The MAA’s residential sound insulation program is guided by Federal regulations, including defining initial eligibility as being within the Day Night Average Sound Level (DNL) 65 dB noise contour of BWI Marshall Airport’s Part 150 Study. Noise greater than DNL 65 dB is what the FAA considers as the threshold for residential land use compatibility around airports. The objective of the sound insulation program is to reduce the interior noise levels within eligible residential dwelling units to at least 45 dB with a minimum 5 dB reduction by installing new acoustically-rated windows, doors, ventilation, and other customized treatments approved by the FAA. More information on BWI Marshall Airport’s Part 150 Study is located here.
BWI Marshall Airport’s FAA-accepted forecast Noise Exposure Map (NEM) for the year 2019 identified a number of single-family residential properties and multi-family structures (apartments, duplexes and condominiums) that are located within the DNL 65 dB noise contour and thus potentially eligible for sound insulation. Eligibility for those homes within the DNL 65 dB NEM is also subject to acoustical testing of the structure. The MAA will be preparing updated NEMs beginning in 2019, and upon FAA acceptance, the updated NEMs will be used to update or refine the geographic limits of program eligibility.
In 1985, the MAA began a program to acquire residential properties with cumulative noise levels of 75 Ldn or greater. In 1988, the MAA completed a Federal Aviation Regulation Part 150 Study and expanded the program to homeowners residing in communities that were exposed to cumulative noise levels of 70-75 Ldn. Properties which were determined to be impacted, became eligible for federal noise mitigation funds. Property owners, who volunteer to participate, were paid fair market value for their property at its highest and best use, and were provided relocation assistance. Properties located in areas whose day-night average sound level (Ldn) was greater than 70, as determined by Airport Noise Zone contours, were eligible for this program provided the property has been zoned by local government to transition from residential.
Progress as of March 31, 2008
School Sound-Proofing Program
The school sound insulation program was completed in 1991 by providing sound insulation at four schools which were re-furbished to reduce interior noise levels. The total cost of the program was $9.3 million.
Relocation of Ridgewood Mobile Home Park
In August of 1998 the MAA began the relocation of the residents of the Ridgewood Mobile Home Park. The Park was located within the DNL 65 contour, as determined by the 1998 Airport Noise Zone. The Park land was purchased at a price of $6.35 million for 72 + acres. 122 families resided in the Park at the time of MAA’s purchase; there were a total of 140 mobile homes in the Park. The program was completed in March 2000 at a total cost of 9.7 million.
In April 1987, the Maryland Aviation Administration (MAA) initiated the Homeowner Assistance Pilot Program for areas surrounding the Baltimore/Washington International Thurgood Marshall (BWI) Airport. The pilot program included two methods of dealing with homeowner problems and improving land use compatibility in the airport area, a Sound Insulation Project and a Resale Assurance Project.
Under the Sound Insulation Project, existing houses were modified to make aircraft noise less intrusive. By replacing windows and doors with new components specifically designed to reduce sound transmission, increasing the mass/weight of some walls and in general, sealing cracks and crevices that act as entry paths for sound energy, the interior noise levels in these houses were significantly reduced. Additional ventilation systems and/or central air conditioning were installed to ensure fresh air circulation since insulating the houses results in less outside air (as well as noise) leaking into the building.
The Resale Assurance Project* was designed to financially assist homeowners who wished to move out of the Noise Zone by guaranteeing that they would receive fair resale value for their homes.
All phases of the pilot effort are now complete, and an ongoing Homeowner Assistance Program was established under a grant from the Federal Aviation Administration through the completion of a Federal Aviation Regulation Part 150 Study. The Study identified homeowners residing in communities that were exposed to cumulative noise levels of 70-75 Ldn. Properties which were determined to be impacted, became eligible for federal noise mitigation funds to provide sound insulation through modifications to their homes, with a goal of reducing interior noise levels to an average of 45 Ldn. In 2007-2008 the MAA updated its Part 150 Study which expanded eligibility to homeowners exposed to cumulative noise levels of 65 Ldn, although the overall noise contours have been reduced considerably due the phase out of older noisier aircraft. The sound insulation option is the only program currently active.