• Construction Noise
• Measurement
• Noise Barriers
• Noise Compatible Planning
• Regulation and Guidance
• Resources
• Tire Pavement Noise
• Traffic Noise Model
• Training

Recommended Best Practices for the Use of the FHWA Traffic Noise Model (TNM)

Appendix G. Sample Checklist for Noise Study Reports Supporting Environmental Documents

The sample checklist in this appendix is intended to be used during the preparation of a noise study report that contributes to and supports an environmental document under NEPA and/or applicable state environmental laws and regulations. Examples of such environmental documents include Environmental Assessments (EAs) and Environmental Impact Statements (EISs). The purpose of these studies is to evaluate potential noise impacts from the proposed project, and to determine if noise abatement to mitigate those impacts would be feasible and reasonable according to FHWA and SHA policy. Portions and/or conclusions from these reports are used in the body of the Affected Environment and Environmental Consequences sections of environmental documents such as EAs and EISs. The complete noise technical report is published as an appendix to the environmental document, and is reviewed by state and federal agencies and often by members of the public through online access or at public hearings.

Checklist for Noise Study Reports Supporting Environmental Documents

1. Executive Summary
   • A synopsis of the project improvements, noise impact criteria, affected noise-sensitive land use, predicted noise impact by alternative, and potential noise abatement measures by alternative.
2. Introduction
   • Project overview. Appropriate background, specific details of the proposed roadway improvements, existing year, design year.
   • Study Area. Summary of noise-sensitive land uses in the study area and their locations. A map of the study area is useful in this section.
   • Study Participants. Report authors and those who provided data for the study.
3. Noise Terminology and Criteria
   • Regulations and Guidelines. FHWA and SHA regulations, guidance documents, full references and active links to documents.
   • Noise Abatement Criteria. Definitions, Table of Activity Categories, criteria and descriptions, description of acoustical metrics including dBA and L_eq, "approach or exceed" discussion and the definition of one decibel as "approach," discussion of the "substantial increase" impact criterion and the SHA's definition of substantial increase in existing levels.
   • State DOT Noise Abatement Guidelines. (Details of this discussion can go here or in Section 7.) Description of feasibility requirements including acoustical feasibility (minimum 5 dBA reduction) and constructability. Description of reasonableness requirements including cost-effectiveness criteria, noise reduction design goals, and consideration of property owner viewpoints. Differences between the cost-effectiveness evaluation approach for Activity Category B uses and that for Categories C and E.
4. Existing Noise Environment
   • Existing Noise Monitoring. Narrative summary of noise monitoring program, including dates, times, locations, noise sources (traffic and otherwise), range of measured sound levels. Tables of pertinent information at each noise monitoring site, including location, time, measured L_eq (traffic only and total, if available), dominant noise sources. Graphic showing locations where noise monitoring was conducted. For long-term, 24-hour measurements, graphs of the measured hourly L_eqs and other metrics, as appropriate.
   • Predicted Existing Noise Levels. Summary of the methods used to predict existing noise levels at all receptors evaluated for noise impact.
5. Predicted Noise Levels
   • Noise Prediction Model. Discussion of the noise model used for noise predictions - TNM version number and general description of the modeling approach, level of detail, and the modeled elements.
   • Noise Model Validation. Discussion of the noise model validation procedure, table comparing measured and predicted sound levels with counted traffic, showing difference to tenths of decibels. Potential reasons for substantial variations, explanations for differences greater than 3 decibels.
   • Traffic Data for Noise Prediction. Description of traffic data sources, characteristics, how loudest traffic hour is determined. Refer to appendix that includes tables listing all traffic data used in noise modeling.
