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Project Title & Location
I-5 Ship Canal Bridge Noise Study,
Seattle
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Project Description
WSDOT has been evaluating new and innovative noise-reducing elements to address freeway traffic noise in neighborhoods surrounding the I-5 Ship Canal Bridge. We have identified three potential options for reducing noise: 1) For reverberant and/or reflective noise: Noise-absorptive materials on the ceiling above the I-5 express lanes. 2) For direct noise: Street-level noise walls near the bridge approaches. 3) To reduce noise at the source: Replacement or rehabilitation of the pavement.
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Contractor/Consultant
EnviroIssues, Parsons Brinckerhoff, HDR
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Recent Progress
WSDOT plans to install a 1,000-foot test section of noise-absorptive material on a portion of the ceiling of the I-5 express lanes. We will monitor the test section to evaluate the noise reduction benefits and durability in this location.
The results of a recent structural analysis show that the north approach would require retrofit work to accommodate a ceiling modification, while the south concrete approach would not require this additional work. The project team plans to proceed with a test section on the south concrete approach. We are determining the exact configuration and limits of the test section, and plan to begin installation in late 2009. We will continue to evaluate the feasibility and effectiveness of other options proposed by the expert panel.
In the past few months, the design team participated in briefings with local community council and neighborhood groups to share information about the project.
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Design Construction Impacts
Construction is expected to begin in late 2009 and will involve the placement of a ceiling treatment test section on the I-5 Ship Canal Bridge. Details of the design will be finalized as plan preparation is completed.
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Environmental Impacts / Compliance
A Shoreline Permit Exemption was received on 12/19/2007 for the south approach staging area.
A Shoreline Permit Exemption is expected for the north approach staging area. The design office is waiting on the final documentation.
No other environmental permits are expected for the project.
Requests for noise variances for night time work are planned to be submitted to the City of Seattle later this year.
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Impacts to Traffic
Work related to Traffic Control Strategies will begin next quarter. The work could involve modifications to off-ramps and possible lane restriction on I-5 for night work. Details of these impacts will be finalized as plan preparation is completed.
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