I recently got the following question from our bike and ped coordinator. I'm a bit rusty as I have not used census in a while so I thought I'd throw it out there for all you census experts to see how you would respond.

What dataset is the best to look at to see how many people within a project area do not take a car to work and/or own a car?

Mark

<Elaine.Murakami@dot.gov>
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12/27/2010 01:20 PM

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Subject	RE: [CTPP] mode to work by small workplace geographies

Hi Everyone! Hope you had a relaxing weekend!

Tables for small geography at the WORKPLACE. The ACS tables for 2005-2009 (5 – year summary) do NOT have small geography “for workplace geography.” This kind of table will be available in the CTPP 5-year (2006-2010) which we expect in 2012. The reason is that the Census Bureau’s regular geocoding for workplaces only goes down to county and place. About 25% of responses do not have sufficient detail for block level geocoding, therefore an imputation routine is required to report workplace at tract or blockgroup geography. We call this imputation routine “extended workplace allocation” and the work is currently being developed for the CTPP. Once it is in place for the CTPP 2006-2010, we hope that the Census Bureau will be able to apply it for the ACS standard products.

Historically, the CTPP was the only decennial census “long form” product that included tabulation for workplace geography and for the flow between home and work. I was glad to see that the ACS Office started to include workplace tabulations in the ACS standard table set.

Elaine Murakami
FHWA Office of Planning, Wash DC
206-220-4460 (in Seattle)

As you probably know, the CTPP 2006-2010 will have additional small area data that is synthetic or “modeled.” This is NCHRP 08-79 project, in progress by Westat. This work is to avoid the heavy data suppression we expected given the CB requirement to protect individual confidentiality, and some of the small shares of specific commute modes that increase the probability of matching to a unique record. The job is to develop models that retain the characteristics of the original data, so that the resulting data is still usable for transportation planning, but still protects individual confidentiality. Because the work is done at the Census Bureau, the perturbed data can be compared to the original data.

From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Flintoft, Anna E.
Sent: Monday, December 27, 2010 6:49 AM
To: ctpp-news@chrispy.net
Subject: [CTPP] mode to work by small workplace geographies

Does anyone know when the census will release mode of transportation to work by smaller workplace geographies than place? I was disappointed that the 2005-2009 ACS didn't have it. Coming up with a work trip mode split for downtown is something people ask us about all the time.

Thanks.

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Anna Flintoft, PTP
Transportation Planner
Department of Public Works - Transportation Planning and Engineering
City of Minneapolis
Room 301, City of Lakes Building
309 2nd Avenue South
Minneapolis, MN 55401
(612) 673-3885 (office)
(612) 269-9410 (cell)
anna.flintoft@ci.minneapolis.mn.us
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