Assessing the Impacts of Development Choicesuivii �peciai Articie Assesing tne impacts of L)evelopment Uhoices Page I of 41
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The G13rowth Management Institute
ASSESSfNG THE IMPACTS OF
Horne
i
Ism=
Projects by Linda Hollis, ATCP,
Advisors Douglas Porter, AICP, and
Directors Holly Stallworth, Ph.D.
April 1997
Prepared for the Governor's Commission for a
Sustainable South Florida (GCSSF) and its
Full -Cost Accounting Committee
Prepared by
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The Growth Management Institute,
through a cooperative agreement with the
U.S. Environmental Protection Agency
Office of Sustainable Ecosystems and Communities
Section Page No.
I. Executive Summary 1
A. Purpose and Approach of this Paper 1
B. Economic Impacts 5
1. Economic Impacts on the Private Sector 5
2. Economic Impacts on the Public Sector 5
C. Social Impacts 6
D. Transportation Impacts 7
E. Environmental Impacts 8
F. Conclusions 9
II. Economic Impacts 10
A. Economic Impacts on the Private Sector 10
1. Calculation of Direct Economic Impacts 10
2. Modeling of Indirect and Induced Impacts I I
a. Economic Base Models 11
b. Input -Output Models 11
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c. Econometric Models 12
d. Economic Impact Analysis and
Development Patterns 12
B. Economic Impacts on the Public Sector:
Fiscal Impact Analysis 13
1. Recommended Methodologies 14
a. Per Capita Method 14
b. Case Study Method 14
c. Econometric Method 15
d. Fiscal Impact Analysis and
Development Patterns 15
III. Social Impacts
A. Preservation of Historic and Cultural Resources 18
B. Open Space, Parks and Recreation 18
C. Environmental Design 18
D. Housing 19
E. Equity 19
F. Quality of Life 20
G. Social Impact Analysis and Development Patterns 20
TABLE OF CONTENTS (Continued)
Section Page No.
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IV. Transportation Impacts 21
A. Traffic Impact Analysis 21
B. Transportation Analysis 21
C. Integrated Models 22
1. Linking Land Use and Transportation 22
a. ITLUP 22
b. LUTRAQ 22
c. CUFM 23
d. STEP 23
2. Linking Land Use, Transportation and
Air Quality 23
D. Transportation Impact Analysis and
Development Patterns 24
V. Environmental Impacts 27
A. Analysis of Pollution 27
1. Air Quality 27
2. Water Quality 28
3. Noise 28
4. Stormwater Runoff 29
B. Carrying Capacity 29
C. Ecology 30
D. General Analysis Techniques 31
1. Checklists and Matrices 3I
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2. Weighting -Scaling Techniques 31
3. Distributional Techniques 32
4. Monetary Valuation 32
5. Geographic Information Systems 33
E. Environmental Impact Analysis and
Development Patterns 34
References 35
This paper presents an overview of current methods and measures for
evaluating the potential impacts of land use patterns. It is written to
assist the Governor's Commission for a Sustainable South Florida
(GCSSF), and particularly its "Full -Cost Accounting Committee," in
understanding the state of the practice, for consideration of quantitative
and qualitative costs and benefits that may be associated with future
development in the Eastward Ho! area.
This paper was prepared as part of a collaborative effort by The
Growth Management Institute, through a cooperative agreement with
the United States Environmental Protection Agency, and with
assistance from EPA staff in the Office of Sustainable Ecosystems and
Communities. The views expressed in the paper are only attributable to
the authors and in no way represent official EPA policies.
A. Purpose and Approach of this Paper
The Governor's Commission has worked for over two years to
determine ways and means of reconciling urban growth needs in South
Florida with restoration of the Everglades ecosystem. Based on its
intensive studies, the Commission has targeted for urban revitalization
a three -county area stretching along the east coast from Miami to West
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Palm Beach. The Commission views the redevelopment and infill of
this Eastward Ho! area as essential to reduce the continuing spread of
development towards and into the Everglades.
As part of implementation of the concept of Eastward Ho!, the
Commission established a "Full -Cost Accounting Committee." The
Committee's charge is to identify ways to consider all potential effects
of proposed development actions. These effects include secondary
impacts or externalities that are frequently overlooked or discounted in
impact evaluations. The Commission further charged the Committee to
examine "full cost accounting" principles including social, political and
ecological impacts; economic costs and benefits; legal costs; and
technical feasibility. (Governor's Commission Report, p. 43.)
The Commission's charge to the Committee points toward a broad
spectrum of effects that should be considered in public policy
evaluations. In its discussions to date, the Committee has attempted to
understand the complex interactions of potential effects, and the tools
that are available or should be considered in measuring those effects.
This paper is focused on a particular aspect of the Commission's and
Committee's concerns: ways to assess the impacts of various forms of
development that might be considered for the Eastward Ho! Area. We
present a framework for assessing and evaluating various impacts with
one specific focus: patterns of land development.
Ours is a common sense or "matrix" approach. The first step in the
matrix approach is to identify and list all consequences of concern for a
particular policy. This is not radically different from what practitioners
of cost -benefit analysis may view as identifying all costs and benefits.
However, the matrix approach allows consideration of both
quantitative and qualitative impacts. Restricting assessments of effects
to factors that can be stated in specific monetary terms poses a number
of problems.
Most importantly, it reduces the scope of analysis due to the vast
number of factors that defy the price -based paradigm. Such factors
include social equity, ecosystem health, aesthetics, and quality of life.
Monetization is particularly problematic in cases of uncertainty, where
it becomes impossible to identify and quantify all possible outcomes.
In these cases, rather than placing a burden of proof on monetized
"benefits" exceeding monetized costs, decision makers might want to
consider the nature of the uncertainty -- and how both action and
inaction present different "risks" or outcomes to society.
Our summary matrix is shown at the end of this section. In it and in this
paper, we have grouped development impacts into four broad
categories: economic, social, transportation, and environmental. These
categories provide a useful way to consider the general implications of
development, although they overlap and interact. For example, some
environmental impacts can and do have economic consequences, such
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as destructions of habitats and species reducing tourism or
opportunities for commercial and recreational fishing. However, we
believe that a large number of environmental impacts defy
monetization, and therefore should stand alone.
Similarly, quality of life effects can have negative economic
consequences. For example, perceived decreases in public safety or the
quality of public education, can lead to decreased investment in the
urban core and the inner suburbs. Again, because many social impacts
defy monetary expression, we list them separately.
Finally, transportation is shown as a unique category for two main
reasons. First, there are a wide range of techniques and models used to
conduct various types of transportation impact analysis. Second, there
are significant interactions between transportation, social and
environmental impacts, which are not easy to quantify or monetize.
The first two columns of the matrix list major impacts which can be
attributed to changes in land use. The third column shows methods of
impact measurement and/or sources of information on effects. The
fourth column indicates whether or not measures can be monetized.
In the rest of this Executive Summary, each of the four groups of
impacts is discussed in turn: Economic, Social, Transportation and
Environmental. A more detailed discussion follows in the body of the
paper, as follows: Section II., Economic; III. Social; IV.
Transportation; and V. Environmental Impacts.
Impacts to be
How Measured
Method of
Measures
Measuremt./
Monetized?
Evaluated
Source of
Information
Economic
Direct Impacts:
Economic
Yes
Emplymt,
Impact
Analysis
Income, Retail
Sales, etc.
Indirect/Induced
Economic
Yes
Impacts:
Impact
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SociallQuality
of Life
Emplymt,
Income, Sales
Costs &
Revenues to
Local Govts.
