Tag Archives: grates

Catch-22 in old bridge’s HOV lane

 The in basket: Ken Luzbetak of Bremerton said in an e-mail, “The other night I saw a Washington State Patrol running with lights and sirens across the old Tacoma Narrows bridge toward Gig Harbor in the HOV lane. There was a car ahead of him. I couldn’t see how it turned out, but should the driver ahead of him changed lanes on the bridge (despite it’s being prohibited) or fail to yield (against the law) and make the WSP change lanes?”

The out basket: A driver in the HOV lane on the old bridge should proceed until he or she is past the grates that separate the lanes and then pull over for the officer, says Trooper Krista Hedstrom of the Bremerton detachment. 

“The troopers that work in the Gig Harbor detachments will usually shut off lights and sirens as they cross the bridge for (this) very reason,” she said.  “However, there may be times that a trooper will continue with lights and sirens across the old bridge. The recommendation – wait until you are safely across the bridge, then move out of the way.”

The difference in traction between the grates and the pavement is the main reason lane changes are forbidden on the old bridge.



Why aren’t lane changes allowed on old Narrows Bridge?



The in basket: Richard Hood of Belfair e-mails to say, “All my life, I’ve always wondered why you couldn’t change lanes on the (now old) Tacoma Narrows Bridge. I’ve been told that air passing through the grates could flip your car over, but is that true? I’d really love to know the truth.”

The out basket: That sounds like the product of an overly fertile imagination. I told Richard that I believed that lane changes are recognized among highway designers and enforcement agencies as a major cause of accidents, and in the close quarters of the old bridge, even minor accidents meant major traffic delays for want of somewhere to move the cars. 

But Jamie Swift of the Olympic Region of state highways says there’s a more direct reason. 

“Lane changes are prohibited on the 1950 bridge,” he said, “due to the difference in friction between the traffic lane and the grates as drivers switch

lanes.” It has nothing to do with air passing up through the grates, which, as I recall, were made part of that bridge to lessen its wind resistance and avoid the calamitous end its predecessor, Galloping Gertie, met.

Original plans for retrofitting the old bridge after the new one opened called for taking out those grates to facilitate making the bridge three wider lanes westbound with a shoulder. But plans changed after public sentiment for four westbound lanes prevailed.  As a result, says Claudia Cornish of the bridge staff, “the grates were kept in the bridge deck, and two changes were made to accommodate that design:  1) the right westbound lane now ends at the first exit after the bridge; 2) The fourth lane begins around Sixth Avenue, so when you’re approaching the old bridge, you can get into that fourth lane before you actually reach the bridge.” 

I’ll let the engineers and aerodynamics experts in our readership weigh in on whether there’s any chance that air passing through the grates might affect the performance of a car, but I doubt it.