The Hood Canal Bridge after the failure

On this Day:

In 1979, Washington State USA’s Hood Canal Bridge catastrophically broke up in a windstorm.

The Hood Canal Bridge (officially William A. Bugge Bridge) is a floating bridge in the northwest United States, located in western Washington. It carries State Route 104 across Hood Canal of Puget Sound and connects the Olympic and Kitsap Peninsulas. At 7,869 feet (1.490 mi; 2.398 km) in length (floating portion 6,521 feet (1.235 mi; 1.988 km)), it is the longest floating bridge in the world located in a saltwater tidal basin, and the third longest floating bridge overall. First opened 61 years ago in 1961, it was the second concrete floating bridge constructed in Washington. Since that time, it has become a vital link for local residents, freight haulers, commuters, and recreational travellers. The convenience it provides has had a major impact on economic development, especially in eastern Jefferson County.

The bridge is officially named after William A. Bugge (1900–1992), the director of the Department of Highways from 1949 to 1963, who was a leader in the planning and construction of the bridge.

Design, fabrication, and construction

The design and planning process for the Hood Canal Bridge took nearly a decade amid criticism from some engineers throughout that time. Critics questioned the use of floating pontoons over salt water, especially at a location with high tide fluctuations and the concern that the funnelling effect of the Hood Canal might magnify the intensity of winds and tides. The depth of the water, however, made construction of support columns for other bridge types prohibitively expensive. The water depth below the pontoons ranges from 80 to 340 feet (25 to 105 m). In its marine environment, the bridge is exposed to tidal swings of 16.5 feet (5 m).

The pontoons for the bridge were fabricated in the Duwamish Waterway in Seattle; during fabrication, two of the pontoons sank. When they were attached for the first time, and then towed into place and anchored, sea conditions in the Hood Canal were too severe and the pontoons were returned to a nearby bay until a better method of attaching could be devised. The structural engineers and the contractor decided the design was faulty. A new contractor was hired and the design modified. It was decided to use a large rubber dam between each of the two pontoons as they were attached, clean the concrete surfaces of all marine growth, epoxy, and tension them with a number of cables welded to a variety of attachment points. This system seemed to work from when the bridge opened in 1961 until the disaster of 1979.

The eastern approach span weighs more than 3,800 tons (3,400 tonnes) and the western approach span weighs more than 1,000 tons (907 tonnes)

1979 sinking

The Hood Canal Bridge suffered catastrophic failure in 1979 during the February 13 windstorm. During the night, the bridge had withstood sustained winds of up to 85 mph (137 km/h) and gusts estimated at 120 mph (190 km/h), and finally succumbed at about 7:30 a.m. on Tuesday, February 13. The western draw span and the pontoons of the western half had broken loose and sunk, despite the draw span being opened to relieve lateral pressure.

At the time of the failure, the bridge had been closed to highway traffic and the tower crew had evacuated; no casualties resulted. Evidence points to blown-open hatches allowing flooding of the pontoons as the cause of the sinking (per Wikipedia).

First, a Story:

What do you call a polite professional who builds bridges?

A civil engineer

Second, a Song:

The Hood Canal Floating Bridge is one of the few permanent floating bridges in the world, but what caused it to fail spectacularly in 1979? Quest TV’s video on why the Hood Canal Bridge failed (per I hope you enjoy this!


Thought for the Day:

“He that cannot forgive others breaks the bridge over which he must pass himself; for every man has need to be forgiven.” – Thomas Fuller

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Have a great day!

Dave & Colleen

© 2021 David J. Bilinsky and Colleen E. Bilinsky

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