The I-5 Ship Canal Bridge noise reduction test project officially marked its first anniversary earlier this month and the results haven’t been as dramatic as had been hoped.
The Washington State Department of Transportation is testing the ability of fabric panels to dampen the reflected noise from the I-5 express lanes. The panels were hung under the I-5 Ship Canal Bridge on a 500-foot test section at the south end of structure, between E. Allison St. And E. Gwinn Place. It was hoped that the panels would provide noticeable and measurable levels of noise reduction for nearby residents.
Unfortunately, that hasn’t been the case. The latest readings were similar to the previous three, showing a drop of one to three decibels in noise in the test area. The goal was a four to five decibel reduction. In a press release, WSDOT says its acoustic engineers “have seen a small decrease in noise, but it hasn’t varied much from season to season.”
The press release says the WSDOT is learning more about “the kind of noise that travels and which kind of noisy noise is most frustrating to local residents.” The WSDOT engineers are analyzing the pitch of the reflected noise, its direction and how it bounces to see if the panels can be moved to make them more effective.
The press release notes:
“The noise readings show that residents who have a line of sight to the express lane ceiling see the least benefit. Those who can’t actually see the bottom of the top deck report noticeable changes.”
Unfortunately, there isn’t much money left in the project’s budget, so the WSDOT says we probably won’t be seeing big changes soon. Sound tests will continue until 2013 when a final report on the project will be issued.