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STATE OF THE PRACTICE
This section is presented in two parts. The first part addresses the current state of visual quality
assessment. The second part discusses contemporary techniques for designing and
communicating visual quality effects, with particular focus on communicating with protected
population groups.
Visual quality assessment process
Transportation projects can cause significant visual impacts in the surrounding built
environment. These projects may alter topography, require the removal of existing structures or
landscaping or add new structures or landscaping, cast shadows on sensitive uses, introduce new
streetscape urban design elements, or alter or obscure views and vistas of the existing landscape
or of unique or historic community features.
Visual quality assessments for transportation projects need to address three major components:
affected visual environment, visual impacts, and visual impact mitigation. Each of these
components is discussed below.
Affected visual environment. It is first necessary to identify and describe the existing visual
environment in the project area. In his book Image of the City, Kevin Lynch (1960) identifies
five major components that make environments legible and imageable: edges, paths, districts,
nodes, and landmarks. These components provide a potential structure for grouping and
identifying existing visual characteristics in the project area.
Visual impacts. The second component involves identifying and describing the potential visual
impacts of the proposed project. Visual impacts need to be addressed from two different points
of view: that of the population that will have to look at the project (i.e., people living or working
in the project vicinity), and that of the population that will use the project (i.e., people driving on
the roadway or riding on the train or bus). In instances where protected population groups will be
affected, it is important to understand the community's perception of the visual impact and to
balance that against the perceived benefit of the project. In addition, the visual effects should be
assessed in terms of their distribution in the project area to ensure that negative effects do not
disproportionately impact protected populations. Visual effects that typically need to be
considered for transportation improvement projects include one or more of the following:
· Removal of buildings where existing development needs to be cleared;
· New buildings, such as new maintenance buildings or stations for transit projects;
· New, removed, or changed structures, such as bridges or elevated roadway or track
segments;
· New or changed urban design elements, such as equipment at transit stations, street
furniture along roadways, entry monuments, or signs;
· New or changed landscaping, such as installation of new street trees or removal of
existing landscaping;
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· New or changed lighting, such as new lighting in a transit maintenance yard that may
impact adjacent residential developments;
· New screens, such as noise abatement or visual screen walls;
· New or changed pavements, such as special pavement treatments in downtown areas;
· New public art, such as free-standing sculptures;
· Natural features, such as water bodies, streams, or natural areas;
· Adjustments to topography, such as large-scale excavation or filling;
· Shadows where shadows from buildings or structures may impact adjacent sensitive
developments;
· Views where improvements may block existing views or open up new ones; and
· Visual relationships where improvements may not affect existing facilities directly, but,
because of close proximity or critical view-sheds, may indirectly impact the visual
environment around special uses or features, such as historical districts, historical
buildings or structures, or community landmarks.
Visual impact mitigation. This component involves identifying mitigation measures for
ameliorating potential negative visual effects. Mitigation measures might include modifications
to the basic infrastructure, embellishment of the proposed improvements, or enhancement of the
visual environment of the project area. Where various population groups are affected, the
mitigation measures might vary to provide the most appropriate solution for each affected group.
Although visual quality issues are highly significant for maintaining or improving quality of life,
assessments of visual quality frequently are not given the same attention or weight as other
evaluation criteria, such as transportation safety, air quality, or noise impacts. One reason for this
might be that visual quality issues are much more subjective and cannot be as easily quantified as
other effects. Another reason might be that effects such as air quality and noise are much more
direct and physical, whereas visual quality effects are more subtle and visceral. In addition,
visual quality assessments are very rarely conducted to evaluate environmental justice issues. To
ensure a high-quality visual environment, more attention needs to be paid to the overall visual
quality of projects, as well as to how visual quality relates to environmental justice.
Visual quality design and communication techniques
The techniques described below can be used in all phases of project design to identify the most
appropriate design solutions, to communicate potential visual quality impacts to affected
populations, and to mitigate negative impacts.
Characterizing the potential visual quality effects of a project and communicating those effects to
the affected population are important design and planning components in their own right. They
are also important parts of the process of evaluating the environmental justice aspects of a
project. These techniques can be used to evaluate project design decisions, to communicate ideas
to protected population groups and to obtain feedback from those groups. They can be used in
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combination with the environmental justice assessment methods described later in the Methods
section of this chapter to assess distributive effects.
