30measuring.pdf

(1)

Bruce

B.

Clary

Measuring

Public

Values

in

Environmental

Assessment

Withthe

passage

oftheNational Environmental

Pol-icy Act of

1969

and

many

corresponding state-level

acts,environmental

assessment

has

become

an

impor-tant

component

ofenvironmentalplanning.

A

number

of

assessment

techniques

have been

developed

and

rangefrom simple matrix analysisofstatic,directcause

and effectrelationshipstocomputersimulations based

ongridsystems(Lapping 1975). Mostofthese

assess-ment

methodologiesarehighly technical, butin

some

of

them,the matrixbeing the foremostexample,thereisan

attempt to weigh technical evaluation of Impact with social judgments about the value of the affected en-vironmental features.

This latter approach to environmental

assessment

presents a

number

ofinteresting methodological prob-lems. Most obvious is the problem of determining the value of environmental characteristics. That is, are

these values measurable from the subjective percep-tionsofpeople abouttheirenvironment;forexample, in

comparisontotheenvironmental amenitiesofother lo-cations (Craik and

Zube

1976).

A

second problem is the issue of

who

should

make

thisvaluechoice. Isita matterof

consumer

preference,

somethingthat can beascertained through surveyora typeofmarket research, orinstead is Itthe provinceof

the expert,

who

is usually the project consultant, to

make

the decision?

The

latter alternative

may

be the easier

one

tousein thecourseofaproject evaluation, butitcertainlyisquestionablewhetheritcanbeclaimed

that the judgments are reflective of

community

senti-ment.

A

third problem

may

be less

complex

and relevant

only if the

above

two

have

already

been

solved. If the

valueoftheenvironment has

been measured

according

to

some

scale, then It

becomes

a matterof combining thisdatawith technicalevaluationstoprovideanoverall

assessment

ofthe project's impact.

Inthispaper,thequestionofusingpublicperceptions

in environmental

assessment

is approached from two

perspectives. First,matrix analysis,an approachtothe determinationofenvironmentalvalues,isdescribedand

other approaches which utilize citizen input are briefly

analyzed. Inthe second part, research findings from a

study conducted on a public development project are discussed.

The

research design

was

based on amatrix

and

community

responses

were

employed

to

measure

thevalue ofthe environment to local residents.

Problems

and

Strengths

of

Matrix

Assessment

One

ofthevaluesofmatrix

assessment

is its

simplic-ity

and ease

of application.

The

matrix structure pro-vides a clear

and

straightforward organization and

al-lows a rudimentary classification of cause-effect

rela-tionships.

The

Leopold efal. (1971) model is the best

known

oftheseapproaches.

The

matrixiscomprised of

100categoriesofactionsand 88environmental

charac-teristics that can be affected by these actions. This

matrixproduces 8,800cells, eachofwhichIdentifiesan

environmental impact For each cell, two values are assigned.

A

magnitudeestimateis

made

forthelevel of

impactand thisscore is weighted by asubjective

judg-ment

aboutthevalueoftheenvironmentalcharacteristic that Is being affected.

Itisthelattercharacteristicofmatrixassessment,the

assignment of

community

values to the environment,

thatisofinterest tothe socialscientist.This

methodolog-ical approach provides a

way

to interject

community

attitudes into the planning process and to integrate technical and social data into a comprehensive

sum-mary

of a project's impact.

Matrix analysis,however, is notwithout its

shortcom-ings, especiallyonthetechnicalsideofevaluation.

The

sizeofthematrix, 8,800cellsintheLeopoldmodel,can

make

conciseanalysisverydifficult(Fischerand Davies

1973, p.21₁)and oftenresultsIn nothing

more

thanan

inventory of probable impacts (Lapping 1975, p. 125).

The

analysisiscross-sectionalintimesolongitudinalor

seasonal

changes

intheenvironmentthatmight

change

the natureoftheimpacts arenotanalyzed (Fischerand Davies 1973, p. 211).

A

Bruce

B. Clary is Assistant Professor ofPolitical

Sci-ence

at North Carolina State University, Raleigh.

Portionsofthisarticle

were

presented

by

theauthorata

symposium

on Airport

Development

in North Carolina

held at North Carolina State University on

June

19,

(2)

Another area of controversy in matrix assessment, which is

more

germane

tothepurposesof thispaper, is

the assignment of subjective values to environmental characteristics. Leopold (1974, p. 31) has stated that

scientists should

make

the technical and social value

judgments in matrix assessment. In the latterrole, the

scientist has

become

the surrogate representative of

community

values. There are two important questions thatstemfromthisroleassignmenttothescientist.

