Paul Carpenter Associates, Inc. (PCA) performed a detailed construction-related noise assessment related to a track and viaduct replacement project in Brooklyn. Due to the proximity of residential buildings and a church to the existing viaduct carrying the M train from Broadway to Myrtle Avenue, demolition and construction activities associated with the project had the potential to generate noise impacts.
In order to determine the existing noise exposure in the vicinity of the existing viaduct, continuous 24-hour noise levels were documented in two locations. Certified meteorological data was obtained from the National Oceanic and Atmospheric Association (NOAA) for the closest meteorological monitoring station and was utilized to filter measurement data during time periods when weather conditions were inappropriate for noise monitoring.
PCA recommended noise impact criteria for construction activities for the duration of the project. PCA was provided with details regarding stages of construction and reasonable equipment quantity assumptions to perform installation of new foundation, demolition of existing structure and installation of the new structure. SoundPLAN was utilized to estimate construction-related noise levels for each phase of construction. Absolute noise levels were utilized to determine weekday daytime noise impacts for each construction phase. In addition, increases in construction-related noise over existing background noise levels were utilized to assess Saturday daytime noise impacts.
Due to the multitude of noise impacts predicted, PCA developed reasonable mitigation measures for each phase of construction. PCA provided a comprehensive report detailing which activities could be performed with no impact and therefore no need for mitigation. In addition, PCA designed reasonable mitigation measures in order to minimize noise impact. Reasonable mitigation measures included installation of ground-level acoustic blankets along the work area perimeter as well as elevated platforms. Finally, PCA identified activities requiring advanced mitigation measures. Advanced mitigation measures included avoiding certain activities from being performed on Saturday daytime periods as well as potential residential relocations through a strong community involvement program.