Preservation of
Historic &
Cultural
Resources
Analysis
Fiscal Impact [Yes
Analysis
Environ.
Impact
Analysis;
local
experts/grps
Not easily
Availability of
Acres per
Not easily
Open Space,
1,000 pop.;
Parks &
Recreation
local &
regional info.
Environmental
Visual
Not easily
Design
Preference &
other public
opinion
surveys
Availability of
Local &
Not easily
Affordable
Regional
Housing
Information
Equity of
Social
Not easily
Development
Accounting
Impacts
Matrix; local
& regional
info.
Quality of Life
Transportation VMT; LOS on
Exist. Rds.:
New Capacity
Needed
Environmental II Air Quality
Public Not easily
Opinion
Surveys; local
& regional
info.
Transportation Not easily
Impact
Analysis
Pollutants; 11 Not easily
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Non-Attainmt.
of Stds; Urban
Airsheds
Water Quality
Sediments;
Not easily
Turbidity
Hyrdological
Models
Noise
Decibel
Not easily
Levels
Noise Contour
Analysis
Stormwater
Volumes,
Not easily
Runoff
Peak
Discharge
Computer
Models
Carrying
Water; Sewer;
Yes
Capacity
Landfills
State, Reg. &
Local Info.
Preservation of
Nos. Of Pop.;
Not easily
Species &
Acres of
Habitats
Habitat; Local
Info.
II. Economic Impacts
In this paper, economic impacts are discussed in two sections.
Economic impacts on the public sector, commonly called fiscal
impacts, are in subsection 2. below. Economic impacts on the private
sector follow in subsection 1.
1. Economic Impacts on the Private Sector
Economic impacts are commonly included with environmental
assessments. Stand-alone economic impact analyses are also conducted
for large development projects such as sports stadiums, conference
centers, and gambling casinos.
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Measures of economic impact include employment, income and
expenditures. Direct increases in these measures due to new
development are straightforward calculations using data from local,
regional, state and Federal sources.
Indirect increases in these measures are usually estimated through the
use of input-output models. A commonly used model, RIMSII,
contains multipliers for counties, MSAs and states, based on the U.S.
Department of Commerce's national input-output data. This type of
analysis is most useful to compare impacts by types of jobs or
industrial sectors associated with new development, or to compare
different land uses on the same site. This type of economic analysis
also predicts conditions at buildout of a proposed project or plan, based
on existing conditions.
Indirect economic impacts can also be calculated through the use of
econometric models. Such models are time-consuming and expensive
to apply. However, they can account for interactions over time between
growth and the economic base. What this means for Eastward Ho! is
the following.
If public policies and regulations discourage new development in the
outer suburbs and encourage development in existing urbanized areas,
over time residential and employment locations in the urban core and
inner suburbs will become more desirable. As a result, property values,
household incomes and employment opportunities there will increase.
An econometric model can account for such improvements, and for the
redistribution of households and jobs over time. Therefore this
technique is most usefiil to compare economic impacts of compact
versus sprawl development.
2. Economic Impacts on the Public Sector
Fiscal impact analysis compares the costs of public facilities and
services needed to serve new development, to the revenues generated
by growth. The result of this comparison is net revenues or costs to the
local government, school district, or other public entity.
Fiscal impact analysis most commonly uses the per capita method, or
average costs per new resident and per job. Another technique is the
case study method, in which the true marginal costs of growth are
captured. This is important where the capacity of expensive public
facilities such as schools is an issue.
In South Florida, a case study fiscal analysis may show cost savings for
compact development due to less need for costly new infrastructure.
However, using such a method, revenue projections are likely to be
based on today's market values. Due to lesser desirability of the urban
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core and inner suburbs as locations for new houses and jobs, lower
market values there may generate lower revenues for compact
development.
As with economic impact analysis, the use of econometric modeling
can address this problem with fiscal analysis. That is, if new
development in the outer suburbs were discouraged, market values in
the inner suburbs and the urban core should increase over time. This
would result in revenue projections less likely to penalize compact
development vis-a-vis sprawl.
C. Social Impacts
The direct social impacts of new development are generally increases
in population and employment, which are basic inputs for economic,
fiscal, transportation and environmental analysis. Population and
employment in turn generate demands for public facilities and services
such as school buildings, teachers, and public safety personnel. Once
these direct social impacts are quantified, they become inputs to fiscal
impact analysis.
Some indirect social impacts are documented as part of environmental
impact analysis. These include the preservation of historic and cultural
resources; the availability of open space, parks and recreational
facilities; the quality of environmental design; and the availability of
affordable housing. These impacts are usually described based on
locally available data and surveys. They may be described
quantitatively but are difficult to monetize. Social impacts are most
often described qualitatively.
Indirect social impacts not usually documented are issues of equity, or
who wins and who loses from changes in land use. A promising, but as
yet rare, technique here is to develop a "social accounting matrix." This
disaggregates the results of input-output economic analysis to
households and workers by race, sex, age and income.
A comprehensive analysis of social impacts would compare changes in
the level of community well-being, before and after development takes
place. This technique is also rarely applied, although cominunities are
beginning to document baseline quality of life indicators. Documenting
the baseline permits monitoring of change and tracking conditions in
the future.
D. Transportation Impacts
Since the 1960s, the transportation impacts of both projects and plans
have been analyzed using the four -step travel forecasting process. In
this process, population and employment projections by geographic
area or zone, are used to estimate the generation of trips. Trips are then
distributed to destinations by zone. Trips are also distributed to modes,
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either automobile or transit. Automobile traffic is then assigned to links
on the existing road network. When traffic from trips due to new
development is added to existing traffic, levels of service (LOS) on
existing roadways often decrease.
In addition to measures of LOS or traffic congestion, outputs of
traditional transportation models include average daily trips and vehicle
miles of travel. Estimates of mitigating improvements to transportation
capacity (whether highways or transit) and costs of such improvements
are outside traditional transportation planning models.
As with economic and fiscal models, traditional transportation models
do not calculate interactions between growth and the base. Rather, they
compare conditions at buildout to existing conditions. A new
generation of models is attempting to integrate land use forecasting
with transportation planning. That is, compact development patterns
are likely to show positive transportation impacts over time. This
assumes that discouragement of new development in the outer suburbs,
results in more development in the inner suburbs and urban core. As
higher density locations become more desirable, so should alternatives
to commuting alone. The new models therefore seek to account for
greater use of alternatives to single occupancy vehicle automobile trips
under compact development scenarios, by including walking,
bicycling, paratransit and other options among their choices of travel
mode.
Finally, data is being compiled to permit the linking of land use types,
driving patterns, and automobile emissions. However, models that
successfully integrate land use, transportation and air quality are not
likely to be perfected for several years.
Use of current transportation models is likely to show that compact
development results in lower vehicle miles of travel, fewer average
daily trips, and lesser declines in LOS, especially on roadways in the
outer suburbs. Compact development will also look more positive than
sprawl if existing transit systems can accommodate additional trips by
the greater number of households and jobs assumed to be located in the
inner suburbs and urban core. Costs for significant improvements to
transit, or for new systems such as light rail, can outweigh savings on
roadway improvements.
E. Environmental Impacts
Environmental impact analysis became a formal discipline after
passage of the National Environmental Protection Act (NEPA) in 1970.
Since then, over 20 states have passed "mini-NEPAs." In Florida,
environmental impacts are included in Developments of Regional
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Impact (DRI) analyses, and in local comprehensive plans. Although
NEPA includes social, economic and other impacts, in this paper
environmental impacts are focused on natural resources such as air,
water, soil, species and habitats. Generally, compact development will
result in lower consumption of natural resources and fewer negative
environmental impacts.
