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Sound Barriers Guidelines - Type II Sound Barrier Program

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PROGRAM OVERVIEW


This is a voluntary program which assesses impacts adjacent to existing fully access - controlled highways not being expanded, where the majority of the impacted development was built prior to the original construction, or approval of a highway. A program to implement Type II projects is an optional decision by the State, as the development and implementation of Type II projects are not mandatory requirements of Federal law or regulation.

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



CRITERIA FOR COMMUNITY ELIGIBILITY




Type II Criteria



For a project to be approved as a Type II project, it has to meet all the following criteria:

IMPACT CRITERIA

  • Existing noise levels have to equal or exceed 66 decibels.

    66 decibels was set as the impact threshold because research has shown that conversation between two people standing 3 feet apart and speaking in a normal voice is impaired above a noise level of 66 decibels.


  • 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 were in existence before the community.


  • Must be on an access-controlled highway.

    An access-controlled highway is one which has limited access and can only be accessed by ramps or interchanges at very limited points. When a highway is not access controlled, it means that the highway has too many access points or intersections that prevent the construction of a sound barrier from being feasible. Some examples of access-controlled highways are I-695, I-95, I-495, I-70, I-68, I-97, etc.


FEASIBLE CRITERIA

  • The sound barrier should be able to yield a significant noise reduction for impacted residents.
  • Sound barrier construction should have no significant impacts on existing drainage and utility, and should not restrict pedestrian or vehicular access.
  • The construction of a sound barrier should not impact publicly owned recreation areas and parks, wildlife areas, conservation areas, and historic sites.
  • The right of way needed for the construction or permanent location of a sound barrier should be donated to the state.

    Sometimes, barriers need to be built on land not belonging to the state or not under state jurisdiction. These areas need to be made available to the State for a sound barrier to be construcred.


REASONABLE CRITERIA

  • A barrier system will be 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 also agree to fund 20% of the project. If the money is not available and the project meets all other criteria for a Type II project, it will be placed on an eligibility wait list pending availability of funds.


  • At least 75% of the homeowners impacted should be in favor of the barrier.







PROJECT EXAMPLES


The following examples are meant to illustrate specific applications of the previously discussed Type II eligibility criteria.



EXAMPLE 1



There is an existing 2-lane highway which was originally constructed in 1958. Sixteen single-family homes are located in a residential neighborhood 800 feet from the highway and complain about traffic noise. Two of the homes were built in the 1960s; the other fourteen were built between 1974 and 1975. The development was not yet planned when the highway was constructed.


EVALUATION PROCESS

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 had been constructed.




EXAMPLE 2



There is an existing 4-lane highway which has a system opening date of 1980. Twenty single-family homes are located in a residential neighborhood about 500 feet from the highway and complain about traffic noise. All the homes were built between the years of 1969 and 1975. The measured noise level in the community is 59 decibels.


EVALUATION PROCESS

Type II Criteria


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

REASON: Although the community pre-dates the original construction of the highway, the existing noise level does not exceed the impact threshold of 66 decibels.



EXAMPLE 3



There is an existing 4-lane highway which was originally constructed in 1962 as a 2-lane highway. The highway was dualized in 1981. Twenty-five single-family homes are located in a residential neighborhood 150 feet from the highway and complain about traffic noise. Twenty of the 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 be required to significantly reduce noise levels in the area.


EVALUATION PROCESS

Type II Criteria


DECISION: The construction of a barrier will be considered.

REASON: The existing noise level in the area exceeds the impact threshold of 66 dBA and the community pre-dates both the original construction and dualization of the highway. The resulting square footage per benefited residence would equal 2,608 square feet, less than the 2,700 square feet maximum allowed.





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

 

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