One

questionis normative, theotherempirical. First, should

itbethe role ofthescientisttobe anarbitrator of social

values? Itwould

seem

presumptuoustosayyes, since

heisnot actingas a

member

ofasocial

community

inhis role as evaluator, but as a

member

of a professional

community

with

norms

very different from those ofthe former. McElrath (1973,p. 56)has

made

this point. His view is that the primary client of the professional is

government and the public is a "distant, secondary

clientdimlyviewedthroughanorganizationalscreennot

directly related to their activities."

"This

methodological

approach

provides

a

way

to interject

community

attitudes

into

the

planning

process

and

to

integrate

technical

and

social

data

into

a

comprehensive

summary

of

a

project's

impact."

The

empirical question is not whether the scientist

should

make

the decision, but

how

he can

make

it.

Even

if

we

accord himtherightto

make

thisjudgment,can

we

reallyexpecthimtoadequately

make

an

assessment

of

community

values?

What

standardwill he use and

how

will he apply it?

Maybe

Plato's philosopher king could adequately performthisrole, but I

am

somewhat

reluc-tant to

concede

thatthe scientistas consultant hasthe

perspective that Plato gives to his ruler.

IncontrasttoLeopold'sattitudetoward determination

of the importance of environmental characteristics in matrixanalysis isthe positiontaken bysocial scientists working in the area of environmental perception and

behavior. Graik and

Zube

(1976, pp. 3-23) havecalled

for the development of standardized indicators of en-vironmental qualitybased on

human

perception, which

they refer toas Perceived Environmental Quality

Indi-ces (PEQIs). It is their position thatthe

measures

can

provide a complementary set of indices to

physically-based ones,servetoincreaseourunderstandingofthe relationship between

man

and his environment, and

provide an alternative

method

of project-related en-vironmental assessment.

Substantial research has

been

conductedonthe

de-velopmentofsuchindicatorsandthevalidityand

reliabil-ity problems associated with

them

(Graik and Zube,

1976).

The

problem of community perception of en-vironmental values in matrix assessment is a related research questionandthe

same

typeofmethodological considerations should apply. Matrix evaluation would

not be based onagenerally accepted setofindices as exemplifiedby GraikandZube's conceptofPEQIs, but

would be project-specific.

The

same

measurement

is-suesapply, however, anddata couldbegatheredinthe

same way

whether through verbal surveys or graphic simulations ofan environment.

Surveytechniqueshave been used in othertypes of

assessment

methodologies to

measure

environmental values.

One

such methodology has

been

developed by Burnham, Nealey and

Maynard

(1975) for the siting of

nuclear

power

plants. This approach employs respon-dent evaluations of project alternatives as weights to

technicaljudgments on environmental impact.

The

re-searchers

present the

respondents

with

"mini-environmental impact statements" for hypothetical

power

plantoptions.

Each

statement describes the im-pact of each alternative according to eight criteria: aesthetic, land use, water, air, economic,

cultural/-recreational, health/safety, and animal/plant. Visual representations are also used in areas like aesthetic values

where

verbal descriptions prove inadequate. In contrast to the matrix approach, respondents are in-structed to rate project alternatives according to their

level of acceptability.

In matrix assessment, a sample ofcomniunity

resi-dents would only indicate the value ofa particular en-vironmental attribute to them. Identification of project alternatives

and

theirimpacts would not be a part ofa matrix evaluation. Inthis regard,the matrixapproachis

much

less comprehensive in the level of

community

input it provides, but highlights basic

project-environ-ment

relationships that

make

iteasierto

communicate

information about impacts. In doing so the matrix

ap-proach facilitates

community

involvement in the en-vironmental planning process.

An

Exploratory Application

of

Matrix

Assessment

to

an

Airport

Development

Project

Underagrantfromthe Environmental Studies

Coun-cil, University of North Carolina, research

was

con-ducted on the application ofthe Leopold matrix tothe

Raleigh-Durham airport development project and the

Residentattitudestowardsthenearbyairportwere measured.

(3)

use of this information asthe basis of a questionnaire

measuring environmental preferences.

The

goal ofthe research

was

todetermineif itisfeasibletoderive social

rights from a matrix

assessment

methodology.

The

environmentalparametersthatarefocusedon in the questionnaire are ofthree types: resources, prob-lems,

and

processes.Resourcesrefersto

environmen-tal amenities like parks,

employment

opportunities, health and safety, and forests. General land use pat-terns arealsoincludedinthiscategory. Aircraftnoiseis

an

example

of a problem.

