In highway noise abatement, the main requirement is a solid, acoustically opaque barrier which is relatively durable. Many of the barrier walls in existence today have been constructed with elaborate detail, using expensive materials. In many cases, even these barriers lack visual quality or aesthetic appeal. A better solution might be to utilize less costly but durable materials, such as concrete, and achieve a visually attractive noise barrier through a combination of wall design and plant materials. The savings gained in material costs could offset the additional costs of adequate planting, with far better visual appeal and acceptance by the public.
The added cost of visual quality in a design is often the subject of discussion among highway planners, administrators and citizens. This is often due to the misconception that visual quality in design means the substitution of highly expensive materials for more economical, widely available materials like concrete or concrete block. While it is true that a number of textural walls illustrated in this manual would indeed cost more to construct than a plain concrete wall, a visually attractive wall can be built without excessive additional expense. The principles covered in this manual, such as line, form, color and texture, can be applied using any material, with minimum additional cost. Due to the speed of the moving observer, wall materials used on the highway side of a barrier are less important than overall line, form and color, and the relationship of the barrier to other elements in the landscape. Such an observer sees a barrier as a mass in the overall highway scene, without regard for subtle details. On the residential side of a barrier, attention to detail may be more important, but a visually attractive barrier can be achieved using concrete that is accented with vines and other plant materials. The use of the most expensive materials in the construction of a noise barrier does not guarantee visual quality. Visual quality must be a product of the design process, and basic principles such as those contained within this manual must be used.
Epilogue". . . The quality of the total landscape . . . is dependent upon the balanced relations which are achieved between the structural developments of man and the rock, earth, water, and plant forms of nature. While most city fathers and officials, owners, planners, architects, designers, developers, bankers, and builders will accept this thesis in general, few will fight for it in specific practice. All too easily, with polite regrets, they eliminate the saving, natural, "landscaping" elements 2 to 20 percent of the budget in the interests of "economy," "functionalism," "practicality," "maintenance," "higher and better use of the land," and at times even "urbanism" or "architecture." They forget, or never learn, that this small fraction of the total budget, properly spent, may well account for 50 percent of the ultimate visual aspect ten years hence."
-Garrett Eckbo The Landscaping We See
