Fast Track

Gantry Crane and Precast Panels Speed up a Bridge Rebuild in N.J.

Route 46, a critical artery for traffic flowing from New York, needed a major overhaul in a tight timeframe.

by Natalie Keith

The four-lane bridge where New Jersey's busy Route 46 crosses Overpeck Creek in Bergen County was in bad shape.

More than 75 years old, corroded by rust, and deteriorating, the bridge linking the towns of Ridgefield and Ridgefield Park had never undergone major repairs, said Steven Manera, program manager on the job for the New Jersey Department of Transportation.

Under a fast-track effort, an $18 million reconstruction of the bridge is nearly complete this spring - with traffic pouring over the newly installed lanes since February.

The department's standard technique for such a fix would require channeling all traffic onto two of the bridge's lanes in order to demolish and reconstruct the two free lanes and their underlying abutments and piers - then switching sides to repeat the process on the other half. When the agency planned the project under that approach, it came up with a $20 million budget and a schedule of two to three years because for each set of lanes, the team would need a full construction season to rebuild the steel frame and to form, pour, and cure a new concrete deck.

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But Manera said local residents and community leaders consulted about the project objected to the schedule because that stretch of Rt. 46 is also a vital artery for traffic flowing from the George Washington Bridge, which is 5 mi. to the east. About 40,000 vehicles a day cross the 510-ft.-long bridge, which carries westbound Rt. 46 traffic away from Manhattan and funnels it to the New Jersey Turnpike, Interstate 80, and other local roads.

"The locals understood what a 2.5-year project would mean for them," Manera said. "They asked if we could find an alternative."

In addition, a long work schedule would stretch the number of days the area would suffer $19,000 in daily "road-user costs," a transportation department-generated calculation for the value of lost time for motorists, said Samir Shah, the agency's project manager on the effort.

The $18 million alternative that the project team developed met the community's challenge by cutting the schedule to less than a year. Manera said work began last summer and is finishing this spring because of three major choices: narrowing the reconstruction to the deck superstructure while preserving the abutments and piers of the existing foundation; using massive precast concrete deck panels instead of pouring onsite; and installing the panels by use of a gantry-crane system that avoided additional lane closures.

The adjusted plan grew under the umbrella of the transportation department's "Hyperbuild" initiative spearheaded by its former commissioner, Jack Letteire, who retired after Gov. Jon Corzine took office this year. The program aims to reduce time spent on traditional design and construction methods for selected projects.

"New Jersey is one of the most congested states in the nation and our goal is to get out as quickly as possible to minimize impact to motorists," Manera said. "The approach is not appropriate for every project, but it is considered on every project."

The initiative also streamlines design decisions to make choices that limit the overall budget impact. In the case of the Overpeck Creek Bridge, the adjusted plan ended up saving from the original $20 million budget not because the precast deck and gantry crane were cheaper than a traditional onsite pour setup, but because the team found a way to repair the existing foundations rather than demolishing them and constructing new ones.

Indeed, the panels and gantry crane are more expensive than an onsite pour, but they were the difference in shortening the schedule, said Joseph Occhiogrossi, project manager for Railroad Construction of Paterson, N.J., the general contractor.

"What we did is not a cheap solution," he added. "But having the public inconvenienced for less time is valuable."

Shrink 30 Months into Less Than 12

The six-span bridge crossing Overpeck Creek - a short, wide basin that drains into the Hackensack River - was originally a bascule drawbridge whose moving gears were deactivated in the 1950s, and has since been locked in place, Occhiogrossi said. It carried all Rt. 46 traffic until 1951, when an adjoining bridge was built and eastbound lanes shifted over, leaving the older structure for westbound traffic.

Only the older span required attention, and once the transportation department chose a shortened timetable, it studied three prefabricated deck systems, an option the agency had only used once before in its history, Manera said. It chose a precast panel and pedestal system by Fort Miller Co., of Schuylerville, N.Y., and selected McCormick Taylor of Philadelphia as its design consultant.

"[By fabricating] panels offsite, the work has minimal impact on traffic," he added.

Fort Miller cast the deck slabs and beams as one piece, and as part of the contract, preassembled the bridge at its factory in order to ensure that all of the pieces fit, Manera said.

The project's original bid documents anticipated use of conventional hydraulic truck cranes, which are large enough to have required nighttime closings of the bridge to install the precast panels - and in turn would have required shifting westbound vehicles onto a lane of the eastbound bridge by using temporary crossovers, Occhiogrossi said. But Railroad determined that conventional cranes would have been too large and heavy.

"There wasn't enough room to work on the bridge with those cranes," Occhiogrossi said. "And it wasn't clear the old bridge foundation would be able to support them."

The contractor also had to find a way to ensure that work could take place 24 hours a day, seven days a week, in order to meet the aggressive project schedule.

Railroad proposed a gantry crane system and won the job, Occhiogrossi said. The system avoided loading the cranes directly on the old bridge as well as any traffic crossover because crews could work on two lanes while traffic flowed on the other two.

Work began last summer to build the gantry-crane framework of brackets, beams, and girders supported on one side by the 1951 bridge and on the other by the original bridge's piers, Occhiogrossi said. After installing railroad tracks on that framework, the two 70-ft.-wide, 40-ft.-tall, 90-ton MiJack cranes were able to roll across the entire bridge length.

The cranes - assembled and disassembled onsite - were first used for demolition. Nacirema Industries of Bayonne, N.J., used hoe rams to break the original concrete deck, with dumpsters set on floats beneath the bridge to catch debris.

Then crews used the cranes to lift and install the precast panels. After completing that demolition-and-installation process on the first two lanes, the team repeated it on the other pair.

The 42 precast panels weigh up to 70 tons each and measure up to 9 ft. 4 in. by 93 ft. They connect to the existing piers on 86 precast pedestals and bearings created because the new deck system's beams are closer together than the old piers.

Some work took place at night to ensure that wideload trucks carrying the panels did not cripple local roadways, the transportation department's Shah said.

The project also entailed repairing cracks in the abutments and piers, some more deteriorated than expected, both in the water and above the surface. Ongoing tasks this spring involved repairing a sidewalk, constructing a railing over the parapet wall, and installing new lighting.

The project hit snags, such as heavy rain last year that raised the water level, Shah said.

"They couldn't bring the barge in to complete the work," he added.

But all four lanes are back in business, and in the end, the project will clock in at under a year.

Key Players

Owner: New Jersey Department of Transportation

General Contractor: Railroad Construction Co., Paterson, N.J.

Designer: McCormick Taylor, Philadelphia

Panel Fabricator: Fort Miller Co., Schuylerville, N.Y.

Demolition Contractor: Nacirema Industries, Bayonne, N.J.