Some

processes are soil erosion, compaction and deposition, and aquatic

cy-cles. Air and water quality could be resources,

prob-lems,orprocesses depending

upon

thepollution levelin the area. Individualsrespondaccordingto their percep-tionsofthevalueorsignificanceofaparticular environ-mentalfeatureofthe area. Forexample,aconcernover erosion islikelytobeafunctionof

how

a personvalues water

and

landquality.

". .

.research

was

conducted on

the

application

of

the

Leopold

matrix

to

the

Raleigh-Durham

airport

development

project."

Interviews

were

conductedwith a

random

sample of

localresidents togatherthisinformation. Respondents

were

not asked to estimate the degree of impact they thought the airport would have on the environment.

They were

simply required to indicate whether they thought an environmental resource

was

an important

one

or that a problem

was

significant.

The

technical

judgment aboutthelevel ofimpactisthedecision

made

bytheexpert

and

isa separate evaluatory process.

The

choices

made

by local citizensrepresentthepriorityor weightthatshould begiven anenvironmentalfeaturein

the planning process, quite apart from the degree of

impactthat a projectalternate could

have

on it.

This dual definition ofenvironmental quality, impact

and

value, provides an approachto environmental

as-sessment

that is analogous to cost-benefit analysis in

economics. For example, a proposed projectalternate could result in a significant disruption of an ecological system. Yetifthe affected residents

do

not place high

priority

on

this aspect of their environment, should the

alternative be

abandoned

solely on the basis of the "objective"

assessment?

A

negative decision of this

type, whilejustified ontechnicalgrounds, would notbe an accurate reflection of

community

sentiment. Given

the lowvaluation placed by residents on this environ-mental attribute, a preferable alternative would be to

weightthe technical

assessment

withtheenvironmental preferencesofthepublic. Thisapproach wouldprovide

an integrated "community-expert" profile ofa project's

anticipated environmental impact.

Itshouldbenotedthattheuseof citizenperceptionas the basis ofdetermining environmental value is based

on

theassumptionthatthenetwork ofcostsorbenefits

that derive from a particular environment are

inter-nalized bythe public most immediatelyaffected by the

proposed project. This assumption, although a neces-sary

one

forpurposesof this methodology, is question-ableforenvironmental problems, like airorwater

pollu-tion. Environmental resourcesgenerallyhavea

compo-nentaffectingalarger

segment

ofthe population outside the locality.

The

questionofvalueextendsfurtherthan the preferences of local residents and places

con-straints on the applicability of this matrix technique to

projects that affect features of the environment that

have broad geographic significance.

With theselimitationsinmind,theLeopoldmatrix

was

applied to the Draft Environmental Impact Statement

(DEIS) issuedbytheFederalAviationAdministrationon

the proposed Raleigh-Durham airport expansion.

The

approachidentified

240

environmental impacts from the 5 project alternates considered in the document.

In Figure 1, the types of impact are identified.

The

mostfrequentlyoccurringimpactisonphysical

proces-ses likeflooding, soilerosion, deposition, and

compac-tion. Twenty-two percent of the impacts are in this

category. Water-related problemsare thesecond most

frequent impact.

Runway

construction will necessitate construction of

dams

filling

some

marshes

inthe area.

Aircraftnoise,themostpublicizedenvironmental impact

from airports, accounts for justfourpercentofthetotal

number

of impacts.

A

majorlimitation ofthe Leopold matrix isthe lackof

specificationofsynergistic

and

secondary

environmen-talimpacts.Aircraftnoiseisan example. Itisaneffect of

airport expansion if air traffic is increased or different

flight patterns are adopted

due

to runway relocation.

Residential neighborhoods

may

be

exposed

to higher noise levels in either case. Additionally, there is

some

evidence that aircraft noise can depress residential property values(Gautrin 1974;McGlure 1969)andso it

canfunctionas acauseorindependentvariable. Noise

fromaircraftcanalso

combine

withsurfacetrafficnoise

to produce a synergistic effect on the ambient noise

level in a neighborhood.

This

example

clearlydemonstratesthesimplified na-tureof matrix analysis.

The

technique, however, does

allow basiccategorizationofcause-effectrelationships

and

thiscouldbesufficientin

some

casesfor

construc-tion of a questionnaire to

measure

environmental

val-ues.

The

problem is that if higher orderor synergistic

causes have not

been

specified, then all the

conse-quences

of the action

have

not

been

identified.

The

questionnaire would not reflect all the features of the

environmentthatmightbeaffectedbyaproject actionin

thistypeofmultiplecause-effectpattern.

