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· How the proposed changes would affect protected population groups.
The methods presented in this chapter include many effective techniques for identifying
protected populations using demographic data. This information can be collected either directly
or from sources such as the U.S. Census Bureau. In addition, various geographic information
system (GIS) and database applications allow you to process 1990 and 2000 census data and
apply a number of the methods presented in this chapter.
The methods presented generally involve the following steps:
· Collect the necessary information.
· Verify the accuracy of the information if possible.
· Calculate pertinent population statistics.
· Assess the presence or absence of protected populations.
Many of the methods are quantitative and use census data, survey data, and GIS. Other methods
are more qualitative and rely heavily on local knowledge and the public participation process.
Which method is best to use depends on various factors including the probable magnitude of a
particular impact, data availability and cost, and the capabilities and experience of the person
performing the analysis. The most important factor is whether or not the method is appropriate
for the type of transportation system change being evaluated. For example, some effects of
transportation system projects are distributed geographically, whereas other effects are
distributed among system users based on their demographic characteristics. The best methods
and data for identifying the demographic characteristics of affected populations may differ from
case to case.
One purpose of any protected population assessment is to accurately represent the demographic
characteristics of the affected populations. Any assessment should include input from members
of the public and individuals with comparatively high levels of knowledge of the local area.
Many methods rely directly upon these sources of information. For other methods, such as those
that rely on census data, local knowledge and public input can be used to validate source data
and study results.
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) census
data. These special topics are addressed in this chapter and in the appendices to this guidebook.
STATE OF THE PRACTICE
Most studies conducted since the mid-1990s to conform to requirements of the National
Environmental Policy Act (NEPA) include some level of demographic review that includes
analysis of minority and low-income population information. Inclusion of this information in
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transportation planning studies is common but not universal. A review of recent NEPA-
conformance studies and a survey of practitioners show that local knowledge and analysis of
large-scale census data are the most commonly used techniques for identifying protected
populations (Sheeley and Forkenbrock 2002). Similar types of environmental justice assessment
are also becoming commonplace in planning products such as major investment studies (MISs).
Field survey and data collection techniques also are commonly used. Assessment results released
to the public often are brief summaries with very little detail. The specific methods used and
analytical results obtained generally are not documented in detail.
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. The state of practice could clearly be enhanced, however, if these rigorous assessment
methods were more accessible to practitioners. Making these methods more accessible is one of
the goals of this guidebook.
The methods presented in this chapter cover the spectrum of potential approaches from simple to
complex and qualitative to quantitative. A key consideration in environmental justice analyses
related to potential transportation projects is how protected populations move about in time and
space. Because few people spend the majority of their time at home, it often is not sufficient to
determine only where minority and low-income populations live; it also is important to ascertain
prevalent daily activity spaces.
Trip diaries and surveys are the most common means of identifying how people move about in
time and space. These methods can be very simple in nature or quite involved. The survey data
can reveal the activity space within which protected populations frequently, occasionally, or
seldom travel.
Revealed preference analyses are a practical way to evaluate how people actually respond to the
choices available to them, and therefore what their preferences are when trading off attributes.
These analyses enable you to assess, for example, how groups of people balance lower prices
against convenience when purchasing goods. With sufficient data, this approach can enable you
to "make direct inferences about the trade-offs travelers make among site and distance attributes"
(Pipkin 1986, p. 183). When using these analyses, you should keep in mind that people will
reveal preferences only in terms of the available alternatives. In considering shopping trips,
Pipkin pointed out that individuals who do not own a vehicle or are otherwise disadvantaged
might be forced to forego certain kinds of trips or to restrict their travel to nearer, smaller, and
perhaps more expensive alternatives.
Variables that help explain travel patterns include the following:
· Personal attributes such as age, ethnicity, income, and level of education;
· Site characteristics such as price, quality and convenience for shopping, service, or
recreational destinations; and
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