[CTPP] Commuting to Downtown - Methodology

Here are some ideas for organizing your research for the Commuting to Downtown project. Hopefully this is not too intimidating. **************************************************************************************************************************************************************************** Detailed Methodology / Commuting to Downtown 0. What Cities should be examined? We have 58 U.S. cities of over 300,000 population, and 68 cities of over 250,000 population. Since this is strictly a volunteer opportunity, let's work on ANY city greater than 250,000 population. OR, any city with a downtown employment greater than 30,000 jobs. This is not intended as a hard and fast rule, just a starting point. Hey, if someone wants to volunteer the analysis for Toronto or Mexico City or London, heck, why not? 1. Assemble the computer files from the 1970 UTP and 1980 UTPP, if available. These will be in the possession of the metropolitan planning organization, the state department of transportation, or perhaps copies were maintained by the state data center, local data centers, local universities or local consultants. If and when you do find the 1970-1980 databases, please make sure that the FHWA has a copy for their Journey-to-Work Data Archive (contact: Nanda Srinivasan at the FHWA). These 1970-1980 data may be impossible to locate, or they may never have existed, for certain cities. The Commuting to Downtown analysis for those cities would then focus on 1990 to 2000 trends. This is the "treasure hunt" element of this project! 2. Assemble the computer files from the 1990 CTPP and the 2000 CTPP. The 1990 CTPP data has been widely distributed by the BTS via CD, and is currently available on the BTS transtats site. (transtats.bts.gov). The 2000 CTPP data has been directly mailed to MPOs and State DOTs, and is also available on the BTS transtats site. 3. Downtown definitions, Part 1. The first step may be to examine the downtown boundaries in the 1977 Census of Retail Trade. These are the official downtown boundaries as used in the 1980 UTPP. For the 1990 CTPP, MPOs were provided the option of re-defining their downtowns. The "CBD of work" is a summary level in both the 1980 UTPP and the 1990 CTPP (but not the 2000 CTPP). The analyst may find that the '77 Retail Trade Census CBD boundaries are totally inappropriate for their cities, so the analyst may want to draw on other resources: chambers of commerces, "Business Improvement Districts" (BIDs); downtown development councils; main street organizations; urban geography professors; your own knowledge and experience. The definition of downtown, or the "central business district" is more of a cultural and traditional notion, than a strict definition based on employment density. The WWW is a great resource for this sort of exercise. 4. Expanding downtowns? It will be easier for this cross-downtown analysis to maintain a consistently-sized downtown area from past to current census years. My recommendation is to use the best, current definition of downtown and use those boundaries to assemble data from the 1970, 1980 and 1990 censuses. Your own downtown may have physcially expanded, or contracted, over the decades, but it is much harder to make statements about increasing or decreasing employment densities when the downtown land area is changing. As an option, you can assemble background appendix materials on the geographic expansion/contraction of the CBD. 5. Downtown definitions, Part 2. Be sure to develop and maintain a correspondence file between your downtown definition and the component geographic areas, be they census tracts, block groups, or census travel analysis zones. Maintain these correspondence files for all census years, given that the component geographic areas may be a different basis (e.g., our data from the 1970 is from our old 440-zone system; from 1980, at the block-group level; and from 1990-2000, the census zone level.) 6. Multiple downtowns? We will want to have multiple downtowns for certain cities including Manhattan and Chicago, perhaps San Francisco. This would show the characteristics for the "greater downtown" compared to the "core downtown." 7. Map of downtown. The prototype maps for downtown San Francisco, Oakland, and San Jose are quite fuzzy. (That's my fault.) The final product will need to be much sharper. The idea is to develop a map of about a half-page, showing the downtown boundaries, major transit/transportation facilities, significant landmarks (skyscrapers, parks, city hall, etc.), scale and north arrow. We will probably want to export any finished maps into encapsulated post-script or some other high-resolution format. Recruit your GIS staff to prepare a map of downtown. 8. MPO Employment data. It will be VERY useful to show the trends in total employment in the downtown area, AND the metropolitan area, based on the employment databases maintained by the COG/MPO. The Census "workers-at-work" SHOULD be less than the MPO/COG estimates of "total employment" due to multiple jobholding, weekly absenteeism, and seasonal variation, and errors in both the CTPP and the MPO/COG total employment estimates. 9. Commute mode shares. Data on workers working in downtown by aggregated modes: drive alone, carpool, transit (excluding taxi), taxi (for NYC, others), walk, bicycle, working at home. Data on workers working in the region for transit, and total. This is used in understanding downtown's share of regional transit commuters, and regional total commuters. Even though our focus and interest is in "transit commute share" the assembled data will also be useful in understanding bicycle, walk, carpool and working-at-home shares. 10. Living downtown. Assemble data on total population and total households. Much of the downtown literature focuses on living in downtown, and this study can be very helpful in assembling these data. Use standard census products like PL 94-171, SF1, or the CTPP part 1. 11. Land area. Assemble statistics on land area, in acres. This will be useful in describing the overall worker (job) density as well as downtown population (resident pop.) density. We will focus on gross densities as opposed to net densities (e.g., households per residential acres) due to the difficulty in assembling net acres (residential acres; employment-serving acres.) 12. What's the Story? The analyst should provide some text describing what is happening in the downtown, what are the significant events including transit system openings and changes in major buildings. What are the hopes and aspirations for the downtown in your community? ****************************************************************************************************************************************************************** ************************************************************** Charles L. Purvis, AICP Principal Transportation Planner/Analyst Metropolitan Transportation Commission 101 Eighth Street Oakland, CA 94607-4700 (510) 464-7731 (office) (510) 464-7848 (fax) www: http://www.mtc.ca.gov/ Census WWW: http://www.bayareacensus.ca.gov/ **************************************************************