The

validityof

matrix survey questions ultimately

depends

upon the

thoroughness of the determination of the impacts by

technical experts.Sorenson's(1972) attempttodevelop

a matrix which deals with the multiple and interactive

causaldimensionsofenvironmentalimpacts represents a substantial improvement over Leopold's

more

direct

causal model.

A

methodologicalimplicationforquestionnaire design from an approach which identified cause-effect

(4)

Figure 1

Matrix_{Identification of Effects of}_{Raleigh-Durham} AirportExpansion

tnects (Changes in . . .)

N

50

%

Physical Processes ₂₁

Water ₄₃

18

Land Use ₂₈ ₁₂

Aesthetics ₂₅

10

Fauna

21 9

Flora ₂₀

8

Earth ₁₄

6

Cultural Land Use 11 5

Noise ₁₀ ₄

Man-Made Factors ₉ ₄

Atmosphere ₅

2

Cultural Conditions ₄ ₂

Total Numberof Impacts 240 100*

•Percentages do not sum to 100 dueto roundingerror.

accurately

measure

_{environmental preference}

_based

on systemsofinteraction ratherthandiscreteelements.

In the Leopold matrix, environmental features are treated as single, unrelated items. If a matrix is

employed

that

merges

these

phenomena

intoa system,

e.g.,ecological orsocial,isitvalid toaskarespondentto

assign a value tothe entire setof

phenomena?

With a large

number

of elements in the system, there would always loom the internal validity problem of "are

we

measuring what

we

think

we

are measuring?" Thatis,

on what basis would the _{respondent be making} _his decision: the system in its entirety ora particular

ele-ment

ofit that he might thinkimportant?

Problems

In

Questionnaire

and

Scale Construction

The

first problem in constructing the questionnaire

was

the

number

of impacts.

Two

hundred and forty

items are too

many

for any type of sample survey, including a personal interview. Sincethere

were

multi-plecausesforasingleeffect, it

was

possibletoreduce

this to a single item. Pre-testing of the questionnaire

also

showed

that inclusion ofthe causal action along

withtheeffecttendedtoconfusethe respondent.

When

a cause

was

identified, the respondent often tried to

make

animpactjudgmentratherthan simply estimating the valueofthe environmentalcharacteristic.This

prob-lem did not occur

when

only effects were listed.

Identification ofthelocationoftheimpactprovedtobe

a problem. With

many

physical, air, andwater proces-ses, the location oftheactual impact could not be

iso-latedtoasingle place.Therefore,forthese processes, it

was

necessarytoincludethelocationofalltheprobable impacts. In mostothercases

where

aphysical process

was

not involved, only

one

locational variable

was

specified since the effect

seemed

to be isolated to a

particulararea.

Seventy-three impacts

were

includedinthefinal ver-sion ofthe questionnaire.

They

rangedfrom controver-sial issues like "aircraft noise over Raleigh and Gary

residential neighborhoods" to straightforward items

such as "soil _{composition surrounding}

runways on air-port property."

The measurement

scale used in _{the questionnaire}

was

a Q-sort."

Each

ofthe seventy-three

environmen-tal _{parameters were} _listed

on a separate card and the

respondents were asked to sort

them

on a ten-point scale ranging in _{value from important}

to unimportant

The

_{cards could} _be _re-sorted

any

number

of times' providingtherespondentwithflexibility inhis rankingof

the _{environmental}

attributes.

The

advantageofa Q-sortisthatitallowsthe respon-dentto

make

_comparisons

_between

items in assigning

them

ranks. Scales

based

on comparative appraisals

producelessvariabilityinrespondentchoice than

prefe-rential_judgment _scales

_where

rankings are

made

on a single _{issue-by-issue basis} _(Craik

and

Zube

1976 _pp

14-20),

The

issues themselves are the frame of

refer-encewith_{the Q-sort technique, although the usual}

pro-cedurein using comparative appraisal scalesto study environmental perceptionhas

been

toask_respondents

to_{evaluate a}_{particular setting}

againstsettingsthat

pos-sess different characteristics _(Zube _1974). _This

latter

approach is

more

_{complicated since}

_many

more

ele-ments have to be introduced intothe _{research design}

and

thus would limitthe easewith whichthe technique could be applied by planners.

Data

Analysis

This exploratory survey

was

administered in July 1977, to 130 residents of Gary, North Carolina This

community was

chosen as thesampling area

because

mostofthecity

was

withinthezoneoflowest noiselevel

where

landuseimpactshave

been

established (Federal Aviation _{Administration 1971,}

p. 49).

