Tests Indicate Modest Noise Levels from Mission Bay Helipad

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When the University of California San Francisco Benioff Children’s Hospital opened last winter one of its features was San Francisco’s first rooftop helipad.  The helideck allows critically ill newborns, children and pregnant woman to be transported to and from the facility in a way that minimizes complications associated with ground transportation, providing access to advanced, lifesaving medical care in the swiftest manner possible.

The 289-bed complex includes a family-centered children’s hospital with 183 beds, non-life threatening and emergency care; clinics for pediatric primary care and specialties, such as cardiology and endocrinology; a 70-bed adult hospital for cancer patients; a women’s hospital for cancer care and specialty surgery, such as neurological and thoracic; and a 36-bed birth center and women’s clinics.

Inclusion of the helipad at Children’s Hospital wasn’t without controversy.  Prompted by community concerns about noise, UCSF assessed the potential for adverse sound levels from helicopter transport.   Since 2001, UCSF has held more than 60 meetings to provide community members with opportunities to opine on numerous issues, including hospital location and design, traffic and noise.

In 2007, UCSF retained Harris Miller Miller & Hanson Inc. (HMMH), a national consulting firm that specializes in transportation noise, to assist in analyzing the racket associated with helicopter transport. “I can confidentially say that in comparison to other hospitals’ noise mitigation programs UCSF is considerably more generous,” said Eugene Reindel HMMH vice president and aviation services group leader. According to Reindel, UCSF conducted expansive and indepth noise testing, and adopted a community noise reduction program.

To assess the potential din, particularly nighttime helicopter landings and takeoffs, UCSF used Single Event Noise Exposure Level (SENEL), a metric that includes both level and duration of noise events.  UCSF chose SENEL over Community Noise Equivalent Level, which measures and averages helicopter sound impacts over a 24 hour period. By using SENEL UCSF ensured they evaluated every incident, rather than an averaged outcome.

Community input prompted UCSF to relocate the helipad northward, to the center of their Mission Bay campus, and place an elevator shaft, already set to be constructed within the building, to the south to act as a barrier to reduce helicopter noise propagating southwards towards the closest residents on Mariposa Street. 

“The UCSF accommodation of community concerns, the relocation of the helipad, and the placement of the elevator shaft proved quite useful,” said Reindel. “In addition, the hospital buildings help shield helipad noise from those closest neighbors.”

“I was very interested in the pad and the hospital when it was first proposed, so I kept pretty close tabs…,” said Edward Lotz, who has lived on 19th and Texas streets for 30 years, where he now has a direct view of Children’s Hospital. “I barely noticed it” during an afternoon test last summer “and only heard it for 10 seconds, and only then after it lifted off. I only heard it because I was sitting on the deck reading in the nice weather; partner inside never heard it. It had landed at 2:40 p.m., and I didn’t notice that until it was on the pad, having been quieter than the ubiquitous traffic choppers hovering over 280 on busy mornings and the red and white sightseeing choppers. Today, it happened again when I was reading on the deck, and again I barely noticed it…I think the flight paths are well designed to stay over water as much as possible.”

Community advocates prompted UCSF to develop a Residential Sound Reduction Program (RSRP), which was approved in 2009 by the San Francisco Board of Supervisor. RSRP addresses noise effects from individual helicopter transports.  According to survey data collected by the Federal Interagency Committee on Noise (FICON), 30 percent of people are wakened by aircraft events measured at 80 decibels (dB) SENL inside the room in which they’re sleeping. Because most homes reduce aircraft noise from outside to inside by at least 5 dB, UCSF used an exterior noise level of 85 dB to define the sound parameter, or contour, around properties which would qualify to apply under the RSRP. HMMH determined that no residential properties experienced 85 dB, or 80 dB inside, from normal helicopter transports.

“We – UCSF Medical Center, the local community and the City – were all pleased that our multi-year collaboration resulted in a win-win not only for the children and pregnant women needing our immediate care via helicopter transport but for the neighbors living nearby…,” said Cindy Lima, former executive director for Mission Bay Hospitals Project, and current executive director for UCSF Health Organizational Program Management.  “We are very pleased that the newer, quieter medical transport helicopters will have less noise impact than we originally expected.”

If, through additional testing, any sleeping areas within the noise contour developed by HMMH are shown to experience SENL higher than 80 dB, they’d qualify for sound reduction measures, financed by UCSF. Additional testing will be done on the blocks defined by Mariposa and 18th streets between Tennessee and Minnesota streets. If sound mitigation is required UCSF will work with HMMH to determine what’s needed, which could include insulation, new windows and doors, weather stripping, or other measures.

“It’s better a few seconds slight extra noise if it means a child is being saved,” said Lotz.