[CTPP] Software needs for TAZ definition and submission to CB for TIGER

The Census Bureau Geography Division has asked us to submit to them software requirements for TAZ definition by the end of Calendar Year 2006. We are working on the assumption that the CTPP pooled fund proposal will move forward through AASHTO's process. In 1998, FHWA contracted with Election Data Services to produce the TAZ-UP for software creating the 2000 TAZs used for CTPP 2000. TAZ-UP greatly simplified the ability to create and export TAZs to CB's TIGER files. The process was a big improvement over the paper-map-pencil drawings, which were used for the 1990 CTPP. For the 2010 Census, the CB has a contract with M-cubed and its subcontractor Caliper Corporation for software development to support the "Participant Statistical Areas Program" (PSAP). The PSAP includes the tract and block group definition process. The software being developed for this program can be modified to accommodate TAZ, SuperTAZ or any other geographic units that the transportation planning community would like to have added into TIGER. In our last regular CTPP meeting, we did discuss concepts of corridors and downtowns, but we think those would be best left as aggregates of TAZs that are handled later through a TAZ-equivalency process for CTPP, rather than adding them into TIGER. Below is a summary of our discussions from a meeting held on October 18, 2006. PLEASE LET US KNOW IF YOU THINK WE ARE MISSING SOMETHING IMPORTANT! Please send your remarks to nanda.srinivasan(a)dot.gov by November 10. Elaine Murakami FHWA Office of Planning 206-220-4460 Summary of Specifications The software should have the ability to create 3 levels of TAZs - one is a base TAZ which will be subsequently used to define two other larger size aggregations (optional by county). The base TAZ would be similar to the traditional "small area geography" TAZs in 2000. The software must provide ability to aggregate these TAZs to medium size (about 4,000 population) and larger size (about 20,000 population) aggregations (much like Block Groups being aggregated to Tracts, or Tracts aggregated to PUMAs), if desired by the MPO/State. The functional specifications include: 1. Load TIGER/Line 2008 or 2009 files in their native format, including TAZ, Tract, Block Group, Roads, water, and other polygon layers. 2. Display TIGER layers. 3. Import and display background layers: a. Import and display of other MPO or State owned data (shapefiles - points, lines, or polygons), as long as these files are in decimal degrees, NAD 83 projections. b. Import and display of aerial photography, as long as these files are in decimal degrees, NAD 83 projections. 4. Create or Devise Traffic Analysis Zone (TAZ) polygon features using screen digitizing starting from: a. 2000 TAZ geography, if defined, or else current Tracts or Block Groups. b. Using primary polygons in TIGER, if 2000 TAZs were not defined, or if the agency does not choose to use Tracts or Block Groups as starting point. c. The software should have the ability to aggregate polygons using a lassoing function (to zoom in or out), select polygons, or draw a line around (point-by-point) and add them to a TAZ. 5. TAZ Definition Guidelines: a. The software should prompt the user to create TAZs to cover the whole county without any discontiguity. Importantly, there should not be any sliver TAZs or duplicate TAZ numbering in any county. b. The maximum number of alphanumeric characters for TAZ might be set at 8. c. There may be cases where a TAZ boundary might require segment(s) to be added to TIGER. If there is a valid geography that does not show as a line segment (e.g.: a polygon bounded by a new road), the software must provide the ability to use the line segment as a TAZ boundary, and allow the user to print the view/map, annotate it, and submit it to electronically/via hardcopy to the Census Bureau. d. Counters: i. Count and display * 2000 total residential population (using 2000 block population counts). * 2000 resident worker population (workers by place of residence), and 2000 workers by place of work (using 2000TAZ/Block Group values) for each delineation of a TAZ. NOTE: CTPP Part 2 should be used for place of work counts. TAZ and Block Group counts are not available nationwide, although tract counts are available nationwide. * If the currently defined TAZ cuts across 2000 geography (TAZ/BG), then use proportion of TAZ by area in that BG/TAZ to estimate resident/worker counts. Because this task might be difficult, a separate cost estimate should be requested from the software developer. ii. Count and display the sum of resident workers, and workers by place of work to aid to determine the size of the TAZ. 6. Final Checks: Once TAZ definition is complete, and before export, the software must check for items 6a through 6e, and flag the items on a list. Export should be allowed only if all the following items are flagged. If any of these items are not satisfied, the software should loop the user through each entry. a. Completeness b. Contiguity c. Uniqueness: Ensure no duplicate TAZ numbers anywhere in a county. d. Check for polygon closure for each TAZ. e. Distinguish whether the user wants the TAZ boundary to move with a tract/BG boundary (since the tract boundaries will be draft at that time), or if the user wants the TAZ boundary to be locked and not move with a tract/BG boundary. 7. Export output: Upon completion of the TAZ definition and after completion of final checks (Step 6), the software should provide ability to: a. Export the file to the requirements of the Census Bureau, Geography Division. b. Export the final TAZ shapefile copy for MPO/State use. 8. (Optional by County) Aggregations of TAZs. Once basic TAZs are developed, the software must allow the ability to aggregate these TAZs into two other transportation geographies - A medium sized TAZ (Med TAZ), and a large TAZ (Lg TAZ). a. Use final TAZ shapefile as starting point to develop medium size (Med TAZ) or Large size (Lg TAZ) aggregations. b. The software should have the ability to aggregate polygons using a lassoing function (to zoom in or out), select TAZ polygons, or draw a line around (point-by-point) and add them to MZ or LZ polygons. c. Provide counters similar to item 5c to check the population/employment of these zones. d. Prior to completion and export, do final checks similar to item 6. e. Provide export outputs similar to step 8. B. Provide the final software on CD-ROM or through a web-based retrieval process. C. Provide a "Help" button to explain software features.