This report examines the noise abatement feasibility and reasonableness factors in the Federal Highway Administration (FHWA) noise regulation in 23 Code of Federal Regulations (CFR) Part 772 (the "regulation') as implemented in individual state highway agency (SHA) noise policies.1
Feasibility and reasonableness are determined based on the effect the abatement measure has on adjacent noise "receptors." A receptor is an activity area on a parcel of property being studied for noise impacts from a nearby highway project. Receptors can be residential or non-residential land uses.
The way that non-residential receptors are treated in a project noise study - how their intensity of use and placement on the property are determined - can have a significant effect on the feasibility and reasonableness of a noise abatement measure. Task 2 of this research, reported separately, examined receptors on non-residential land uses and addressed alternative methods to quantify the number of receptors at these locations. The focus of Task 3 is on residential receptors only.
The feasibility and reasonableness factors that have been studied include:
In addition to these factors, the regulation requires consideration of the viewpoints of benefited residents and owners in the abatement reasonableness assessment. This factor is not considered in this study.
The analysis examines how changes in the permissible ranges for each factor affect noise abatement decisions while the others factors remain static. The analysis also examines how changes to multiple factors in combination affect decisions. The goal was to identify combinations of factors that are likely to result in inclusion of noise abatement or exclusion of noise abatement.
The first subtask was to examine each factor individually and in combination with each other to identify optimized combinations of values. The first objective of this subtask was to identify the range in potential decisions based on the combinations permitted under the regulation. A second objective of this subtask was to aid in future guidance and planning.
The second subtask was to apply the results of the first subtask. This work included performing a sensitivity analysis on the feasibility and reasonableness factors to identify outcomes of possible combinations of factors. It also included applying the combinations to actual highway projects to identify the effects of changes in these factors individually and in combination with the likelihood of abatement.
This report includes stakeholder feedback from TWG members after the Subtask 5.1 and 5.2 webinars that were part of the Task Order.
The study results include all digital files developed for this analysis, including noise prediction model runs and spreadsheets, which have been delivered to FHWA.
A second part of this research was the development of a tool to evaluate the effects of policy changes on the feasibility and reasonableness of noise abatement. This work is included in a separate report. Two tools were developed during this task to allow users to evaluate various combinations of factors to determine the effects of policy changes on the feasibility and reasonableness of abatement.
1This report summarizes the process used in Task 3 of Task Order No. DTFH61-D-00028-T12-002, 23 CFR 772 Streamlining, Analysis, and Outreach. Specifically, it represents the results of Subtasks 3.1 and 3.2 of this research. This report is the first deliverable under Task 3 and was prepared under Subtask 3.3 through 3.5.