Since 2021, residents near the Golden Gate Bridge in San Francisco, California, have been complaining about a strange humming sound emanating from the world-famous bridge. This peculiar noise is often heard when winds hit the newly-installed railing slats on the west sidewalk from a slightly off-kilter slant.
The said railing slats were initially established to protect the bridge from damages caused by sustained high winds of up to 100 mph. Engineers have installed these to prevent the Golden Gate Bridge from experiencing the same unfortunate fate as Washington’s Tacoma Narrows Bridge, which collapsed in 1940 — shortly after it was built — due to strong winds.
Existing Structural Specifications
Golden Gate Bridge could originally withstand a maximum of 69.34 mph sustained wind speed. However, it had been repetitively shut down due to powerful winds gusting from 69 mph to 75 mph in 1951, 1982, and 1983. While there has been no damage in the past 84 years, engineers developed new railing systems to help the Golden Gate Bridge endure a maximum of 100 mph wind speed, which is estimated to happen every 10,000 years.
However, since residents have been complaining about the humming sound from the bridge, the Golden Gate Bridge District is implementing new designs to minimize the sound from the bridge’s vibration by 75%. Richardson Metals is working with the Golden Gate Project team to develop solutions to reduce or eradicate the sounds that occur during high wind events with our aluminum extrusion.
To eliminate the Golden Gate Bridge’s humming sound, engineers and leading bridge aerodynamics and acoustics experts have proposed to install thin, U-shaped clips affixed to both edges of all 12,000 vertical slats on the west railing. Thin rubbers will be inserted in these 1/8” thick 6061 aluminum extrusion clips to dampen the vibrations contributing to the bridge’s sound.
Through these clips, “vortex shredding” — the result of small vibrations in the air — will be minimized as they will lightly disrupt airflow as it passes over each slat. In addition, the clips will cover the slats from top to bottom and be painted in the Golden Gate Bridge’s famous International Orange to make it invisible to most bridge users.
Engineers and bridge experts guarantee that this new installation will not negatively impact Golen Gate Bridge’s architecture. The project is expected to be complete by the end of 2022.
Richardson Metals Aluminum Extrusion
The Golden Gate Bridge project utilizes one of Richardson Metals’ most popular grades of aluminum — aluminum 6061. This aluminum extrusion offers good strength, weldability, machinability, and formability, making it a popular choice for numerous applications.
Richardson Metals’ aluminum extrusion is an immensely versatile manufacturing process that produces many components that can be used for various purposes. Aside from aluminum 6061, we also offer aluminum 6063, which provides the finest combination of extrudability, strength, and high surface finishing attributes.
Our products may be applied in the following industries:
- Aerospace and military
- Sports and recreation
Since 1980, the Richardson Metals team has been true to our commitment to delivering high-quality custom aluminum extrusions to our consumers. We focus on low to medium production runs and offer the following capabilities:
- 4-1/2” diameter press — parts must fit within a 4” diameter circle and weigh less than 2.5 #/ft.
- 550-ton RAM press
- Thicknesses as low as 0.020” and tolerances as low as ± .005” if required
We can also extrude the following shapes for our aluminum extrusions:
- Solid shapes
- Hollow shapes
- Semi-hollow shapes
- Custom shapes