Social Aspects of Urban Forestry
FREEWAY ROADSIDE MANAGEMENT: THE URBAN FOREST BEYOND THE WHITE LINE
by Kathleen L. Wolf
Abstract. A national survey was conducted in the
United States to learn more about public preferences and
perceptions regarding forest and vegetation planning and
management in urban freeway roadsides. In response to
images depicting a visual continuum of landscape
management treatments, drivers most preferred settings having
tree plantings that screen adjacent commercial land
uses. Preference results suggest solutions for landscape
practices that create visual quality for drivers and provide visibility
for commercial properties adjacent to freeway roadsides.
The research also investigated public attitudes about
roadside functions, uses, and public willingness to support
roadside management expenditures. Increasingly,
transportation agencies are designing urban roadside landscapes to
achieve multiple objectives and perform multiple functions.
This research offers insights on how to incorporate
urban forestry into the planning and management of
high-speed urban transportation corridors.
Key Words. Urban forestry; public
perceptions; transportation; social science.
Beyond the white line at the freeway edge is the
roadside, strips of public land that provide a buffer between
high-speed driving and adjacent land uses. Roadsides are
a sizeable landscape resource in the United States. The
state of Washington alone has 39,000 ha of roadside lands.
The driving public has ever-increasing experiences of
the roadside landscape, with U.S. drivers spending more time
in their cars each year. In recent decades in the United
States, the annual average km of travel, number of trips,
and mileage per trip have increased 60% to 82% (U.S.
FHA 1990). Much of that road time is spent on urban
high-speed roads. Drivers in the United States currently travel about
3.8 billion vehicle km per day on 102,000 km of urban
freeways and highways (U.S. FHA 1998).
Most public lands, including freeway roadsides,
have become multi-tasking. Public lands in cities face
continually expanding programs of activities and functions due
to public needs and citizen urgings. While initially dedicated
to providing safety buffers, Lady Bird Johnson's
Highway Beautification movement of the 1970s expanded the role
of roadsides to include visual and aesthetic quality.
More recently, roadsides are managed by transportation
to facilitate wildlife movement, reduce stormwater
runoff, and enhance air quality.
Urban stakeholders influence such management practices. One roadside user group can be
particularly insistent. Commercial and business interests often
pay premium prices for roadside real estate, acknowledging
the visibility of such parcels to thousands of daily
passing motorists. Meanwhile, design standards have been
developed to enhance visual quality of highway roadsides
and rights-of-way. The guidelines often urge conservation
and preservation of existing urban forests, while
promoting additional tree plantings. Often, business interests strive
to maintain "commercial windows" in the roadside and
may deter efforts to implement urban forestry and
other landscape design goals in public roadsides.
What is the driver's experience of the roadside? What
is the importance of that experience in relationship to
the planning and management of roadsides? This report
comprises one phase of a national study on the role of
vegetation in roadside visual quality in urban and semi-urban
settings. The survey-based research evaluated public response to
trees and views in the freeway roadside environment
using landscape assessment methods. Results integrate
visual preference outcomes and perceptual responses.
BACKGROUND AND RESEARCH QUESTIONS
The social sciences offer theories and methods for
assessing multiple stakeholder perspectives associated with any
public landscape. These approaches, used often in studies
of human response to urban residential settings and
parks (Schroeder 1992; Dwyer et al. 1994) or wildland
landscapes (Ribe 1989), have rarely been applied to the study
of transportation landscapes. Schauman et al. (1992)
observed that there is "no body of research on the
relationships between the driver and the landscape beyond the
paved area of the road." An overview of the infrequent
research efforts yields insight into the complex yet subtle
interrelationship of roadside environment, human psychology,
and the driving experience.
Visual and Aesthetic Quality
Public opinion about a scenic corridor in California is
an example of how visual values can be integrated into
highway planning (Evans and Wood 1980). People judged
simulations of proposed roadside residential development
scenic quality. "Cluttered" and "ugly" were terms
drivers used to describe roadside development, while
"pleasant" and "beautiful" were descriptions of highway
corridors containing mostly vegetation.
Generally, high complexity in urban scenescreated
by roadside objects, building density, utility poles,
overhead wires, and signagedegrades perceived visual quality.
Visual richness (e.g., moderate complexity) evokes interest;
visual clutter and chaos reduce preference (Nasar 1998).
Roadside Appearance and Cognition
There are multiple levels of psychological response
to environments. Judgments of aesthetics are often
associated with affect, cognition, and behavior. Two studies
illustrate the associative behaviors of visual interpretations.
