Precast Process Speeds Bridge Construction for PennDOT
An Accelerated Solution: PennDOT Decreases Bridge Construction Time with Precast Elements
Shortly after the Pennsylvania Department of Transportation (PennDOT) approved standards for precast elements, District 5 engineers deployed the Precast Bridge Element System on six bridges crossing Interstate 78 in Berks County and significantly decreased the time needed for construction.
“The precast was an opportunity to complete the six bridges quickly with the least amount of disruption to traffic” says Chris Kufro, Assistant District Executive for Design at PennDOT District 5, who adds that the department would use precast again. “We are looking to utilize the technology more.”
The six bridges required replacement because under clearance was about 14 feet, rather than the current standard 16 feet, 6 inches. Consequently, trucks frequently hit the bridges. PennDOT knew it was time to replace them.
In fact, during the project, an oversized load hit the Northkill Road Bridge, causing serious damage to the fascia beam. Fortunately, that bridge was scheduled to begin construction the following month and the precast components had been fabricated. Adjustments were made to the schedule to start on this bridge sooner.
The original plan called for working on a half of each bridge at a time, while traffic flowed on the other half of the structure. That convention construction method would take significantly longer to complete about nine months to a year, and in community meetings, PennDOT officials floated the idea of entirely closing each bridge and completing each within 40 or 60 days, depending on the structure.
“The public liked the idea of our getting in and out, quickly,” Kufro recalls. “We put all of the projects together and used some economy of savings.”
A Faster Result
PennDOT and several consultants designed the plan to replace the bridges. Those consultants included Benesch of Allentown, Pennsylvania; Johnson, Mirmiran & Thompson, also of Allentown; AECOM of Philadelphia; and Erdman Anthony of Harrisburg, Pennsylvania.
HRI of State College, Pennsylvania, received the $37.5 million construction contract in late 2015. Founded in 1947, HRI’s heavy and highway work is concentrated in central and eastern Pennsylvania. The company is owned by Colas of Morristown, New Jersey.
“The short duration time frame at each of the six bridge sites was a big hurdle to overcome, which we did successfully with PennStress’ help,” says Mike Sulesky, Regional Manager with HRI. Although HRI had built precast bridges in the past, it was not to the magnitude of this project.
HRI hired PennStress, a division of MacInnis Group in Roaring Spring, Pennsylvania, to fabricate the precast bridge pieces.
“It’s innovative,“ said Greg Gorman, Senior Vice President and Chief Operating Officer of PennStress. “We were impressed that District 5 PennDOT decided to let six of these bridges in one contract. As far as I know, this was the first District 5-initiated total precast bridge project.”
In 2014, MacInnis Group acquired the former Newcrete Products, a division of New Enterprise Stone & Lime Co., which has produced prestressed concrete bridge beams since 1957. The company has been fabricating total precast concrete bridge elements and currently has more than 40 of these bridge projects under its belt. Gorman says he sees the process is gaining traction.
The company fabricates precast/prestressed products for Department of Transportation jobs, including beams and bridge components, and performs commercial work, including parking garages, stadiums, correctional facilities, and industrial and commercial buildings. Its current challenge is fabricating the Tower of Voices Flight 93 National Memorial. The company works in Pennsylvania, New York, New Jersey, Maryland, Virginia, West Virginia, and Delaware.
“The fabricator was good to work with,” Kufro says.
Precasting the Pieces for the I-78 Project
PennStress used building information modeling to see the casting and refined any issues before starting fabrication.
“That helped with layout and internal components of the structure itself,” Gorman says. “We used wood templates to match up the nearly 6,000 splice sleeve connections.”
The bridges were scheduled about every two months apart. PennStress would work one structure at a time. Once one was complete, the company started on the next one.
“Doing six bridges in a row and getting the same high quality I think goes far,” says Shawn Hite, Senior Project Manager for PennStress. “The quality of every one was superior, because it was cast in a controlled environment. That helped with the overall appearance.”
From footings to decks, all six bridges were constructed with prestressed and precast concrete elements: the girders, the abutments and wings, the deck panels and approach slabs. The joints between the panels required closure pours with ultra high-performance concrete. Five of the bridges have precast foundations; one was poured-in-place concrete.
The pieces ranged in size from 2 tons to 53 tons. Some of the pieces had voids to make the pieces lighter. A 27-inch diameter corrugated pipe was placed in that void. Crews in the field filled the void with concrete.
Cumulatively, the bridges required 540 prestressed and precast concrete components, containing 687 linear feet of bridge. The average span was 115 feet long.
High Steel Structures of Lancaster, Pennsylvania, erected the pieces. HRI crews grouted the pieces into place.
All of the pieces fit as planned. Not one piece had to be remade, Gorman says. To ensure that would happen, PennStress completed a “dry fit” in its yard prior to erection, bringing in a 300- to 500-ton crane to lift the pieces into place in sections.
“We actually built the bridges here before we shipped them to the field,” Hite explains.
Using precast components, the bridges were completed much faster, from 37 to 58 days, within a span of less than two years.
Four of the bridges were at interchanges, two off ramps and two on ramps in both directions, which required excavation, grading and asphalt work by HRI. Two were overhead bridges, with no intersections.
The PennDOT team designed the bridges with aesthetically pleasing architectural features created with form liners. For instance, one bridge appears to be covered in stone, but that shape of the ashlar stone was created with a form liner, and HRI stained the surface to give the appearance of natural stone.
PennDOT and PennStress are pleased with the results. Gorman hopes this construction method catches on.
“There is huge advantage to the speed,” Gorman said. “We are proud to have met all of the goals. Everything went well. The quality was good.”
- Owner: Pennsylvania Department of Transportation
- Design Team: Benesh, Allentown, Pennsylvania; Johnson, Mirmiran & Thompson, Allentown, Pennsylvania; AECOM, Philadelphia, Pennsylvania; Erdman Anthony, Harrisburg, Pennsylvania
- Contractor: HRI, State College, Pennsylvania
- Precast Producer: PennStress, Roaring Spring, Pennsylvania
- Erector: High Steel Structures, Lancaster, Pennsylvania