Following is a discussion of some of the more commonly used evaluation methods, ranging from
the relatively simple to the complex, for illustrating various types of visual quality impacts and
for responding to various public concerns. Table 11-1 summarizes the visual quality design and
assessment techniques.
Table 11-1.
Summary of techniques for visual quality design and assessment
Assessment Appropriate Use Data Expertise
Method level uses when needs required
1. Existing Screening/ Document existing Always Low Photography
condition detailed environment,
photographs illustrate special
features
2a. Illustrative Screening Communicate size, In early stages of design, when Medium Drafting
plans or location, and basic design resources are limited, and/or
diagrams intent of elements when realistic background computer-
material is not available, when aided design
2b. Illustrative Screening/ Illustrate vertical,
photo-realism is not essential, or and drafting
sections detailed horizontal scale
when there are technical issues (CADD)
2c. Perspective or Screening Convey massing, that are best represented in plan
axonometric scale, image, and view
sketches character of a
project
3. GIS view-shed Screening/ Identify view-sheds Appropriate GIS terrain data are High Geographic
analysis detailed and lines of sight available or there are significant information
view-shed or line-of-sight issues systems (GIS)
4. Photo Screening Visualize proposed Existing condition photographs Medium Manual paste-
simulation or designs are available, the design is fairly up or digital
montage advanced, or the audience is photo editing
skeptical or poorly informed (e.g.,
Photoshop)
5. Computer Detailed Visualize proposed Existing condition photographs High 3-D CADD
imaging designs are not available, the design is
fairly advanced, the project will
radically alter existing
environment, or the audience is
skeptical or poorly informed
6. Computer Detailed Visualize proposed Changing views over time are High 3-D CADD,
animation or designs required or the view as seen from, Computer
virtual-reality for example, a train window is Animation
modeling required
7. Three- Detailed Visualize proposed Inadequate budget for computer Medium Model-
dimensional, designs animation and/or virtual reality building
physical
models
8. Videos Detailed Illustrate similar Whenever comparable, Low Video
existing designs completed projects exist production and
editing
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It is important to illustrate visual quality impacts, whether they are positive or negative, in a
realistic and accessible fashion. The illustration and analysis technique(s) selected for the
communication process should be appropriate for the target audience and for the level of design
that is being represented. Too much abstraction or introduction of stylistic design elements can
distort the potential visual quality impacts and confuse the viewing audience.
Technique 1. Existing-condition photographs. The most common illustration technique used
in visual quality assessments is existing-condition photographs. These photographs are used to
supplement text describing the current conditions in the project area. In most assessments,
photographs are used in conjunction with one or more of the design and assessment
methodologies that illustrate the proposed project improvements. Although they can be used by
themselves, existing condition photographs are much more effective if they are referenced on a
base map or aerial photo of the project area. Such referencing provides accurate information
regarding where the photographs were taken and which areas of the project they illustrate. Figure
11-1 represents typical panoramic photographic images and a key base photo used for illustrating
existing conditions in a project area.
Figure 11-1. Example of panoramic photographic images and key map
Existing-condition photographs are an essential component of virtually all visual quality
assessments. The following data and equipment would be required:
· Information regarding where the project is to be located,
· Film or digital photo camera, and
· Methods for copying or reproducing the images.
Computer equipment and software provide a quick and easy method of taking, splicing, and
reproducing the required photographic images. Existing-conditions photographs can be
presented at meetings using printed copies or electronically, for example in PowerPoint
presentations. Care should be taken that these photographs represent all of the typical conditions
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in the project area. This is especially important on projects where protected populations have
been identified.
Technique 2. (a) Illustrative plans or diagrams, (b) illustrative sections, and (c) perspective
or axonometric sketches. Illustrative plans, sections, and image sketches represent design and
illustration techniques that can be used on most projects. This type of material is relatively easy
to generate because the information needed is readily available for most projects and the tools
used can be as simple as a sketchpad or conventional drafting equipment. This does not mean,
however, that these techniques will always involve the least effort or be the least costly. Some
image sketches may require a considerable amount of preparation, layout, and rendering time.
Figures 11-2, 11-3, and 11-4 represent examples of typical illustrative plans, sections, and image
sketches, respectively.
