A Kobelco 2500 crawler crane is the key to the $21-million Mantoloking Bridge, Route 528 over Barnegat Bay in Ocean County, NJ, according to Gregory Borovskis, project engineer and project manager of J.H. Reid General Contractors of South Plainfield, NJ.
Borovskis said the Kobelco 2500 became the key to the project because of its 250-ton (227 t) capacity.
“We purchased the Kobelco 2500 especially for this project. We mounted it on floats and used it to drive piles, set forms and set the bascule steel for the bridge.”
Other equipment used includes a Manitowoc 777, which was used to set forms and handle materials, and two 30-B cranes, one of which was used to set up a concrete pump truck, and the second 30-B crane was used for material handling and for miscellaneous tasks, he added.
All of this equipment, along with a 10-yd. (9.1 m) hopper built on top of the concrete pump truck to feed the pump, is being used to construct what Borovskis called “a unique” project because it is a two-leaf bascule bridge, complete with hydraulics to lift the spans of this draw bridge.
The old bridge, he continued, had a 15-ft. (4.6 m) clearance when closed. The new bridge will have a 30-ft. (9.1 m) clearance when closed and an unlimited clearance when it is open. The reason for the doubling of the clearance is to reduce the number of annual openings of 4,000 for the old bridge to 2,000 for the new bridge. The reduction in openings was specified by the project’s owner, Ocean County, which Borovskis said, believes will have a less impact on traffic.
Included in the project, which began in December 2003, Borovskis explained, is construction of the new, 1,200-ft.-long (365.8 m), double-leaf bascule bridge adjacent to the existing 50-year-old, single-leaf bridge.
It also includes construction of the approach spans. The approach spans will consist of concrete beams on 24-in. (61 cm) steel pipe piles. The bridge span will consist of steel girders with a lightweight concrete deck, he added.
Project plans also call for demolition of the existing 1,100-ft.-long (335.3 m) concrete-on-wood-timber-piles bridge, except for 200 ft. (61 m) on the west side of the bridge, which will be used for a fishing pier.
Continuing, Borovskis said, the project also calls for road work. The road work will consist of realignment on the east and west ends of the bridge and construction of = 180-ft.-long (54.9 m) concrete retaining walls on all four corners of the bridge.
In addition to the challenge of requiring a larger capacity crane, other project challenges included protecting winter flounder in the area and access to the project site — namely Barnegat Bay, Borovskis said.
Protecting the winter flounder, he continued, was a mandate by the New Jersey Department of Environmental Protection and by the U.S. Department of Environmental Protection. The solution to this project challenge was to work seven days a week to build two 3,200-sq.-ft. (297. 3 sq m) steel sheet pile coffer dams, said Borovskis. These dams were built to allow for the construction of the two concrete bascule piers, each of which required 100 steel pipe piles.
Site access was not included in the project contract. As a result, “this access had to be acquired. It was accomplished by leasing property on the west side of the bridge. This property contains our dock and it also serves as our staging area.”
In addition to the leased property, construction was also facilitated by sequencing the construction.
Construction sequencing consists of three phases, Borovskis noted. The first phase, which is currently under way, calls for construction of the west abutment and the new bridge, and then make the new bridge operational.
The second phase calls for construction of the partial ties and maintaining one lane of traffic on both the old and new bridges. This phase also calls for completion of the construction of the east abutment.
The third phase requires the opening of both lanes of traffic on the new bridge.
The project is on schedule and on budget and it is expected to be completed by February 2006. CEG