Second test readings made on I-5 Ship Canal Bridge noise panels effectiveness

The state Department of Transportation made its second set of measurements of the effectiveness of the I-5 Ship Canal Bridge noise reduction test panels on Thursday, Feb. 10.

The test program saw fiberglass noise reduction panels suspended beneath the southern end of the upper deck of the Ship Canal Bridge. The hope is that the panels would reduce the amount of reflected noise that comes off the lower deck and spills over into adjacent neighborhoods.


When noise levels were first tested at 18 locations last fall, the results weren’t as encouraging as hoped for. According to a WSDOT press release in late October, “the panels are working as well as predicted in about a third of the locations, but not as well as predicted in about two-thirds of the locations.”

Engineers had hoped to see a three to five decibel reduction in noise levels in the neighborhood along Harvard and E. Allison. Instead, levels were only down about two decibels. A WSDOT press release says: “This second round will give noise experts two data points to more accurately compare noise levels.”

Data on this second round of tests will be posted to the project’s web page by Feb. 25. The test project will last three years, after which the WSDOT will determine if it would be effective to deploy more of the panels on the bridge.

To see an Eastlake Ave. video on the project, go to our previous post.