In local environmental assessments, baseline conditions are
documented and compared to expected future conditions after buildout
of the proposed project or plan. Analysts use available data such as
surveys, engineering and scientific studies, and data bases which link
environmental impacts to types of land use. Comparison of baseline to
future conditions is often done through the use of checklists and
matrices. Another common method of comparison is through maps
produced using Geographic Information Systems (GIS).
Measurements of impacts include acres of open space, wetlands, and
wildlife habitats either lost or preserved; levels of pollutants in the air
and water; volumes of stormwater runoff; and decibels of noise. The
carrying capacity of related manmade systems, such as water,
wastewater and solid waste, can also be compared to the projected
demands generated by new development.
Because environmental impacts are expressed in so many different
units of measurement, analysts have constructed techniques and models
that attempt to weight and scale impacts in the same units of
measurement, and even to assign monetary values. Such techniques and
models present obstacles for decision makers in following the steps in
reasoning, and in challenging the judgments involved in assigning
values to enviromnental impacts. Evaluating the significance of
environmental impacts is best done by an interdisciplinary team of
professionals, working with decision makers.
F. Conclusions
Development impact analysis is an art practiced by analysts trained in a
number of disciplines, and working in a number of settings. To the
extent possible, this paper documents the current state of the art by
such practitioners. Also to the extent possible, this paper makes
conclusions about the usefulness of the various forms of analysis, to the
comparison of compact and sprawl patterns of land development. The
reader is referred to the matrix on page 4 for a summary of measurable
impacts, and whether or not they can be monetized.
One major conclusion from this analysis is that many impacts of
development cannot be easily quantified or monetized. Without "hard"
numbers and absolute measures, it is still possible to assess the
significance of impacts, and to compare impacts among alternatives,
using qualitative measures.
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It seems to these authors that decisions by both the Federal and State
governments about the importance of restoring the Everglades
ecosystem constitute mandates. A February 1995 report by the U.S.
Army Corps of Engineers finds that, where such mandates exist,
"Calculations of the monetary benefits of such actions are ... not
required. The use and nonuse values of those environmental actions are
implicit in the directive. Explicit monetary valuation of the benefits
would be a costly ancillary exercise." (Feather et al, p. 5.)
Nevertheless, it is important to identify and evaluate potential impacts
of land use patterns as one tool in decisionmaking. In South Florida, we
have the opportunity to expand our knowledge and techniques in
econometric modeling of economic, fiscal and transportation impacts;
linking land use forecasting, transportation modeling, and air quality
assessment; and documenting social impacts, including who wins and
who loses under different patterns of land use.
Economic impact analyses have been conducted for over 100 years. In
particular, "estimates of the econ omic benefits associated with a
particular proposed action have been used as a selling point in the
legislative arena" since the nineteenth century (Jain, p. 188). This is
especially true for massive public works and other development
projects.
For almost 60 years, a distinction has been made between economic
impacts on the private sector, and economic impacts on the public
sector (Muller, 1976, pp. 3-4). The latter field is generally referred to as
fiscal impact analysis, and will be discussed in subsection B below.
A. Economic Impacts on the Private Sector
According to the Development Impact Assessment Handbook, most
economic impact studies are part of environmental impact assessments.
These assessments are undertaken when the proposed changes in land
use are significant in scope. These include planned unit developments,
mixed use developments, and military base closings. In some states,
such as California, economic impact analysis is required as part of the
General Planning process for local governments.
Economic impact analysis is also conducted for large development
projects such as sports stadiums, conference centers, and -ambling
casinos. Economic impacts are studied mainly by consulting firms and
academics with backgrounds in planning, economics, business and
geography. (Burchell et al, 1994, p. 107.)
Economic impacts include employment, income, and expenditures
generated by new development. Impacts are both direct and indirect.
Direct impacts are discussed first.
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1. Calculation of Direct Economic Impacts
Direct economic impacts of a project or plan include the following:
o Jobs created as a result of the new development
Wages and salaries from the new jobs
Spending on personal consumption by residents of new
housing units and workers in new jobs
Calculations of direct economic impacts is straightforward and can be
done using available data, without the use of computer models.
2. Modeling of Indirect and Induced Impacts
Over time direct impacts bring about indirect impacts, which in turn
cause induced impacts. Indirect and induced effects are calculated by
means of economic impact models. Types of models are discussed
below.
a. Economic Base Models
Economic base models were first developed in the 1930s to gauge the
relative strength of metropolitan economies for residential mortgage
underwriting. They trace the interaction of purchases by local
government, households and businesses of goods and services
produced by basic industries (or the export sector) and by non -basic
industries (or the import sector). The impact of a dollar increase in
spending at any point is traced through the cycle to its logical
conclusion. The annualized results indicate the relationships of total
economic impacts to basic economic impacts. That is, a multiplier is
produced which indicates that one dollar of income to the export sector
results in more than one dollar of income to the total economy. The
Economic Impact Forecast System (EIFS) used by the Army Corps of
Engineers is an economic base model.
b. Input -Output Models
In the 1950s input-output models were developed as an extension of
economic base models.
These models generate multipliers to estimate employment, earnings,
expenditures and output effects; and coefficients to allocate these
effects to the sectors of the local or regional economy. Construction of
unique regional models is time-consuming, expensive, and usually
done by academics.
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In recent years, analysts have come to rely on models derived from the
national input-output data which is updated annually by the U.S.
Department of Commerce. These models include the following: AIMS,
used by the Army Corps of Engineers; IMPLAN, used by the Forest
Service of the U.S. Department of Agriculture; REML from Regional
Economic Models, Inc.: RSRI, from the Regional Science Research
Institute; and RIMS, from the Bureau of Economic analysis of the U.S.
Department of Commerce.
An extension of RIMS, called RIMSII, has been widely used since
1986 by consultants, researchers, and government analysts. Users
include the U.S. Department of Defense (the impact of military base
closings) and the Florida Department of Transportation (Developments
of Regional Impact for major facilities). RIMSII multipliers are
available for single counties, groups of counties, economic regions
such as Metropolitan Statistical Area, individual states, and groups of
states. RIMSII multipliers have also been incorporated into packaged
models such as Arthur Andersen's Insight and Georgia Tech"s LOCI.
c. Econometric Models
As with unique regional input-output models, econometric models are
generally constructed and applied by academics. These models consist
of a system of simultaneous equations that link economic activities
such as consumption, production, investment, and wage and price
determination. A recent example is the 1992 model of the economy of
New Jersey developed by the Center for Urban Policy Research at
Rutgers University.
d. Economic Impact Analysis and Development Patterns
The state of the practice of economic impact analysis is that it is most
commonly applied to site -specific projects such as conference centers,
arenas and stadiums. The alternatives are often two -- without the
project (the status quo) and with the project.
Another common application of economic analysis is as part of
comprehensive and general plan updates. These analyses often
document only the direct economic impacts due to new development.
These include increases in employment as they relate to types of land
use (office, industrial and retail/commercial). These analyses also tend
to include impacts to their sponsoring local governments, such as
increased retail space (sales tax revenues), and increased household
incomes (local income taxes). Often these economic effects are
calculated based on existing average sales per square foot and median
household incomes. Therefore, to the extent that compact development
results in the construction of fewer new homes or fewer new
nonresidential square feet, its direct economic impacts are likely to
appear to be lesser in magnitude than those under sprawl.
