Noise Study Process

The Federal Highway Administration (FHWA) published regulations for noise analysis under 23 CFR 772. Noise analysis is done for two categories of projects, Type I and Type II. Type I projects are new roadways or improvements which increase capacity (a through travel lane) or change the horizontal or vertical alignment of an existing road. Type II projects are noise barrier retrofits to an existing roadway.  Mitigation of traffic noise can include noise walls, earth berms and acoustical insulation of public buildings. Eligibility criteria for the consideration of noise abatement is shown in NJDOT Traffic Noise Management Policy and Noise Wall Design Guidelines (pdf 183 kb).

Noise studies are also required for Executive Order 215 documents.

The findings of a noise study will identify noise impacts as defined by Federal Regulation and recommend mitigation measures to be pursued, if any.

(See Noise Study Process (pdf 52 kb))

Scope Development Stage

Step 1 - Identify if project is a Categorical Exclusion (CE), EA or EIS.

Step 2 - For CE projects, the Bureau of Landscape Architecture and Environmental Solutions (BLAES) will obtain from the Division of Project Development (DPD):

  1. Traffic (Intersection LOS) Data
  2. Project Plans and Profiles
  3. Project Description

Step 3 - BLAES performs a brief qualitative analysis of the effects of the project on noise levels in nearby residential areas. A very few projects may require a quantitative (simplified) analysis. This information is used by BLAES to complete the documentation for the CE.

Step 4 - For EA/EIS projects, BLAES will obtain the following:

  1. Environmental Traffic Data from the Travel Projection Unit
  2. Project Plans and Profiles
  3. Noise Monitoring Data from the Environmental Services Support Unit (ESSU)

Step 5 - BLAES staff or a consultant performs the appropriate level of noise analysis. Projects such as new alignments, major road widenings (23 CFR 772), completion of remaining sections of interstate or state highways, etc. will require detailed noise analysis using FHWA approved computer modeling. This includes performing computer analysis of impacts, the identification of recommended  noise mitigation measures and preparation of a report on the findings. A completed acceptable final report is forwarded to the DPD Lead Engineer for review and to BLAES for incorporation in the environmental EA/DEIS.

Design and Final Design Stage

Step 6 - BLAES receives engineering information from Designer.

After the FONSI or Record of Decision is issued by FHWA, the following information is needed to complete the Final Noise Study Report which provides final details on mitigation.

Data Requirements For Final Barrier Analysis

  • Design Year Traffic Data -DHV, % truck, speeds.
  • Plan Sheets (50% design).
  • Cross Sections by Station.
  • Photogrammetric mapping showing location and elevation of noise sensitive areas up to 180 meters from alignment depending on scope of project. Require 1:1000 to 1:4000 scale.
  • Aerial photography or mapping of project area to present noise contours and barrier locations in Final Noise Study Report. Require 1:2000 to 1:4000 scale, covering a corridor up to 180 meters from the alignment.
  • For projects where noise barriers may need to be added to existing structures, an analysis of what height barriers can be accommodated and the associated cost to modify the structure.
  • Relative availability of material for earth berms.

Step 7 - BLAES Technical staff completes detailed computer analysis and recommends noise barriers based on reasonable cost and barrier effectiveness utilizing the technical criteria in Attachment 9.

Step 8 - BLAES initiates barrier material selection process and requests assistance from the Office of Landscape Architecture. Innovative designs and materials which reduce costs are considered. BLAES calls for review meeting with Project Management to present recommended barriers. Aim is to determine if there are any overriding constraints to proposed barriers.

Step 9 - After concurrence of barrier engineering by Project Management, BLAES presents barriers to FHWA for informal review and preliminary approval.

Step 10 - To develop presentation materials for a public information center, Bureau of Research develops videotape showing barrier proposal.  Noise levels before and after barriers are incorporated into this video presentation. DOT or consultant personnel develop renderings of the proposed barriers.

Step 11 - The Project Manager, with support from BLAES, through Community Relations, holds meetings with municipal officials and those residents near proposed barriers to explain and demonstrate the characteristics of highway traffic noise, the effects of noise barriers in attenuating traffic noise and types of noise barriers that may be considered. Community Relations requests that municipal officials provide the DOT with a resolution either for or against proposed noise barrier after completion of the meeting process. This will be used in making the decision on the inclusion of barriers in the project.

Step 12 - BLAES prepares Final Noise Study which incorporates proposed locations of noise barriers (if any), noise contour maps and community resolutions.

Step 13 - After Project Management approval, Final Noise Study (FNS) transmitted to FHWA for concurrence.  Any FHWA comments are then addressed and concurrence received.

Step 14 - BLAES sends approved FNS to communities.  This includes noise contour maps identifying areas of future high noise along project.  Communities can use this information in planning future use for undeveloped areas.

Step 15 - Development of structural design, specifications and barrier details during which BLAES is consulted on design details and modifications which may occur due to design constraints.

Step 16 - During noise barrier installation, Resident Engineer, Materials, BLAES conduct periodic quality control monitoring.  Resident Engineer would be the lead in solving problems on unsatisfactory construction practices or inappropriate barrier materials.  We learn from our construction experience what designs to use or avoid in the future. At the point of 60% barrier completion, the Project Manager, with support from BLAES, will provide a formal review to the Resident Engineer. This review will obtain input from Landscape and Structures and Bridges. Resident Engineer will be the lead in coordinating a solution to any problems that develop.

Criteria for Community Built Noise Barrier Project within the State’s Right of Way

Noise impacted communities can build noise barriers within the State’s Right of Way at no cost to the State.

In order to ensure that safety to the motoring public is considered, including future maintenance of the noise barrier, the following process has been established:

  1. Where a community desires to build a noise wall within the State Right of Way, a written request must be submitted by the governing body (county, city, town, municipality, etc.) to the Department.
  2. Prior to construction of the project, the governing body must enter into a “right of entry” agreement with the Department.
  3. The noise barrier design must follow NJDOT design standards and construction specifications and be certified by the requesting engineer as to its compliance.
  4. The requesting governing body must assume full maintenance, jurisdiction and responsibility for the noise barrier by means of jurisdictional agreement.
  5. The proposed noise mitigation must not create safety or maintenance problems on State highways.
  6. Efforts must be made to provide architectural treatment and landscaping for the highway side of the barrier consistent with other treatments on the roadway.

Noise Abatement Criteria,
Noise wall Design Criteria

Refer to NJDOT Traffic Noise Management Policy and Noise Wall Design Guidelines (pdf 183 kb).

Last updated date: January 7, 2020 3:02 PM