"A

major

limitation

of

the

Leopold

matrix

is

the

lack

of

specification

of

_synergistic

and

secondary

_{environmental}

impacts."

To

determine the priority of _{the seventy-three}

en-vironmental attributes, a coefficient of variation

was

computed

foreach itemand theattributeswere ranked

according to this value. This

measure

is

based

_on _the

mean

andstandarddeviation,thusallowingtheaverage

score for a given item to _{be weighted by} _the _{level of}

agreement

among

the _{respondents on} its importance. Using a

mean

to _{determine an} _item's _priority

is a mis-leading statisticifthere

was

_substantial _variance

inthe

distribution of the scores.

The

importance of an

en-vironmentalfeature should be afunction ofthe level of

consensus on its significance as well as the value as-signed to it on the ranking _scale.

The

level of _{consensus on} _{the value} _of _an

environ-mental_{dimension has}

_{been emphasized}

intheliterature

on environmental perception.

_A

higher level of

agree-ment

among

the public overparticular issues or

prob-lems provides a

more

reliable data base on which to

(5)

There area

number

of

ways

toanalyze thedata. For thepurposesof thispaper,therankingsofthe issueswill

be

examined

according to the type of environmental

problem and resource and its location. This type of

analysis would bethe

method employed

in matrix

as-sessment. Alternatively, questionscan be asked about

thepatternofindividualresponses. Studiesindicate that

environmental

perception is a function of

many

backgroundvariables: politicalideology, environmental

knowledge, education, and lack of personal efficacy (Arbuthnot 1977); self-confidence and

esteem

(Kaplan 1977); and occupation or role (Althoffand Grieg 1974; Constantiniand Hanf 1972). Forexample, inthissurvey did the respondentstend to group certain types of im-pacts together in that they assigned

them

all similar

scores?

A

pattern of this type would suggestthatthey

viewed the impacts from perspectives that reflected

broader concerns such as conservation, recreation,

economic

developmentorevenenvironmental ideology (see Tognacci efal. 1972).

Questions comprising nine attitudinal scales

were

also included in the survey which

measured

attitudes

toward such dimensions as aesthetic values, environ-mental regulationandutility, business,technology, and

ruralism.

Responses

totheseventy-three

environmen-talissuesidentifiedbythe matrixcan becorrelated with these scales to determine whether general attitudes

towardtheenvironmentandother

phenomena

affected

what issues the respondents thought

were

important.

These

questionsabout backgroundand attitudinal cor-relatesofthe matrixresponses, althoughimportant,will notbe discussedinthisreportonthe study'sfindings. In thesubsequentdiscussion,the

emphasis

willbeplaced

on analysis of thedata in a matrix format.

Individual-Level

Environmental

Parameters Ratings

In Figure 2,the rankingsforthe top25 percentofthe issues (ranks1-18)appear.Thereisafairlyevenmixof

issues dealing with the physical and biological

dimen-sions ofthe environment along with cultural elements, although thelatterfactorstendtobe rankedhigher.This combination of issues indicates a concern

among

the

respondents with both the natural and social environ-ment.

The

social dimension of environmental impact

has

been

increasingly stressed in discussions of en-vironmental assessment. Forthis reason, theanalysis

of the rankings will focus on the social factors.

The

FederalAviationAdministrationina recent

circu-lar (U.S.

Department

of Transportation 1975)

em-phasizedthe importanceofestimating cultural impacts

ifrom airport development projects.

Among

the social

impactswhich

were

identified as items that should be

consideredinanEnvironmental ImpactStatement(EIS)

weredirect effectsofsurface trafficdisruptionon

com-munity socio-economic structure (roads and highways

was

ranked 18th in this survey) and indirect impacts

such as population

movement

and

growth,

and

public service

demands

(waste disposal and publicutility use

were

ranked 2

and

6, respectively).

The

highest ranked issue is an

example

of a broad

cultural dimension, healthandsafety.

The

respondents

most

likely perceived this environmental problem in a general sense without special referenceto theairport.

However, thereis a directimpact on

community

safety thatisproducedbyanairport.Operational malfunctions

likeanairplanecrashcanresultinaseveredisruptionof

a community. Nevertheless, the probability ofsuch an occurrenceisverylow,sothisissuewould be an

exam-pleofanenvironmentaldimensionthatwould receivea

Figure 2

Rankingof Environmental Parameters (Top25 Percent)

Rank*/Environmental Parameter** /Type)***

1.

HEALTH

AND

SAFETY

_OF

_POPULATION

in

Wake

andDurham Counties (CO)

2.