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Even using input-output multipliers and including indirect and induced
impacts, economic analyses are blunt tools with which to compare
compact and sprawl development. One reason for this is because most
economic analyses are static, looking only at the impacts of new
development in the base year and the buildout year. In a static
economic analysis, the impacts of new development in the inner
suburbs and urban core are likely to appear, not only of lesser
magnitude.. but also of lesser value than those in the outer suburbs.
Under current economic conditions, the most desirable land uses, and
those located in the outer suburbs, are single family detached housing
and suburban employment centers with free parking. These are the land
uses that are accompanied by higher household incomes, higher retail
sales per square foot, and often higher paying new jobs. Land uses
associated with compact development, and with locations in the inner
suburbs and urban core, are multifamily housing and high density
employment centers accessed by transit. Under existing economic
conditions, those land uses may well be accompanied by lower
household incomes and lower retail sales. (To the extent that high
density employment centers include office uses, they may, however,
include high paying jobs.)
Econometric models, such as used for the analyses in the State of New
Jersey and in Loudoun County, Virginia, are dynamic and consider
interactions between growth and the economic base. As a result, they
are more applicable to the situation in South Florida. These models can
be used to look at the regional economy as a whole. They can consider
the redistribution of households and jobs over time.
That is, if new development in the outer suburbs is discouraged, over
time residential and employment locations in the urban core and inner
suburbs are likely to become more desirable. As those locations
become more desirable, market values, household incomes, and
employment opportunities should increase. In other words,
revitalization should take place. An analysis which considers the likely
gradual increase in economic value of locations in the urban core and
inner suburbs, is likely to permit a fair comparison of compact and
sprawl development.
B. Economic Impacts on the Public Sector: Fiscal Impact Analysis
The measurement of economic impacts on the public sector is done
most commonly through fiscal impact analysis. Fiscal impact analysis
may be defined as follows:
"A projection of the direct, current, public costs and revenues
associated with residential or nonresidential growth to the local
Jurisdiction(s) in which the growth is taking place." (Burchell and
Listokin, 1978, p. 1.) Fiscal impact analysis may also be defined as
cost -revenue analysis.
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There are four basic steps of fiscal impact analysis:
o Calculate the projected increases in population and
employment due to growth;
Translate these increases into public costs;
Project the revenues due to growth and
Compare costs to revenues.
The next section discusses the three recommended methodologies of
fiscal impact analysis. The methods mainly differ in the techniques
used to estimate public costs.
1. Recommended Methodologies
a. Per Capita Method
The most common type of fiscal impact analysis uses the per capita
multiplier method. This means that a local government's current per
capita costs are applied to the population generated by new
development. Because this technique uses average costs, it should not
be used where local public facilities or services are either under- or
over -capacity.
The per capita method is often used by consultants and local
government analysts, using custom -designed spreadsheets. Packages
such as Arthur Andersen's Insight also use the per capita method.
b. Case Study Method
In the case study method, the analyst interviews local service providers.
Through these interviews, information is obtained on the true marginal
costs of serving the projected new development. This method is
particularly appropriate when the capacity of costly public facilities,
such as schools, is an issue.
Elements of the case study method may be included in otherwise
largely average cost fiscal analyses done by local governments and
many consultants. Marginal costs are often applied to capital facilities,
based on available capital improvement programs (CIPs), engineering
studies, and master plans for schools, parks and recreation, etc.. Some
consultants attempt to apply the case study method in every analysis.
Among this group is Tischler & Associates, Inc., which also holds the
license for several fiscal impact models (MUNIES, FISCALS and
CRIM).
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c. Econometric Method
Elements of the econometric method may be included in either per
capita or case study fiscal analyses. That is, where it is known that
increases in local assessed value will result in lower shares of revenues
distributed by states and counties, reductions in such revenues may be
phased in over time. Dedicated use of the econometric method may
make sense for large projects with long buildout periods. However, it
requires significant setup time and is much more expensive to use. In
the early 1990s an econometric model was developed by the
Government Finance Research Center. It was implemented in one
jurisdiction, but was difficult for staff to update and for citizens to
understand. The econometric model developed for the State of New
Jersey by Burchell et al also includes fiscal impact analysis.
d. Fiscal Impact Analysis and Development Patterns
Fiscal impact analysis is routinely included as part of the long range
planning process at the local, regional and State levels. This type of
analysis is a sharper tool with which to compare patterns of land
development than is traditional economic analysis.
Outputs of a fiscal impact analysis include costs for infrastructure
which is sensitive to distance, such as water and sewer lines and
roadways. These capital costs are likely to be lower under compact
development patterns. Of course, some of these distance -sensitive
capital costs are borne by the private sector. This includes the
construction of local roads and connection to existing water and sewer
systems. However, the public sector is usually responsible for part or
all of construction or expansion of regional facilities, such as
wastewater treatment plants, and water and sewer distribution lines.
The need to construct or expand centralized facilities is often greater
under sprawl than under compact land uses.
Other outputs of a case study, marginal cost fiscal impact analysis
include costs for infrastructure which is sensitive to capacity. This
includes school buildings and arterial and collector roadways. If
existing systems have available capacity, these capital costs are also
likely to be lower under compact development patterns. If existing
systems do not have available capacity, and retrofitting is necessary
(such as installing larger water and sewer pipes, or widening existing
roads), infrastructure costs under compact development patterns may
be significant.
To the extent that operating costs are associated with capital facilities
which have existing capacity, they will tend to be lower under compact
development than sprawl. However, recent research indicates that a
GMI Special Article Assesing Impacts of Development Choices Page 20 of 41,
number of other operating costs, such as public safety and traffic
control, tend to increase with density.
A third output of fiscal impact analysis is revenues. Large proportions
of public revenues are based on the market values of real property. To
the extent that assumptions regarding consumer preferences and hence
market values of new housing and workplaces are based on a snapshot
of existing conditions, revenues may project out as higher under sprawl
than under compact development. However, if the fiscal analysis is
linked to econometric analysis, the assumptions driving revenues under
compact development patterns may become more positive over time.
The final output of fiscal analysis is the net impact, or revenues minus
costs. Fiscal analyses with revenue projections based on existing
conditions may show that compact development generates lower net
revenues, or even higher net costs, than sprawl. Fiscal analyses with
revenue projections based on changing conditions over time are less
likely to show net benefits to sprawl.
The basic social impacts of changes in land use, such as population and
employment, have long been documented by developers and their
consultants and by government analysts. Indeed, economic, fiscal,
traffic and transportation analysis cannot proceed without such
projected impacts.
A broader look at social impacts has become more common in the
years since passage of the National Environmental Planning Act
(NEPA) in 1969. Environmental Impact Statements (EISs) prepared to
comply with NEPA include such social components as housing and
historic and cultural resources. In states such as California and Florida,
required Environmental Impact Reviews (EIRs) and Developments of
Regional Impact (DRIs) also include social impacts.
To the extent that social impacts can be quantified, they are often
included in the fiscal impact analysis of new development. That is, the
demands that new population and employment place on public
facilities and services may be considered social impacts. Once these
demands are quantified, they may also be costed out and considered
fiscal impacts. For example, new development usually generates the
need for more police officers, for school buildings and teachers, and for
parks and recreational facilities.
Beyond such direct impacts, social impact analysis theoretically should
compare changes in the level of community well-being before and after
the new development. "In practice, there is little agreement on the exact
methodology to be followed and the variables to be evaluated in
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conducting a social impact analysis. This lack of agreement is
especially apparent when it comes to ascertaining `well-being,' which
is recognized as an important component of the analysis, but one most
difficult to quantify." (Burchell et al, pp. 88-89; italics added.)
