The laws and guidance governing the equity analysis of regional transportation plansgenerally do not prescribe specific analytical practices. In the absence of explicit requirements,an approach has evolved that relies upon methods developed for traditional environmental justiceanalysis based on geographic aggregation of target populations and a conception of equity thatgenerally ignores existing disparities. This article uses activity-based travel demand modelingdata provided by the Metropolitan Transportation Commission, the metropolitan planningorganization (MPO) for the nine county San Francisco Bay Area, to perform a sensitivityanalysis on geographic thresholds and compare estimates of aggregate and disaggregate travelbehavior. The sensitivity analysis provides important information about existing commute timeby local bus in communities with increasing concentrations of people of color. Additionally,aggregating over all modes and several different protected populations obscures importantdifferences that are only visible when disaggregated. Both threshold approaches and disaggregateanalyses can provide important information about inequities, but because the particular thresholddefinition employed can entirely predict the outcome of an equity analysis, care must be taken toensure that the outcomes from the analysis are meaningful. This result suggests that members ofthe public and transportation advocates participating in the development of regional equityanalyses must shift their focus from indicators and metrics to consider the importance of themethods used to calculate those indicators. The paper concludes by proposing one example of arevised equity analysis that is more informative than previous iterations and is responsive tofeedback from regional equity stakeholders.
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