Cohousing-L Mailing List: Any data on traffic studies for cohousing?

[mike slama (mike.slama.coho]

Puyallup Cohousing is a forming community in Pierce County near Puyallup, WA. 
We own 10.75 acres zoned for medium density residential at 4 units/acre.  We 
are in the process of working with a local civil engineering firm to conduct 
the necessary studies for development.  Wetlands, Septic, GeoTech, and Water 
look good so far.  The next study requested by the county involves traffic 
analysis.  The ‘dance' in this county involves a (well-known, respected) 
traffic engineering firm making a “Traffic Impact Analysis Scoping" proposal to 
the county. After their discussion and acceptance, a “Traffic Impact Analysis" 
of the local streets and intersections is performed.  Their first draft 
“Scoping Proposal” includes the following verbiage:

<<...The magnitude of the anticipated vehicle trip generation for the proposed 
project was derived from
the Institute of Transportation Engineers (ITE) publication, Trip Generation 
Manual, 11th Edition.
In review of the trip generation manual, there are no defined Land Use Codes 
(LUC) for
community co-house style units. Therefore, LUC 215- Single-Family Attached 
Housing was
determined to be the most representative which is commonly applied towards 
townhouse units
and was considered similar in nature...>>

There’s lots more in their proposal, but the end result is that they come up 
with an assumed number of 6.4 daily trips per unit.  I’ve heard many anecdotal 
reports suggesting that the actual number of trips/day for cohousing 
communities is lower.  Sadly, my engineering background has convinced me that 
the plural of ‘anecdote’ is not ‘data’.  Does anyone on the listserve have any 
leads on real traffic data for actual cohousing communities?   

Thanks in advance,

Mike Slama
https://puyallupcohousing.org <https://puyallupcohousing.org/>