Large-scale models of social impacts have been developed to look at
Western boomtowns and other such projects. However, most of the
information needed to conduct social impact analysis is either already
available or can be collected by means of surveys. Results are not
likely to be monetized.
Because of the difficulty of quantifying measures of social well-being,
the Preview/Quickway model offered with the Development Impact
Assessment Handbook includes only the direct impacts of growth on
public facilities and services. The assumption is that "an individual's
well-being improves when a larger number of that person's needs are
satisfied." (Burchell et al, p. 90)
In the rest of this section, some qualitative social impacts are discussed.
A. Preservation of Historic and Cultural Resources
To comply with both NEPA and the National Historic Preservation Act
of 1966, EISs must document impacts on historic and cultural
resources. "Cultural" resources have been defined as historic,
archaeological, native American and other resources which predate
modern American culture. "Historic" resources are synonymous with
historic properties which either are included in, or are eligible to be
included in, the National Register of Historic Places.
The identification of affected resources is usually in the form of a
survey by professional archaeologists and architectural historians. (Jain
et al, pp. 291-294.) The value of these resources is normally not
monetized.
B. Open Space, Parks and Recreation
One of the key components of quality of life for many people is the
availability of open space, parks and recreational facilities. EISs and
other development impact analyses routinely address this issue. EISs
document whether or not the proposed project directly affects existing
park lands. EISs and other analyses also include the developer's plans
for the provision of parks, recreational facilities and open space. The
existing levels of service (LOS) for parks and open space (acres per
1,000 population) and recreation (square feet of buildings per capita;
tennis or basketball courts per 1,000 population, etc.) can then be
compared to the proposed LOS after the new development is
completed.
C. Environmental Design
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More and more urban planners are attempting to measure citizens'
opinions on environmental design. Techniques include Visual
Preference Surveys, which are slide presentations used to elicit public
responses to various design options. (Diamond & Noonan, p. 63.)
Since passage of NEPA, Federal agencies have developed techniques
of Visual Impact Assessment. Prominent among these are the Bureau
of Land Management of the U.S. Department of Interior and the U.S.
Forest Service. These techniques are used by professionals in the field,
to determine the significance or severity of changes in the quality of
visual resources, due to changes in land use. (Smardon, pp. 171-172.)
D. Rousing
The availability of housing is addressed in EIS, EIR and DRI analyses.
Such housing analyses use locally available data and plans. In many
states, local comprehensive plans routinely include housing elements.
Local housing agencies are also required to issue annual updates to
their Comprehensive Housing Affordability Strategy (CHAS) or
consolidated plans, to comply with HUD regulations. (Bregman et al,
p. 194.)
A housing analysis begins with an inventory of existing units, adding
new housing to be built as part of the development project. The
analysis should consider the needs of project employees, and the needs
for housing affordable to both new residents and employees. If a
development is projected to create demand for more affordable units
than currently exist, the local government may seek mitigation
measures.
Development impact analysis does not routinely consider who wins
and who loses from changes in land use. One attempt at such analysis
is the Community Accounting Matrix developed for the East Side of
Buffalo, New York. The matrix is an extension of an input-output
economic model. It includes details on the race, age, sex and income of
households and workers. (This method is generally called a "social
accounting matrix.") An analysis using the matrix found that a shift of
$1 from manufacturing industries on the East Side to services
industries elsewhere in Buffalo, resulted in a total decrease of $1.02 to
East Side businesses. Also using the matrix, this same decline in $1 of
income was allocated differently to the elderly, female -headed
households, African -Americans, and others. (Cole, pp. 107-124.) This
social accounting matrix has potential for application to social impact
analysis.
Another analysis addressing equity was entitled, "Jobs/Housing
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Balance for Traffic Mitigation," and was completed in 1985 by the
Association of Bay Area Governments in San Francisco. The study
examined the availability of affordable housing and the potential for
employing local residents. It also surveyed traffic mitigation measures
in the study area. California communities routinely address the issue of
jobs/housing balance in their land use and transportation plans. Outside
of California, this type of analysis has not been standardized.
F. Quality of Life
One problem with conducting social impact analysis is defining the
baseline, or existing conditions. Once that is established, the impact of
future changes can be compared and assessed.
One Florida jurisdiction developed a "community report card," or a set
of indicators of quality of life. Since 1985, the City of Jacksonville has
tracked its performance on the following: Education; Economy; Public
Safety; Natural Environment; Health; Social Environment;
Government/Politics; Culture/Recreation; and Mobility. (Gregory, p.
1.) Jacksonville is also beginning to compare these indicators across its
17 neighborhoods; the results will be published in an "equity
index." (Andrews, p. 14.)
Researchers at the University of Texas developed similar local
indicators of quality of life in a widely cited 1973 study. Indicators
were measured using locally available data such as the following:
Economy - Retail sales per 1,000 population
Education - Average per pupil expenditures
Public Safety - Crime rates per 100,000 population
Transportation - Percent of street miles served by public transportation
(Lyon, pp. 152-153.) G. Social Impact Analysis and Development
Patterns
Social impact analysis is an emerging field, but not yet an art. At the
most basic level, its outputs serve as inputs to all other forms of
development impact analysis. These outputs include population, school
enrollment, and employment. These outputs are also linked to the
inputs of fiscal impact analysis, as follows. Given current levels of
service, population generates the need for police officers, firefighters,
and other public staff and facilities, and schoolchildren generate the
need for classroom space, teachers, and other school staff and facilities.
Beyond such direct social impacts, a comparison of development
patterns miZD
ght attempt to include measures of quality of life (OOL)
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through the use of community surveys. To date, such qualitative
measures are not routinely included in development impact analysis.
Communities are bezn
ginning to document their baseline level of well-
being, however, as with the City of Jacksonville's QOL indicators.
Transportation impact analysis is conducted at three different levels of
complexity. For individual projects which are relatively small in scope,
a traffic impact study is conducted. For projects and plans which are
significant in scope, a transportation analysis takes place. Finally,
efforts are underway to develop integrated models of the interactions
between various dimensions of the urban environment, such as
transportation, land use, and air quality. Each type of analysis is
discussed below.
A. Traffic Impact Analysis
Since the 1960s, both local government analysts and consultants have
conducted traffic impact studies based on travel forecasting. Basically,
this method involves documenting conditions on the existing road
network; estimating trips to be generated by the proposed new
development; distributing the new trips on the road network; and
comparing the levels of service (LOS) before and after the new
development. If LOS have decreased significantly (that is, congestion
has increased), mitigation measures are considered.
With the widespread use of personal computers and standard sources of
data, traffic analysts have been able to automate their calculations. The
Transportation Research Board's standards for LOS, the Highway
Capacity Manual, are now accessed through computer software. The
Institute for Transportation Engineers' Trip Generation manual
contains data which analysts typically enter into their own
spreadsheets. In Florida, State LOS standards and the Highway
Capacity Manual have been combined into a system of linked
worksheets.
There are also packaged models designed for traffic impact studies.
These include SITE and SITE/TEAPAC. According to one
transportation consultant, however, 90% of traffic impact studies are
conducted using only the Highway Capacity Manual.
B. Transportation Analysis
Transportation planning models have been widely used since the late
1960s. They are gravity -based, four -step, travel forecasting models.
These types of models are used by local governments as part of their
long-range planning process. They are used by the Metropolitan
Planning Organizations in regional transportation planning. And they
are used by both the public
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and private sectors in evaluating major changes in land use, such as
Florida's Developments of Regional Impact.
