Traffic Q&A: Some Narrows Bridge tiles have fallen, DOT testing new application

Staff writerApril 27, 2014 

Question: Has anybody else noticed that the sound walls on the new Tacoma Narrows Bridge are coming apart? Driving across, you can see that a bunch of the big acoustic tiles on the walls are missing. What’s going on with that?

If I remember right, the walls were put up after neighbors complained about the noise of cars crossing the steel joints at the ends of the bridge. Has anybody complained about increased noise?

— Karen, Gig Harbor

Answer: You remember right. The sound walls were put up after the bridge was completed to help reduce the zipper noise of tires rolling across the new bridge’s two expansion joints.

The 24-inch-square tiles on the walls are made of a special aerated concrete material called “SoundSorb,” and they were stuck onto the walls with adhesive supposedly designed specifically for that purpose.

The adhesive didn’t stick.

“Some of the tiles loosened and fell off the walls,” said Washington State Department of Transportation spokeswoman Claudia Bingham Baker. “When we noticed the problem, we checked each tile and proactively removed those found to be loose to eliminate the potential of them falling into a lane.

“The tiles that remain tightly attached with the adhesive will continue to be monitored by bridge crews and will remain as is as long as they stay tightly attached,” Bingham Baker said. “We’ve reattached 50 new tiles using an epoxy plus a rod that has been drilled through the tiles and into the concrete wall.

“We’re monitoring to see how those tiles stay adhered through the various seasons, and once we know that, we’ll decide how to best move forward.”

Bingham Baker said WSDOT has not taken any noise level measurements so it’s unclear if the noise level has changed.

“Nobody has complained that I know of,” she said.

Rob Carson: 253-597-8693
rob.carson@thenewstribune.com

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