20designinghillside.pdf

(1)

Visual

Value

Robin

Corathers

44AH

toooftenin thiscountry

we

think

we

have

two

/V

choices....to

buy

land

and

lockit

up

foreverina

park or a preserve, or to let anything-goes, horrible,

schlocky

development

occurrightnextdoor.

Those

are

nottheonlychoices

we

havein thiscountry.

There

isa thirdchoice,

and

thatis

we

canhave

growth

and

devel-opment

that respects the characterof a place

and

re-spects

and enhances

thecharacterofourlandscape."

[Edward

T.

McMahon,

director,

American Greenways

Program,

The

Conservation

Fund

November

25,1991at

The

Hillside Trust's "Hillside Protection Strategies"

conferenceinCincinnati, Ohio.]

The

Greater Cincinnati metropolitanarea in

south-west

Ohio

and

northern

Kentucky

is graced with

an

extraordinarynetworkofriversand greenhillsidesformed thousands ofyears

ago

bythreedifferent glaciers.

The

forestedhillsides

and

theriversystemsgivetheregion a

uniquevisualpersonality

and

contributesignificantlyto thearea's qualityoflife.This hillsidesystem provides

aesthetic,

economic and

environmental benefits tothe

urban region.

The

ribbons of green

open

space offer spectacularviews

and

opportunitiesfor

outdoor

recrea-tionwithinan urbansetting.Realestatevaluesforareas

with views, or adjacent to or near unspoiled slopes,

remain

high.

The

hillsides are an integral part of the

urban ecosystem, providingwildlifehabitat

and

migra-RobinCorathersisexecutivedirectorof TheHillsideTntst.

She

served asproject

manager

for the Tnist's research projects

and

editoroftheproject publication 'A Hillside Protection StrategyforGreaterCincinnati.'

She

previously

worked

as

an

environmental plannerforthe

Ohio-Ken-tucky-IndianaRegionalCouncil of Governments.

Thisarticleisbasedinpart

on The

Hillside Trust's publi-cationprincipallyauthoredby

Samuel

V.Noe,

an

architect

and

professorintheSchool ofPlanningatthe Universityof

Cincinnati.

Noe

isaboard

member

of

The

Hillside Trust.

tioncorridorsaswell asrelief

from

airpollutioncaused by

urban

congestion.

The

forestedslopes prevent soil

erosion

and

flooding

and

help conserveenergyby

shad-ing buildings in

summer

and

blocking cold winds in winter.

The

hillsides are also quitefragile; Greater

Cincin-natiis

known

foritscostly landslides.U.S. Geological

Surveystudiesindicatethe costsoflandslide

damage

to privateproperty

and

public infrastructureinthe Cincin-nati area are in the millions ofdollars annually.

The

geological historyoftheregion hasresultedin

an

abun-dance

ofsteep valley slopes, consistingofglacialclays

and

till,atop

bedrock

formations containing high per-centages ofshale.

Many

hillsides,particularlyalongthe

Ohio

River, arenotyetinastateofgeological

equilib-rium, a condition geologists call

"immature

topogra-phy."

These

factors,together withahigh averageannual

rainfall,contribute to thearea's

many

landslides.

But

it

has

been

insensitive

development—

cutting intothe toes

ofslopes, placingfill

on

slopes, regrading

and

paving without controlled

drainage-which

has triggered the vastmajorityoflandslides.

Inadditiontolandslide

damage,

insensitive

develop-ment

and poor

designhave

changed

thevisualcharacter

of the hillsides

and

destroyed valuable natural areas. Until about fifteen years ago, the region's hillslopes

remained

largelyundeveloped, with

most

construction

occurringinvalley

bottoms

and

on

hilltops. Inthe past

decade, however,

development

pressures foreven the steepest slopes have sharply increased

due

to several factorsincluding

growing

scarcity of

undeveloped

flat

land; technological advances in earth

movement

and

retentionmethods;

and

the increasing

number

of people

who

want and

canafford propertieswithaview.

