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2 CHAPTER 2 STATE OF THE PRACTICE REVIEW OF THE LITERATURE of context-sensitive design and the incorporation of this mindset into the highway design process, from geometric Aesthetics is a branch of philosophy dealing with the design of the roadways to the aesthetic components within theory and perception of beauty and the psychological re- and extending beyond the roadway.(5) sponses to it. How and why things are perceived as aesthet- With the exception of planting design, guidance on when ically pleasing is a subjective matter, yet many standards for and how to use specific aesthetic elements or treatments in the beauty or aesthetics exist. In terms of highways and their highway environment is virtually nonexistent. The question of components, Leonhardt(1) discusses the design of a structure when, where, and why to use color, pattern, textures, art, light- as containing many variables that affect aesthetic visual qual- ing, and so forth appears to be generally left to individual or ity. In agreement with many other designers and engineers, group decision processes and is done in ad hoc manner. The the basics of design are function, form, color, and texture. type of criteria used in these decision processes (other than Yet other design characteristics, especially for linear struc- safety and cost issues) is not well established. Experience of tures such as a concrete barrier or bridge rail, include pro- the authors suggests that the most common criteria are proba- portion, symmetry, rhythm, repetition, and contrast. Harmo- bly consensus, embodied by the phrase: "Whatever everybody nious proportion is a valuable component of linear design. will agree to." Evidently this is a common occurrence.(6) The manner in which various parts of the structure (height, Many highway design scenarios exist where selection of width and depth, masses and voids, closed and open surfaces, aesthetic elements and treatments may not pose any significant light and dark created by sun and shadow) relate creates the conflicts or issues. Obviously, however, since the roadway has character of the structure. Tang, in his "Philosophical Basis a potentially hazardous element to its environment, a more for Chinese Bridge Aesthetics" describes the concept of clear set of criteria would be desirable to aid designers in their "yin and yang" in aesthetics. "The one form has no reality decision making. Two areas of study that offer a framework without the other, they are in opposition, comparison, har- for roadway aesthetics design are environmental psychology mony and succession."(2) The structures express their unity and human factors. Each relates to the other in that both use by opposition as they reflect, complement, and transform research from both fields. one another. Environmental psychology seeks to understand and de- Although the aesthetic component of design is the most scribe humanity's relationship with the environment. Subsets visible to the user, few guidelines exist. Highway con- of this field include environmental cognition and assessment struction generally follows the safety and economy rule and environmental design. These disciplines study visual per- first. The Federal Highway Administration (FHWA) real- ception and communication, as well as emotional responses, izes that aesthetics and context-sensitive design are impor- and how these things affect decision making in real-world tant factors in the design-making process and should be environments.(7) This information also applies to deciding placed ". . . on an equal basis with mobility, safety and eco- what is important in terms of cognition and the prediction of nomics."(3) Safety is the primary concern in highway design, choices or preferences by an individual.(6) A large part of the yet safety and aesthetics are not mutually exclusive. "The study in this field attempts to describe this relationship in successful inclusion of highway aesthetics can be achieved terms of scenic quality, our preferences for a certain aesthetic, for any project by giving consideration to these five "C's" of the level of satisfaction we gain from a setting, or our comfort design: context, comprehensiveness, cost, contractibility, levels during certain activities. Much of the literature involves and community."(4) human responses to the natural environment and how positive The basic philosophical intent of creating highway aes- experiences can be maximized, particularly in urban settings. thetics is to balance the safety and mobility needs of the Of particular interest in terms of aesthetics is the work done transportation systems with the human need for a sense of in the areas of driver perception,(8) the visual quality of the community and aesthetic satisfaction. Both the FHWA and driving environment,(9) the effectiveness of signed communi- the American Association of State Highway and Transporta- cation,(10,11) and driver performance related to visibility con- tion Officials (AASHTO) are working to develop the issues ditions.(12) These and other studies find that as the roadway