Agenda - 08-25-2008- c2 - Laserfiche WebLink

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l~3 Zones comprised primarily or wholly of parks, military bases, prisons, airports or industrial facilities are outside the scope of this analysis and were eliminated from the data base. The Variables The dependent variables are vehicles available per household and vehicle miles traveled (VMT). Average vehicle availability for each zone is from the 1990 U.S. Census. VMT per vehicle is derived from odometer readings recorded when owners take their vehicles in for emission systems inspections (smog checks) in California and Illinois. Average VMT per household is calculated as the VMT per vehicle times the number of vehicles per household for each zone. The dependent variables were tested against a wide range of potential explanatory variables, including the most important socio-economic factors of household income and household size. Locational variables tested were: density, transit service and access to jobs by transit, availability of local shopping, pedestrian and bicycle friendliness, and proximity to jobs. The density measures tested were households/residential acre, population/acre and population/residential acre. Households/residential acre (I-Ih/ItA) had the strongest correlation to vehicle ownership, while households/total acre (Hh/TA) had the strongest correlation to VMT/vehicle. Total acreage includes residential, commercial, industrial, agricultural, parks and open space, and any other categories reported. The data were compiled from the census and regional planning organizations. Household and per capita income ($/Hh, $/P) and household size (P/Hh) were derived from 1990 census data. The measure of transit accessibility is zonal transit density (Tr) , which is the daily average number of buses or trains per hour times the fraction of the zone within 1/4 mi of each bus stop (or 1/ami of each rail or ferry stop or station) , summed for all transit routes in or near the zone. There is some double counting where stops are less than 1/4 mile apart, but correcting for this would not substantially alter the order of the TAZs nor the relative differences between zones. Therefore this measure provides a robust assessment of transit service. An alternative measure, the zonal transit density times the number of jobs reached within 30 minutes by transit (Tr,~ , provided no better correlation with auto ownership or driving than the zonal transit density alone. So the simpler zonal transit density is reported. Routes, schedules and stop locations are from the transit agencies or the metropolitan planning organizations, who also calculated the number of jobs accessible by transit. The measure of center proximity (CP) is the number of jobs within a 30 minute drive, calculated by the Metropolitan Transportation Commission for the San Francisco region. An alternative measure is the number of jobs within a 15 minute drive divided by the number of jobs within a 30 minute drive (E15/E30). This provides a measure of the relative availability of jobs locally. Including CP in the VMT/vehicle analysis provided a marginally higher RZ, but was available only in San Francisco and therefore not included in the general analysis. E15/E30 did not improve RZ as much as CP did.