Those “Severe Side Wind” warnings at Narrows bridges

The in basket: John Veatch of Bremerton writes, “One of my pet peeves is the habit by the state to claim there are severe high winds on the (Tacoma) Narrows Bridge when there is barely enough wind to make the wind sock jiggle. 

“I feel they shouldn’t turn on the ‘Severe Winds’ sign until the velocity is up to at least 15 knots.  Do you know what their policy is and how it is triggered?  The way it is results in my thinking it’s just another false alarm and grow to ignore its importance.”

I had noticed the same thing.

The out basket: Well, John and I in our passenger cars aren’t what you might call the key demographic for whom those messages are intended.

Hal Weiblen, Traffic Management Center supervisor for the state, replies, “Wind warnings at the Narrows are activated by either of the two criteria.

“One, the TMC operators notice that the wind socks on either end of the bridges are extended, or two, when notified by the WSP that wind conditions are being reported or experienced that may cause a concern for motorist or truckers crossing the bridge.  

“There are no weather instruments located at the bridge deck (where the traffic is) to indicate wind speed at that level, only the wind socks,” Hank said. “It should also be noted that wind will often be indicated by the socks at one end of the bridge, but not at the other, but motorist must cross both ends of the bridge (we hope).  

“As such, we always want to err on the side of safety,” he said, “as no one can tell us what an appropriate wind speed would be for activating the alerts.  A mild breeze barely felt by a motorist in a car, could be quite severe for a semi-truck, or for someone on a motorcycle, so the wind warning message is activated upon a visual observation, and allows the motorist to at least be prepared to encounter an unusual driving condition. 

“Years ago, we did a survey with the trucking industry to try and determine what a wind speed criteria would be for trucks, and the responses I got back were across the board, which basically came back to me as ‘What is the cargo?’  

“A truck carrying a load of  (plastic) foam cups will be much more negatively impacted then a cargo of iron anvils.  So you can see there is no clear-cut answer to the question of what speed to activate such messages.” 

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