How strong must winds be to close Narrows bridges?

The in basket: With a Baker family function scheduled for Saturday on the east side of the Tacoma Narrows Bridge, there erupted quite a flurry of Facebook posts and e-mails wondering whether the predicted weekend storm posed a threat of family members being stuck in Tacoma should the gusts close the Narrows bridges.

I know there is a widely publicized standard for closure of the state’s floating bridges (sustained winds of 45 miles per hour, I think) but I’d never heard comparable thresholds for the Narrows. So I asked about that and when they activate the common precautions of “severe wide winds on bridge’ on the electronic signs on each side of the spans.

The out basket: Claudia Bingham-Baker, spokeswoman for the Olympic Region of state highways, had the answer ready and waiting, having already fielded a request for the information from the Tacoma newspaper.

“We don’t have a specific wind speed criterion for closing the bridge; it’s a call we make based on the (following) criteria, and we err on the side of public safety,” she said.

“Staff at our Traffic Management Center monitor the wind blowing across the Tacoma Narrows Bridge decks in three ways, all low-tech and all effective:

1) They monitor the wind socks on the bridges and issuing a warning when the socks are fully extended.

2) They monitor how well motorists, and large trucks in particular, are staying in their lanes.

3) they use input from WSP and other partners to help gauge when winds are getting unruly.

“We do have electronic wind monitors on the eastbound bridge that relay wind data directly into our Traffic Management Center. That instrumentation is, however, on the tops of the towers and wind speeds at that elevation are often different than wind speeds at the roadway deck level.

“We know the word “severe” is not a term used on the Beaufort Wind Scale. We use it because it matches static signs approaching the bridge. Our goal is not to be alarmist, but to warn drivers of all types of vehicles when they need to be aware of the wind conditions so they can adjust their driving accordingly.

“We care more about the safety of drivers crossing the bridges than we do about the nautical correctness of the term or the frequency with which the wind conditions justify the warning.  After all, it is not unknown for semis to be blown over while trying to cross those bridges.”

The target audience for those warnings, I’ve been told in the past, are those semis, not passenger cars, though all drivers should heed them.

She could recall the closure of one or both bridges only twice, once during an ice storm and the other when a semi was blown onto ints side, she said

3 thoughts on “How strong must winds be to close Narrows bridges?

  1. So wouldn’t it be smart to put an electronic wind device at the bottom of the bridge to monitor wind speed on a traffic level.

    1. They’re not going to consider ridiculous questions such as those my good man! What are you, are you out of your mind? If their system for describing how to determine conditions doesn’t make any sense it must be that we are unable to believe as they do. The thing is, something must be terribly wrong with those who doubt when things do not make sense.

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