The New Jersey Parapet Proposal
|George Harms Construction Company, Inc., is currently at work slipforming parapet in Newark, New Jersey. So far, they've slipformed 12,000 feet (3658 m) of parapet as part of a $50.4 million contract.
The contract called for the construction of the new Route 21 viaduct over the northeast corridor for the Amtrak®, CONRAIL®, and New Jersey Transit rail lines, as well as providing the ramp tie-ins of Route 21 into Route 78 eastbound and westbound. On Route 78, the contract required the removal of the existing concrete barrier and parapet and the slipforming of new parapet.
Harms Construction purchased a Commander III to slipform the new parapet.
"We purchased the Commander III because we thought it was the most versatile machine," Darrell Harms, project manager, said. "We wanted to be able to use it to slipform this parapet, but we also wanted a machine we could use on various other slipform or curbing operations we may encounter in the future."
Two different types of parapet will be slipformed on the project by the time it's completed. The first is a New Jersey Department of Transportation (NJDOT) standard parapet standing 34 inches (864 mm) high. The parapet was slipformed over an epoxy-coated reinforcing cage.
"We ended up slipforming 12,000 feet (3658 m) of that barrier," Harms said. "On Route 78, we did approximately 5000 feet (1524 m) and on the Route 21 viaduct we did the balance."
The contract also calls for the slipforming of approximately 900 feet (274 m) of split parapet, 32 inches (813 mm) tall by 15 inches (381 mm) wide.
"It's one of the last things we're doing on the project," Harms said. "It could present a challenge to us as far as coordinating and staging the work."
The split parapet is just one of the challenges Harms Construction has faced on the project. The NJDOT has several restrictions of its own.
Before Harms Construction could even begin to slipform the project, they had to prove to the NJDOT that they could produce a superior parapet with a slipform paver.
"We had to provide a detailed submittal to the NJDOT on the historical performance of the machine in order to gain approval of its use," Harms said. "What they look for in a slipform contractor and machine is historical performance. The company needs to have a resumé of performing this type of work in order to get approved and we were able to meet the criteria."
The NJDOT also had time limit restrictions on the ready-mix trucks. The restriction made the timing of concrete delivery crucial.
"Representatives from American Concrete, our concrete supplier, were on-site, full-time during the day of the pours to coordinate the trucks," Harms said. A lot of coordination between the plant and Harms was required in order to obtain a uniform mixture day-in and day-out. The mix had to allow the form to slide and not pull, which is extremely critical."
A heavy traffic load on Route 78 created another challenge. Route 78 is an interstate highway consisting of three lanes of local traffic, three lanes of express traffic and is the main artery from Pennsylvania into New York City.
Harms Construction also dealt with tight clearances and fill-in sections for junction boxes.
"In some areas, we only had a 13 to 14 foot (3.96 to 4.27 m) wide work space," Harms said. "It obviously presented a challenge in the staging of the trucks and manpower.
"The junction boxes for the lights were also a challenge. We wished we could have slipformed over those, but obviously you can't," Harms explained.
Contraction joints were saw cut every 10 feet (3.05 m). The wall was finished with a broom finish.
Harms Construction is into the final phasing of this project with plenty of work lined up for their Commander III in the future.
"Anything is an option right now," Harms said. "We feel that we're going to be on the cutting edge of technology because we'll be more diversified with this machine. We feel the Commander III's applications are almost unlimited as far as our line of work goes, from curb, to parapet, to the potential for paving in the future."
George Harms Construction Company, Inc., is based out of Farmingdale, New Jersey. This year marks their fortieth anniversary in the construction business.