Figure 11-2. Typical illustrative site plan
Although illustrative plans, sections, and image sketches can be used for the design and
assessment of most projects, they are especially appropriate in situations such as the following
where:
· Detailed designs have not yet been developed, such as in the early stages of the design
process;
· Design resources do not permit the use of more elaborate presentation techniques;
· Realistic background material is not available, such as for aerial perspectives where aerial
photographs have not been taken;
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Figure 11-3. Typical illustrative section
Figure 11-4. Typical illustrative perspective
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· Photo-realism is not essential; and
· The visual quality impacts evaluation involves technical issues, such as viewsheds that
are best represented in plan view rather than as photographs or computer imaging.
The data and equipment requirements can be quite simple for preparation of illustrative plans,
sections, and image sketches. Illustrative images can be created using sketch pads or
conventional manual drafting equipment. However, with the current advances in computer
technology, most of these illustrations are just as easily, and sometimes more conveniently,
prepared using computer programs. As a minimum, the following data and equipment would be
required:
· Base maps;
· Existing conditions information;
· Design information regarding the proposed improvements, such as location and siting,
massing, dimensions, materials, textures, and color schemes; and
· Manual drafting equipment or computer programs, such as AutoCAD, Freehand, or
CorelDRAW, for drafting and rendering the drawings.
This method produces schematic and illustrative drawings that represent the general intent and
appearance of the proposed improvements and their visual quality impacts. Because this material
is more technical and schematic than photographic images, it should be tailored to the target
audience. The material should not be so technical and detailed that the general public will have a
hard time understanding the intent of the design. Written or verbal explanations can help make
the material accessible to the public.
Technique 3. GIS view-shed analysis. Topographic base information can be used to identify
view-sheds and lines of sight in the project area. These in turn can be used to establish which
parts of the project would have visual quality impacts on which populations. GIS view-shed
analysis is most appropriate at the macroscale level or for very large and/or tall projects where
long vistas are important.
Technique 4. Photo simulation or montage. The photo simulation or montage technique has
evolved into one of the most widely used methods for illustrating visual quality impacts. This
technique consists of superimposing images of the proposed improvements on photographs of
the existing environment. Because the results of this technique are very realistic images, the
design of the proposed improvements has to be advanced enough to permit realistic
interpretation and representation.
The primary benefit of this technique is that it illustrates proposed improvements in the context
of existing conditions. The viewing public has a much easier time relating to images of known
conditions than to more abstract drawn or computer-generated scenes. This technique is
especially effective when the material is presented using "before" and "after" images, which
allows for easy comparison between the two. An even better comparison can be made when the
"before" and "after" images are presented in an interactive mode, such as on a Web page, where
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a viewer can instantly click between them. Figure 11-5 represents typical "before" and "after"
photo simulation images for a project.
Before
After
Figure 11-5. "Before" and "after" photo simulation images
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Photo simulation or montage techniques should be used in the following situations:
· Existing condition photographic backgrounds are available and applicable;
· Designs have been advanced far enough to clearly define the proposed improvements;
and
· Photorealism is very important to illustrate the visual quality impacts--especially to
highly skeptical audiences or where the impacts may be dramatically different from what
the audience is expecting.
One drawback of the photo simulation or montage illustration technique is that each image is
"frozen," which means that it represents only a single viewpoint. If another viewpoint is desired,
a totally new photo simulation image needs to be created.
Technique 5. Computer imaging. Computer imaging is similar to photo simulation or montage
in that it can be used to create realistic images and scenes of proposed improvements. The major
difference between the two is that in computer imaging everything is artificially created, whereas
photo simulation or montage uses actual photographs of project components and backgrounds.
Another important difference between the two is that in computer imaging, a 3-D model is
created of the project. This model provides much more versatility and flexibility than the still
images that are created with photo simulation or montage. With computer-generated 3-D images,
different views of the proposed project can be very easily generated and presented. Many
examples of such images, including videos, are available on one of the URS Corporation's Web
sites (www.ursimaging.com/2002onlineportfolio/). Figure 11-6 represents a typical example of a
computer-generated 3-D image.