WASTE

DISPOSAL

in

Wake

and Durham Counties

(MMF)

3. RESIDENTIAL

LAND

_USE

In

Wake

and Durham

Counties (LU)

4.

AIRCRAFT

NOISE in Raleigh and Cary Residential

Neighborhoods (N)

5.

EMPLOYMENT

OPPORTUNITIES

in

Wake

and

Durham Counties (CC)

6. PUBLIC UTILITY

USE

in

Wake

and Durham (MMF) 7. INDUSTRIAL

LAND

USE

in

Wake

and Durham

Counties (LU)

8.

LAND

ANIMALS

AND

THEIR

HABITATS

on

Air-port Property, Airport Peripheryand In Umstead

Park(FA)

9.

FLOODING

AROUND

STREAMS

on Airport Prop-erty,Airport Periphery and in Umstead Park (P) 10.

EROSION

ALONG STREAMS

on Airport Property,

Airport Periphery and in Umstead Park (P)

11.

STREAMS

in Northwest Raleigh (W)

12.

WASHING OF

DIRT INTO

STREAMS

on Airport

Property, Airport Periphery and in Umstead Park

(P)*'

13.

COMMERCIAL LAND

USE

in

Wake

and Durham

Counties(LU)

14. AIR

QUALITY

overAirport Property, Airport

Periphery and Umstead Park (AT)

15.

STABLE

SOIL

CONDITIONS

ALONG STREAMS

onAirport Property, Airport Periphery and

Umstead Park (P)

16. INDUSTRIAL

LAND

USE

in Research Triangle Park (LU)

17.

WATER

CYCLE

(PRECIPITATION, FILTERING

AND

EVAPORATION)

on Airport Property, Airport

Periphery and in Umstead Park (W)

18.

ROADS AND HIGHWAYS

in Airport Property

(MMF)

*Coefficientsof Variation ranged from 22.9 (rank

no. 1) to40.4 (rank no. 18).The coefficient forthe

73rd ranked issue (the lowest rank) was67.6. **For manyofthe environmental parameters relating

to physical processes, the terminologywas

simpli-fied for purposes of thequestionnaire.

***Thegeneral categoryofeffectforthe specific en-vironmental parameter is listed in the parentheses.

Theabbreviations referto: (AE) Aesthetics, (AT) .

Atmosphere, (CC) Cultural Conditions, (CLU) Cul-tural Land Use, (E) Earth, (FA) Fauna, (FL) Flora,

(LU) Land Use, (MMF)

Man-Made

Factors, (N)

(6)

high social value weighting, but the impact score, de-rived from an estimateoftherisl<and magnitude ofthe event, would be low.

The

problemofweighing risk

ver-sus magnitudeindeterminationofasingleimpact score

isnotsimple.

As

inthecaseofnuclear

power

plants,the

likelihood of catastrophic event is very small, but its

magnitudecouldbe enormous.

How

thisdecisionmight

be

made

is

beyond

the scope of this paper, but the

example serves to illustrate atypical problem

encoun-teredinmatrixassessment

where

asingleimpactscore

hastobe assignedforanenvironmentalparameterthat

has multiple dimensions.

Among

the top eighteen ranked issues (25 percent)

arefour thatdeal with landuse around anairport.

These

issues areexamples ofenvironmental dimensionsthat

would likely receive high impact along with high value scores although the direction of the impact could be

positive or negative.

The

relationship between airports and land use in

theirperipheryisacomplex,multi-facetedproblem.

Air-ports can exert a major

economic

influence on their

environment through direct, indirect and secondary

employment

(employmentopportunities

was

ranked5th

inthe survey), and purchaseof

goods

andservice.

The

economic stimulus provided by airports createsa high

demand

forcommercial landand residential housing in

theirperiphery (U.S.DepartmentofHousing

and

Urban

Development

1972).

In contrast, aircraft noise has an adverse effect on

existing residential neighborhoods. Its effects include

residential turnover and reduced

demand

for

single-familydwellings (Environmental StudiesBoard1971,p.

105), and lower residential property values (Gautrin 1974; McClure 1969).

The

importanceof this environ-mental dimension ofthe airport's expansion is clearly

shown

by the high ranking (4th) given aircraft noise in

Raleigh/Cary residential neighborhoods.

"The

importance

of

an

environmental

feature

should

be

a

function

of

the

level

of

consensus

on

its

significance

as

well

as

the

value

assigned

to

it

on

the

ranking

scale."

The

evaluation ofthe actual impact of the airport's

expansion, as described above, can be problematic.