Transportation engineers design paving,
associated structures, and signage to meet functional expectations
for specific road types (freeways, arterials, etc.). If
drivers misperceive a road type, they may operate their vehicle in
a way that is inconsistent with the road specifications,
endangering themselves or others. A study of road categorization
was conducted to compare driver perceptions of road types
to "official" road categories (Riemersma 1988).
Contextual conditions and roadside elements contributed more to
drivers' subjective distinctions of roads than did intentional
indicators (e.g., road markings, placement of emergency lanes).
Another study tested route choice (Ulrich 1974).
Two parallel roads provided access to a nearby
shopping centerone a scenic parkway route, another a faster
and nonscenic expressway route. Despite the parkway
route taking more time and having more stops, study
participants chose the scenic route more than half the time.
Drivers reported feelings of relaxation and enjoyed views of
nature on the parkway route. The study demonstrates
positive affects of naturalistic roadways and suggests one
strategy for traffic routing in transportation planning.
Driving and Physiology
As drivers spend more time on the road and in
congested traffic each year, driving stress becomes a public
health issue. Changes in mind and body are documented for
all driving experiences. Both heart rate variability and
blood pressure increase when a person is driving compared
to nonactivity situations. Demanding driving conditions,
such as on-ramps, off-ramps, and roundabouts, increase
stress response (Rutley and Mace 1972).
Commuting may be one of the most stressful
experiences of urban life. Stress indicators, such as increased
blood pressure, are associated with longer or more
difficult commutes. Other affects have also been
notedlowered job satisfaction, higher illness and absenteeism rates,
and lower performance on various cognitive tasks (Novaco et
Empirical studies confirm the restorative effects
of passive nature experiences in many situations (Ulrich et
al. 1991; Kaplan 1995). A comprehensive evaluation of
the effects of roadside character on stress response reveals
that driver viewing of built-up, strip-mall-style roadside
environments both slows down and impedes physiological
recovery from stressful stimulus (Parsons et al. 1998). Study
participants exposed to roadside nature scenes (forests or
golf courses) returned to normal baseline measures faster
and had a greater ability to cope with introduced stressors.
An "immunization effect" was confirmed; exposure to a
natural roadside setting decreased the magnitude of response to
a later stressful task.
The sparse research literature hints at the
psychological importance of drivers' visual experiences of the
roadside. Human perceptions and benefits should be integrated
into planning for high-speed transportation. Several
research questions guided this investigation of roadside amenities
in urban and semi-urban settings:
1. How does the urban forest, and other physical
elements, contribute to the visual quality of the
2. Does the public support roadside management
for visual and other landscape functions?
3. Are differences in drivers' roadside
perceptions associated with demographic traits?
The research data were obtained in October 1999
using surveys. The eight-page instrument began with a
photo-preference activity. Several additional banks of
variables were provided to capture attitudes about roadside
views, features, suitable uses, and fiscal support for
roadside programs. Demographic variables elicited information
about driving behaviors and socioeconomic traits.
A photographic image sample was generated for
the survey using a combination of photography of
actual freeway roadside settings and digital editing. Six
base images, selected by an expert panel, were judged to
be freeway conditions typical of temperate North
American cities. Base images contained foreground views of
roadside and mid-ground views of commercial usesmotel,
retail mall, auto dealership, recreational vehicle sales lot,
mid-rise office building. Known confounds in public
preference response were avoided (e.g., overhead utility lines,
littered or untidy settings). Each base image was digitally edited
to include six conditions of varied landscape treatment.
The final presentation set contained 36 black-and-white
images, randomly presented.
Licensed drivers were sampled within designated geographic areas of the United States. A nested
procedure was used to first identify geographic areas
for mailing and then specify the questionnaire recipients
within those locations. Local partners identified "edge cities"
within major metropolitan areasSeattle, Washington;
Minneapolis, Minnesota; Detroit, Michigan; and Baltimore,
Marylandfor mailings. Addresses were randomly selected
from a combination of statedrivers licensing agencies and
list broker sources.
After pre-testing, 3,000 surveys were mailed, followed
by reminder cards. Mailing procedures generated 404
reasonably complete responses and, given that 421 were nondeliverable
or were returned without response, the response rate was
16%. Sommer et al. (1990) report that typically 20% to 25% return
is expected of mail surveys of city residents, while Elmendorf
and Luloff (2001) report that response rates have fallen.
The possibility of nonresponse bias must be considered.
