Pennsylvania Turnpike tests composite sound barriers

July 2009 » Web Exclusive
Jared Brox
The Pennsylvania Turnpike Commission is evaluating a lightweight composite sound barrier along a stretch of highway near the Ohio border.

For years, precast concrete has been the industry standard for highway sound barriers, largely because of a lack of acceptable, cost-effective alternatives. However, the Pennsylvania Turnpike Commission recently completed a sound barrier project using a composite alternative that is not only easier to install and environmentally friendly, but also has the potential to save hundreds of thousands of dollars.

Project
Pennsylvania Turnpike sound barriers

Participants
SAI Consulting Engineers (structural engineers)
McTish, Kunkel & Associates (civil engineers)
Joseph B. Fay Company (contractor)

Product application
Eco Sound Barrier incorporates recycled material into a lightweight panel that costs less and is easier to install than precast concrete.

The Pennsylvania Turnpike was the first to use the new barrier—Eco Sound Barrier by CENTRIA—on the $100 million renovation of a 7.5-mile stretch of highway near the Ohio border. The overall project involved reconstructing a section of the turnpike, expanding the existing four-lane highway to six lanes. The sound barrier was used to provide noise mitigation on the section of the turnpike that runs through Enon Valley, Pa.

CENTRIA presented Eco Sound Barrier to the turnpike commission as an option for the project. According to the manufacturer, it is the only highway product to be “cradle-to-cradle” certified—made from 25 percent recycled material and 100-percent recyclable at the end of its useful life. Cradle-to-cradle is a model based on lifecycle assessment of human industry, materials, and design and their impact on the natural environment. The barrier panels are constructed out of a polymer composite core with galvanized or aluminum substrates.

“There is certainly something to be said about the environmental benefits of this product,” said Kevin Scheurich, project manager for the Pennsylvania Turnpike. “It’s hard to put a real cost to it, but it is definitely something we consider.”

Raymond Henney, of SAI Consulting Engineers, was in charge of the sound barrier design for the project. He said that Eco Sound Barrier was an effective option and didn’t create any engineering burden for him. “It wasn’t any more difficult to design the barrier using Eco Sound Barrier than it would have been using precast [concrete],” Henney said. “The only real difference with this project was that the footings had to be a little wider. This was because of the sandy soil conditions of the jobsite and to accommodate the sound barrier panels’ light weight.”

The wall was positioned back from the road to take advantage of a natural slope, which minimized the amount of earthwork needed to reach the required height. By utilizing this slope and placing the wall farther from the road, the footings could be raised, reducing the height of the wall and lowering costs. Bedding was also placed to make a more suitable pad for the footings. The only concern with Eco Sound Barrier was whether the lighter panels would stand up against high winds, but the slightly wider footings addressed that issue. The footings were also continuous along the length of the barrier instead of being spaced at the posts. This, however, was a contractor preference, not a requirement of the sound barrier.

Even though the environmental benefits were interesting to the Pennsylvania Turnpike, what was most appealing was the up-front cost savings. Eco Sound Barrier material cost is about one-third as much as precast concrete. “It was very innovative, so we wanted to give it a try,” Scheurich said. “It seemed like a cost-efficient alternative to precast sound barriers.”

The Pennsylvania Turnpike, in turn, approached Joseph B. Fay Company, the contractor for the turnpike renovation, with the new product. “We received some preliminary information on the panels, and right away we saw the potential advantages of using Eco Sound Barrier,” said Eric Klimas, project manager for Joseph B. Fay. “We then had our engineers spend some time with it and found it to be a good alternative to precast.”

The 1,800-foot-long by 15-foot-high sound barrier cost almost $385,000 under budget. Material costs for the barrier project were originally bid at $600,000. Precast panels were quoted at $25 per square foot for the Pennsylvania Turnpike project. However, Eco Sound Barrier panels cost only $10 per square foot, which translated into an estimated savings of about $366,000 in material costs alone.

Composite panels weigh only 2.25 to 4.25 pounds per square foot and require fewer workers and smaller cranes for installation.

Eco Sound Barrier offered additional benefits during the construction process, beginning with transportation of the panels to the jobsite. At only 2.25 to 4.25 pounds per square foot, the composite panels weigh dramatically less than precast panels. The original estimate, which accounted for using the precast panels, called for 45 truckloads to deliver the product to the jobsite. In the end, only six truckloads were needed. That saved almost $24,000 on transportation to the site and labor unloading the trucks at the jobsite.

“More product on fewer trucks means less labor spent on unloading and fewer trucks in and out of traffic around the jobsite, which also really helps to increase overall safety,” Klimas said. “Reducing labor costs and risk is one the biggest factors to staying under budget in any construction job.”

Joseph B. Fay also saved on labor during the installation process. “Precast would have taken a four-man crew three to four weeks to install,” Klimas said. “The same crew completed the Eco Sound Barrier installation in only five days.”

The four-man crew plus one crane operator would have cost an estimated $45,000 for four weeks of work, but because the project was completed in only five days, Joseph B. Fay was able to save more than $33,000 in labor. And, although they used the same size cranes and equipment they would have used with precast panels on this project, Klimas said they could have easily used much smaller machines. They just decided to use what they already had on hand.

Lifecycle analysis
Pennsylvania Turnpike Project Manager Scheurich agreed that the cost savings are impressive, but now the barrier must withstand the test of time. “We are looking at it from a lifecycle perspective right now,” he said. “The initial savings are great, but if we have to replace it too soon, it might not be cost effective over the life of the barrier. Winters in Pennsylvania can be very harsh, and we would like to see how the panels hold up against freezing temperatures and road salt. We really have to weigh the risk against the reward at this point.”

The manufacturer offers a 20-year finish warranty on Eco Sound Barrier panels. Although the Pennsylvania Turnpike project was the first time the technology was applied to a transportation project, CENTRIA has been using the same composite materials in structural building applications for more than 40 years. According to Rick Mowrey, director of marketing and business development for CENTRIA, these composite walls have been standing for 40 years or more in architectural applications without requiring any maintenance.

Overall, both the Pennsylvania Turnpike Commission and Joseph B. Fay said the project was successful. And the residents of Enon Valley seem to be satisfied as well. “Typically, if the people are happy, we don’t hear from them,” Scheurich said. “They only speak up if they’re disappointed, and we haven’t heard anything yet. So, I’m taking that as a good sign.”

This article was written by Jared Brox, Two Rivers Marketing, Des Moines, Iowa, on behalf of CENTRIA, Moon Township, Pa.


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