One of the world's largest floating cranes arrived on Oct. 6 at the site of the new Tappan Zee Bridge near Tarrytown, N.Y., after being fitted with fresh wire rope and undergoing tests this summer to prove the rig was ready to tackle the project's heaviest modules, some of which are expected to weigh up to 1,000 tonnes.
Officially dubbed the Left Coast Lifter from its first assignment on the San Francisco- Oakland Bay Bridge (project officials have nicknamed the machine "I Lift N.Y."), the twin-boom, sheer-leg crane had to be inspected, upgraded and tested before working on the bridge site. Earlier this year, the crane passed through the Panama Canal on its way to Jersey City, N.J., where it was recommissioned.
"It is in working condition," reports Dan Bell, construction manager for Tappan Zee Constructors LLC, the joint venture of American Bridge, Fluor, Granite Construction and Traylor Bros. that is building the new bridge. He says the crane was equipped with fresh, 1-7/8-in.-dia main hoisting rope—all 17,000 ft of it—reeved in 24 parts of line. Crews performed a 538-tonne load test on the main hoist in August by picking up a barge filled with water.
When a joint venture of American Bridge and Fluor purchased the supercrane in 2008 from Zhenhua Port Machinery Co., it received a 2,000-tonne load test, ENR reported. After using the $50-million crane in California, the contractor transferred ownership of the rig to TZC. Project officials say its next assignment after Tappan Zee has not yet been determined.
Before it floated up the Hudson River, TZC lowered the 328-ft-long twin booms to a 27.5° angle so they could clear the George Washington Bridge. At the jobsite, crews planned to pump 2.5 million gallons of water into the rig's 400-ft-long, 100-ft-wide and 22-ft-tall barge to bring down its draft to between 12 ft to 13 ft from its normal 6 ft to 7 ft, so it could clear the existing Tappan Zee Bridge.
After repositioning the crane upstream of the bridge, the ballast tanks would be emptied. That operation is expected to be complete by Oct. 9, project officials say. Although the crane can't move on its own, it still has plenty of lifting grunt, provided by three 738-horsepower main engines and two 67-hp house engines.
For the next three years, the 1,750-tonne-capacity crane will enable crews on the bridge to erect modules, built upriver at the Port of Coeymans, near Albany, as well as take a leading role in dismantling the 60-year-old bridge. Heavy lifts will include new precast-concrete pier caps and 130 double and triple steel-girder modules, each measuring up to 400 ft long and 12.5 ft deep, with catwalk, electrical and plumbing elements already installed.
"If we had to receive and assemble these girders, which are typically 100 ft long, it would take a fleet of many more barges," says Bell. "It would be a much more congested jobsite."
The prefab method also is expected to cut the $3.9-billion bridge's schedule and save more than $1 billion in costs, according to New York Gov. Andrew Cuomo (D), who greeted the crane's arrival at the bridge. Working for owner New York State Thruway, TZC also expects the process to improve safety and quality control.
"Efficiency of labor goes up [and] insurance goes down. Quality goes up and variability goes down," says Darrell Waters, president of TZC. But with such a big machine on the critical path, keeping it running smoothly will be a priority. Any potential breakdown "has to be addressed immediately," Waters notes.