About

fifteenyears ago, thecityofCincinnati

(2)

"Environmental

Quality

(EQ)

Hill-sideDistricts,"azoningoverlaywithin

which

protective

measures

could be

established.

To

date only halfofthe hillsides in the city have

been

desig-natedas

EQ

HillsideDistricts,

and

in

most

oftheregionthe

need

for hillside protection has not

been

addressedat

all.

Two

factorshavelimited the

adop-tionofrational

and

well-coordinated

policies

and enforcement

ofstringent regulationsbylocalgovernments.

Many

government

officialsintheregionhave supported unlimited

growth

and

have beenreluctanttoantagonize

develop-ers

who

they believe

would oppose

hillsideprotectionmeasures.

The

lack

of information about the "environ-mental

and

visualsensitivity"of

hill-sideswithin the variouspolitical juris-dictions located in the Greater

Cin-cinnati metropolitan region has fur-ther

hampered

protectionefforts.

In 1988, the Hillside Trust, a private nonprofit re-gional landconservation organization,

began

research to provide better information about the hillsides

and

better tools forboth its internal decision-making

and

that oflocal

governments and

others

concerned

with

hillside

development and

preservation.

The

Trust

for-mulated thefollowingresearchquestions:

•

How

should _the_relative_aesthetic_qualities

and

envi-ronmental

significanceofhillsides in the

metropoli-tanarea beassessed?

•

How

canthese distinctionsbe_related_to_{vulnerability}

tolandslides

and development?

•

What

_areappropriate_guidelines

and

_regulations_for

cases

where

sensitive hillside

development

is pos-sible?

•

Which

hillsideareasdeservepriorityattentionbythe

HillsideTrust

and

local

governments?

The

HillsideTrustrecognized thata

comprehensive

approach

to hillside protection

was needed

to guide

sound

decision-making.

The

Trust's staff

and

consult-antsdesigned

two

research projects:

one documenting

the relative sensitivity ofhillside land

and

identifying

criticalnaturalareasforpriorityattention;

and

asecond

creatinga

model

setofhillside

development

guidelines

andregulationsforadoption bylocalgovernment.

The

HillsideTrust

proposed

to studythe impact of

development

type,density,design,

and

locationfactors

on

perceptions ofvisualquality

and

how

toincorporate

AsthisviewformPriceHillillustrates,Cincinati's hillsidescombinewith theOhioRivertoformanatural

visualamenity. '

this information into planning guidelines, goals

and

objectives.

The

Trustcontactedthe U.S.ForestService fortechnical

and

financialassistance. It

was

referred to the ForestService's

North

Central Forest

Experiment

StationinChicago,Illinois,

which

had

done

research

on

visualpreferences

and

visualresourceassessment

meth-odology.

The

Forest Service

had

developed a Visual

Management

System

for evaluating wilderness areas,

butthis

methodology had

never

been

adaptedto

urban

environments nor incorporatedintoageographic

infor-mation

system (GIS). Previous research by the

North

Central office in Cincinnati

had

shown

that intense hillside

development

can negativelyaffectperceptions ofvisual quality.

The

ForestServiceexpressedinterest in thisproposal

and

agreed to fund it through cooperative research grants. In addition to the Forest Service funding, the HillsideTrust

was

able tosecurefinancial

and

in-kind servicesupportforthe

two

studies

from

elevenstate

and

local

government

agencies

and

private foundations,

and

from

scores ofindividual professionals

and

interested citizens

who

volunteeredtheirexpertise

and

time.

Although

the geographic scope of the Trust's

re-searchis limited to the Greater Cincinnati region, its

work

shouldbe ofinterest toelectedofficials,planning

and

zoning

commissioners

and

staff,design

and

devel-opment

professionals, park commissioners,civic

lead-ers,

and

others

concerned

with land conservation

and

development

issues in hilly terrain. In particular, the design ofthe Hillside Trust's studies

and

the

develop-ment

guidelines theygenerated can serve as a useful

(3)

environ-mentally sensitivehillside land is subject to

develop-ment

pressures.

GIS

Study

The

HillsideTrustdecidedtousea

computer-based

geographic information system (GIS) toprovidea

flex-ible

and dynamic

techniqueforidentifyingcritical

hill-sideareas.

