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Where can I find the Sound Barrier Policy?

The Sound Barrier Policy can be found here.

What does MDOT State Highway Administration hope to accomplish through noise abatement?

The primary objective of  MDOT State Highway Administration (MDOT SHA) Noise Abatement Program is to fulfill their responsibility as outlined by the Federal Highway Administration (FHWA). The FHWA noise regulation, found at 23 CFR 772, requires a highway agency to investigate traffic noise impacts in areas adjacent to federally funded highways for the proposed construction of a highway on a new location or the reconstruction of an existing highway that either significantly changes the horizontal or vertical alignment or increases the number of through-traffic lanes.

Through feasible and reasonable noise abatement, MDOT SHA aims to:
  • provide discernable abatement
  • enable impacted residents standing 3 feet apart outside their homes hold normal conversations without having to yell.
  • provide uniformly consistent noise levels (no hotspots).
  • block line-of-sight from the highway to the community

How to inquiry about highway traffic noise?

To inquiry about highway traffic noise, please submit complete the online form, or call toll free at 1-888-228-5003.

What are the factors used by MDOT State Highway Administration in determining my community's eligibility for a sound barrier?

The MDOT SHA will determine if the community is impacted by highway traffic noise and if the construction of a sound barrier is reasonable and feasible. Only barriers that are determined to be both reasonable and feasible will be approved.

My community was determined to be eligible for a sound barrier a while back but no sound barrier has been constructed. Why is this?

Sometimes, the construction of a Type II sound barrier may be both feasible and reasonable and the community deemed eligible to have a sound barrier constructed. However, funds are not always readily available for the construction of these barriers. Therefore, the project will have to be put on an eligibility wait list and the barrier will be constructed once funds become available.

What properties are considered impacted and benefited?

The following impact levels are the most commonly used:

Type I: A sensitive land use is impacted if:

  • Design year noise levels are projected to equal or exceed 66 dB(A) - OR -
  • Projected noise levels are anticipated to increase over the existing year’s noise levels by the amount shown in Table below. For example, if a land use has an existing noise level of 41 dB(A), the design year noise level must increase by at least 15 dB(A) for a noise impact to occur.


Existing Noise Level

Projected Increase

45 dB(A) or less

15 dB(A)

46 dB(A)

14 dB(A)

47 dB(A)

13 dB(A)

48 dB(A)

12 dB(A)

49 dB(A)

11 dB(A)

50 dB(A) or greater

10 dB(A)


Type II: A noise-sensitive use is impacted if existing noise levels equal or exceed 66 dB(A).

A benefited property is one which benefits from a sound barrier by up to a 5 decibel noise level reduction but is not necessarily impacted.

Why was the impact level set at 66 decibels?

Research has shown that conversation between two people standing 3 ft apart and speaking in a normal voice is impaired above a noise level of 66 decibels.

Note: 66 decibels is less noisy than a vacuum cleaner (70 decibels) and a lawnmower (90 decibels).

When will MDOT SHA conduct a noise measurement at a citizen's request?

A noise measurement will only be conducted at a citizen's request if the citizen's community meets preliminary criteria for a Type II project. A very important criterion considered is the date eligibility criterion. For a Type II project, majority of the impacted residences should have existed prior to the original construction of the highway.

Also, it has to be determined that noise abatement measures can be implemented and will be effective by examining the topography of the area and its horizontal distance from the highway.

Do local officials have any input?

The control of highway noise, to be effective and comprehensive, must be done in partnership between SHA and local land use planning officials. The Maryland SHA will furnish the results of all highway traffic noise analysis to local government officials and will encourage local communities and developers to practice noise compatible development.

What do I do if an existing wall is damaged?

Sound barriers built by the state are maintained by the state. To submit a complaint about a damaged wall, please complete the online form, or call toll free at 1-888-228-5003.

What can be done to regulate "Jake Brakes"?

These are compression release engine brakes usually installed in large trucks and trailers. Jake Brakes are a brand of these engine breaks manufactured by Jacobs Vehicle Systems. Cummings makes a C-brake and other companies make similar systems. A beneficial aspect of this system is that it reduces stress on a truck’s hydraulic brake system extending its life and reducing the chances of overheating and fatigue. On the other hand, this technology has been associated with increased engine noise.

