Bridging the Preservation Gap: Documenting Our Historic Infrastructure
Bridges are at once thoroughly practical structures and icons of the American landscape. As a unique part of our infrastructure, they play a special role in transportation and history, and often have immense local historical importance.

In this first of a two part series, we will look at the vital need to preserve records that document these bridges not just as engineering projects but as part of our culture.

America’s transportation infrastructure is seriously troubled. Financial strains and budget cuts to federal, state, and local public works projects have become a fact of life. At the same time, the various parts of the system are aging, travel demands are increasing, and costs of labor and materials are rising. That is both common knowledge and a political battlefield where citizens, corporations, pundits, and politicians debate what should be done about it.

In particular, the state of the nation’s bridges offers an instructive example. Our aging spans have suffered major challenges in recent years. The 2007 collapse of the I-35W bridge over the Mississippi River in Minneapolis provides a stark reminder of what is at stake. Efforts to save the most important bridges face a widening conflict between preservation and demolition.

One-third of the US’s 600,000 bridges are over 50 years old and are in need of repair or replacement. Fewer historic spans are being saved because the political driver often is the cost of renovation or restoration, instead of a more judicious evaluation process that balances financial concerns and cost effectiveness with the socio-cultural significance of preserving these heritage landmarks of our “built environment.”

Whether a bridge’s fate is repair, renovation, or demolition for replacement, accurate documentation is imperative. The most critical documentation is principally of two types: specific engineering records and general contextual information.

(1) Engineering records of primary value are design drawings (including early design sketches that were not adopted), measured drawings, reports and studies (for example, “Final Report on Design and Construction”), site surveys, environmental studies, field notes, photographs (large format/high resolution), drawings and other records related to structural modifications, site modifications, seismic retrofits, and wind tunnel studies. The technical data is vital for ongoing maintenance and long-term preservation, or in the case of a bridge failure for repair or for diagnosing the cause of the failure in detailed structural engineering terms.

(2) Contextual information often is neglected for years, even decades, and may be more difficult to collect. These records document the social, political, and community significance of the structure. Typically the most valuable are photographs, newspaper clippings, trade and technical engineering magazines, correspondence, records of public hearings, city or county commissioner meeting minutes, even oral history interviews with engineers and prominent community leaders involved in creation of the bridge.

From construction to completion, maintenance, repair, and eventual replacement or long-term preservation, bridges present powerful testimony to the importance of documenting our historic infrastructure. Today, archivists face a compelling need and opportunity to work hand-in-hand with preservationists, engineers, citizens, and others to mindfully transcend the growing gap between preservation and demolition.

In part two of this series we will look at who safeguards the records of our bridges and how technology is changing the nature of those records and how they are preserved.