CHAPTER 3

Challenges Involving Historic Properties

Historic Bridges

Challenge Summary

Bridges are key pieces of infrastructure and are often bottlenecks in regional transportation systems. Therefore, they often need to be repaired and upgraded for modern use or even replaced because of extensive structural and safety problems. On the other hand, members of the public and Section 106 consulting parties often highly value historic bridges, especially as gateways into communities, and want them to remain as they are. These tensions often set up historic bridges as the focus of contentious Section 106 reviews. Some of the most common challenging bridge rehabilitation and replacement projects include the following:

• Common bridges,
• Cumulative effect of replacement of certain types of bridges,
• Whether the in-kind replacement of bridge elements constitutes No Adverse Effect or an Adverse Effect,
• Safety improvements to bridges,
• Bridges in historic districts or listed in the National Register (both urban and rural), and
• Rehabilitating bridges for pedestrian use.

Challenges associated with projects involving historic bridges stem primarily from disagreements between SHPOs and other consulting parties and FHWA and state DOTS on the assessment of effects; for example,

• “For No Adverse Effect, at what point does a rehab become an Adverse Effect if extensive in-kind material replacement is required? Examples include both covered bridges and steel trusses.”—State DOT Respondent
• “Historic bridges also pose a challenge because the difference between adverse and no Adverse Effect can come down to the type of railing used on a rehabilitation, and sometimes it’s hard to come to an agreement between all the parties involved.”—State DOT Respondent

The case study on the SR 4001/English Center Suspension Bridge rehabilitation in Pennsylvania addresses the question of the extent to which replacement of the original material with a different, compatible material constitutes a loss of integrity and therefore an Adverse Effect.

Overcoming the Challenge

To address the challenges associated with historic bridges, survey and interview respondents have used some of the following strategies:

• Identify the aspects of the bridge that convey its historic significance and integrity and retain those things in the bridge rehabilitation. (See the case study on the rehabilitation of the Bridge Street Bridge in New Hampshire and Vermont.)
• Produce digital renderings of proposed changes.
• Solicit comments on the project from a bridge engineer.
• Present more than one design option to consulting parties (e.g., one option affecting the historic bridge design more and one option affecting the historic materials more).

In one example, a state DOT did not find the bridge railing to be a character-defining feature of the bridge and therefore determined that its replacement would not be an Adverse Effect; however, a consulting party disagreed. Through additional consultation, which involved a redesign to preserve the historic rail while allowing crash barriers on the interior side, the disagreement was resolved.

Additional Information and Resources

• NCHRP Web-Only Document 278: Context-Sensitive Design Options for Workhorse Bridges in Rural Historic Districts: Practitioner’s Guide and Research Report (Bedford et al. 2020).
• Guidelines for Historic Bridge Rehabilitation and Replacement (AASHTO 2008).

Linear Historic Resources

Challenge Summary

Many of the linear resources encountered on transportation projects are active transportation systems such as roads and railroads. The results of the online survey and follow-up interviews showed the following key issues in assessing effects on linear resources:

• Assessing the integrity of long transportation networks,
• Lack of state- or regionwide studies of linear resources, and
• Type of effect when one or a few contributing features are affected within a long linear resource.

Evaluations of National Register eligibility and assessments of effects are generally done on a project-by-project basis, because most projects only involve a segment of these resources and not the entire resource. The lack of a comprehensive evaluation of significance that identifies which segments of the entire resource retain integrity on the basis of the resource’s significance and which elements of the linear resource are or are not contributing to its significance makes assessments of effects rather problematic when only a small segment is involved in a project. For these reasons, some states have developed historic contexts that address National Register significance and integrity of linear resources to provide a framework for evaluating segments encountered through a project. A few of these historic contexts have included resource-specific National Register evaluations.

One SHPO respondent raised the issue of cumulative effects of continuous improvements to historic roads:

Many projects that convert intersections along historic roadways that are considered NRHP [National Register of Historic Places]-eligible from traditional designs to roundabouts are considered to have No Adverse Effect. When reviewing projects independently of one another, this seems true; however, it appears that eventually a tipping point will be reached where enough intersections have been converted that a design element of the historic roadway will have been lost without ever having been considered an Adverse Effect. This issue also appears in projects that propose to add sidewalks along segments [of] NRHP-eligible roadways where the rural shoulder is considered a contributing element.

Overcoming the Challenge

Survey and interview respondents suggested several strategies for overcoming the challenges associated with making findings of effect regarding linear resources, particularly for historic roads:

• Take a holistic approach toward the assessment of effects on historic roads.
• Consider and compare the integrity of the historic road in the APE versus the entire road.
• Include linear resource procedures in statewide delegation PA updates.
• Complete statewide highway studies with National Register evaluations of all state highways in entirety.
• Communicate with SHPOs and FHWA on new approaches to linear resources.
• Consider the historically significant boundary for linear resources—the historic boundary may be smaller than the actual ROW.
• The historic boundary may be different in different segments of the linear resource.

It should be noted that some state DOTs currently do not implement a few of these strategies, given their focus only on the APE associated with their projects and on not extending their research or investigations beyond the limits of the project APE.