Experience has shown, however, that vehicles with improperly maintained, defective, or modified exhaust systems are the ones that make the loud noise associated with engine breaking and thus violate the noise limits established by the State. Law enforcement agencies are able to enforce State laws relating to exhaust systems and excessive or unusual noise. Maryland Law prohibits vehicles from:
  • exceeding established sound limits (Title 11 DEPARTMENT OF TRANSPORTATION Subtitle 14 MOTOR VEHICLE ADMINISTRATION—VEHICLE INSPECTIONS Chapter 07 "Noise Abatement Program" Authority: Transportation Article, Section 22-601, Annotated Code of Maryland ), and
  • modifying exhaust systems or any other vehicle noise abatement device.
Vehicles equipped with a Jake Brake, or a similar engine retardant system, may be lawfully operated on highways in Maryland as use of this equipment is not prohibited by Maryland Vehicle Law.

Does the SHA provide noise insulation for private residences?

No, SHA does not fund such projects. However, fixing double pane windows, sealing wall cracks, and hanging of heavy draperies can help to reduce noise from highway traffic. (Source: Washington State Dept. of Transportation Website, Noise FAQ)

Can I build my own noise wall?

Some residents choose to build their own walls to protect their property from highway traffic noise. These walls are normally made out of wood and located at the property line. To reduce noise levels, the wall should have no gaps, should block the line of sight of the noise source, and should be long enough to enclose the area to be protected. These walls are not funded by SHA.

What is noise masking?

Some residents use white noise, such as noise from a fan or waterfall, to drown out traffic noise. While some people have reported some success with this technique, it is not a practical noise abatement tool on a community scale and will not be sponsored by SHA. (Source: Washington State Dept. of Transportation Website, Noise FAQ) 

Can vegetation such as trees and shrubs be effective in reducing highway traffic noise?

Research has shown that a 5 dBA reduction in noise can result from a stand of vegetation 100 feet wide, and up to a maximum reduction of 10 dBA from a stand of at least 200 feet wide. In addition, the following features must also exist:
  • A mixture of low growth (shrubs and bushes) and tall mature trees of sufficient density so the highway cannot be seen.
  • Tree height should be at least 15 feet above the line-of-sight (straight line view between the houses and the highway).
  • A mixture of deciduous and evergreen plants to maximize effectiveness in both winter and summer.
These types of vegetated areas are typically natural and not man-made features. Such features are impractical to create or replace especially along a highway. However, these areas are preserved whenever possible. In more practical terms, one or more rows of trees may be planted to provide some psychological relief and to act as a visual shield from highway traffic.

What if my community was previously turned down for a barrier? Am I eligible now? When will I be eligible?

Your community can appeal a decision. Appeals of decisions not to build sound barriers are considered by the Secretary of the Department of Transportation and the State Highway Administrator. An appeal is considered when there is a question about the interpretation/application of the sound barrier policy criteria or there is a question about the preparation and accuracy of the technical noise analysis. Noise policy criteria are not the basis for appeal.

Note: If MDOT SHA initiates highway improvements near your community, MDOT SHA may conduct a noise analysis affecting eligibility.

How does MDOT SHA’s Highway Noise policy address the February 2016 FHWA guidance on “Use of Freeway Shoulders for Travel?

In February 2016, FHWA provided guidance entitled Use of Freeway Shoulders for Travel. The implementation of part-time shoulder use along Freeway is a Type 1 project. Inside shoulder use is less likely to have noise impacts compared to right side part-time shoulder use, which places the traffic closer to sensitive receptors. Lower speeds with the similar traffic characteristics is less likely to have noise impacts compared to the higher speed with similar traffic characteristics. Abatements that may be consider for part-time shoulder use include, but are not limited to;
  • Construction of noise barriers; landscaping is NOT considered a noise abatement measure.
  • Traffic management measures, such as traffic control devices and signing for prohibition of certain vehicle types, time-use restrictions for certain vehicle types, modified speed limits, and exclusive lane designations.
  • Acquisition of property (typically undeveloped or unimproved) for establishing a buffer zone to prevent future development which would be adversely affected by traffic noise.
  • Noise insulation of land use facilities, defined in 23 CFR 772 as Activity Category D to address INTERIOR noise impact. These include auditoriums, day care centers, schools, libraries, hospitals and medical facilities, places of worship, public meeting rooms, public or nonprofit institutional structures, radio, television, and recording studios. This abatement measure is ONLY applicable if:
o Exterior abatement is determined to be not feasible and reasonable, or
o If no noise sensitive exterior uses exist on the subject property. 
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