Precast concrete and living plants come together to create the perfect sound barrier for a park in Chicago.
By Matt Werner
The popularity of urban trails has increased exponentially in recent years as communities use them to connect neighborhoods, mitigate traffic congestion and encourage exercise. The trails also create green space, which can be hard to come by in congested cities like New York or Chicago.
The 606 in Chicago, a $95 million urban trail project that took a decade to plan and build, opened to the public in 2015. The city repurposed an elevated freight train line to create a 2.7-mile path that connects six ground-level parks and areas that were cut off by the abandoned rail line while adding much-needed green space to several neighborhoods on the city’s northwest side.
At the eastern end of the trail sits Walsh Park, a major entryway for the trail that is nestled right next to Interstate 90/94. The trail comes to a head in the park, with a six-lane highway on one side, two sides buffered by residential housing, and the fourth side opening to an outdoor amphitheater.
To keep the highway noise out of the park and ensure concerts don’t disturb the 80,000 nearby residents, a sound barrier was needed. But given the significance of the project, no ordinary barrier would do.
With the city and neighbors of the project wanting something that would be both aesthetically pleasing and an effective sound barrier, a precast concrete Evergreen Wall provided a solution for not only the city, but the surrounding area.
A green solution
When designing the renovation to the park, landscaping was identified as a way to provide an aesthetically pleasing backdrop to the outdoor plaza. The landscaping needed to be mature enough and tall enough to effectively block noise coming from the park as well as provide a buffer from the nearby expressway.
Enter a precast concrete Evergreen Macro Wall for the project, checking off all the boxes the design team and city officials wanted.
“The wall’s aesthetics, once planted and matured, was a big draw as well as the wall’s ability to absorb sound and resist and hide graffiti,” said James Hamelka, the project manager for Collins Engineers. “A barrier and retaining wall were needed at the end of the trail to bring the elevated trail down to grade, but neither the design team, nor our clients, were satisfied with a typical wall or barrier.”
Collins was responsible for the project management and engineering, while Michael Van Valkenburg and Artetal were responsible for the aesthetics. Hamelka noted several other benefits in using precast concrete.
“Precast was chosen because of the anticipated low maintenance that a precast product would offer,” he explained. “Precast concrete is a unique material that allows for creative forms and shapes while still providing structural capacity, durability and design properties that we are used to working with as engineers.”
On time delivery
Wieser Concrete Products, based in Maiden Rock, Wis., was selected for the project. Its plant in Portage, Wis., produced more than 100 pieces for the project. Pieces were 16 feet wide and 2.5 feet high and used a 5,000 psi concrete mix. Vice President Mark Wieser noted that extensive planning made the project easier and mitigated production issues.
“Pretty much every piece had to be custom,” said Wieser. “It was being set on a radius around the trail and park there, so the ends were tapered. As you came up the wall, the tapers all changed.”
With mere feet of clearance between the project site and the surrounding neighborhood and highway, the job site came with its own set of constraints. Hamelka credited all the skilled professionals who “worked their magic” to overcome the incredibly tight job site.
“It came down to a matter of delivering, especially with several different pieces,” Wieser noted. “We had to deliver it as they needed to set it. That way they could set it right off of our trucks and into place where they needed to go.”
Once all the elements were stacked in place, the interior cavity was filled with a local material and compacted. Then, the exterior trays were filled with topsoil and plants added to give the wall the “evergreen” look all sides were hoping to attain.
“(Using the Evergreen Wall) provided an opportunity to extend the landscape design of the trail onto the vertical wall surfaces and provide additional green space in the heart of an urban environment,” Hamelka explained. “Our client team was great to work with and was open to outside-the-box thinking throughout the project; if it wasn’t for them, none of this would have been possible.”
Now, instead of graffiti-stained walls and constant highway noise from the six-lane elevated expressway, the park has a living, breathing wall made from precast concrete. Hamelka, who used to live near the project area, said it’s been exciting to see the project come to fruition both professionally and personally.
“I was at the trail last summer, and the wall looked great,” he said. “As the plant life continues to mature, I imagine it will only look better with time.”
Matt Werner is the managing editor of Precast Solutions magazine and is NPCA’s communication manager.