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Environmental process | Environmental review | Noise guidance

Noise Analysis process

Purpose

The purpose of this guidance is to protect the public health and welfare from traffic-related noise pollution and provide noise mitigation when applicable. This document is a broad overview of MnDOT’s noise requirements. You can see additional noise subject guidance on the official MnDOT noise website.

Federal threshold criteria

If the project is a Federal Highway Administration (FHWA) undertaking (e.g., FHWA obligation authority (funding) or an FHWA approval action is required), determine if it meets any of the Type I definition criteria below. To assist with the Type I determination and further guidance, please contact the appropriate personnel in the Office of Environmental Stewardship.

Type 1 projects involve:

  1. Construction of a highway on new location

  2. The physical alteration of an existing highway where there is either:
    • Substantial Horizontal Alteration
      • A project that halves the distance between the traffic noise source and the closest receptor between the existing condition to the future build condition
    • Substantial Vertical Alteration
      • A project that removes shielding, therefore exposing the line-of-sight between the receptor and the traffic noise source by either altering the vertical alignment of the highway or the topography (not including the addition or removal of vegetation) between the highway traffic noise source and the receptor

  3. A bridge replacement that satisfies item (2), above

  4. The addition of a through traffic lane(s) including the addition of a through traffic lane that functions as a high occupancy vehicle (HOV) lane, contraflow lane, high occupancy toll (HOT) lane, bus lane, or truck climbing lane

  5. The addition of an auxiliary lane, except when that auxiliary lane is a tum lane

  6. The addition or relocation of interchange lanes or ramps in a quadrant to complete an existing partial interchange

  7. Restriping existing pavement for the purpose of adding a through traffic lane or an auxiliary lane

  8. The addition of a new or substantial alteration of a weigh station, rest stop, ride-share lot or toll plaza

If a project a Type I project as defined above, then the environmental document will define the entire project area as a Type I project.

Whether to use the FHWA’s or Federal Transit Authority’s (FTA’s) noise analysis and procedures depends on the specific circumstances of a project. The FHWA noise regulations under 23 CFR §72 apply to multimodal projects even though the regulation does not define the term “multimodal.” A transit project that would share existing highway right of way is not necessarily a multimodal project. A transit-only project that meets all three of the following criteria is not a multimodal project for the purposes of 23 CFR §772:

  • Lead agency
    • The FTA is the lead agency in the National Environmental Policy Act (NEPA) process and FHWA is not a co-lead
      • The FHWA’s participation is limited to that of a cooperating agency
  • Project purpose
    • The main transportation purpose of the project in the purpose and need statement of the NEPA document is related to transit but not related to highway
  • Funding
    • There are no federal aid highway funds on the project

Use the FTA’s Transit Noise and Vibration Impact Assessment Guidance Manual procedures for transit-only projects to evaluate noise impacts for the transit and highway elements of transit projects that meet all three of the criteria above. 

If the project meets the above threshold criteria, see the current MnDOT Noise Requirements and Guidance.

If the project does not meet any of the federal threshold criteria, include the following state in the environmental documentation:

The referenced project meets the criteria for a Type III project established in 23 CFR 772. Therefore, the project requires no analysis for highway traffic noise impacts. Type III projects do not involve added capacity, construction of new through lanes or auxiliary lanes, substantial changes in the horizontal or vertical alignment of the roadway or exposure of noise sensitive land uses to a new or existing highway noise source.

MnDOT acknowledges that a noise analysis is required if changes to the proposed project result in reclassification to a Type I project.

If there was a modeling analysis conducted to determine Type I versus Type III designation, include the results lf that analysis as an appendix to the environmental document.

State threshold criteria

No noise analysis is required for state-funded only projects that are not FHWA undertakings unless the project crosses mandatory Environmental Quality Board (EQB) thresholds for highway projects according to Minnesota Rules, part 4410.4300, subpart 22 or if there will be a voluntary Environmental Assessment Worksheet (EAW) for a project on the trunk highway system.

If the state project does not cross any EQB thresholds, simply check the “no significant impact” box on a checklist-type report.

Considerations for environmental document preparation

Note: You must consult with FHWA, OE, and/or the State Aid for Local Transportation (SALT) Office in all classes of action.

Class I Actions (Environmental Impact Statement (EIS) Projects)

Draft EIS (DEIS)

Conduct an impact analysis for each alternative (assuming “prepared statement of no effect” does not apply).  See MnDOT 2017 Noise Requirements Section 4.0. Describe future predicted noise levels relative to existing noise levels plus federal criteria and discuss the impacts. Discuss mitigation techniques in general, not specifics. (A special Preliminary Noise Report may be appropriate.)

Final EIS (FEIS)

Conduct the mitigation analysis for the preferred alternative. The FEIS must include feasible and reasonable noise abatement measures (if any) that you will likely incorporated into the project.

Class II Actions (Categorical Exclusions (CATEX) Projects)

Non-Programmatic CATEX

The non-programmatic CATEX needs to address noise from the standpoint of whether there is a traffic noise impact according to 23 CFR §772. Describe future predicted noise levels relative to existing noise levels plus federal criteria and discuss the impacts. Conduct mitigation analysis for the preferred alternative. The non-programmatic CATEX must include noise abatement measures (if any) that you will incorporate into the project.

Programmatic CATEX

Programmatic CATEX projects are Type II projects because Type I projects cannot be programmatic CATEX according to the Programmatic CATEX Agreement. Type III projects do not require a traffic noise analysis. Simply use the prepared statement or checking the “no significant impact” box on a checklist report is adequate.

Class III Actions (Environmental Assessment (EA)/Environmental Assessment Worksheet (EAW) Projects)

The EA needs to address noise from the standpoint of whether there is or is not a traffic noise impact according to 23 CFR §772. You must follow the procedures of 23 CFR §772. Describe predicted future noise levels relative to existing noise levels plus federal criteria and discuss the impacts. Conduct mitigation analysis for the preferred alternative. The EA must include feasible and reasonable noise abatement measures (if any) that you will incorporated into the project.

Construction noise

You must consider construction noise and discuss if sensitive receptors are near the project. Reference to applicable noise control specifications or local ordinance may be appropriate. See 2017 MnDOT Noise Requirements Section 6.0 Construction Noise (PDF) and sample construction noise write ups for environmental documents under construction impacts for construction noise details.

Public engagement

You will have to do a community noise engagement process as part of the overall public engagement process for the project. See the Community Noise Engagement Process Goals and Objectives (PDF) for more information.

Agency involvement

The FHWA is typically the only agency involved. If the environmental process includes multiple federal agencies as co-leads or cooperating agencies, there might be multiple noise analyses. There are typically no direct outside agency approvals, although noise may be an issue raised relative to other approvals (401 Certification, for example).

Guidance documents on the MnDOT noise website are considered formal guidance agreed upon by MnDOT, FHWA, and MPCA that are incorporated into this TPDP by reference.