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16 CHAPTER 3 CONSIDERATIONS FOR DEVELOPING AN AESTHETIC BARRIER The evaluation plan for developing a guide for designers proved visibility, principally as a combination of color, line, for aesthetic treatments of concrete barriers originally ad- and contrast with other roadway elements or activities. dressed both safety performance and the application of context-sensitive principles for selecting the appropriate bar- DEVELOPING A DEFINITION FOR AESTHETICS rier for the drivers and their environment. Research into the principles for selecting the appropriate barrier for drivers and The issue of when something is considered "aesthetic" is their environment was performed early in the study. A re- important because many people consider aesthetics to be view of the literature and an investigation into context- a heavily subjective assessment. For the sake of discussion sensitive principles was performed. However, following the regarding bridge rails and barriers, a more objective defi- submittal of the project interim report and the project panel nition is needed. This is because, when a community asks members' meeting with the researchers, the scope of the for a more "aesthetically pleasing" design, designers must project and research objectives were modified to only (1) be able to know what that means. assemble a collection of examples of longitudinal traffic The 2002 AASHTO Roadside Design Guide(18) describes an barriers exhibiting aesthetic characteristics and (2) develop aesthetic barrier to be a barrier that harmonizes with the nat- engineering design guidelines for aesthetic surface treat- ural environment. This definition is clearly appropriate where ments of concrete safety shape barriers (e.g., New Jersey the natural environment provides a strong visual presence, but and F-shape profiles). The focus of the design guidelines the definition offers little when dealing with urban contexts. would be to determine the crashworthy geometric configura- A general definition of aesthetic barrier that has emerged and tion of surface asperities that could placed into the traffic has been suggested in the literature is "anything different face of New Jersey and F-shape concrete barriers. The inves- from what is now used." This is a reaction of course to the tigation of geometric configurations of crashworthy surface common safety shape barrier or other smooth concrete barrier asperities would be performed using finite element simu- designs. This definition, however, offers no guidance on what lation and full-scale crash testing. Therefore, additional makes a barrier "aesthetic." For that, more objective criteria research relating to driver behavior and context-sensitive are required. A starting place is with the characterization of design principles was stopped. The information presented the common traffic barrier. hereafter was gathered prior to the change of project scope The common concrete barrier is probably considered non- and is presented as documentation of project work per- aesthetic based simply on its unadorned, utilitarian character. formed. This information may be considered incomplete and This is characterized by: is only presented for the reader's edification. · Uniformity of line. Line typically infers linear direc- Aesthetic barrier design has been poorly described as a tech- tionality in the context of a barrier. Line is found in the nique dealing strictly with aesthetics. Previous studies dealing edges of surfaces, shapes, or patterns, but most promi- with barrier rail design have focused on structural performance nently as the edge of the structure that is silhouetted and testing rather than the evaluation of aesthetic characteris- against the background. Unchanging lines over long tics of a barrier and its effect on the driver, the roadway, and distances can become static and boring. environment. The project work plan originally addressed de- · Uniformity of profile. Profile is the shape of the barrier. veloping guidelines for designers of aesthetic treatments of Typically this is a form constantly repeated throughout concrete barriers that addressed both safety performance and the length of the barrier. A consistent profile can also context-sensitive principles. The researchers approached this become boring, particularly if it is a very simple form. plan from both the viewer preference level and the behavioral · Uniformity of surface. A uniform surface can also be- level. The viewer preference level focused on applying char- come static and boring over long distance simply due to acteristics that cause a rail or barrier to elicit a favorable its plainness. response from a viewer, either consciously or subconsciously. · Lack of color. White in the context of most highway The behavioral characteristics study identified for the engi- structures is not a color but rather may be considered an neer/designer those characteristics of rails that promote im- absence of color. This includes the lighter shades of gray.