CTPP and Geography Census Geography Nesting Tracts and Blocks TAZs and TADs Resources

CTPP and Geography

Nesting County State Blocks Block Groups Tracts TAZs TADs County Blocks

What is a … Census Block -- Smallest geographic entity, generally bounded by streets, streams, and the boundaries of legal and statistical entities. Block Group- -A grouping of census blocks Tract --relatively permanent small-area geographic divisions of a county or statistically equivalent entity defined by a local committee of data users or the geographic staff of a regional census center. Census tract boundaries are delineated with the intention of being stable over many decades, so they generally follow relatively permanent visible features.

Important sizes How many Block Groups can be contained in a single Tract?

Moving to the CTPP Why is CTPP Data so Important? 1. It’s Parts, especially Flows 2. It’s Universes, especially workers 3. It’s Custom Geography Traffic Analysis Zones - defined by the transportation community for the transportation community

Geography for 2000 CTPP Data

8 For 2012 CTPP Data New Geography

9 “NEW” TAZs Traffic Analysis Zones 0Delineation%20Business%20Rules_CTPP%20Final.pdf Developed in Summer 2011 TAZs will nest with TADs GIS equivalency process Funded under Consolidated Purchase FHWA is contacting state DOTs to set up contacts TAZ Traffic Analysis Zone Traditional Size TAD Traffic Analysis District 20,000 population

What is an equivalency process? Take the map at the right and based on some business rules make 9 contiguous regions It’s the same for TAZs Blocks cluster into TAZs

A real world example ● Blocks will make up TAZs ● TAZs will nest with TADs ● TADs will nest in Counties ●Nesting with Tracts is optional

TaskStartFinish AASHTO/FHWA submits short version of requirements to Census Bureau November 2009 AASHTO/FHWA submits formal version of requirements to Census Bureau February 2010 MAF/TIGER Partnership Software Development February 2010February 2011 Spatial Files, MTPS, Delineation Guidelines and Documentation Distributed to MPOs April 2011 State DOTs and MPOs delineate TAZs and TADs April 2011August 2011 Census Bureau reviews and inserts TAZs into MAF/TIGER database August 2011November The schedule

Creating TAZs files/PPT_12_TAZ%20White%20Paper_NOV07_FINAL_CS_Keli_Wu.ppt FDOT_TAZ_White_Paper.pdf Florida Standard Urban Transportation Model Structure White Paper on Recommended Approach to Delineating TAZ

PUMAs defined Summer 2011 Urbanized Areas and Urban Clusters Released Spring of 2012 Look for additional webinars on these and other Census data related topics Join the CTPP List Serve Other Geography to think about

Thank You Ed Christopher FHWA Resource Center 4749 Lincoln Mall Drive, Room 600 Matteson, IL