ANALYSIS AND RESULTS
Reported age of respondents reflects demographic trends of
the United States: 45% were in their 40s or 50s, 32% indicated
30s or younger, and 23% specified 60s or older. Gender
distribution is approximately that of the U.S. population. Income was
well distributed, with 25% of reporting households having incomes
of up to US$35,000, 43% indicating US$35,000 to
US$75,000, and 32% earning more than US$75,000.
When asked, "What is the size of the community you
live in?" large city (>100,000 population) was indicated by
22%, small city (20,000 to 100,000) was chosen by 21%,
and "suburb of a large city" registered at 42%.
Respondents were also asked to recall their typical driving habits.
Most drivers claim to spend fewer than 10 hours per week in
a motorized vehicle (57%). Of time in a vehicle, 36% claim
3 hours or less per week on a high-speed road, compared
to 28% for 4 to 6 hours.
Image Preference and Perception
Preference Means. How do drivers react to
roadside vegetation content and arrangement? Respondents
were asked to indicate how much they liked the kind of
depicted in each scene by circling a number on a
five-point Likert scale, with 1 denoting "not at all" (low
preference), while 5 indicated "very much" and high preference.
Several analytic procedures were used to interpret
data meaning. Images were sorted by preference means; high
and low scenes are in Figure 1. An approximate
three-point difference between the high- and low-rated images
indicates the degree to which the public associates trees and
reduced views of built settings with visual quality.
Dimensional Analysis. Principal axis factor analysis
with Varimax rotation generated factors based on
observed covariation of individual items. Several decision rules
were employed to determine inclusion of images and
promote meaningful definition and naming of underlying
response categories (Kaplan and Kaplan 1989).
Five categories accounted for 57% of the total
variable variance. A total of 27 images were included; nine
remaining items did not meet the category criterion. New
dependent variables were constructed by aggregating mean values
for each variable across all category items for each
participant. An expert panel reviewed and labeled the categories:
Barren Edge, Prominent Buildings, Ornamental Frame, Tree
Buffer, Tree Screen (Figure 2).
Barren Edge images display no trees and few shrubs
in the roadside; visible vegetation is scruffy or roughly
mown grass and weeds. Adjacent commercial property uses
(e.g., buildings, large products) are highly visible.
Prominent Buildings scenes also contain little vegetation, and
buildings dominate views. Ornamental Frame depicts shrub and
tree combinations that soften visual obtrusiveness of
built elements and screen ground-level views into the
commercial zone. The Tree Buffer category shows dispersed trees
acting to visually diminish mid-ground buildings or products
and create a greater sense of visual balance between the
built and natural elements of the scene. Finally, Tree
|Mean 4.52 (high), 0.76 SD||Mean 1.40 (low), 0.78 SD|
Figure 1. High/low preference scenes.
|Barren Edge||Prominent Buildings|
|8 images, loadings .616 to .794||2 images, loadings .590 to .640|
|Category mean 1.56, .70 SD||Category mean 1.66, 0.77 SD|
|Ornamental Frame||Tree Buffer|
|10 images, loadings .590 to .744||2 images, loadings .497 to .674|
|Category mean 2.71, 079 SD||Category mean 2.88, 0.86 SD|
|7 images, leadings .419 to .797|
|Category mean 3.87, 0.74 SD|
Figure 2. Image categories.
contains nearly solid masses of trees that conceal what
lies beyond the right-of-way; the viewer detects buildings
but has no cues as to their commercial purpose.
Comparing Response. Means comparisons tests
were conducted on category preferences for driver
subgroups ( = .05). No significant differences across image
category means were detected for driver age, household income,
time spent in a motorized vehicle each week, or time spent per
week in a vehicle on high-speed roads. Differences were
discovered in Ornamental Frame; mean ratings by drivers from large
cities are significantly lower than preferences expressed by
respondents from suburbs (F = 4.43, df = 2, p < .01).
Roadside Views Features
Respondents indicated their level of agreement with
20 statements about visible features in the roadside, using
a scale from 1 (not at all) to 5 (a great deal). Again,
descriptive statistics were generated, followed by dimensional
analysis and respondent group comparisons (Table 1).
Sixteen statements sorted into categories; four items did not
meet the inclusion criteria.
Considered from high preference to low, Vegetation
Views describes the most appealing landscape features.
"Seasonal changes of roadside plants are interesting"
attained the highest rating (4.53) of the entire item set, suggesting
the visual value of careful plant selection in design.
Also included is the lowest-rated item, "having lots of
plants along the road is boring," with the 1.43 mean
indicating disagreement. The category mean of 4.37 is notably
than the remaining four categories, reflecting the degree
to which quality landscape is valued by the public.