Although tremendous advances have been made in the development and refinement of computer
imaging techniques, the technology has not yet reached a level where computer-generated
images are indistinguishable from actual photographs. Therefore, this method is mostly used
where photo simulation or montage techniques are not feasible.
Computer imaging typically is used in cases such as the following:
· Existing-condition photo backgrounds and/or images of comparable proposed
improvements are not available;
· Designs have advanced far enough to clearly define the proposed improvements;
· The proposed improvements would alter the existing environment to such a degree that
very little of the existing conditions would remain; and
· Reasonably realistic images are important to illustrate the visual quality
impacts--especially to highly skeptical audiences or where the impacts may be
dramatically different from what the audience is expecting.
This type of imaging product requires computer equipment and 3-D rendering programs. At a
minimum, the following would be required:
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· Data about the existing conditions, such as AutoCAD plans, massing of existing
buildings and structures, materials, textures, and color schemes;
· Design information regarding the proposed improvements, such as location, massing,
dimensions, materials, textures, and color schemes; and
· 3-D computer drafting and rendering programs, such as AutoCAD, 3-D Viz, or
Photoshop.
Figure 11-6. Computer-generated 3-D image
This approach produces highly realistic images of the proposed improvements and their visual
quality impacts. However, because everything is artificially created, there may be less credibility
with this technique than with photo simulation or montage. This technique can also be more
expensive and time consuming than the previous methodologies, although it does have the major
advantage of built-in flexibility and versatility. Once a model has been created in 3-D, it can
easily be rotated to illustrate various viewpoints or perspectives, as illustrated by the examples on
the Web site listed under Resources. This ability to manipulate or vary viewpoints can be set up
as an interactive process and can be very effectively used in meetings to respond to various
questions or requests from the viewing audience. Computer images can also be made available
on a Web site for easy access.
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Technique 6. Computer animation or virtual reality modeling. Computer animation is one of
the most advanced methodologies for designing and illustrating visual quality impacts. It is also
the most involved and expensive. Some computer animation can be relatively simple. By
building upon the 3-D models produced with computer imaging, simple "drive-by" or "fly-
through" sequences can be created for the proposed project. In these simple scenes, everything
appears static. More advanced and complex computer animation, such as the animation of a
proposed highway project, involves adding cars, people, and other objects and carefully
choreographing their movement and timing in the 3-D animation sequences. Computer animation
techniques can also be used to illustrate project staging and the impact of the proposed
improvements upon the existing landscape. Examples of computer animation are presented on
the URS Corporation Web site at www.ursimaging.com/2002onlineportfolio/.
Computer animation should be used when it is important to illustrate the visual quality impacts of
a proposed project in three dimensions, as well as in time. For example, animation may be the
best way to illustrate the changing views of a corridor from a moving vehicle, the movement of a
train through a neighborhood, or the impact of a project on existing uses and facilities.
For computer animation, the following are required:
· Data about the existing conditions, such as AutoCAD plans, massing of existing
buildings and structures, materials, textures, and color schemes;
· Design information regarding the proposed improvements, such as location, massing,
dimensions, materials, textures, and color schemes; and
· 3-D computer drafting and rendering programs, such as AutoCAD, 3-D Viz, and
Photoshop, and computer animation equipment and programs.
This method produces highly realistic animated sequences of the proposed improvements and
their visual quality impacts. It is the most expensive and time consuming of all the techniques
available. However, the cost may be justified due to the large amount of information that can be
conveyed in a very short time and the dramatic impact it can have. Computer animation may be
viewed as part of a PowerPoint presentation or on a Web site. In this sense, it does require
special equipment (e.g., a projection system or computer) and thus is slightly more difficult to
access than computer imaging or other visual presentations.
Technique 7. Three-dimensional, physical models. Where issues of massing or spatial
relationships need to be addressed, three-dimensional physical models can be useful in
conveying a large amount of information in a very concise and direct way. Physical models are
especially useful in illustrating conditions of extremely complex urban conditions.
Technique 8. Videos. A technique that is sometimes used to convey information regarding the
visual appearance of a proposed project, and to address issues such as noise impacts is to take a
video of a comparable situation in a similar project. Videos are frequently taken of Light Rail
Transit (LRT) systems to allow impacted populations to experience, as realistically as possible,
how a proposed LRT system will work, look, and sound.
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