The Golden Gate Bridge district began plans this week to study a new noise emanating from the bridge that can be heard for miles on gusty days.
The sound is the result of fast northwesterly winds passing through new railings and wind fairings on the western side between the two towers as part of on ongoing wind retrofit project.
It has been described by the district as “singing,” but some local residents during Friday’s bridge board meeting had other choice words, calling it screeching that sounded like torture and saying it caused such physiological distress that it was impossible to ignore.
After the noise became noticeable at the beginning of June, the district put out a statement on June 6 stating that the “new musical tones coming from the bridge are a known and inevitable phenomenon that stems from our wind retrofit project during very high winds.”
District officials seemed to walk back the comments at the meeting on Friday.
“We had no idea that this would happen,” bridge chief engineer Ewa Bauer-Furbush told the board.
Director Sandra Lee Fewer of San Francisco said she has received “a couple dozen emails” and correspondence expressing concern about the noise.
District staff spoke with a consultant on Monday to discuss plans to study the cause of the noise and develop changes to potentially muffle it. In the meantime, Bauer-Furbush said they plan to record the sound and compare it to their weather station data to create a baseline record of when and under what conditions the noise occurs.
What is known is the noise emanates when the winds are fast enough and pass through the railings at the right angle, Bauer-Furbush said.
“I don’t want the public to think that the bridge is singing each and every day, but just on these occurrences when the wind is hitting it just right,” director David Rabbitt of Sonoma County said during the meeting.
The wind retrofit is being performed to ensure the bridge can withstand winds of up to 100 miles per hour, Bauer-Furbush said. It is also required as part of the installation of the bridge’s suicide barrier that is under construction. About 75% of the new railings have been installed and about 10% of the wind fairings.
The project’s final environmental impact report, published in 2010, found that the new railings and fairings would not result in any substantial increase in ambient noise compared to before its installation.
“Do we have any explanation as to why the EIR … didn’t predict this noise?” director Dick Grosboll asked during the meeting. “Was it just a mistake?”
Bauer-Furbush said the district had engaged experts to conduct multiple tests on a 1:20 scale model of the bridge. The model bridge was constructed of aluminum and plastic, however, not of steel as it is on the actual bridge, she said.
“There were predictions that the wind retrofit may cause some new sound on the bridge simply because no air is allowed to pass over the roadway,” she said.
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