The second category, Built Attractions, has a relatively
high rating (3.64) compared to public judgments of built
environments in other urban studies (Kaplan and Kaplan
1989; Herzog and Gale 1996). The highest-rated category
item, "there should be a blend of built and natural features near
the road," suggests that favored urban driving environments
can include a visual balance of natural elements and buildings.
The latter three categories, composed of two
statements each, capture specific attributes of the view beyond
the road. Large signs are not preferred in roadside views,
which is consistent with MacGillivary (1969), who found that
as the density of billboards increases within a section of
road, there is a corresponding decrease in public opinion of
visual quality. Category 4, with a low rating, indicates that
drivers do pay attention to the streaming
landscape while driving. Finally, Trees and Safety responses suggest that trees
are not considered to be safety hazards. This outcome
merits further research because transportation engineers
often limit tree planting in roadsides on the premise that
they present hazardous visual or physical obstructions
One-way ANOVAs and t-tests were conducted to determine the relationships between demographic traits
and category responses; significant results
( = .05) are reported. Considering age,
older drivers are more likely to regard trees as
safety hazards (F = 4.17, df = 2, p < .02) but are
less likely to pay attention to roadside content (F
= 14.92, df = 2, p < .000) and do not find
large signs to be as serious an issue as do
younger drivers (F = 7.22, df = 2, p < .001).
Household income also is associated with varied attitudes.
Higher-income respondents (>US$75,000) report paying more
attention to the roadside (F = 5.38, df = 2, p <
.005) and being less concerned about trees as safety hazards (F
= 5.93, df = 2, p < .003).
Table 1. Roadside features.
|Factor categories and items||rating||SD||loading
|Category 1: Vegetation Views||4.37||0.57
|I like to see a variety of plants in the roadside||4.43||0.73||.752
|Having lots of plants creates a pleasing setting||4.46||0.76||.628
|Having lots of plants along the road is boring*||1.42||0.79||.560
|The seasonal changes of roadside plants are interesting||4.53||0.67||.545
|I enjoy seeing large trees while driving||4.52||0.67||.480
|I often choose travel routes because they are scenic||3.86||1.21||.415
Category 2: Built Attractions||3.64||0.70
|I find the views of nearby architecture to be interesting||3.38||1.01||.585
|There should be a blend of built and natural features near the road||3.57||1.05||.559
|I find views of neighborhoods to be interesting||3.14||1.07||.548
|I enjoy driving through communities with character||4.33||0.83||.474
Category 3: Large Signs||2.18||0.90
|Large signs are appropriate for roadside advertising||2.30||1.06||.635
|Billboards and large signs should be regulated*||4.03||1.08||.599
Category 4: View Attention||1.86||1.03
|I don't pay much attention to what's beyond the paved edge||2.04||1.19||.872
|I rarely notice the view while driving||1.77||1.20||.659
Category 5: Trees and Safety||2.22||0.97
|Trees can block or distract me from seeing signs||2.39||1.19||.652
|Trees near the road are a safety hazard||2.00||1.10||.514|
*Inverse value used for category calculations.
Those who spend more time each week in vehicles on
high-speed roads claim to pay more attention to the road (F
= 5.24, df = 2, p < .006), while those spending
moderate amounts of time on the road (4 to 6 hours per
week) indicate higher interest in Built Attractions (F = 3.60, df
= 2, p < .02).
In earlier decades, safety or beautification were
roadside design priorities; today other functions are planned
for roadside lands. How suitable does the public find
these uses? Respondents were asked to indicate their level
of agreement with 18 statements, using a scale from 1 (not
at all) to 5 (very much). Table 2 displays results of
dimensional analysis (13 variables sorted into three categories).
The highest-rated statement (4.31), "planned to
create a scenic highway," double loaded and, therefore, was
not included in any category. The next highest-rated
item (4.29) was "location for directional and mileage
signs." High ratings on both statements suggest drivers
are pragmatic in approving guidance aids at the freeway
edge but desire attention to aesthetics in design and
placement of such operational elements.
Reviewing category breakouts, Management
Traditions has the highest mean rating, again reflecting public
interest in practicalities of visual screens and noise buffers.
Fairly high rating of Ecological Functions demonstrates
public support for an emerging strategy in transportation
design. Finally, item ratings within Commercial
Communications suggest public ambivalence about various
commercial signage and view options at the freeway edge.
