Section 106 of the National Historic Preservation Act of 1966 requires that Federal agencies take into account the effects of their undertakings on properties eligible for listing in, or listed in the National Register of Historic Places ("historic properties") and afford the Advisory Council on Historic Preservation (ACHP) a reasonable opportunity to comment. According to 36 CFR 800.5(a)(2)(v), adverse effects specifically can include the "introduction of visual, atmospheric, or audible elements that diminish the integrity of the property's significant historic features". While the analysis of effects resulting from alteration or diminishment of setting by visual changes are a common element of Section 106 consultation, analysis of noise effects on historic properties is less common. Further, the typical definition of what constitutes a noise “impact” may or may not be applicable to effects on historic properties, an ambiguity that often characterizes discussion between noise and historic preservation experts at state DOTs. Finally, mitigation of noise impacts can involve mitigation practices that may constitute effects (e.g. construction of barriers may diminish historic setting and feeling). These ambiguities and potential conflicts are what this research project would seek to address.
In 2012, NCHRP Task 72 examined the practices used to address the potential effects of construction vibration on historic buildings. Since that time, there has been considerable interest in taking a similar approach to examine highway noise impacts to historic properties. The issue has been vetted at workshops and sessions at the Transportation Research Board Annual meeting, events co-sponsored by TRB's Committees on Historic and Archeological Preservation in Transportation (ADC50) and Transportation-Related Noise and Vibration (ADC40). There is no published work related to this topic or synthesis of effective nationwide practices. The sources of information used for this study will be noise and historic preservation experts among the state DOTs, State Historic Preservation Officers (SHPOs), and DOT contractors charged with the analysis of noise impacts and Section 106 effects on historic properties.
The continuing and exponential increase in properties 50 years of age or greater will result in more historic properties being defined in proximity to existing highways being modified for increased capacity and new location highway projects. There will be a corresponding increase in instances where highway noise is considered a potential source of effect on historic properties. Resolving analytical ambiguities between what constitutes a noise impact versus a Section 106 effect on historic properties, augmented by a synthesis of effective mitigation practices, will enable state DOTs to be better prepared to address these issues.
The purpose of this study is to build on NCHRP 25-25, Task 72, Current Practices to Address Construction Vibration and Potential Effects to Historic Buildings Adjacent to Transportation Projects, and answer the following questions:
- What constitutes an effect or adverse effect on historic properties with regard to highway noise?
- What are the most effective practices or analytical methods to determine if there are highway noise effects on historic properties?
- What methods are effective in mitigating the effects of highway noise on historic properties?
- Does the introduction of barriers to mitigate the effects of highway noise itself constitute a potential effect on historic properties? If, so how?
- Are there situations in which not mitigating noise effects is seen having less harm to historic properties than mitigation using a barrier? If so, what are they?
- Are there "standard" barrier designs that are considered acceptable for historic areas, or are barrier aesthetics determined on a case-by-case basis? If so, what are they?