A good example of this type of model is FSUTMS, the Florida
Standard Urban Transportation Model Structure. This model is
maintained by the Florida Department of Transportation, and used by
most of the MPOs throughout the State. This model has evolved from
the PLANPAC system developed by the Federal Highway
Administration, and the UTPS system developed by the Federal Transit
Administration (then UMTA).
Transportation planning analysis follows the same basic steps as traffic
impact analysis. The difference is that a model is used to estimate trip
generation, to distribute trips by location, time of day, and mode of
transit, and to compare LOS before and after the proposed land use
changes.
A shortcoming of the traditional transportation planning models is that
they were designed to include only motorized travel, or trips by auto
and transit. They were also designed to vary residential location but to
assume employment location as fixed. In the next section, attempts to
address these shortcomings are discussed.
C. Integrated Models
1. Linking Land Use and Transportation
a. ITLUP
An early model which links land use and transportation is ITLUP, or
the Integrated Transportation Land Use Package. It was developed at
the University of Pennsylvania in the 1970s, and has been continually
expanded and improved. ITLUP has been calibrated for many
metropolitan areas in the U.S. Real -world applications include land use
projections for the Kansas City area, and transit investment options in
Seattle and Houston. (Giuliano, p. 319.)
b.LUTRAO
A well-known and recent attempt to integrate land use and
transportation is the LUTRAQ project in Portland, Oregon. LUTRAQ,
an acronym for Land Use, Transportation and Air Quality, arose in
1991 in response to a proposed Western Bypass in Portland. A state
growth management organization, 1000 Friends of Oregon, contracted
with consultants to examine alternatives to construction of the new
highway.
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The consultants developed projections based on transit -oriented
development (moderate density, mixed uses, and pedestrian friendly
design). They also included nontraditional transportation
improvements, such as pedestrian and bicycle facilities and a
Transportation Demand Management (TDM) package. The LUTRAQ
alternative was selected by the Oregon Department of Transportation to
be included in the environmental impact statement (EIS) for the
proposed Western Bypass, required by the National Environmental
Protection Act (NEPA). The project has issued reports on the Bypass
analysis and on an alternative Countywide land use and transportation
plan. LUTRAQ also serves as a resource to other communities in
modifying their planning practices.
c. CUFM
Other areas of the country are experimenting with improvements to
their ability to link land use forecasts to transportation modeling. One
example is the California Urban Futures Model (CUFM). Developed at
the Institute of Urban and Regional Development at the University of
California, Berkeley, CUFM uses detailed land information in map
form generated by a geographic information system (GIS). (Wegener,
p. 24.) The model projects the demand for housing units in each
jurisdiction in a region; identifies sites where projected units could be
developed, given existing zoning, infrastructure and envirommental
constraints; and estimates future population growth. (Diamond &
Noonan, p. 34.) However, CUFM does not model congestion, or
include the regional transportation network. (Wegener, p. 22.)
d. STEP
Another model developed in the Bay area was originally called TRIPS,
and is now called STEP. Like CUFM, it does not include the regional
transportation network. However, STEP analyzes travel demand and
activity using the individual or household as the unit of analysis. It
considers variation in location of residences and jobs, and in trip
frequencies, destinations and mode choices. STEP's outputs can be
disaggregated by income level or age. (Harvey, pp. 1-2.) STEP is now
being used by transportation planners at Portland's Metropolitan
Service District, and elsewhere in the U.S.
2. Linking Land Use, Transportation and Air Quality
As yet, there are no models which integrate impacts on land use,
transportation and air quality. Research is currently under way to
improve our ability to model vehicle emissions. Such improvements
are being motivated by the 1990 Clean Air Act Amendments (CAAA)
and the 1991 Intermodal Surface Transportation Efficiency Act
(ISTEA). These require that regional transportation plans conform with
their State Implementation Plans (SIPS) for air quality management.
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Currently, air quality models are run by State agencies. Outputs of the
air quality models are treated as inputs or caps to the regional
transportation planning models. That is, in order to conform to
standards for clean air, regions must attempt to reduce projected
vehicle miles traveled (VMT). In order to reduce VMT, adjustments
are made to the assumptions used in the transportation planning
models.
The Travel Model Improvement Program, jointly funded by the U.S.
Department of Transportation and EPA, is sponsoring the development
of the Transportation Analysis Simulation System (TRANSIMS). This
is a system of linked models designed to be interactive. Its traffic
simulation component is now being tested in the Dallas -Ft. Worth
region. Its trip planning component will be tested in the Portland region
later in 1997. Its air quality component is yet to be developed.
(Wormser, p. 14.)
D. Transportation Impact Analysis and. Development Patterns
The state of the practice of transportation impact analysis is as follows.
Analyses are regularly included as part of the long range planning
process at the local, regional and State levels. Outputs of these analyses
include Average Daily Trips, Vehicle Miles of Travel, and Levels of
Service (LOS) on the existing road network.
Assuming a decline in LOS due to the traffic generated by new
development, transportation planners and engineers can specify a range
of mitigating improvements. They can also estimate the cost of these
improvements. The reader should note that these last two steps --
determination of improvements to capacity, and estimating
improvement costs -- are outside of most transportation planning
models.
That is, traditionally, neither traffic impact studies nor transportation
planning models generated results expressed in dollars. Rather, their
results were expressed in trip volumes, vehicle miles of travel, and
amounts of traffic congestion (declines in LOS). The analysis had to be
extended to determine how much additional highway capacity was
needed, usually expressed in lane miles, intersection improvements,
etc.. An additional step was then required to attach costs to the needed
capacity improvements.
The Preview/Quickway model offered with the Development Impact
Assessment Handbook attempts to address that shortcoming. It
calculates needed expansions to highway capacity and associated costs.
However, Preview/Quickway does not distribute trips based on a
gravity model, but rather on the assumption of equal directional
distribution. As a result, it oversimplifies trip distribution.
The results of transportation impact analysis tend to be more favorable
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for compact development patterns than for sprawl. An example is the
LUTRAQ analysis as reported in a 1995 article. Compared to the
construction of the Western Bypass (and continued suburban sprawl),
the LUTRAQ alternative resulted in a 13.6% decrease in vehicle miles
traveled and a 7.7% decrease in vehicle hours traveled (both for p.m.
peak). LUTRAQ also showed a 3.7% decrease in average autos per
household and an 8.1 % decrease in total daily vehicle trips per
household.
Non -construction of the proposed Bypass, however, resulted in a
16.8% increase in vehicle hours of delay for the LUTRAQ alternative.
In addition, the author found that, " ... land use policies appear to have
little impact on travel outcomes; most of the observed change results
from the TDM (Transportation Demand Management)
policies." (Giuliano, p. 326.) These policies included the assumptions
that all workers in the study area had free access to transit, and that
parking was not free but cost one-third of that in downtown Portland.
(Giuliano, p. 323.)
The author also found that "the magnitude of change in land use
patterns for the LUTRAQ alternative is large.... These results are also
consistent with other simulation studies of density and trip
characteristics that find dramatic increases in development density are
required to affect mode share and trip length significantly." Finally, the
author found that "... the magnitude of the investment in transit service
is larg-e compared to the resulting changes in mode share." (Giuliano,
p. 326; emphasis added.)
In short, compact development patterns may be associated with fewer
new miles of highway construction and lower vehicle miles of travel.
However, as with economic and fiscal impact analysis, if the
assumptions of transportation impact analysis are rooted in today's
market realities, their outputs may not show significant advantages to
compact development. In order to show significant advantages to
compact development modelers may need to assume major changes
over time, in consumers' desires to live and work in low density
settings, drive single occupancy vehicles, and receive free parking.