When considering respondent demographic traits
and category means, no statistically significant differences
Planning and Funding Support
Citizens may indicate agreement with a variety of
roadside functions or uses, but are they willing to commit
the resources needed for implementation? This
research discovered ambivalent attitudes.
Summary statistics and dimensional analysis were
carried out on eight statements, each having a level of
agreement response scale of 1 = strongly disagree to 7 = strongly
agree. Seven statements sorted into three categories (Table 3).
Policy Priority received the highest mean rating,
demonstrating a slightly positive endorsement of public funds
for roadside planting and maintenance. But when asked
about support, respondents were uncommitted. Both
Indirect Support and Direct Revenue Support categories have
means at the neutral point; large standard deviations imply
diverse levels of fiscal willingness to pay for roadside
programs. Review of response dispersions for Direct Revenue
Support reveals that approximately 5% indicate 2 (disagree) or
lower, while about 23% come in at 6 (agree) or higher.
Neither group differs significantly on demographic traits.
Demographics and categories comparisons
revealed several statistically significant responses
( = .05). An increase in age is associated with both
an increase in Policy Priority (F = 5.64, df = 2, p < .004) and decrease in
Indirect Support (F = 9.78, df = 2,
p < .000). Middle-income respondents ($US35,000
to US$75,000 per household) most endorsed Indirect
Sup-port (F = 3.56, df = 2, p < .03), while increased approval of
Direct Revenue Support is consistently associated with
rising income levels (F = 3.40, df = 2, p < .03).
Those spend-ing more time on high-speed roads each week are more willing
to commit both more indirect (F = 9.42, df = 2, p < .000)
and direct resources
(F = 4.51, df = 2, p < .01) to roadside program support.
The purpose of this study was to provide
empirical data that could inform planning and
management of freeway roadsides. This public land
resource, comprising landscape ribbons that
criss-cross many urban areas, may have an impact on
drivers proportionally greater than other more expansive
public lands due to the frequency and duration of
driving activity. Other social science studies of urban
forestry (and urban green in general) reveal a plethora of
Table 2. Suitable uses.
|Factor categories* and items||rating||SD||loading
|Category 1: Ecological Functions||3.58||1.00
|Place for protecting wetlands||3.70||1.24||.873
|Managed to protect native plants||3.96||1.08||.738
|Managed for wildlife habitat||3.20||1.36||.634
|Place to collect and retain rainwater||3.41||1.19||.576
Category 2: Commercial Communications||3.05||0.71
|Managed for open views, to better see near by businesses||2.40||1.02||.735
|Display space for business signs||2.37||1.05||.641
|Gateways and welcoming signs for communities||3.66||0.96||.560
|Views that include a combination of built and natural elements||3.54||0.94||.494
|Location for clusters of small signs that list nearby businesses||3.19||1.14||.469
Category 3: Management Traditions||3.99||0.62
|Planted with vegetation to screen adjacent buildings||4.09||0.92||.612
|Designed to buffer traffic noise for nearby homes||4.13||0.90||.486
|Managed for a formal, refined appearance||3.45||1.08||.414
|Location for directional and mileage signs||4.29||0.79||.397|
*Principal axis factoring with Varimax rotation.
Table 3. Policy and funding.
|Factor categories* and items||rating||SD||loading
|Category 1: Policy Priority||5.18||1.30
|State government should set aside more money for roadside planting and maintenance||5.27||1.46||.894
|Federal government should set aside more money for roadside design and maintenance||5.01||1.59||.723
|Roadside landscape and planning for scenic views should be a public priority||5.23||1.50||.569
Category 2: Indirect Support||4.11||1.65
|I would be willing to volunteer for local roadside planting projects,|| 4.11||1.75||.916
| to install trees and shrubs
|I would be willing to volunteer for local roadside maintenance projects,|| 4.12||1.71||.888
| such as Adopt-a-Highway
Category 3: Direct Revenue Support||4.34||1.98
|I would be willing to pay a 1/4¢ per gallon gas tax for roadside improvements||4.23||2.12||.878
|I would be willing to pay an additional $1.50 for my motor vehicle registration|| 4.45||2.15||.757
| for roadside improvements|
*Principal axis factoring with Varimax rotation.
social benefits associated with passive experiences of
nature. In addition, prior research indicates that roadside
elements influence driving cognitions, behavior, and physiology.
An effort was made to systematically assess
public preferences for blends of built and natural elements
in roadside views. Using digital editing, variations in
amounts and arrangements of trees and associated vegetation
were presented to licensed drivers in urban areas across
the United States for preference response. Additional
questions were used to gauge public support and agreement
with various functional attributes of roadsides and to gain
some understanding of the level of resources support that
citizens are willing to commit.
