Zone Correspondence & Equivalency Files
Background: What are Zones? MTC maintains a set of regional travel analysis zones for use in MTC planning studies. These travel analysis zones, or TAZs, are typically small area neighborhoods or communities that serve as the smallest geographic basis for travel demand model forecasting systems. From time to time, MTC updates the regional travel analysis zone system to reflect changes in decennial census geography, changes in computing capability, and forecasting needs for particular corridor studies. The original MTC zone system, with 290 zones, was created in 1965 by planners of the MTC predecessor agency, the Bay Area Transportation Study Commission. MTC has since updated the zone system several times over the past decades, increasing to 440 zones in the mid-1970s, to 550 zones in the early 1980s, to 651 zones in 1987, to 700 zones in 1989, to 1,099 zones in 1993, and to 1,454 zones in 2002.
The current MTC travel demand model forecasting system uses the 1,454 zone system. The MTC 1,454 zone system nests within the 1,405 Bay Area Census 2000 census tracts. There is a "one-to-one" correspondence between 1,375 MTC zones and Census 2000 census tracts. The remaining 30 census tracts are split into a total of 79 MTC travel analysis zones.
In addition to regional travel analysis zones and counties, MTC supports an intermediate geographic scale, "superdistricts," for analysis and reporting purposes. There are 34 superdistricts in the nine-county Bay Area.
Census Geography. The Geographic "Building Blocks" The U.S. Bureau of the Census maintains a comprehensive geographic database of every street, road, and address in the United States. This immense database is used to support data collection and data reporting for the decennial census. Census "blocks" (i.e., city blocks) are the basic "building blocks" for creating larger geographic areas such as MTC travel analysis zones. The Census Bureau also defines larger units of geography, such as block groups and census tracts for data collection and data reporting purposes. According to Census 2000, there are 1,405 Census Tracts; 4,422 Block Groups; and 76,249 Blocks in the nine-county San Francisco Bay Area. An additional "standard" Census geography level are the 54 Public Use Microdata Areas (PUMAs) defined for use with the 5-percent Census 2000 Public Use Microdata Sample (PUMS) for the Bay Area. An additional layer of geography, created by MTC for use with the Year 2000 Census Transportation Planning Package (CTPP) is the 4,069 Census Travel Analysis Zone (or CTAZ) system. The CTAZ zones range in size from multiple-block level in downtown San Francisco, Oakland, and San Jose to block group and tract level in suburban and rural areas of the region. The CTAZ zones nest within the older, MTC 1099 regional travel analysis zone (RTAZ) system.
The following data files will primarily be of interest to technical audiences concerned with the geographic equivalence between MTC and census geography. For ArcView "shp" (shape) files for these geographic layers, visit the MTC GIS & Maps Data page (use the left-side navigation bar.)
1,454 Travel Analysis Zone Documentation. The November 2002 documentation for the MTC 1,454 regional travel analysis zone system, based on Census 2000 geography, is available in PDF format (TechSummary_TAZ1454System.pdf)(353KB), and in the original MS-Word and MS-Excel formats, in a zipped archive file (TechSummary_TAZ1454System.zip)(531KB). This documentation includes equivalency tables between MTC 1,454 zones and Census 2000 geography, 1,099 zones, and MTC 34 superdistrict and nine Bay Area counties. Several tables also discuss the "external zones" used as gateways to the Bay Area (zones 1455 to 1475.)
Zonal Equivalency Files used in Travel Forecasting (MTC's CUBE/Voyager Software). A complete set of zone-to-superdistrict-to-county equivalency files, as used in MTC's travel forecasting system, is available in a zipped archive file (tpplus_equivalencies.zip) MTC uses the commercial software package CUBE/Voyager for travel demand forecasting work, but the equivalency files are in simple text and database file formats.
1990 Census Block to 1990 Census Travel Analysis Zone (CTAZ) Equivalency Files. These are the files used to create the census travel zones incorporated in the 1990 Census journey-to-work package (CTPP/UE). Download the archived version of the equivalency file (mtctaz2.zip) (213KB). Download the text-format file documentation (readme.1st) (2KB). Requires WINZIP or PKUNZIP to extract archived files.
1990 Census Tract to MTC 1099 Zone Equivalency File. This is the 1990 census tract to MTC 1,099 travel analysis zone equivalency files. Certain of the tracts in this file are "MTC tract equivalents" that represent MTC splits of standard census tracts. Refer to the technical summary: 1,099 Regional Travel Anaylsis Zone System: Technical Summary (June 1993) for a discussion of these tract splits. Download the text file of this tract-to-zone equivalency file (ct2z1099.cr4) (32KB). Download the text-format file documentation (readme.too) (0.4KB).
MTC 1,099 Zone to 700 Zone to 34 Superdistrict to 9 County Equivalency File (EXCEL format). This spreadsheet has four columns: 1,099 zone, 700 zone, 34 superdistrict and 9 county; and 1,099 rows. Download the EXCEL format file (z1099.xls) (72KB).
Superdistrict List with 1,099 Zones. This text file has 34 records, one for each MTC superdistrict, with the range of MTC 1,099 zones within each superdistrict. Download this text file (sd-corr.txt) (2KB).
Last updated: October 29, 2004
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