The

Trust

was

particularlyinterestedinusing

GIS

to:

• analyze_potentialimplications_of_alternative_patterns

of

development

and

planningstrategies;

•

"zoom

_in"

on

_{specific sites}_within_{the electronic}

maps

and

conduct

more

detailedstudies;

• allow

government

plannerstoadjusttheparameters

ofthe analytical models,based

on

new

or different

environmental data ordifferentsetsofassumptions;

• _rapidly update data

and produce

maps

_at _different

scales.

Although

the HillsideTrust is

concerned

with the protection ofhillsideresourcesina five-countyareain

southwest

Ohio

and

northernKentucky, it limited its

GIS

study to hillsides in

Hamilton

County,

Ohio

and

Kenton

County,Kentucky,

an

area

encompassing

over

370,500acres.This choice

was

made

because of budget

constraints

and

because thesecounties had their

own

GIS

orareintheprocess ofestablishingone.

Research

involved thedesign

and

testingof

system-atic

computer-based

models

for

mapping

hillsides.

The

analytical

models

rate hillsides according to relative visualquality,landslidehazard,valueasecological

cor-Exiaisivcgradingofhillsidesmakesthemsusceptibletolandslidesanderosion.

ridors,

and

susceptibilitytodevelopment.

These

classi-fications

were

then

combined

to

produce

six

color-coded composite

maps

showing

therelative sensitivity

ofhillsidelandtodevelopment.

The

analytic

models determined

the data

require-ments

forthestudy.HillsideTruststaffcollected

exist-inginformation

from

a greatrange oforiginal

mapping

scales

and

map

types.Landsatsatelliteimagery

was

used

to update land use/land cover information.

The

map

coordinate system selected

was

Universal Transverse

Mercator

(UTM).

ERDAS

GIS

software

was

chosenfor

useindigitizing

map

informationinto the

GIS

because ofitsefficiency

and

speed.This transformationprocess

was

closely

monitored

because ofinaccuraciesin

some

ofthe originalmaps.

The

TrusthiredDr.

Douglas

Way,

alandscape archi-tect

and

consultingprincipal ofthe

SWA

Group,

Co-lumbus,Ohio,todevelopthe analytical

models

in

con-sultationwith the HillsideTruststaff

and

an advisory

committee,

which

includedrepresentatives

from

allthe

supportingorganizations.Dr.

Way

produced

aseriesof primary

and

summary maps

ofhillside characteristics fortheproject.

Analytical

Composite

Maps

VisualSensitivity.

An

analytical

model was

developed

todeterminetherelativevisual qualityofhillsidesas a function of land use/land cover, proximity to water, diversityofpositive landscape elements,

and

location

alongthehillsideupland

edge

(thearea

most

criticalto visual impact.) Natural,

undeveloped

areas that are close towater, witha

combined

view offorests,water, agriculturallandorpastures,

and

are located

on

the sen-sitivehillsloperim

were

rated highestin

vis-ualquality

and

sensitivity.

Landslide Potential. Geological

infor-mation, degree ofslope,

and

evidence of

previouslandslides

were

usedtodetermine

relative landslide hazard. In the Greater Cincinnatiregion, landslides are

most

likely tooccur overthe Fairview

and

Kope

bed-rock formations,

which

contain

up

to eighty

percentshale.Slopeinstabilityisalso asso-ciatedwith areas located

above

lacustrine

clays. Steepness of slope

and

proximityto existing areas of instability are the other primaryvariables indetermininglandslide susceptibility.

Ecological Corridors.

While

studies in

otherpartsofthecountry have

documented

the

importanceof

forestedareasin filtering particulates

from

theair

and

absorbing and

storingcarbondioxide,in

moderating

tem-peratures,

and

in preventing erosion and

(4)

was

availablein the Cincinnatiarea. After conferring

withbiologists

and

other scientists,the Hillside Trust

instead decided to focus

on

the region's pattern of

ecological corridors

which

sustain an

abundance and

varietyofwildlife.