Generally, visual preference for roadsides increases
with both increased quantities of vegetation in the image
and increased height and density of trees in relationship
to commercial views. Scenes with barren roadsides and
views beyond of prominent buildings or large products earned
the lowest ratings. Unfortunately, they depict the visual
condition of many urban roadside situations. In the mid-range
of preference are images with intermittent trees and/or a
low-growing shrub mass. Plants create horizontally or
vertically framed views of commercial uses, combining
vegetation amenity with the opportunity to determine what types
of commercial uses lie beyond the road. Finally, full
tree screening is most appreciated by survey
participants, suggesting underlying tensions in roadside
management policy as business interests insist on open views.
Some demographic traits are associated with minor variation
in image response, yet the prevailing trend in
preference across all respondent groups is greater appreciation
of freeway roadsides having trees.
These outcomes are consistent with public
evaluations of many landscape settings. Kaplan (1983) and
Schroeder (1989) concluded, in reviews of research on nature in
the urban environment, that trees are highly valued
components and that unkempt nature is less preferred than
Also, in prior research, people respond to scenes
based on the relationship or balance between human
influence and natural content (Kaplan and Kaplan 1989).
Generally, scene ratings above 3.5 for images depicting
human influence are bestowed on scenes containing an
element that does not dominate natural content, say a boardwalk
or a single small structure in a park setting. Here, highly
rated scenes depict settings that are distinctly urban,
suggesting that visual quality in urban settings can be enhanced
with careful blending of hardscape and nature.
Respondents are ambivalent about contributing
additional resources, be it volunteer time or money, to
roadside management. Perhaps an unwillingness to dedicate
resources is due to an observed perception that plants
can "take care of themselves." Urban forestry
professionals must often convince the public and elected officials
that trees in urban environments require sustained care.
Ecological functions, such as wetlands protection
or stormwater retention, are deemed moderately suitable in
the roadside. While the width of most roadside lands
may preclude large-scale ecological restoration, the linearity
of roadsides may provide connectivity for fragmented
Respondent age influences roadside attitudes.
Older drivers highly prefer trees as visual screening but are
more likely to regard trees as safety hazards. They are not
as concerned about large signs. They indicate greater
agreement with roadsides as a policy priority but are no more willing
to commit indirect or direct resources for program
support. This information is valuable as transportation agencies
find themselves interacting with an ever-older client base.
Black-and-white photographs offer a low-cost approach
to providing visual images for public response, and
preferences for places shown in photographs correlate highly
with response to onsite locations (Stamps 1990). Nonetheless,
in this research static images were used to represent
high-speed landscape experiences (due to budget constraints).
Additional research is needed to corroborate reported image
preferences and perceptions, perhaps using driving simulators.
Despite considerable effort to construct a
representative sampling frame, nonresponse is a serious impediment
to making inferential interpretations of urban
populations. Individuals who did not respond to the survey may
hold different values and perceptions regarding roadside
amenity than comparable individuals who did respond. Thus,
results should be considered narrowly applicable to
populations having a demographic profile similar to the respondents.
Little research has been done to understand the role
of urban forestry in roadside visual quality. Generalizability
of these findings may be limited, yet they provide initial
input on a situation that is important not only to
the driving experience but also to the environmental health
Design and Planning
While other roadside functions and features were
included in the research, the most direct experience of the
freeway edge is visual. Agencies and organizations (e.g., U.S.
Forest Service, Federal Highway Administration) have
devised normative guidelines for managing visual quality in
transportation corridors. Most focus on rural and wildland
settings, failing to address urban and semi-urban (e.g., suburbs,
strip development) contexts. Eighty percent of Americans live
in urban communities and spend most of their travel time
in built environments.
Applied guidelines for urban visual quality are
desirable, but creating standards can be fraught with
complexity. Respondents most preferred having views of trees
versus built elements. However, this design response is not
always feasible. In some climatic zones, such a landscape
approach is extremely costly. In addition, roadside designers
must often juggle the demands of multiple (sometimes
competing) interest groups. Drivers may prefer screening
vegetation, but this practice may not be consistent
with expectations of adjacent property owners or the
economic development plans of neighboring communities.
