It so happens that the work which is likely to be our most durable monument,
and to convey some knowledge of us to the most remote posterity, is a work of bare utility; not a shrine,
not a fortress, not a palace but a bridge.
— Montgomery Schuyler, 1883, writing about John Roebling's Brooklyn Bridge
This is the home of the Bridge Aesthetics Subcommittee of the Transportation Research Board.
The Subcommittee on Bridge Aesthetics is a subcommittee of the Committee on General Structures (AFF10) of the Transportation Research Board, which is part of the National Academies, "advisors to the nation on Science, Engineering and Medicine". The site has two target audiences, transportation agencies and their consultants, and members of the general public who would like to see better looking bridges in their own locales.
The aesthetics of large bridges often receive much attention because of their size and prominence in the landscape. However, the numerous “everyday” bridges, such as highway overpasses and small river crossings are usually approached as purely technical problems, with little thought given to their appearance. The public has begun to realize that these bridges, taken together, can have a greater influence on the visual quality of the transportation environment than the landmark bridges. They are insisting that transportation agencies improve the appearance of their everyday bridges.
In response to this interest the General Structures Committee of the Transportation Research Board (TRB) and the Subcommittee on Bridges and Structures of the American Association of State Highway and Transportation Officials (AASHTO), requested the Subcommittee on Bridge Aesthetics develop these aesthetic design guidelines for the typical bridges that they work on every day. The guidelines support the Subcommittee’s mission statement: "To educate the profession on how to improve appearance of bridges and other structures during design, construction and operation.”
It was the committee's decision to make these guidelines available in two forms: this web site, and a companion sourcebook. The goals of the web site and sourcebook are:
Bridge design is an art, an art that uses science and mathematics to support many of its judgments. Other judgments are made during the design process that science cannot help, such as decisions about appearance. The guidelines give bridge designers a basis to support those aesthetic judgments, so that their decisions about appearance can be just as definitive as the judgments they make about structural members, safety, or cost.
Aesthetic ideas, like any other, change over time as people working in the field gain new insights, respond to new materials and technologies, and learn from their own experiences and those of others. The web site and sourcebook enable engineers to respond to these developments and contribute aesthetic insights of their own. The strategy of the web site/sourcebook is to provide engineers with basic principles and tools of analysis that will help them think through questions of appearance. The case studies then show how those ideas have been applied to example bridges.
Appearance is a subject that does not benefit from hard-and-fast rules. Each bridge is unique, and should be treated that way. The web site/sourcebook do more than present guidelines, rules of thumb, and comparative examples; they also encourages engineers to make their own judgments about what looks good and what does not, and which guidelines apply to a particular structure and which do not.
The web site/sourcebook encourages practitioners to seek aesthetic quality in their bridges through the shapes and sizes of the structural members themselves, and not depend on the accretion of non-structural add-on features. The aesthetic impact of a bridge is primarily a product of the structural members themselves. Details and color are important, but secondary. The recommended guidelines integrate efficiency, economy and elegance in the design of everyday bridges. The guidelines also incorporate appropriately the goals of Context Sensitive Design/Solutions and the Section 106 historical review process.
The sourcebook focuses on the basics of design, which are best presented in a written text since they represent fundamental information not likely to change over time. The sourcebook can also be used as the text for TRB Workshops and training courses such as those put on by the National Highway Institute. Case studies and other information that is evolving over time are best presented in a web environment, since revising and updating content is relatively easy when compared to printed material which requires publishing a new edition has. A web site has other advantages, too. The web is now the medium of first resort for almost all types of information gathering, especially among the younger engineers for whom the guidelines would be most valuable. Also, by being interactive, the site encourages an ongoing discussion of aesthetics in which every bridge professional and anyone else interested in bridges can participate.
The sourcebook will be made available in pdf format from this web site. Comments and suggestions on the sourcebook and web site are welcome and can be made on the Forum section of the web site once that is up and running in the Spring of 2008. The specific goals of the web site are to present an overall picture of the guidelines, to provide case studies and current information in the field and to provide the forum.