What makes a bridge “historic”?
Many people assume that they know a historic bridge when they see one.
- The Edmund Pettus Bridge in Selma, Alabama, is one example because of the extraordinary civil rights events that took place on it in 1965.
- The Brooklyn Bridge is another because of its architectural grandeur, extraordinary setting, and design by notable builder John Roebling.
- The Golden Gate Bridge is clearly one because of its age, iconic design, and the way that it so elegantly enhances its natural location.
However, what makes a bridge an actual historic landmark isn’t a personal choice. The National Register of Historic Places (NRHP) has specific criteria that they use to evaluate bridges to determine whether they’re eligible to be given that designation.
Bridges that are deemed historic or are eligible for consideration receive special protection from the United States Forest Service. Bridge managers, maintenance personnel, and contractors have to be extra careful when it comes time to make repairs or improvements on these bridges. It’s almost impossible to change them significantly, move them, or tear them down. If historic bridges become inadequate to serve their purpose, new structures and roadways are usually built that bypass them so their integrity stays intact.
In most cases, for bridges to be considered for listing on the National Register of Historic Places, they must:
- Have achieved at least 50 years of age (although there are exceptions made for remarkable newer structures).
- Be historically significant.
- Demonstrate a high degree of original structural integrity.
A bridge’s significance in American history is often determined by its location. The factors related to this include the integrity of the historic district that it’s part of, its specific site, the buildings around it, the structures associated with it, and historic objects that are part of the bridge and its surroundings.
For a bridge to be deemed historically significant, it has to meet at least one of these criteria:
- It’s associated with — or has contributed to — significant historic events in the United States.
- The structure is a unique and distinct example of a type of bridge, historic style, or method of construction. It could also demonstrate high artistic merit and/or represent the work of a master bridge designer, builder, or developer.
- It is associated with the life of a person or persons who played a significant role in American history.
- It plays an integral part in a historic district, even if it does not have architectural integrity of its own.
- The bridge provides information about a significant period in history or prehistory.
The first two criteria listed above are the most common reasons for bridges to achieve a historic designation from the National Register of Historic Places.
Even though the NRHP is a national register, bridge properties can be considered historic by the organization for local, state, or national reasons. Also, individual bridges may be historically significant on their own or because they are a part of a larger historic district. Examples of this are the bridges that are part of the Route 66 Historic Corridor District in the western United States. Individually, many are not that special. Taken together, however, they help support a unique driving experience and part of early American automotive travel history.
Not only must a bridge meet one or more of the NRHP criteria outlined above, but it must also have a high degree of integrity, which is when a property possesses characteristics that convey its historical significance through its setting, materials, design, location, workmanship, feeling, and association with other structures.
To demonstrate its integrity, a bridge must retain, to a significant degree, at least five of the following seven elements of its original design:
- Setting. This includes how the bridge contributes to the character of its location and how it is situated in its environment.
- Materials. The structure must be constructed of building elements that were part of its original design. Modern replacements (such as substituting stone elements with concrete) could jeopardize its integrity.
- Design. The viaduct has to retain its historic function and look as it did when it was constructed.
- Location. The bridge must be in its original location or where a historic event occurred. This is often an extremely important consideration. Many buildings and some bridges lose their historic value if they are moved from where they were originally built or a notable event happened.
- Workmanship. The structure must retain evidence of the bridge builder’s craft, skills, and abilities.
- Feeling. The bridge must still express the aesthetic or historic sense of the time period that it represents.
- Association. The viaduct should retain physical features that directly link it to an important historic event, location, or person.
The process of designating a bridge as historic begins with a heritage resource specialist completing an initial inspection of the structure and recording its features. They also do background research about the bridge. Once that’s complete, the specialist then applies the evaluation criteria outlined above. Finally, working with others, they make the final recommendation for NRHP eligibility.
How to protect your business when you work on historic bridges.
Once a bridge is being considered for historic designation or becomes a historic landmark, the United States Forest Service must analyze the effect that any maintenance work or other undertaking will have on the bridge and nearby historical resources. This includes any activity — such as painting, resurfacing, guardrail repairs, and utility installation — that has the potential to cause any positive or negative change to the quality of the historical, architectural, archeological, or cultural character that got the bridge listed on the National Register of Historic Places in the first place.
The conclusions that the Forest Service could make related to maintenance and repair activities are:
- No Effect. If any activity is likely to result in no change to the characteristics that qualify the bridge for listing on the NRHP, either directly or indirectly, then it is determined that the activity has no effect and it can take place.
- No Adverse Effect. If an undertaking on the bridge could have an impact on the characteristics that allow the bridge to earn a historical designation, but the expected effect does not have an adverse impact, The Forest Service will determine that it has no adverse effect on the bridge. The maintenance or repair activities will likely be allowed with a few or no changes.
- Adverse Effect. A bridge maintenance, repair, or rehabilitation project will be determined to have an adverse effect when one or more of the following conditions are likely to occur:
- Destruction or significant change of all or part of the bridge.
- Isolation from its surrounding environment, especially if it’s a historic one.
- If it adds elements that are out of character with the bridge.
- If the property around it is transferred to another owner or is changed significantly.
- If it could cause the eventual destruction or deterioration of the bridge.
If you are ever involved with a project on a historic bridge that could result in adverse effects on it, be aware. It could be a big time and money drain on your business.
You should consult with a legal expert with experience in historic preservation projects before you ever get involved in one. Make sure you understand the complexities that you could be facing before you sign on. Check that your contract provides adequate protection should the project be put on hold, stalled, or changed significantly once underway. It’s the only way that you can rest assured knowing you and your team are doing everything possible to help preserve an important structure while also protecting your operation.