Mid-level responses on this study's verbal and
visual variables suggest how to achieve compromise in
design, thereby "getting to yes" (Fisher and Ury 1991) with
diverse interest groups. Visual categories Ornamental Frame
and Tree Buffer contain intermittent vegetation masses
(vertical and horizontal) that exclude the visual impact of
complex ground-level elements (e.g., parking lots). Trees and
vegetation serve as a green "frame" to momentarily focus
the driver's eye. Presenting businesses and their products
using vegetation frames may help drivers to more easily
distinguish individual retailers within an unceasing stream
of complex roadside stimulus, while reducing visual
distractions that can influence driver response and safety.
Better understanding of public perceptions has
had impacts on policy, planning, and design of a variety of
built and natural environments. This project and others like
it advance integration of public interests and
professional practices in roadside landscapes. Empirical data
can contribute to more defensible policy regarding
urban forestry and greenspace in transportation corridors.
Dwyer, J.F., H.W. Schroeder, and P.H. Gobster. 1994. The
deep significance of urban trees and forests. In Platt, R.H.,
R.A. Rowntree, and P.C. Muick (Eds.). The Ecological
City: Preserving and Restoring Urban Biodiversity. University
of Massachusetts Press, Amherst, MA. 291 pp.
Elmendorf, W.F., and A.E. Luloff. 2001. Using
qualitative data collection methods when planning for
community forests. J. Arboric. 27(3):139151.
Evans, G.W., and K.W. Wood. 1980. Assessment of environmental aesthetics in scenic highway
corridors. Environ. Behav. 12(2):255273.
Fisher, F., and W. Ury. 1991. Getting to Yes:
Negotiating Agreement Without Giving In. Penguin Books, New
York, NY. 200 pp.
Herzog, T., and T.A. Gale. 1996. Preference for
urban buildings as a function of age and nature
context. Environ. Behav. 28(1):4472.
Kaplan, R. 1983. The role of nature in the urban context.
In Altman, I., and J.F. Wohlwill (Eds.). Behavior and
the Natural Environment. Plenum, New York, NY. 346 pp.
Kaplan, S. 1995. The restorative benefits of nature:
Toward an integrative framework. J. Environ. Psychol.
Kaplan, R., and S. Kaplan. 1989. The Experience of
Nature: A Psychological Perspective. Cambridge
University Press, New York, NY. 340 pp.
MacGillivary, C.I. 1969. A study of billboards
and junkyards as related to some aspects of the aesthetics
of the highway environment. Final Report: Joint
Highway Research Project, Engineering Experiment Station,
File No. 9-5-4, Project No. C-36-48D. Purdue
University, West Lafayette, IN.
Nasar, J.L. 1998. The Evaluative Image of the City.
Sage Publications, Thousand Oaks, CA. 182 pp.
Novaco, R.W., D. Stokols, and L. Milanesi. 1990.
Objective and subjective dimensions of travel impedance
as determinants of commuting stress. Am. J.
Community Psychol. 18:231257.
Parsons, R., L.G. Tassinary, R.S. Ulrich, M.R. Hebl, and
M. Grossman-Alexander. 1998. The view from the
road: Implications for stress recovery and immunization.
J. Environ. Psychol. 18(2):113140.
Ribe, R.G. 1989. The aesthetics of forestry: What
has empirical preference research taught us?
Environ. Manage. 13(1):5574.
Riemersma, J.B.J. 1988. An empirical study of
subjective road categorization. Ergonomics 31(4):621630.
Rutley, K.S., and D.G. Mace. 1972. Heart rate as a measure
in road layout design. Ergonomics 15(2):165173.
Schauman, S., J. Heerwagen, and A. Vernez-Moudon.
1992. Visual Perception of the Roadway and Roadside
Elements by the Observer in Motion: Final Report.
Washington State Department of Transportation Technical
Report No. WA-RD 283.1. Olympia, WA.
Schroeder, H.W. 1989. Environment, behavior and
design research on urban forests, pp 87117. In Zube,
E.H., and G.T. Moore (Eds.). Advances in
Behavior and Design (Vol. 2). Plenum, New York, NY.
. 1992. Householders' evaluations of street trees
in suburban Chicago. In Gobster, P.H. (Ed.).
Managing Urban and High-Use Recreation
Settings. USDA Forest Service, General Technical Report NC-163.
North Central Forest Experiment Station, Chicago, IL.
Sommer, R., H. Guenther, and P.A. Barker. 1990.
Surveying householder response to street trees. Landscape
Stamps, A.E. 1990. Use of photographs to
simulate environments: A meta-analysis. Percept. Mot.
Ulrich, R.S. 1974. Scenery and the shopping trip:
The roadside environment as a factor in route
choice. Unpublished doctoral dissertation, University
of Michigan, Ann Arbor, MI.
