30 Apr
1999
30 Apr
'99
7:52 a.m.
Jack, first as you can see i posted your note to the listserve. this is
exactly the type of information we need to hear and i think other would
benefit. as to the specific of the zone sizes if it were a perfect world and
we were doing typical travel demand forcasting we would want to look at
trips procuded and trips attracted and use those numbers to ease into zones
that are all realatively ballanced on a travel basis. i suppose this is one
reason why folks gravitate to census tracts. in theory they are balanced
atleast on the residents side. other issues play into the zone creation as
well like geography and network configuations.
it sounds like counties are certainly a geography that is too rough for you
but something smaller would work. given the context of what the ctpp is
(resident location data, work location data, and data on the flows between
zones) and where you might speculate the state is heading, could tracts be a
suitable geography or would you prefer something smaller? in one hand
sounds like you have the population base and travel demands to develop you
own TAZs in the non-MPO counties. on the other hand tracts are more off the
shelf and a decent geography to use as a starting point. ultimately, you
will be making the call.
Jack Pascoli wrote:
Ed,
In West Virginia, we have several county studies that are not in MPO
areas. We use essentially the same procedures that an MPO would use. If
we had the information from the Census that we use as our independent
variables on a TAZ basis it would save us a lot of work in trying to
manipulate the block group data into TAZs. In addition to
that, we have many projects that will have a profound effect on our
smaller communities that we would like to use simplistic models (QRS II)
to determine the traffic impacts of project alternatives.
While we do not have a statewide model at this time, I
suspect that in the
next ten years we will. Depending on the requirements for the work to
develop TAZs for CTPP, as a minimum we would expect to coordinate the TAZs
in the five (5) separate active county studies we currently have. As a
maximum we would do the whole state outside of the
MPO areas.
I would appreciate your comments.
Jack Pascoli P.E.