One state DOT and two SHPOs have developed guidance for evaluating the significance of linear resources and assessing effects on these resources. Following are some tips from these states:

• A nonsignificant linear resource checklist is good to use to establish whether a linear resource, including roads, is significant or not on the basis of established historic contexts for linear resources.
• The process of using a checklist should be agreed upon by the SHPO.
• If the resource is not significant, a full SHPO inventory form for that resource could be replaced by the checklist.
• Project effects on linear resource segments within an APE should be considered with regard to the overall effect on the resource as a whole.
• The features of the resource that are being affected should be considered; effects on a singular feature or scarce features, such as locks, trestles, and dams, are more likely to result in an Adverse Effect on the overall resource than are the minor features of a linear resource. (See the case study on U.S.-93 Improvements in Idaho.)
• Conducting significant historical and archival research regarding the potential presence of linear resources is recommended prior to fieldwork to determine the need for or level of recordation for individual features.
• Conducting a site file search to gather information on whether a linear resource has been previously evaluated, either in total or as a contributing segment of the larger resource, is helpful.
• Historical documentary research should be commensurate with the size and scope of the undertaking.

Archaeological Sites

Challenge Summary

Archaeological sites that extend outside the ROW are a particular challenge with respect to making effects findings. If a site extends partially within the ROW, most state DOTs do not test outside the ROW to (1) delineate site boundaries and (2) evaluate National Register eligibility. The challenge is how to assess eligibility and, in turn, effects, when only a portion of an archaeological site is investigated and may be affected by a project.

Overcoming the Challenge

To address these challenges, state DOTs take various approaches. As one state DOT noted, “For long, linear projects, we routinely consider only if portions of the archaeological site within the APE contribute or not to the eligibility of the overall site. Built environment resources are almost always considered as a whole, even if they extend outside of the APE.”

Some state DOTs assume the overall site is eligible and designate the tested portions in the project ROW as either contributing or noncontributing to the significance of the overall site. If the archaeological deposits in the ROW are not intact (i.e., lack integrity), the portion in the ROW is considered noncontributing, and the effect finding would be either No Effect or No Adverse Effect. This scenario assumes that the site is not a property of religious and cultural significance to tribes and that there is no potential within the ROW for human remains.

Following are additional examples of how state DOTs address the challenges associated with archaeological sites:

• “Usually, we work towards avoidance. Minimization is rarely used [with archaeological sites].”
• “No Adverse Effect can be reached by [fencing off the site] but in general, most sites just get avoided.”
• “We treat unevaluated sites as eligible, but we are cautious when there is ground disturbance.”

For a highway project in Iowa, cultural resource staff, designers, and engineers worked together to avoid an impact to an adjacent archaeological site. (See the case study on riverbank stabilization along Highway 31 in Iowa.)

Additional Information and Resources

Archaeology: Resources for Conducting Archaeological Studies (NCDOT n.d.). NCDOT supplies separate forms for archaeological resources for documenting findings of “No Adverse Effect” and “Sites Affected.” Forms require NCDOT, North Carolina SHPO, and FHWA signatures.

Historic Districts

Challenge Summary

Transportation improvement projects within historic districts can be challenging in a number of ways, depending on the proposed project and the significance of the district. Some of the most common challenging projects conducted within historic districts include the following:

• Bridge or culvert replacements,
• Streetscape, pedestrian safety, and other micromobility improvements, and
• Highway widening.

These types of projects pose challenges throughout the Section 106 process, including definition of the APE, determination of the appropriate level of effort for identification, and assessment of the effects. Several survey and interview respondents noted that their biggest challenge was establishing an appropriate APE and level of effort for identification that was commensurate with the nature of a project:

• “We also struggle with what is the appropriate level of effort to identify what might be a very large rural historic district when the project involves an on-line replacement of a culvert with minimal right-of-way acquisitions in the surrounding quadrants. What identification of resources is commensurate with such a small scope of work?”—State DOT Respondent
• “[It is important to] properly defining APE for projects that generate foreseeable associated development.”—SHPO Respondent

Within a rural context, introduction of streetscape, traffic safety, pedestrian safety, and other micromobility improvements where none have existed before can be a challenge to assessing effects, particularly in large rural historic districts where the project constitutes a small portion of the overall historic district or within the viewshed of properties where setting is important. (See the case studies on I-695 TSMO in Maryland and on the I-495 Capital Beltway NEXT Project in Virginia.)

Replacement of historic culverts and bridges in rural historic districts can also be a challenge when effects are being assessed. One state DOT respondent commented,

One challenge [our agency] regularly faces is replacement of small bridges in large rural historic districts. What makes a state standard bridge with no distinguishing design features or use of local materials contribute to, for instance, an agricultural historic district? Is it the location and presence of a crossing, allowing farmers to get their products to markets, which contributes to the district’s significance? Or is it the physical bridge itself? If it’s the former, then is its replacement with a bridge of similar size and scale adverse? If it’s the latter and it is being replaced with a similar bridge, then is it adverse? Is there a standard design that could be used in these situations to either avoid or mitigate for an Adverse Effect?

Culverts or bridges within rural historic districts can be contributing elements to the district because they were constructed during the period of significance for the district. However, sometimes these structures are not documented or recorded in a National Register evaluation of a historic district, and the absence of documentation adds another complexity to assessing project effects on the district. There is also the challenge of the scale of projects involving bridges and culverts as compared with the size of the rural historic district and how that influences the potential for an Adverse Effect.

Overcoming the Challenge

Many state DOTs and SHPOs have been struggling with all the challenges outlined previously, and there are few solutions to overcoming these challenges. Some SHPOs have developed a process for looking at projects and their effect on these resources where the setting is an important aspect of integrity. One SHPO outlined several questions to ask to ascertain the effect of a project on a district:

• Is the setting a character-defining feature of the resource?
• Will the project introduce new features into the setting?
• Will the project remove existing features from the setting?