RE: [CTPP] Are you writing GIS code to estimate Urbanized Area Boundaries using 2010 Census

Yes, this is the NLCD 2006 data that is being used to qualify urban territory according to a high degree of impervious land cover. The Census Bureau will only use the 2001 NLCD in areas where the 2006 vintage is not available (outside conterminous U.S.). According to the 2010 Census urban area delineation criteria, a census block qualifies for inclusion in an initial urban core if it is associated with a high degree of impervious surface cover and is compact in nature, or shares a significant boundary with qualifying territory. In order to identify this territory, the Census Bureau first extracts the NLCD cells with 20% or higher imperviousness. After a raster to vector transformation on the extracted cells is performed, the Census Bureau then intersects the polygons with the census blocks. If more than 1/3 of the area of the census block is impervious, the block is flagged as a potential impervious block. However, the census block must then meet the shape index or contiguity criteria in order to qualify as belonging to the initial urban area core. Please see the Federal Register notice for a full description of these criteria: http://www.census.gov/geo/www/ua/urbanruralclass.html The Census Bureau allows for the inclusion of non-compact census blocks because the Census Bureau found in testing a number of elongated census blocks with a high degree of imperviousness were associated with road medians that artificially separated qualifying territory. In some cases, the presence of these census blocks prevented further iterations of the initial core qualifying criteria effectively disqualifying territory that should have been considered urban. Thus, as described in the Federal Register notice, some interactive review is necessary to determine whether classification of the additional urban territory is appropriate during these additional iterations of the core building criteria enabled by the identification of these census blocks. Christopher J. Henrie Geographic Standards and Criteria Geography Division U.S. Census Bureau 4600 Silver Hill Road Washington, D.C. 20233-7400 Mail Stop: 7400 Phone: 301-763-9086 Fax: 301-763-4710 From: "Seidensticker, Dan" <DSeidensticker(a)cityofmadison.com> To: "'ctpp-news(a)chrispy.net'" <ctpp-news(a)chrispy.net> Date: 09/27/2011 12:04 PM Subject: RE: [CTPP] Are you writing GIS code to estimate Urbanized Area Boundaries using 2010 Census Sent by: ctpp-news-bounces(a)chrispy.net Not sure if I’ll get the time to do this but I was giving some thought to it. Does anyone know for certain if this is the NLCD impervious dataset that is being used in the criteria? http://www.mrlc.gov/nlcd06_data.php The Federal Register doesn’t go into much detail on how the percent impervious area data is used in the criteria. Is the impervious area translated to census block geography (raster to vector)? The footnotes in the register suggest some subjectivity which would could make it difficult to incorporate into code. Dan Seidensticker GIS Specialist Madison Area Transportation Planning Board: A Metropolitan Planning Organization (MPO) City of Madison Planning Division 121 S. Pinckney Street, Suite 400 Madison, WI 53703 Voice: 608-266-9119 Fax: 608-261-9967 Email: dseidensticker(a)cityofmadison.com www.MadisonAreaMPO.org From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Elaine.Murakami(a)dot.gov Sent: Monday, September 26, 2011 1:57 PM To: ctpp-news(a)chrispy.net Subject: [CTPP] Are you writing GIS code to estimate Urbanized Area Boundaries using 2010 Census I can’t remember who told me they were writing some ArcGIS code to estimate what the Census Bureau’s new urbanized (50,000+) areas might be, based on the CB’s Federal Register notice of the final criteria. If you are willing to share your code, I think that there are others who would be interested in applying it in their own area. I checked with the Census Bureau Geography and they said they were NOT going to share their code. FHWA decided NOT to attempt this task, as we will just WAIT for the list and boundaries to be released from the Census Bureau. Elaine Murakami FHWA Office of Planning 206-220-4460 (in Seattle) _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news