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Environmental impact analysis became a formal discipline with the
enactment of the National Environmental Policy Act (NEPA) in 1969.
This type of analysis has been defined as the "systematic identification
and evaluation of the potential impacts (effects) of proposed projects,
plans, programs, or legislative actions relative to the physical -chemical,
biological, cultural and socioeconomic components of the
environment." (Burchell et al, 1994, p. 67.)
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While NEPA is primarily directed toward actions by the Federal
Government or projects eligible for Federal funding, environmental
impact analyses are also undertaken as a result of State and local
review requirements. Burchell et al report that over 20 states have
"mini-NEPAs," which require environmental impact assessments of
changes in land use. Environmental reviews have also become
important at the local level, in conjunction with land use planning,
permitting and zoning requirements.
In actual practice, environmental impact analysis covers a wide range,
including impacts discussed earlier in this paper, such as economic,
social and transportation. To the extent that specific environmental
impacts are discussed in this section of the paper, they are ecological
impacts, or impacts related to natural resources.
A. Analysis of Pollution
Among the most commonly analyzed environmental impacts are
pollution in various forms. Specialized models have been developed to
analyze different pollution effects.
1. Air Quality
As discussed above under Transportation Impacts, evolving Federal
laws are requiring improvements in our ability to predict emissions
from mobile sources such as vehicular traffic. Currently, most analysts
use EPA's MOBILE model, which includes emission rates from a
sample of vehicles. (Garrett and Wachs, p. 24.) Emissions from mobile
sources in turn serve as inputs to models of air quality, along with
emissions from area sources and emissions from point sources.
(Wayson, pp. 102-103.)
The most common application of air quality analysis is through the
Urban Airshed Models generally run by State Departments of
Environment. Urban Airshed Models are used in monitoring
attainment with Federal air quality standards. For subregional level
analyses, Counties also monitor air quality and can provide data
regarding existing conditions.
Measurements of air quality are usually expressed in terms of
pollutants such as hydrocarbons, nitrogen oxide, and carbon monoxide.
(Morris and Therivel, pp. 133-139.) These measures can be used to
compare the baseline or existing conditions to predicted conditions
after buildout of a development project or a proposed land use plan.
Assuming an increase in air pollution, mitigation measures can then be
considered.
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2. Water Quality_
Factors affecting water quality include both point and non -point
sources of pollution. Point sources are usually associated with
industrial process, wastewater treatment, and other closely regulated
land uses. An important non -point source of water pollution is
stormwater runoff, which is discussed further below. (Morris and
Therivel, p. 192.)
Modeling of water quality is done by State and County departments of
environment and health and local water authorities. Water quality
modeling is also conducted by hydrologists in academia and
consulting, and by Federal agencies such as EPA, the Department of
Interior, and the Army Corps of Engineers. The Corps is currently
working with EPA, the South Florida Water Management District, and
others on hydrodynamic modeling of the Everglades.
Measurements of water quality may be expressed in terms of sediment
load, turbidity, and oxygen levels. Commonly measured water
pollutants include nutrients, biocides, organics, heavy metals, and.
pathogens. (Morris and Therivel, pp. 188-189.)
Baseline measures or existing conditions of water quality may be
compared to predicted conditions after buildout of the project or plan.
Assuming an increase in water pollution, mitigation measures can then
be considered.
3. Noise
Noise pollution is generated by such land uses as highways, airports,
and heavy industry. Most environmental impact analyses include
estimates of projected noise levels from the proposed new
development. Computerized models of noise contour analysis may be
used, or existing conditions may be compared to published estimates
by types of land use. The U.S. Department of
Housing and Urban Development has developed Noise Assessment
Guidelines based on traffic data. (Burchell et al, 1994, p. 80.)
4. Stormwater Runoff
One measure of "land pollution" is soil erosion, erosion in turn is
heavily influenced by rainfall and storm frequency and intensity.
(Morris and Therivel, p. 157.) A related subfield of environmental
impact analysis, with a specialized set of analysis techniques, is the
study of stormwater runoff. Analysis of stormwater runoff is
particularly relevant to compact versus sprawl development, due to the
smaller amount of impervious surface associated with the former.
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A recent report compared five techniques of stormwater analysis for
watersheds in West Central Florida. These techniques are listed below.
o The Rational Method - Useful for comparing changes in
land use. Recommended for watersheds with drainage
areas less than five square miles in size. Simple and easy
to use.
Regional Regression Equations of the U.S. Geological
Survey - Recommended for watersheds with no significant
urban development.
Natural Resources Conservation Service model - Widely
applicable; can be calculated manually.
HEC-1 (Hydraulic Engineering Center-1) model of the
Army Corps of Engineers
SWMM (Storm Water Management Model) of the EPA
The latter two models are the most complex and difficult to use.
(Trommer et al, pp. 6-16.)
Measurements of stormwater runoff are usually expressed in terms of
peak discharges and runoff volumes. In a recent analysis of the Harbor
Watershed in Charleston, South Carolina, a comparison of two land use
patterns found that sprawl generated a 43% higher volume of
stormwater runoff than more compact development. The study also
found that compact development generated fewer adverse impacts on
water quality. (Jones Ecological Research Center. Charleston Harbor
Project. Columbia, S.C.: State Department of Health and
Environmental Control, 1996.)
B. Carrying Capacity
Carrying capacity may be defined as the natural and manmade limits to
development, beyond which harm will occur. Carrying capacity
analyses have been conducted in a number of Florida jurisdictions. On
Sanibel Island, carrying capacity was defined to include the number of
people who could be evacuated in the case of a hurricane. This
manmade limitation on coastal development is being used to limit the
location and quantity of growth on the island. Those limits in turn are
reducing the hazards associated with thunderstorms and other natural
disasters. (Beatley et al, pp. 164-165.)
Environmental impact analysis of specific projects typically includes
elements of a carrying capacity analysis. That is, the baseline is
documented for elements such as water supply, wastewater treatment
and solid waste capacity. Future demands by new population and
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employment, expressed in gallons of water and sewage and tons of
solid waste, are then estimated. Those demands are compared to plans
for expansion of water, wastewater and solid facilities, to determine if
capacity will be adequate. If projected future capacities are not
adequate, mitigation measures are considered. These pieces of the
analysis can often be conducted using existing studies and other locally
available data.
C. Ecology
Ecological impact analysis includes what used to be called flora and
fauna, and now may be referred to as wildlife and vegetation, or
species and habitats. This is an emerging field.
Ecological impacts are commonly evaluated based on magnitude and
on the value of the affected systems. Measures of magnitude include
acres of land with either lost or fragmented habitat, and numbers of
species populations or communities lost due to development. Species
are valued based on conservation status, role of the species, amenity
value, rarity, and local, national and international importance.
Ecosystems are valued based on the habitats and communities located
there, larger ecosystems usually being associated with greater
biodiversity. Ecosystems are also valued based on their naturalness,
rarity or typicalness, and fragility or sensitivity.
Ecological evaluation techniques include priority rankings, habitat
evaluations, and composite indexes. Large scale analyses sometimes
include monetary values, economic benefits, and replacement values
assigned to ecological resources. Entire types of ecosystems, or
biomes, have also been simulated by means of computer models.
However, the typical ecological analysis is more likely to use
information from existing studies and expert opinion. (Morris and
Therivel, pp. 217-222.)
D. General Analysis Techniques
As the above topics indicate, environmental impacts cover a broad
range. Beginning in the 1970s, a number of techniques have been
developed to analyze this range. Five types of techniques are discussed
below.