The

relative

importance

of eachhillsideasan ecologi-calcorridor

was determined

by

examining

land

charac-teristics(upland, rim, slope,valley),proximitytowater, land use/land cover,and,

where documented,

the

pres-ence of threatened

and endangered

species.

The

most

ecologicallysignificant zonesare

found

in linear pat-terns followingthe valley systems,alongthelower edges

of the hillslopes, adjacent to or nearstreams,

and

in

areasleastdisturbedbydevelopment.

Development

Susceptibility. Susceptibilityto

develop-meni was determined

to bea function of proximity to existing or

proposed

infrastructure, including

major

roads,water

and

sewerlines; construction costs

deter-mined

bytopographic

slopeand

flood hazard;

and

visual

amenities includingviewpotential

from

hillsideedges andvalleyslopes.

of the

"macro"

analysiswhilealsoincludingappropriate "micro"information.

In this example, desirable land

was

defined as all

undeveloped

parcels largerthan

one

acre,rated as hav-ing highvisual sensitivityorhighqualityasanecological corridor

and

rated as having a high susceptibility to landslides.

To

this

was added

more

detailedsite

infor-mation

including analysisofsoiltypes

and

their limita-tions for development; the quality of tree stands as

evaluated bya U.S. Forest Servicelandscapearchitect

who

visited

and

mapped

thesites;

and

information

on

zoning, land ownership,

mean

value of parcels,

and

proximityto

major

roads.

Development

Guidelines

The

HillsideTrustusedseveralresearch

methods

to

formulate appropriate guidelines for

development

in

sensitive hillsideareas (see figure1):

• survey

and

_evaluation of_{legislation in} use by_cities

andcounties withsimilartopographicfeatures

through-out the

United

States;

Summary Maps

Visual

and

Environmental Sensitivities.

To

identify

critical hillsideareas, a

composite

map

was

generated

that identifies hillsideswith highvisual sensitivity,high

quality ecological corridors,

and

highlandslide poten-tial. This analysis provides multiple

justifica-tionforprotectionofthese areasthrough

per-manent

preservation

methods and

through use

of

more

stringent controls over

any

future

proposed development.

HillsideAction Priorities.

As

an additional

planningtool,the

summary

map

ofvisual

and

environmentalsensitivities

was

overlaid

on

the

map

of

development

susceptibility to identify

where

highquality sensitivehillsideareasare also susceptible to future development. This composite

map

locateshigherqualityhillsides thatare

under

lesspressureatthepresenttime

for

development and

may

therefore be less

expensive to acquire, as well as hillsides of

relatively

low

visual

and

environmental

sensi-tivity

where

it

would

be appropriatefor local

governments

todirectfuturedevelopment.

Detailed

Small Area

Analysis

To

demonstrate futureapplications of the

GIS-generated data base for local planning

decisions, the HillsideTrust chosea "micro"

areaspanningthe

Ohio

River

and

illustrated

how

a hypotheticalstudy could beconducted

forparkland acquisition.

The

detailed

model

illustrates the

change

in scale

from

regional analysis to site-specificstudy,usingtheoutput

consultationwithenvironmental,development,

plan-ning

and

legal professionals;

adaptationoftheU.S.ForestService's visual

prefer-encemethodology,focusing

on

a

number

of

develop-J"

Consultationwithprofessional .

advisorypanels: USFS,

developers,environmental designers, ecologists. regulators Collect relevant

hilsideordinances andstudies

1

^

Selectappropriate Rejected

\s

guidelines guidelines

lr

New

guidelines

O

Studiotestof guidelines guidelines

[

New

guidelines

Designvisual preference study

model

iUSFSreview

model

4

New

components

ll

Runvisual preference study

\

Deriveguidelines Professionalpanel

reviewofguidelines

—

Rejected guidelines

O

1 o

HillsideTrustBoard reviewof guidelines

Finalguidelines published

(5)

ment

variables

and

theirvisual impact in

an

urban environment;

• _testing_of _{packages of}_guidelines _in _{a University}of

Cincinnatistudioof

advanced

architecture

and

plan-ningstudents,supervisedbyrespecteddevelopersin the region.

