Effective Methods for Environmental Justice Assessment (2004) / Chapter Skim
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From page 19... ...
This geographic space is commonly referred to as "activity space." To determine the activity space of protected populations, you must examine the social, affective, and physical aspects of these communities. Specifically, we present methods that can assist in estimating: • The location and relative importance of activity spaces.
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A number of special considerations must be addressed when evaluating census data to identify protected populations. Some of these considerations include identifying appropriate comparison thresholds for analysis; selecting the appropriate scale of census data; estimating population characteristics for study areas; and comparing historic census data with current (2000)
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Some techniques are used more rarely because of their technical complexity. These include formalized public participation-based qualitative assessment techniques, detailed assessment of small-scale census data, and complex methods such as historical data analysis and population projection.
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Table 2-1 summarizes the protected population identification methods presented in this chapter. We present 12 methods below, which generally pertain to identifying the areas in the community where protected populations currently reside and where they may live in coming years.
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Customer survey Detailed All System users could experience distributive effects Medium/ high Survey design 6. Population surfaces Detailed Regional plans/ corridor/ project Scenario modeling or integration with gridbased modeling packages is required High GIS, Census data 7.
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Even if other methods are used to identify protected populations, local knowledge and public input should be used to verify results (see box titled "Using local knowledge and public input to validate census data," p.
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is a good example of why local knowledge and public input must be used to identify protected populations and issues that can arise if census data are not augmented by additional information sources. In 1994 the Nuclear Regulatory Commission (NRC)
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Large-area census data can be obtained for states, counties, census tracts, and censusdesignated places. Small-area reporting units available in census data include traffic analysis zones (TAZs)
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Relative level of environmental justice concern in the Houston district Area Percent minority Percent low income Relative level of concern Threshold value (State of Texas) 47.6 17.0 -- Brazoria County 34.6 12.5 Lower Fort Bend County 53.8 7.3 Higher Galveston County 36.9 16.8 Lower Montgomery County 18.6 11.9 Lower Harris County 57.9 14.9 Higher Waller County 50.1 20.0 Higher
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Similar results were obtained in a review of minority population data. Based on this information, it could be concluded that there is limited concern about adverse distributive effects to protected populations.
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Most techniques that use census data assume that populations and population characteristics are uniformly distributed within census units. This assumption can be especially problematic when working with largearea census data.
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Figure 2-2 shows the census block and census block group geographies used to derive population estimates for a 1-mile study area surrounding a proposed bridge location. The shaded census units show the area from which the 1-mile area estimates are determined.
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Spatial interpolation using small-area census data Small-area census data at the block, block group, and TAZ level offer the most detailed nationally available demographic information useful for identifying protected populations. Database, spreadsheet, and GIS software are often necessary for this type of analysis because even relatively small study areas commonly encompass a large number of small-area census units.
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For more information, see the discussion on "GIS-based techniques to estimate demographic characteristics." Step 4 – Estimate demographic characteristics of the study area population. The demographic characteristics of the study area population can be tabulated once the census units within the area of effects have been identified.
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Maps are the best means of presenting geographic patterns and are often essential for conveying the proximity of protected populations to sources of beneficial and adverse effects. Maps should be relatively simple, showing only the census data theme, such as percent minority by census block, and enough other features to orient the reader.
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Field surveys are especially important in situations where project effects such as noise and air quality will be highly localized and census data do not provide a fine enough level of resolution. A field survey is also a good technique for verifying the accuracy of small-area census data.
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Be on the lookout for "sensitive receptors" such as schools, hospitals, and nursing homes, as well as locations that visually do not appear to corroborate census information. This could include large areas with no population that are depicted as having high population on the census map or affluent neighborhoods marked as low income.
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A field survey is an effective technique for gaining local knowledge of areas potentially affected by transportation system changes. The method is well suited to use in combination with techniques for evaluating small-area census data.
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Yes _____ No _____ Figure 2-5. Survey questions to identify protected populations Step 2 – Administer the survey.