1. Checklists and Matrices
Checklists are one-dimensional, lists of potential impacts. They may be
expanded to two-dimensional matrices by listing a range of actions
along the second axis. One of the better known matrices was prepared
by Leopold et al in 1971 for analysis of the impacts of construction
projects. The Leopold matrix has a maximum of 8,800 cells. A ten -
point scale is used to score levels of impact, both positive and negative.
The results of such large matrices may be summarized into "grand
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indexes." This is done by summing positive and negative cell contents,
and even weighting cells, rows, or columns to achieve a net result.
The advantage of a grand index is its ability to summarize large
amounts of data for decision -making. The disadvantage is that the
relative contributions of different elements and actions are obscured.
(Westman, pp. 133-142.)
2. Weighting -Scaling Techniques
Analysts have been concerned that the grand indexes which summarize
matrices combine both empirical observation and normative judgment.
They have therefore developed techniques that make explicit the basis
for ratings and scales.
Among the best known of these weighting -scaling techniques is the
Environmental Evaluation System (EES). This was developed at
Batelle Laboratories for use with water resources projects. The EES
measures the impact of actions on 78 components of the environment.
Those values are then converted to common units using scalars. The
resulting scaled impacts are then weighted by importance values, and
the final products summed to calculate a grand index. The index may
then be compared to a grand index calculated for the baseline, or
existing conditions.
Use of the EES requires development of new scalars for each project.
This in turn requires extensive baseline data. Weighting of the scaled
impacts fiirther relies heavily on expert opinion. The resulting
"numbers have the patina of scientific respectability" due to "burial of
subjective judgment within numerical scores." (Westman, pp. 149-
152.)
3. Distributional Techniques
Several other techniques document the distribution of impacts among
affected groups. These include the Planning Balance Sheet and the
Goals Achievement Matrix. Both of these techniques require that
impacts be expressed either in monetary terms or in physical units.
A promising distributional technique is the Simple Tradeoff Matrix.
This shows the environmental impacts on affected groups, as costs and
benefits expressed in both qualitative and quantitative measures. The
advantage to this type of matrix is that it leaves the assignment of
weights to decision makers. The disadvantage is the size of the
resulting matrix, and the difficulty of summarizing net benefits and
costs. (Westman, pp. 155-162.)
4. Monetary Valuation
The Army Corps of Engineers has conducted cost -benefit analyses of
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the water resources projects under its domain since the 1930s. These
analyses have focused on the value of such projects to economic
production and economic development. The Corps is now seeking
more of an equilibrium between economic and environmental impacts.
Toward that end, it is conducting a multi -year Research Program,
entitled the Evaluation of Environmental Investments (EEIRP).
A February 1995 report from this program lists a number of monetary
valuation methodologies, " ... including market -based, surrogate
market, and nonmarket techniques. The market -based techniques
include changes in factors of production and next best alternatives.
Surrogate market techniques include the travel cost method and
hedonics. Finally, among the nonmarket techniques are the contingent
valuation method....." (Feather et al, pp. 3-5.)
Throughout the report, multiple authors point out the limitations on
monetary valuations and cost -benefit analyses as tools for
environmental decision making. These include "the (misleading)
implication that they carry a `right' answer" (p. 15); the fact that "There
is no clearly dominant approach" (p. 23); and the "difficulties with
assigning monetary values to environmental resources" (p. 46).
A definitive criticism is the following: "While many papers and books
are available on benefit -cost analysis, there is a dearth of good data
available on rigorous attempts to quantify these environmental
impacts .... the conceptual models are excellent, but the quality of the
applications is lacking due to lack of rigorous data base
development." (p. 107.)
The Corps report also places cost -benefit analysis in historical
perspective: "The role of benefit computations has not been to establish
values, but rather to serve as a starting point in negotiations over value.
This kind of negotiation went on when the value of drainage works was
negotiated in the 1850s, and 150 years later value estimates are serving
negotiations over the values lost when natural resources are damaged.
To expect value estimation to be any more than another `argument'
introduced into public deliberations is to ignore this history." (p. 161)
The report's introduction also places these tools in the context of the
public decisionmaking arena, using 1990s terminology: "Monetary
valuations and nonmonetary evaluations are intended to serve as inputs
to environmental investment decision processes. Final environmental
investment decisions typically are reached via implicit or explicit trade-
off analyses and negotiations between the various
stakeholders." (Feather et al, pp. 3-5.)
5. Geographic Information Systems
Analysts are making more and more use of Geographic Information
Systems (GIS) in environmental impact analysis. Information stored in
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GIS data bases can be used to map existing conditions. Projected
changes can then be overlaid on the baseline data, to map expected
future conditions.
The Army Corps of Engineers uses GIS and coincidence and conflict
models to analyze soil types, slope, noise, species, habitats, vegetation,
and wetlands, among other applications. Parameters outlining negative
impacts are set (for example, noise levels above 65 decibels) and
compared to baseline data and future conditions. Maps are then
prepared, showing the magnitude and geographic ranges of any
negative impacts.
Another example of the use of GIS in environmental impact analysis is
a model called CITYgreen. Developed by the conservation
organization American Forests, this model uses aerial photography to
create a digital map of the tree canopy. Reductions in the tree canopy
are usually associated with increases in stormwater runoff, energy
consumption and air pollution.
Another GIS model, INDEX, uses GIS to map "livability indicators,"
ranging from the presence of open space to the volume of water and
energy consumption. It is intended for evaluation of alternative plans or
projects. INDEX was developed by Criterion Engineers & Planners in
Portland, Oregon.
E. Environmental Impact Analysis and Development Patterns
In this paper environmental impacts are focused on natural resources
such as air, water, soil, species and habitats. Generally, compact
development will result in lower consumption of natural resources and
fewer negative environmental impacts.
These impacts can be measured in terms of acres of open space,
wetlands, and wildlife habitats either lost or preserved. Impacts can
also be measured in terms of levels of pollutants in the air and water,
volumes of stormwater runoff, and decibels of noise. Finally, impacts
can be compared to the carrying capacity of natural and related
manmade systems, such as water, wastewater and solid waste.
Most environmental impact analysis is conducted as follows. Baseline
conditions are documented and compared to expected future conditions
after buildout of the proposed project or plan. Baseline conditions are
often documented through the use of surveys and previously
commissioned studies. Future conditions are often estimated based on
existing data bases which link environmental impacts to types of land
use. Comparison of baseline to future conditions may be through
checklists, matrices, and indexes. More and more, comparisons are
made by maps produced using Geographic Information Systems (GIS).
Baseline and future conditions are expressed in different units of
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measurement, depending upon the type of impact. In other words,
environmental impacts (like social impacts) are measured in apples and
oranges. Analysts have attempted to construct techniques and models
which permit the comparison of apples and oranges, and even their
valuation in monetary terms. However, the use of such techniques and
models "prevent(s) the public and decision makers from following the
steps in reasoning and challenging judgments." Or, to continue with the
analogy, "it is easier for a decision maker to apply his or her own
weights to apples and oranges when they are presented as such, than
when they have both been scaled to some organic fruit using panel(s)
of experts ...." (Westman, p. 163.)
On the other hand, while documenting baseline conditions and
estimating future conditions can be performed by the average analyst,
evaluating the significance of impacts is best done by a team of
seasoned professionals with expertise in the various environmental
subfields. These include hydrology, biology, ecology, geology, and
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5406 Trent St.
Chevy Chase, Md. 20815
Tel/Fax: 301-656-9560
:,;I �n.,i i- ssu: d ?;�, Bitstream Techno logics. Inc.
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