In 2010, we installed a test section of noise-absorptive ceiling panels on the bridge. The test section is on the outer edges of the ceiling above the I-5 express lanes. The ceiling panels are designed to absorb and block some of the reflected traffic noise that bounces off the ceiling of the express lanes and into the surrounding neighborhoods.
The test section is approximately 500 feet long and begins just south of E. Gwinn Place and end just north of E. Allison Street.
Test section configuration
The test section consists of several rows of panels, on the outer edges of the east and west sides of the bridge, oriented parallel to the direction of traffic (see graphic below). The panels hang down from the ceiling of the express lanes, like a curtain. Each panel is mounted in a rigid frame and is bolted securely to the ceiling.
Ceiling panel material
The ceiling panels consist of a cloth covering on the front, a layer of insulation, and a durable vinyl back. They are stitched together in a quilted pattern with a high-strength thread. While the quilted cloth front helps absorb the sound waves into the insulated portion of the panel, the vinyl backing serves to block noise. This type of material is suitable for outdoor applications, and is typically used in industrial applications and near construction sites to minimize noise.
||Example of the noise-absorptive ceiling panel|
Monitoring and evaluating the test
The ceiling panels are intended to reduce the reflected and reverberant noise that occurs when traffic noise bounces off the ceiling, or other structures, and back into neighborhoods. Based on the results of our noise model, we anticipate that the ceiling panels will result in a noticeable reduction in traffic noise for properties closest to the test section.
Since this is the first time that this type of material has been used in this application, we will monitor the test section for at least one year to evaluate its effectiveness at reducing noise and its actual durability in this environment. The results of the monitoring will be described in a final report. WSDOT remains committed to addressing noise in this area, pending additional funding.