting during peak hours – to somewhat contributing to the erosion in transit patronage, decline in carpooling and increase in commute times.