Section 6: Context Sensitive Transportation Design
Anchor: #i1002673Overview
The process of developing a modern transportation project goes beyond the traditional engineering design process. It requires consideration of influences and impacts that extend far beyond the right-of-way lines.
Context sensitive design at the national level has grown out of what has been learned in the post World War II period during the construction of the interstate highway system and expansion of connected urban freeway systems. During this period the design focus has been guided almost entirely by considerations of cost effectiveness, safety, and mobility. This view of the process has resulted in conflicts with a wide range of community, environmental, and other special interests. The move toward context sensitive design seeks to avoid such conflicts and form partnerships with the communities to meet transportation needs and user expectations.
Where landscape and aesthetics design is concerned, context refers to the physical and cultural landscape of a project site. The physical landscape includes the visual elements of the transportation corridor and its surroundings. The cultural landscape is composed of those influences imposed on the site by tradition or special interests. Context sensitive design seeks to ensure that the character of the transportation facility is appropriate to this surrounding landscape. This will accomplish a sense of visual unity and public acceptance that is the basis of an attractive transportation facility.
Context may be considered in two ways. The first is the relation of the design elements to each other within the right-of-way and the second is the context of the transportation facility in the larger landscape. Each is important and intertwined.
The following subsections cover context sensitive design in relation to contextual parameters, structural design elements of transportation facilities, and aesthetic design of common transportation features.
Anchor: #i1002707Contextual Parameters
Where multiple structural elements come together, relationships may be unattractive, even though each individual element is visually pleasant. To achieve aesthetic harmony structural elements must be designed so that the form, finish, and color of the elements are complementary to one another. Likewise the landforms generated by the alignment may result in objectionable scars in the landscape. Where possible, dramatic revision of the landform should be evaluated for its visual impact.
What aesthetic qualities will be acceptable in a given contextual situation is not always easy to predict. Many of the contextual considerations of a place may be cultural or ephemeral. That is, the landscape may appear average and without areas of obvious visual sensitivity. However, upon further investigation links may be discovered related to traditional beliefs, local cultural importance, or ephemeral qualities such as stands of vegetation that are prized for their seasonal color displays.
The primary vehicle for determining the contextual parameters that will influence the aesthetic design of transportation facilities is the public participation process. Individuals charged with oversight or development of a Landscape and Aesthetics Assessment or Landscape and Aesthetics Master Plan should participate in or review all public participation documents related to a project or target corridor.
Anchor: #i1002730Structural Design Elements of Transportation Facilities
A transportation corridor can be broken down into a palette of fourteen structural design elements. Each of these has aesthetic design properties that can be manipulated to change its visual character and to help it blend with other structures within a corridor.
Common Structural Elements of Transportation Facilities. The twelve most common structural elements of a transportation corridor are listed below. This design manual provides detailed recommendations and design guidelines for each of these elements:
- Anchor: #JTUCCPPS
- bridges Anchor: #GYFKFVRR
- retaining walls and noise walls Anchor: #VDYFJRGI
- topography and grading Anchor: #SVJUWDTV
- character of adjacent properties Anchor: #WEBINKKG
- surface finishes Anchor: #CGSAEACQ
- landscape design Anchor: #UPGTGVSE
- traffic barriers and guard fences Anchor: #IUYFFEBW
- signals and signs Anchor: #CTHURQNF
- illumination Anchor: #ICLBHWYF
- bicycle and pedestrian access Anchor: #PWBSCRUA
- public art Anchor: #WLCVMYML
- medians and traffic islands
Aesthetic Design of Common Transportation Features
Interchanges, intersections, adjacent properties, and right-of-way configurations all impact the visual character of a facility. These features are complex landscapes composed of multiple structural design elements. Depending on the type of facility, the basic structural elements tend to be repeated in similar ways.
For this reason it is useful to provide more detailed discussion of landscape and aesthetic design considerations associated with each of them. They include: