Temporary noise shields are like 7-layer bean dip

When I was growing up, we had to take home economics. The home ec teacher was fanatical about contrasting colors, textures, and flavors to maximize food exposure. I was thinking about that teacher (who marked me down for macaroni and cheese and carrots as an overuse of a single color) when we took a tour of the noise barriers on the I-90 express lanes where we are using jackhammer and generators to remove the 40-ton expansion joints from the bridge deck.

Our temporary noise shields are like seven-layer bean dip. Each layer serves a function. These shields are designed to eliminate some of the noise during the operation of a hand tool, jackhammers, generator, compressor or a a light machine. We use these shields on many of our projects, especially when we work at night, or when working close to homes during the day.

Here is a diagram:

You can see the different types and width of the materials, each piece blocking sound or performing some other essential function, working in its own way to reduce the noise. For example, the cedar lattice holds the sound absorbing materials in place and provides some protection from the elements while allowing the sound access to fiberglass insulation. The fine mesh aluminum screen helps to keep the sound absorbing thick fiberglass material from settling to the bottom of the wall.

Here is a picture of the shields on I-90. You can see how we shield the busy construction site noise from the surrounding neighbors. A secondary benefit is that drivers on both sides of the I-90 bridge do not slow down to "look" at what is going on by the construction site.

Do they work? I checked in with our noise office recently. They’ve been out on Mercer Island every third night with the noise meters to assure residents that we are in compliance with our noise permits. Larry tells me the only thing he’s picking up is the waves lapping on the shore and traffic on the highway and local streets.

Submitted by Jamie Holter.