The

difficulty is not always estimating the actual

mag-nitudeofimpact, butindetermininginwhich cases(e.g., project alternates)itisnegativeorpositive. Mostmatrix

systems useaplus orminusvaluetoindicatethe direc-tionofimpact.

The dilemma

posed bytheairport's land

useimpacts, forinstance, is thatpositive and negative land use impactsoften occurin the

same

section of a

community. It

may

not be possibleto empirically

sepa-rate these effects so the analytic requirement in the Leopold matrix thattheybetreatedseparately

may

not adequately

summarize

the natureof the impact.

BesidesaircraftnoiseinRaleighand Garyresidential

neighborhoods, there are six other environmental

^,

J:

Citizen perceptions are used to help determine the environmental

valueofnaturalareaslikethisoneneartheRaleighDurhamAirport.

Photo byBlairPollock

parameters that deal with aircraft noise. For these

re-maining issues theproblem isperceived asnot

particu-larlyimportant. Surprisingly,aircraftnoiseinastatepark

(Umstead) locatedadjacenttotheairportisconsidered

evenlessofaproblemthan noiseoverairportproperty.

One

reasonisthehighvariance

among

therespondents on itspriority. Ithasthethirdhigheststandarddeviation forthe seventy-three environmental dimensions. Ifthe

mean

alone

were

used to rank the issue, its position

would be49.5,

somewhat

higher.

To

some

degree,the

lowlevel ofconcern evidenced by therespondentsover

the noise problem in the park

may

be a result of the present noise levels, which are substantial in

some

parts of the facility. Local residents

may

consider this

noise level as a "natural" characteristic of the park, sinceit islocated nexttoanairportandis unlikelytobe

relocated.

In contrast, the high rankof aircraft noise in Raleigh

and Gary residential neighborhoods probably reflects

more

ofaconcernaboutthe futurethanan

assessment

of the present noise level. Residents value quiet

neighborhoods andthelevel ofexposuretonoiseunder

currentoperatingconditionsisminimal. Hence,the high ranking given this environmental dimension likely

re-flects a concern with conserving an existing resource,

residential peace.

Aircraft noise in another residential area, Durham, is

ranked

much

lower.This rankingispredictablesincethe survey,duetoitsexploratorynature,

was

restricted toa

community

in the Raleigh area. If a representative

cross-sectionofcitizensfromtheRaleigh-Durham met-ropolitan area were used, this issue would likely be ranked

much

higher.

Intermsofphysicalattributes oftheenvironment, the

respondents expressedsubstantialconcernover

flood-ing

and

erosionproblemsandrelatedwater dimensions.

Stream and runoff problems have been a major en-vironmental issue in the Raleigh area since two major

floodsoccurredin1973.

The

issues,although important toresidents,wouldprobably receive lowimpactscores. Forall the project alternates, theairport has proposed

extensive sedimentation pools and

dams

to prevent

(7)

Group-Level

(Effect

and

Location)

Rankings

An

alternative

way

toanalyzethedataistogroupthe environmental parameters according to two

dimen-sions: category of effect,

and

location. In Figure3, the data are

summarized

utilizing this format. There are twelve categoriesofeffects(orimpacts) rangingfrom a general value dimension, aesthetics, to physical

pro-cessesofair,water, andearth.Locationoftheseeffects are dividedintotwo parameters: singleand multiple.

A

multiple location refers toan action that has an impact

on a

number

of different geographic areas. Multiple locationalimpacts are

common

inregardtoactions that

affectnaturalprocessesalthoughitisalso truefor

some

typesofsocialimpactslikeland use.

The

locationofthe effects orimpacts are almost equally divided

between

single and multiple sites.

Figure 3 indicates that

most

of the impacts of the

airport's expansion,

when

the effects ofthe project

al-ternatesare aggregated, arepredictably within the

facili-ty'sboundaries. Butit isclear that

none

ofthese cate-goryeffectsarehighly rankedby the respondents.

The

rankings for the groups range from

48

to 67, with the

averagerankforairportproperty(across the 12 groups)

being 58.

Incontrast, thegrouped impacts that

were

identified for

Wake

and

Durham

counties receivethehighest

rank-ing, 13.

These

issues deal primarily with social rather than natural dimensions oftheenvironment, e.g., resi-dential land use, density of housing,

employment and

healthandsafety.Thisfindingagainsuggeststhatarea

residents are

more

concerned with the broad, social

dimensionsof theirenvironment. In Figure3,the

mean

ranksforthe categories of effectarepresented without reference to location. Although atmosphere (14) and

water(21)are rankedfirstandsecond, the next highest

ranked groups, cultural conditions (22)

and

land uses

(26), also include

many

social factors.

