Thalheimer has dealt with ventilation noise many times before in projects as small as a pizza oven fan causing annoyance inside an adjacent condo, to as large as multi-billion dollar tunnel ventilation systems to ensure they meet NFPA 130 and 502 standards for emergency communication intelligibility. He has developed an empirically-based fan noise prediction model to estimate fan noise levels inside spaces, and has recommended numerous methods to attenuate fan noise including the use of silencers, housing lagging, alternate fan operating parameters, and new grill design.
Example projects involving industrial and/or power plant noise evaluation and control include the following:
- Sumner Tunnel Ventilation Buildings, Massachusetts Department of
Transportation, Boston, MA – Assessed the need for noise reduction
controls to be applied to Vent Building 10 in the North End of Boston and Vent
Building 11 in East Boston. Measured
noise emission levels through the building’s louvers, modeled neighborhood
noise conditions using the Cadna-A model, and predicted community noise levels
if the tunnel ventilation fans were run at increased power. Modelled and evaluated several noise
reduction options including acoustical louvers, interior walls, and noise
barriers for the penthouse vents.
Performed cost comparison as well, and recommended preferred solutions
- NYC Second Avenue Subway Project Phase 2, Metropolitan Transportation Authority, New
York, NY – Performed ventilation noise assessments for the 125th
Street and 106th Street stations ancillary buildings providing
ventilation services for the new subway tunnels. Noise emissions from large tunnel ventilation
axial fans (TSSM) and smaller building HVAC equipment were modeled using the
AIM noise model and the Cadna-A noise model to evaluate noise levels affecting
the surrounding community. Predicted
noise results at nearby receptors were evaluated against the limits committed
in the project’s FEIS as well as against the New York City Noise Code.
- Denver I-70 Tunnel Jet Fan Noise, Colorado Department of Transportation,
Denver, CO – As part of a design-build team, performed a noise
assessment of ventilation jet fans proposed for use inside a new 1,000-foot
long tunnel to be created as part of a project that will depress Interstate
I-70 through the City of Denver. Tunnel
interior jet fan noise levels were predicted using PB’s proprietary jet fan
noise model and evaluated for compliance with NFPA 502 guidelines. Jet fan
noise levels potentially affecting the community were predicted using the
Cadna-A model and evaluated for compliance with the Denver Noise Ordinance. Several
revisions were needed to satisfy the community noise ordinance which involved
selecting quieter jet fans from Howden and improved fan silencers from
- MARTA Tunnel Ventilation System Renovations,
Metropolitan Atlanta Rapid Transit
Authority, Atlanta, GA – Performed station platform and community
noise analyses for sixteen MARTA stations in which the ventilation systems are
being upgraded. The original 40-year old
ventilation fans, silencers, shafts and ducts are being replaced with
equivalent new units. Used the TAP Model
and the ODEON model to compute fan noise propagation throughout the interior of
the vent buildings, and used the Cadna-A model to evaluate ventilation noise
levels propagating to nearby community receptor locations. Developed noise
reduction requirements if needed.
- Sumner Tunnel Jet Fan Ventilation Noise, Massachusetts Department of Transportation, Boston, MA – Developed sound power level specifications for new jet fans being installed as part of the Sumner Tunnel rehabilitation project. Modeled in-tunnel noise levels to ensure that jet fan noise would not exceed 92 dBA five feet above the pavement in accordance within NFPA 502.
- Midtown-Downtown Tunnels Jet Fan Noise Compliance, Virginia Department of Transportation, Norfolk & Portsmouth, VA - Developed an analytical noise prediction model to evaluate anticipated contractor compliance with submitted jet fans for the Elisabeth River Midtown and Downtown Tunnels. Predicted jet fan sound pressure levels at a position 5 feet above pavement using sound power emissions from proposed jet fans, and evaluated the results against the project specifications limit of 92 dBA. Developed project position paper to justify relaxing tunnel interior noise limit to 92 dBA in accordance with NR85 criterion and NFPA 502 guidelines. Performed jet fan sound power level tests inside the DTWB tunnel to verify sound power data provided by the manufacturer. In-situ tests were performed using a B&K 4204 reference sound source in accordance with ISO Standard 3747. Reverberation time was also measured in the tunnels, using a B&K 4224 loudspeaker and white noise source, to enhance the accuracy of PB’s in-tunnel noise prediction models. Visited the jet fan manufacturer (Clarage) to critique and instruct how to perform sound power level measurements correctly.
- Baltimore Red Line Station Ventilation Noise Assessment, Maryland Transit Authority, Baltimore, MD – Performed a community noise evaluation of ventilation fans proposed for inclusion in five new Red Line transit stations in downtown Baltimore. Predicted ventilation fan sound power levels emanating from air shafts using the TAP acoustics model and propagated fan noise levels to nearby community receptors using the Cadna-A model. The results were evaluated for compliance with the project’s noise criteria established per FTA procedures, and the insertion loss of fan silencers and shaft surface areas requiring acoustical absorption were determined. Also predicted ventilation fan interior noise levels at terminal dampers in the patron platform area for the Inner Harbor Station. Interior fan noise levels were predicted using the TAP model, with the results evaluated for compliance with the project’s 85 dBA criterion for understanding unamplified speech during an emergency and 92 dBA to avoid long-term hearing damage for station employees.
- East Side Access Project Ventilation Buildings Fan Noise, New York Metropolitan Transit Authority, New York City, NY – Performed review of ventilation fan noise studies (done by others) for eight ventilation facilities associated with a new transit rail line through New York City. Evaluated the proper identification and determination of relevant noise criteria limits, computed insertion loss values expected from installation of fan silencers, estimated noise reduction due to use of Pyrok absorptive treatment, confirmed that community noise levels would comply with FTA and NYC exterior criteria.
- Tunnel Jet Fan Community Noise Predictions, Central Artery/Tunnel Project, Boston, MA – Community noise prediction models were developed in order to evaluate potential CA/T Project tunnel jet fan noise consequences in various areas of Boston. The noise models were based on laboratory tested sound power source spectra for the given fans, and took into account tunnel wall surface absorption, intervening boatwall barriers, and the insertion loss characteristics of applied silencers. The predicted noise level results were evaluated within the model for acceptability against the City of Boston's Noise Code. The noise model was featured in a paper given at the 2001 AWMA Conference.