Queens Midtown Tunnel Vent Buildings

Project Description

The Triborough Bridge and Tunnel Authority (TBTA) installed thirteen new motors powering fans within the Queens Midtown Tunnel vent buildings located in Queens and Manhattan Boroughs. When operating at low speed, noise levels associated with the new motors have been reported by maintenance personnel as being disruptive and loud. Further, the TBTA has received noise complaints from a residential apartment building adjacent to the Queens vent building. Therefore, the TBTA requested assistance from Paul Carpenter Associates, Inc. (PCA) in documenting noise levels associated with the new motors and identifying potential mitigation.

PCA documented A-weighted overall and 1/3 octave band sound pressure levels of thirteen new dual horsepower motors within the Queens and Manhattan vent buildings. Sound pressure levels were sampled every second and documented at a reference distance of three feet at mid-motor height and in multiple directions around each motor. Background sound pressure levels were also documented for comparison. PCA downloaded and reviewed all data and identified a distinct tone at 1k Hz when motors were operating at low speed, as was determined to be the speed of concern. Data documented within the vent buildings was also compared to manufacturer test data, as requested by TBTA. A Technical Memorandum was prepared for TBTA, detailing findings of the interior measurements performed at the vent buildings.

PCA also documented A-weighted overall and 1/3 octave exterior sound pressure levels in various locations surrounding the Queens and Manhattan vent buildings during one overnight period. In Queens, both ground level and elevated measurements were conducted in order to obtain data representing upper floors of the closest residential building. Motors were run at low and medium speeds, and measured sound pressure levels were compared. In Queens, sound pressure levels were also propagated from the microphone to the facade of the closest residential building, and interior sound pressure levels were estimated for comparison to the maximum permissible sound level limit for circulation devices within the New York City Noise Control Code Section 24-227 (b). A Technical Memorandum detailing findings of the exterior measurements was prepared for TBTA.