Ulrich, R.S., R.F. Simons, B.D. Losito, E. Fiorito, M.A.
Miles, and M. Zelson. 1991. Stress recovery during exposure
to natural and urban environments. J. Environ.
U.S. Federal Highway Administration. 1998.
Highway Statistics (Annual). FHA, Washington DC.
. 1990. National Personal Transportation
Survey: Summary of Travel Trends. FHA, Washington DC.
Acknowledgments. Many partners assisted with
this research. A special thanks is extended to the
Landscape Architecture and Roadside Management professionals of
the Washington State Department of Transportation.
This research was supported by a grant from the National
Urban and Community Forestry Advisory Council (U.S.
Forest Service, Grant No. WAUF-97-003).
Correspondence concerning this article should be addressed to the author
at firstname.lastname@example.org Additional project
information can be found at www.cfr.washington.edu/research.envmind.
Research Assistant Professor
College of Forest Resources
University of Washington
Seattle, WA 98110, U.S.
Résumé. Une enquête nationale a été réalisée afin
d'en apprendre plus sur les préférences du public et
leurs perceptions en regard de la planification et de la gestion
de la forêt et de la végétation urbaines le long des grands
axes routiers des villes. En réponse à des images décrivant
un continuum visuel d'aménagements paysagers,
les conducteurs ont dit préférer les zones où les arbres
plantés ont pour effet de cacher la vue des secteurs à usage
commercial qui sont adjacents. Les résultats quant
aux préférences suggèrent des solutions de
pratiques d'aménagement qui créent un espace visuel de qualité
pour les conducteurs et fournit une visibilité pour les
propriétés commerciales adjacentes aux grands axes routiers.
Cette recherche a aussi enquêté quant aux attitudes du public
à propos des fonctions des abords routiers, des usages et
du désir public à appuyer des dépenses pour l'aménagement
de ces abords. De manière croissante, les agences de
transport conçoivent des abords routiers aménagés en milieu
urbain afin répondre à des objectifs et des fonctions
multiples. Cette recherche offre des aperçus sur comment intégrer
la foresterie urbaine dans la planification et la gestion
des corridors rapides de transport en milieu urbain.
Zusammenfassung. Es wurde eine nationale
Umfrage durchgeführt, um mehr über die öffentlichen Vorlieben
und die Akzeptanz in Bezug auf Forst- und
Vegetationsplanung und Management in urbanen Strassenzügen zu lernen.
In Reaktionen auf Bilder mit fortgeführten
Landschafts-baumaßnahmen bevorzugten die Autofahrer am
meisten Baumpflanzungen, die die kommerzielle Nutzung neben
der Straße verdecken. Die Ergebnisse zur den
ein klares Votum für Landschaftslösungen, die eine
visuelle Qualität für Fahrer und eine Sichtbarmachung
kommerzieller Grundstücke entlang von Schnellstraßen liefern.
Die Forschung untersuchte ebenfalls die öffentliche
Einstellung zu Straßenfunktionen, Nutzung und öffentliche
Bereitschaft, dieses Landschaftsmanagement zu unterstützen.
Mit wachsendem Anteil entwickeln
Transportunternehmen Straßenlandschaften um multiple Ziele zu erreichen
und multiple Funktioen zu erfüllen. Die Forschung gibt
Einblick, wie urbane Forstwirtschaft in Planung und Management
von innerstädtischen Schnellstraßenkorridoren einzubinden ist.
Resumen. Se llevó a cabo un estudio a escala
nacional para aprender más acerca de las preferencias del público
y la percepción acerca de la planeación y manejo de
la vegetación en los senderos aledaños a autopistas
urbanas. En respuesta a las imágenes de tratamientos que
un continuo visual de manejo del paisaje, los
automovilistas prefirieron escenarios con plantaciones de árboles
que enmarcan usos comerciales adyacentes. Los resultados
de esas preferencias sugieren soluciones para prácticas en
el paisaje que creen cualidades visuales para los manejadores
y proporcionen visibilidades para propiedades
comerciales adyacentes a las autopistas. La investigación
también estudió las actitudes del público acerca de las funciones
de las áreas aledañas en las autopistas, los usos y
las preferencias del público para apoyar los gastos de
manejo. En respuesta, las agencias de transportación
están diseñando paisajes aledaños a las autopistas que
logren múltiples objetivos y realicen múltiples funciones.
Esta investigación ofrece luces de cómo incorporar el
bosque urbano a la planeación y manejo de los corredores
de autopistas de alta velocidad.