Sound Barriers Guidelines - Type II Sound Barrier Program


This voluntary program assesses impacts adjacent to fully access-controlled highways that are not being expanded. The program applies where the majority of the impacted development was built before the original approval or constr​uction of a highway. Implementing a Type II project is an optional decision by the State. Type II projects are not mandated by federal law or regulation.

Programming Type II sound barriers that are reasonable and feasible is based upon the availability of funds in the Consolidated Transportation Program (CTP).


Type II Criteria

For Type II project approval, a project must meet all the following criteria:


  • Existing noise levels equal or exceed 66 decibels. 66 decibels is the impact threshold because research shows that conversation between two people speaking in a normal voice and standing three feet apart is impaired above 66 decibels.
  • A majority of the impacted residences existed prior to the construction of the original highway.
    Sometimes, concerns about highway traffic noise come from occupants of new homes built adjacent to an existing highway. Many of these highways were originally constructed through undeveloped lands and existed before the community.
  • Must be on an access-controlled highway.
    An access-controlled highway is one that has limited access and can only be reached by ramps or interchanges at limited points. When a highway is not access controlled, it has too many access points or intersections, preventing the construction of a sound barrier. Some examples of access-controlled highways are I-695, I-95, I-495, I-70, I-68, and I-97.


  • The sound barrier must yield a significant noise reduction for impacted residents.
  • Sound barrier construction should have no significant impact on existing drainage and utility, and should not restrict pedestrian or vehicular access.
  • Construction of a sound barrier should not impact publicly owned recreation areas and parks, wildlife areas, conservation areas or historic sites.
  • The right of way for the construction or permanent location of a sound barrier must be donated to the State.
    Sometimes, barriers need to be built on non-State land or land that is not under State jurisdiction. These areas must be made available to the State for sound barrier construction.


  • A barrier system is considered reasonable if the area of wall provided per benefited residence is equal to, or less than, 2,700 square feet.
    The local jurisdiction must agree to fund 20% of the project. If the money is not available and the project meets all other Type II criteria, the proposed project will be placed on an eligibility waiting list pending availability of funds.
  • At least 75% of the homeowners favor the barrier.


The following examples illustrate applications of the previously discussed Type II eligibility criteria. 


An existing two-lane highway was originally constructed in 1958. Some 16 single-family homes are located in a residential neighborhood 800 feet from the highway and their residents complain about traffic noise. Two homes were built in the 1960s; the other were built between 1974 and 1975. The development was not yet planned when the highway was built.

Type II Criteria
DECISION: The construction of a barrier will not be considered.

REASON: The community does not pre-date the highway. The community came into existence after the highway was constructed.


An existing four-lane highway opened in 1980. Some 20 single-family homes are located in a residential neighborhood about 500 feet from the highway and its residents complain about traffic noise. All the homes were built between 1969 and 1975. The measured noise level in the community is 59 decibels.
Type II Criteria
DECISION: Construction of a barrier will not be considered.
REASON: Although the community pre-dates the highway, the noise level does not exceed the threshold of 66 decibels. ​


An existing four-lane highway which was originally constructed in 1962 as a two-lane highway. It was "dualized" in 1981. Some 25 single-family homes are located in a residential neighborhood 150 feet from the highway and its residents complain about traffic noise. Twenty homes were built in 1943; the other five were built in 1945.
The existing noise level in the area is 75 dBA. A sound barrier 3,260 feet in length and 20 feet in height would significantly reduce noise levels.
Type II Criteria
DECISION: The construction of a barrier will be considered.
REASON: The noise level exceeds the threshold of 66 dBA and the community pre-dates both the original construction and expansion of the highway. The resulting square footage per benefited residence would equal 2,608 square feet, within the permitted 2,700 square feet.

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Additional questions? Contact the Office of Highway Development(OHD) at 1-888-228-5003.