Sitting in the cab of his Liebherr LTM 1300-6.2, a 300-USt mobile crane, Raymond Gallagher maneuvers a 13-ton pedestrian bridge that will eventually join two buildings. But he knows he has to rely on a team of people to make the lift successful—because he cannot actually see the bridge.
Gallagher is a 16-year veteran of ALL Carolina Crane Rental of Wilmington, a member of the ALL Family of Companies. For 14 of those years he has been an operator, and this was just another day in his “office.”
On this particular day, the office is the River Place project in Wilmington, a $20 million development with 26,000 sq ft of parking, retail shops, and restaurants plus 170 apartments spread across two towers, north and south. The pedestrian bridge will join the two towers near the top, so residents in one tower will have access to the pool and other amenities on the roof of the second building.
Gallagher knows what to expect because the team at ALL prepared a detailed 3-D lift plan ahead of the work. He has studied it and is ready.
A few days before Gallagher and his LTM 1300 arrived on the scene, an operator in a smaller-capacity crane had lifted the multiple bridge sections to the top of the roof, where ironworkers assembled them into the single bridge span. Now, Gallagher is relying on those same ironworkers to rig the 27,000-lb piece in preparation for his hook.
Regarding the rigging, Gallagher said, “Ironworkers rigged the bridge with synthetic slings, and shackles and lugs in a four-way hookup. Each corner was rated for 31,000 lb, so we had plenty of capacity for the bridge span.”
The day of the lift, Gallagher positions his crane partially on a downtown street and partially on a sidewalk, with 6-ft x 7-ft ground matting protecting the surfaces underneath. The Liebherr is configured with 191 ft of main boom and 212,000 lb of counterweight.
Next comes the part where those flaggers become so crucial. Because Gallagher cannot see the bridge himself, he has to rely on the signals of two flaggers positioned atop each building. “I think of them as the real crane operators, and I’m the guy pulling the levers,” said Gallagher.
“Once I have the piece hooked, I boom up away from the building, swing around, and boom down to set the piece,” said Gallagher. Along the way, signals from the flagger let him know when to boom up or down. Taglines attached to the bridge keep it from swaying.
Support platforms had already been installed on the sides of both buildings. Once the bridge is set on these platforms, Gallagher has to hold the bridge in place for 30 to 45 minutes while the span is welded into place.
Four hours later, Gallagher sums up the success: “With everyone working as a team, the lift went as smoothly as possible,” he said. “Thanks to their excellent planning and execution of the pick, it was another great day at work.”