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from population counts such as total persons, total minority, or total low-income. It is therefore necessary to compute population percentages from the various population surfaces using map
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Historical data are also useful to establish population baselines for comparisons to current or more recent data, and they can be useful for identifying population trends. Review of historical data can be especially important as part of various methods for performing population projections, which are discussed later.
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Interstate highway corridors with a significant increase in minority population from 1990 to 2000 Assessment. Historical data can be used to evaluate long-term population trends and distributive effects of transportation system changes that have occurred in the past.
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As such, it is advisable to evaluate all transportation policies, programs, and projects using both current population data and population data projected for some reasonable, informative future-year scenario. However, the complexity and questionable validity of population projections must be weighed against the additional insight they would provide into identifying future effects to protected populations.
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Some examples of symptomatic variables include housing permits, new utility hookups, birth and death records, vehicle registrations, and school enrollment figures. There are various techniques available for developing population projections, and many metropolitan planning organizations (MPOs)
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The first stage is to develop total population projections for counties, cities, tracts, and traffic analysis zones. The second stage is to decompose the total population estimate into the subpopulations of interest, such as minority and nonminority.
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are added to household population estimates to generate the base-year total population estimate for each analysis zone. For purposes of environmental justice assessment, it is important to identify the protected population characteristics of the base-year population.
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Use census data for the base year to generate predictor variables for the response variables percent low-income population and percent minority population. The following variables utilized in Stage 1 should be considered as candidate predictor variables for both percent low-income and percent minority: housing costs (housing unit values and rental costs)
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Using the regression model approach, percent minority and percent low income for each analysis zone can be calculated directly from the model. Reporting the confidence intervals allows for further assessment of the certainty as to
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Trend-based or regression-model techniques can be used to derive protected population projections from baseyear and future-year data. General population projection techniques such as trending and extrapolation assume that current population patterns will continue through time and are not well suited to small-area assessment.
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The standard EJI is represented by the following formula: EJI = DVPOP x DVMAV x DVECO where DVPOP = degree of vulnerability based on population density DVMAV = degree of vulnerability based on presence of minority population DVECO = degree of vulnerability based on presence of low-income populations These factors are computed as follows. DVPOP Population per square mile Score 0 0 > 0 and < 200 1 > 200 and < 1,000 2 > 1,000 and < 5,000 3 > 5,000 4 DVMAV and DVECO Percent minority or percent low income Score < State average 1 > State average and < 1.33 times the state average 2 > 1.33 times and < 1.66 times the state average 3 > 1.66 times and < 2.0 times the state average 4 > 2.0 times state average 5 In the standard formulation, the EJI thus ranges from 0 to 100.
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Block-group-level data are the most commonly used evaluation unit. Census data from 1990 or 2000 are required for the evaluation units (block groups, tracts, or TAZ)
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Activity space analysis using personal interviews This simple approach can be an effective tool to provide a general idea of the areas that comprise the individual and communal activity spaces of the populations of interest. Such information supplements (it does not replace)
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Method 11. Activity space analysis using an abbreviated diary Measuring habitual travel behavior -- determining what places a given population consistently travels to and the routes that they use -- can be an effective way of measuring communal activity space.
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Method 12. Space-time activity analysis using GIS A more advanced method for exploring how the activity space of protected populations is configured within a given community is a form of daily trip diary.
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When to use. With a sufficient sample size and appropriate sample selection design, this method can provide a fairly accurate picture of the activity space of the sample frame (i.e., the protected population within a particular area of a community or across a community)
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It is essential that you select, recruit, and fully brief a representative sample of the low-income population and minority population that potentially would be affected by the proposed project. Special attention may be required to prepare illiterate or non-English speaking participants.
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These files can be downloaded and used with spreadsheet, database, and GIS programs to calculate demographic variables useful in identifying protected populations.
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1996. "Implementation of Enhanced Areal Interpolation using Map Info." Computers and Geosciences, Vol.
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2003. "Activity Spaces: Measures of Social Exclusion." Transport Policy, Vol.
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