Muting the Freeway

How roadside noise barriers are designed to absorb sound and evade attention

The freeway sound wall may be as overlooked as it is ubiquitous. Lining interstates and highways and freeways across the United States, these concrete and cinderblock structures are a blur in the peripheral vision of our automotive world.

This is partially by design: sound walls serve the utilitarian role of blocking and containing the tremendous noise generated by high speed transportation, and they’re built to do their job without distracting the people driving past in thousand-pound vehicles at more than 100 feet per second.

And yet, if you’ve ever looked at sound walls on the freeway, you’ve probably noticed that they are indeed designed, albeit somewhat minimally. A band of brown cinderblock cuts through the beige, a textured row of bricks juts out at the top, a zigzag waves along as you drive by. Sound walls are subtly decorated, and there are designers — mostly landscape architects — whose job it is to design them. There are now thousands of linear miles of freeway sound walls lining roadways in the U.S., and their simple patterns are an indelible part of the American landscape. Despite this abundance, sound walls are little more than an ignorable background architecture, something to look away from or even despise. Given their massive footprint on our built environment, that seems inordinately dismissive.