Restoring the peace

August 2005 » Feature Articles
Noise is an ever-increasing byproduct of our modern world. While there are many sources, transportation noise - buses, trucks, and constant traffic - is perhaps one of the most difficult to cope with, especially for residents next to a busy highway.

Concrete barriers provide cost-effective solution to sound wall challenges.

 

Project
Design of sound walls for Houston's Uptown area

Landscape architect

SWA Group

Project application
Precast concrete sound walls provide a maintenancefree, cost-effective, and attractive solution to highway noise for an upscale Houston neighborhood.

BY CATHY O'NEAL

Noise is an ever-increasing byproduct of our modern world. While there are many sources, transportation noise - buses, trucks, and constant traffic - is perhaps one of the most difficult to cope with, especially for residents next to a busy highway.

In the 1970s, the federal government set noise standards for highways and linked highway noise reduction to approval for federal funding of highway projects.

According to the Noise Pollution Clearinghouse, a national nonprofit organization with extensive resources on noise pollution and solutions, there are three ways to attack the problem of highway noise: vehicle control, land use (distancing residential developments from the highway), and planning and designing buffer zones or barriers.

As available land decreases, particularly in urban environments, separating residential areas from transportation corridors and building extensive buffer zones between highways and housing become less viable solutions. In addition, existing buffer zones are eroded when existing highways are widened. However, Noise Pollution Clearinghouse and U.S.

Environmental Protection Agency studies show that sound barriers can cut highway noise levels in half.

Sound barriers can be built with earth mounds, but that requires a lot of land.

Sound walls made of wood, stucco, masonry, metal, or concrete require less space. According to Barry Stevens of Euless, Texas-based Superior Concrete, designers should consider structural factors and sound characteristics when determining what materials to use to build a sound wall. Superior Concrete designs, manufactures, and installs precast concrete highway sound and privacy walls, as well as walls for corporations, shopping malls, and other applications.

The following factors should be considered to determine the best type of structure: the type of wall to be built; the wall's height; the strength of the soil that will support the wall and anchors; and local street codes that dictate how much load can be applied without affecting the structural integrity of existing infrastructure. For example, a giant masonry wall may not be allowed because of its weight when it is built tall enough to block street noise effectively.

Additionally, sound levels determine the types of materials that will achieve the greatest sound transmission loss. The nature of the sound also is a consideration, Stevens said. Most often, the source is general traffic noise.

Increasingly, civil engineers and city planners emphasize noise barrier designs that are visually pleasing and that blend in with their surroundings. For example, the Uptown area on Houston's west side is everything that the name implies - upscale, tony, and affluent looking.

Expansion of U.S. Highway 59 to the border of the Chimney Rock residential area posed a challenge to the Uptown Development Authority and its prime landscape architect, the SWA Group, based in Sausalito, Calif. They needed a sound wall to suppress highway noise within the neighborhood, but it had to complement a recently built retaining wall that would connect to the new sound wall. The new retaining wall was built at a substantial cost, so duplicating it was not an option, considering the development's budget.

“We wanted to continue that look, but do something with different materials and colors that hadn't been done before,” said Lauren Brown, a project manager for SWA Group, who was responsible for the sound wall's design. “But we needed to do it affordably.” Brown searched landscape architect magazines and the Internet for resources.

She found Superior Concrete and learned that it custom designs walls with decorative patterns and colors to look like expensive wood, brick, and stone, but at a cost that averages 50 percent less than these materials.

The concrete mixtures are consolidated into textured forms to make the concrete panels. The cured, customized panels then are set into an invisible, seamless framework with panel caps to form the walls.

Superior Concrete manufactures the panels, delivers them to the worksite, and installs the framework and wall to the customer's specifications.

Together, SWA Group and Superior Concrete designed a two-color, 8-foot-high sound wall for Chimney Rock using cobblestone-textured panels with alternating horizontal bands of desert tan and buff that cost less than other bids for the new wall. Superior Concrete's precast walls were chosen for Chimney Rock not only for their cost, but also for their flexibility, said Stevens. Uptown Development wanted something that looked attractive on both the street side of the wall and the neighborhood side. Having a sound wall that is maintenance free also is a benefit, so Superior Concrete designed a wall with a multicolor look and texture that would not require repainting after exposure to the Texas sun and rain. The design also gave the sound wall a wainscot look with depth.

“[Superior Concrete] worked closely with us to achieve the different look we were going for,” said Brown. “I don't think people expect much out of prefabricated concrete walls, so we were able to deliver something different.” Stevens calls the Chimney Rock project an “extreme decorative solution” for minimal cost. “Creating patterns and colors for a unique look is a logical extension of our services,” he said. “Since we manufacture our own products, we can be creative.” Chimney Rock was the first project Houston's Uptown Development Authority has done using this type of concrete barrier wall. “Other options were limited as to what we could do, like the contrasting colors in the banding,” said Robert Taube, director of engineering for Uptown Development.

“This is a nicer area of town, so quality is important to the neighborhood.” What's it like living next to a concrete wall barrier? According to Noise Pollution Clearinghouse surveys, residents report that even though only a wall separates their homes from a busy highway, the barriers allow for easy conversation, better sleeping conditions, and a relaxing environment. In addition, they report being able to open their windows more often and use their yards more in the summer. Not only is noise under control, residents said the walls provide more privacy, an improved view, and healthier lawns and shrubs.

Cathy O'Neal is a copywriter for Envision Works, a creative communications company in the Dallas/Fort Worth, Texas, Metroplex.


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