Figure 3, although a useful

way

to

summarize

the data, is

based

on a

number

of questionable

assump-tions that also pertaintomatrix

assessment

in general. Foreachproject alternatein amatrix analysis,thetotal

number

ofcause andeffectrelationshipsareidentified;

each

relationship then receives an impact and social value score;

and

finally these scores are

summed

to

give an aggregate impact score for the project.

How-ever, as

done

in Figure3, it is

assumed

thatthe scores

for differentenvironmentaldimensions canbe

added

to

forman aggregateor

combined

index.

A

valid question iswhethersucha multi-dimensional

index has any

meaning

since it is multi-

and

not

uni-dimensional. Unlikeanairorwaterqualityindex,thereis

no standard interpretation that can

be

assigned to a project alternate's score. In

one

case,ahighscore

may

representmostlyaestheticimpacts.For another alterna-tive, thescore

may

be

due

toimpacts on physical pro-cesses. In an airquality index, ahigh value represents

high pollution levels. Different combinations of

pollu-tants

may

produce the score, but there is general

agreement

on the

meaning

ofthe indexvalues. Thisis

notthecaseforanindexvalueinmatrixassessment.

An

aggregate score does not identify the specific impact: aesthetic, physical, orcombination ofboth. Inthelatter

case,which

one

contributes

more

tothescore?

An

alter-native approach would be togive a project alternate a separate score on each of the twelve categories of

environmental parameterslisted in Figure3.

Summary

interpretationwould be

more

difficult, but thevalidityof

the technique would be higher. It would not be

neces-sary to

make

the highly questionable assumption that

Figure3

Categoryof EffectbyLocational ParameterRankings

Single Locational Multiple Locational

(A)*

Parameter

(D)

Parameter

(B) (C) (E) (F)

Mean

Category of Effect

---Category Rank

Aesthetic 64(5)*' 48(5) 21(2) 50(12)

Atmosphere 14(1) 14(1)

Cultural Conditions 28(1) 21(4) 22(5)

Earth 42(4) 42(4)

Cultural Land Use 56(1) 46(1) 51(2)

Fauna 48(3) 26(2) 39(5)

Flora 62(4) 49(3) 56(7)

Land Use 48(1) 36(4) 16(1) 24(1) 8(3) 26(10)

Man-Made

Factors 55(3) 18(1) 4(2) 32(6)

Noise 67(1) 37(1) 27(3) 68(1) 42(6)

Physical Processes 56(3) 21(7) 32(10)

Water 11(1) 24(4) 21(5)

Mean Location Rank 58(21) 41(15) 22(5) 38(8) 13(9) 24(15)

'Definition of Locational Parameters: (A) Airport Property, (B) Airport Periphery, (C) Durham or Raleigh

or Research Triangle Park, (D) Umstead Park, (E)

Wake

and Durham Counties, (F) Airport Property and/or

Airport Periphery and/or Umstead Park and/or Northwest Raleigh.

'

'Figures represent the rank and number of cases, e.g. 64(5), for a category of effects, e.g., Aesthetics, for

(8)

the twelve dimensions

measure

the

same

phenome-non, whichis requiredifthescores are

added

together to form a composite index.

Conclusion

inthediscussionofthe applicationofsurvey research

methods

inmatrix

assessment

inthispaper,agenerally criticalposture

was

taken toward thevalidity ofthe ap-proach.

The

criticisms made, however, should not be

takenasrejectionoftheapproach.Itcanplaya valuable roleinenvironmentalplanning, butitslimitationscannot be ignored.

Matrix

assessment

representsan "approach, notan

arrival," to borrow a quote from Merton (1957, p. 9).

Leopold efal. (1971, p. 6)

make

essentially the

same

point in evaluating the role that a matrix can play in

preparation of an Environmental Impact Statement

(EIS).

They

state:"Thematrixis,infact,the abstractfor

thetext ofthe environmental assessment."

Some

ofthe possible roles thatamatrixcanperform

wereoutlinedinearliersectionsofthepaper.

By

relating

causes and effects in one comprehensive scheme, it

provides a useful vehiclefor data reduction and

sum-mary.

The

lackofintegrationinEISshas

been

noted by

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emphasized

thata public hearing, whileauseful

means

toobtaincitizen input, is

just a first step.

The

suggestion is

made

that the next

step be for the "airport operators to weight affected

communities' attitudes in their

own

planning process" (Federal Aviation Administration 1972, p. 32).

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combined

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defini-tive, introducesthecitizen

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into

environmen-tal planning and

assessment

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—

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