GuidelinesDerived

_from

ExistingOrdinances. Provi-sionsof ordinances

from

around

thecountry

were

clas-sifiedbytype, relativedegree of importance,

and

typeof

legislative or policy vehicle in

which

they are

most

appropriatelyincluded.

The

guidelinesdetermined to

be

most

applicable toGreaterCincinnati arearange of

publicpolicies;guidelinesforregulationofsubdivisions

ofhillsideland;zoningtoregulate densityofhillside

de-velopment; zoning to regulate the visual characterof

hillsidedevelopment; earthwork,erosion,drainage

and

sedimentationcontrols;

and

retention

and

replantingof

vegetation.

GuidelinesDerived

from

the Visual Preference Study.

Hilltophighr'tsedevelopment shouldbe reserved fora few promontorypoints subjecttorigorous design reviewtoensureproperhillcrestsetbacks.

The

HillsideTrustincorporatedpublicopinionintoits

research using a modified version ofthe U.S. Forest Service'svisualpreferencetechnique.

The

resultsofthe visualpreference study provide

an

additionalbasis for

recommending

where

green space shouldbe maintained

on

thehillsides

and where

differenttypesofbuildings relate

harmoniously

withthe naturalenvironment.

The

conclusions

drawn from

the visualpreference studyalso lendanadditional

measure

oflegitimacytothe

recom-mended

guidelines,becausethe guidelines

embody

the

views of botha representative

sample

oflocalresidents aswellas professionals

whose

work

involvesdifferent aspectsofhillside

development

inthe region.

The

Trusthired

John

Decker,

an

architect,landscape

architect,

and

professorattheSchool of Planningatthe University of Cincinnati, to design

and

execute the visualpreferenceresearch.

The

visualpreferencerating

techniqueinvolved the creationofthirtyviews of char-acteristic hillsides,developedtodifferentdensitieswith

a varietyofbuildingtypes,

and

sited inarange of differ-ent patterns.

Most

oftheviews

were

syntheti-callyconstructed,using a

computer

imaging proc-essingsystemto overlay

photographs

ofarange ofbuilding types

on

a

photograph

ofan

undevel-oped

hillside.This permittedvirtuallyeverylikely

patternofhillside

development

inthe collection

ofviews.

Lay and

professional research participants

were

askedtoindicate the extentto

which

they

found

each

image

eitherattractiveor unattrac-tiveand,incasesof

extreme

reactions,the

rea-sonsfor their feelings.

The

responses

were

then

tabulated,

and

laterusedinthe

development

of

a

number

ofguidelines.

After

examining

thethirty images, each

re-spondent was

askedto

work

withan operatorof the

computer

imaging system to construct a preferredpatternofhillsidedevelopment.

The

totalcollectionof"ideal"

development

patterns

on

the

same

hillside

were

then

superimposed

on

one

another in order to locate the portions of thehillsides

most

oftenleftfreeof

development

and

the locations

most

commonly

favored for differenttypesofbuildings.

The

Hillside "Studio": Testing Guidelines in

the Design Laboratory.

Midway

through the project, a

number

of promising approaches to regulation of hillside

development began

to

emerge from

thepreliminaryanalysisof

legisla-tion inuse inotherpartsofthe country.

These

approaches

were

evaluated

and compared

inan urbandesign studio exerciseatthe University of Cincinnatitotesttheirappropriatenessto local conditions. In this exercise, four teams of

ad-vanced

students

from

the

Department

of Archi-tecture

and

theSchool of Planning

were

asked

(6)

todesignhousing

developments

on two

prototypicalCincinnatisites.

Two

ofthe teams

were

assigned an

eight-acre mid-slope site in an inner

suburbanlocation.

They were

instructed todesignapproximately fifty dwelling

units,witheach

team

followinga differ-entpackageofdevelopmentregulations.

The

other

two teams were

assigned a hillcrest site

on

a

commanding

ridge

overlookingthe

Ohio

River

and

down-town

Cincinnati.

