The suspended ceiling on the Massachusetts Turnpike (I-90) tunnel was originally constructed to provide fire protection for the massive steel girders that support the above Prudential Center and Hynes Convention Center. Since then additional fire protection measures have been implemented, rendering the ceiling unnecessary. The Massachusetts Convention Authority (MCCA) decided to remove the suspended ceiling, but concern over the possibility of increased transmission of noise into conference and dining facilities within the convention center prompted the hiring of Acentech.
Acentech made acoustic and vibration measurements and performed analyses to see what improvements, if any, could be made to Simpson Gumpertz & Heger’s (SGH) new design for the ceiling. These studies took place before, during, and after the removal of the ceiling panels. Measurements were made in various locations including the interstitial space directly above the ceiling, representative meeting and dining rooms within the convention center, and a high-end restaurant adjacent to the convention center.
Post-removal measurements showed that noise levels inside the convention center were similar to or lower than before. Acentech’s consultants concluded that there were two likely reasons for this. First, the ceiling had been hung using stiff metal rods. The lack of isolation provided an efficient flanking path and was the predominant cause of the traffic noise within the convention center. Second, trucks and other large vehicles had very little separation (as little as 12 inches) between their roofs and the underside of the ceiling, resulting in vibrations induced by turbulent air. The new ceiling now has a 10 to 15 foot gap between the vehicles and the convention center structure.
Due in part to the results of Acentech’s investigations, which included vibration, sound, and pressure monitoring, SGH and MCCA decided that a costly new ceiling was not needed under the Hynes Convention Center.