   • Presentation of Results. Descriptions of predicted noise levels by alternative (including Existing and future No-build) in noise sensitive areas (Common Noise Environments). Table of noise levels for noise-sensitive receptors modeled in the FHWA TNM for each alternative. Large projects with hundreds of receptors may show sound-level ranges by Common Noise Environment (CNE) in the report body with an appendix that lists noise levels at all receptors. For each receptor, tables should provide site ID cross-referenced to graphic, site address or description, land use/category, applicable NAC, number of dwelling units or equivalent as well as the predicted L_eq(h) sound levels for each alternative. A scale graphic, preferably with an aerial photograph base, showing the entire project study area, CNE boundaries, line work depicting the proposed roadway improvements, receptor locations and site ID, and project limits as appropriate. As appropriate, receptor markers may be color-coded in the graphic to indicate noise impact status and also barrier benefit status.
6. Noise Impact Assessment
   • Presentation of Noise Impact. Narrative and tabular summaries of the predicted noise impact of the project for all alternatives, grouped by CNE. Residential impact is assessed by number of dwelling units, recreational areas by the SHA's equivalent receptor units. Narrative discussion to include reasons for notable differences in predicted impact across alternatives in areas where they occur.
7. Noise Abatement Measures
   • Alternative Mitigation Measures. Narrative discussion describing alternative abatement measures that were considered, including traffic management, alteration of horizontal or vertical alignment, and the use of buffer zones.
   • Noise Barriers. If not presented in Section 3, discussion of all SHA Feasibility and Reasonableness requirements and criteria (See Section 3, 3rd bullet). Detailed narrative descriptions of all noise barriers evaluated, including those found to be not feasible, those found to be feasible but not reasonable, and those found to be both feasible and reasonable. Tables and narratives should list barrier location, CNE, applicable project alternative, barrier length, barrier height range, barrier surface area, total barrier cost, average noise reduction, number of receptors impacted, impacted and benefited, and total benefited, and the computed SHA cost-effectiveness metric. Graphics should be included to show the locations of all noise barriers that were evaluated for the study, including those found to be not feasible and/or reasonable. Different symbols should be used in the graphics to depict the results of the feasibility/reasonableness determinations, i.e., “Not Feasible”, “Feasible and Not Reasonable”, and “Feasible and Reasonable”.
8. Construction Noise
   • Identification of potential highway construction noise impacts and abatement measures that could or will be used to mitigate the impacts.
9. Public Involvement
   • Discussion of public hearings, meetings and survey/voting details and results, as appropriate.
10. Information for Local Government Officials
    • Noise-Compatible Land-Use Planning. Narrative about communication with local officials about land-use planning adjacent to highways to minimize the potential impacts of highway noise. Provide links to FHWA-sponsored reports on noise-compatible land-use planning.
    • Noise Impact Zones in Undeveloped Land along the Study Corridor. Discussion of and presentation of noise impact zones (distances to NAC contour) in any undeveloped land in the study area.
    • Federal Participation. Discusses the limits of Federal-aid participation in Type II projects (noise abatement only, not part of a highway improvement project).
    • State DOT's Noise Abatement Program. Provides reference and link to SHA noise abatement program guidebook.
11. Appendices
    • Description of Noise Metrics. Additional description of noise metrics may be included, as appropriate.
    • Traffic Data Used in Noise Modeling. Tables including volumes and speeds by TNM vehicle type for all roadway links for all alternatives studied and presented.
    • TNM tables. TNM results and input tables may be provided as appropriate. As-needed, submission of TNM electronic files may be more practical for larger noise studies.
    • Noise Measurement Program Details. Additional information and data from the noise measurement program may be included, as appropriate. Such information may include field data sheets, photographs, noise monitor output, and field calibration records.
    • Predicted Sound Levels. If not included in report body, predicted sound levels by alternative for each receptor with ID cross-referenced to graphic. For each receptor, tables should provide site ID, site address or description, land use/category, applicable NAC, number of dwelling units or recreational receptors represented, and the predicted project sound levels for each alternative.
    • Feasibility/Reasonableness Worksheets. Worksheets for all barriers evaluated and presented in the report, as appropriate.

I have reviewed the report entitled________________________________________________ and I have determined that it complies with the guidance and checklists in this document as well as with SHA policies and FHWA Regulations and Guidance.

Supervisor signature Date