They

were

also given different

development

regulations

and

askedtodesign

between

forty

and one

hundreddwellingunits, ineithera

high-riseor a less obtrusive configuration.

Allteams

were

assigned a practicingresidential

prop-ertydeveloperasa

mentor and

designcritic.

During

theexercise,thestudents

were

askedto evalu-atethesetofguidelinesthey

were working

with

and

to suggest revisions

which

might contribute to designs

more

compatible with the hillside environment.

The

design

work

continued based

on

these revised

guide-lines.

The

range ofarchitecturaldesigns

produced

in the studioproved useful in determining appropriate loca-tions fordifferent typesofbuildings

on

thehillsides.

The

testing of the different

development

guidelines

em-ployedprovedequallyhelpful.

Some

guidelines

had

the potential toplace unreasonable

economic

burdens

on

projectdevelopers. Others,whilepreventing

many

forms of inappropriate development, also

had

the effect of

constraining particularly imaginative

and

desirable

approachestodesign.Thisstudioexperienceinfluenced

finalchoicesfor

development

guidelines, primarilybyhelping to discardlesspromisingapproaches. Expert Consultation.

Throughout

the course ofthis

project, the HillsideTrust consulted with a variety of

hillside

development

professionals,includingsoil

scien-tists,geologists

and

geotechnical engineers, landscape

architects, architects,

urban

designers,ecologists,

biolo-gists,planningofficials,developers,

and

attorneys.

These

experts assisted in the design of the study, participated in

workshops

on

development

guidelines

and

seminars based

on

the studiowork,served as sub-jectsinthevisualpreferencestudy,

and

revieweddrafts of the Hillside Trust'sfinal report.

Inall, 162guidelines

were

generated

from

thestudy.

The

HillsideTrustbelieves

some

ofthese guidelinesare essential toanylocalgovernment's hillsideprotection

program.

Of

particularnoteare the Trust's

recommen-dations for public policies that call fordesignation of

hillside protection overlay districts; establishment of

hillside

development

reviewboards; public acquisition offeesimpletitleor conservation

easements

forcritical

Housingdevelopmentappropriatetoamid-slopesitelocaledonaninnersuburbanhillside.Densityhasbeen kept

lowbyclusteringtheunits,leavingmuchoftheforestedhillsideuntouched.

hillsideareas;

and

requirementsthat public

and

quasi-publicagencies be

bound

byhillsideprotection

meas-uresinadditionto privateproperty owners.

Other

guide-linesare

and

shouldbe

con-sidered a

from which

local

governments

canpick

and

choose,

depending

on

their

own

needs

and

unique

circumstances.

Steps

The

HillsideTrust

announced

the

completion

ofits

research projects inJune, 1991,atitsannual

member-shipmeeting,

and

received favorablelocalpress cover-age.Sincethattime,theorganization has

been working

to familiarize elected officials, planning

and

zoning

commissions

and

staff,design

and development

profes-sionals,

and concerned

citizenswithitsfindings

and

rec-ommendations

throughpublicpresentations

and

meet-ings.

On

November

25, 1991,

The

HillsideTrust helda

day-long public conference entitled "Hillside Protec-tion StrategiesforGreater Cincinnati"

which

175 pro-fessional

and

lay people

from

Kentucky and

Ohio

at-tended.Speakers coveredtopics

from

specificland

con-servation

methods

toregulatingthe qualityof designfor hillsidedevelopment.

[Editor'snote:

A

full account ofprojectmethodologies, findings

and recommendations

can be

found

in

The

Hill-side Trust'sthree-volumepublication

A

Hillside Protec-tionStrategy forGreaterCincinnati. Copies ofthe

three-volume

setof

books summarizing

The

HillsideTrust's

re-search are available for

$45

plus$5.50for shipping

and

handling. _{Copies of}the hillside developmentguidelines

data baseare availableineither31/2"or

5

1/4"floppy disks for

$25

plus $3 for shipping

and

handling.

For

more

informationabout

The

HillsideTrust'swork,writeorcall:

The

HillsideTrust

3012

Section

Road

at

French

Park

Cincinnati,