North America’s first16 September 2019
Portsmouth, Rhode Island-based Steel Giraffe has used its new Demag AC 45 City all terrain, the first in North America, for a project on the Mount Hope Bridge connecting the Rhode Island towns of Portsmouth and Bristol.
The 90-year-old structure that predates the Great Depression is currently in the midst of a ten-year, $52m restoration project.
The current construction phase consists of repairing the bridge pier anchors’ degraded concrete. Work crews needed to have construction materials and containers transferred to the work platform at water level.
Steel Giraffe’s 25USt (22.7t) carry deck crane previously used didn’t quite fit, and the transport costs were cutting into profits. “One option was to position a crane on a barge in the water to transfer the materials, but this would have been costly,” said Steve Kelly, owner/operator of Steel Giraffe.
Steel Giraffe quoted the project using its AC 45 City crane positioned on the bridge deck to lower materials more than 100ft (30.5m) to the work platform below. The 50USt three-axle crane offers a maximum main boom of 102.4ft and a maximum 145ft system length.
The first challenge was to ensure the deck could hold the weight of the crane with load. “The planning software was helpful in determining the weight, radius and outrigger setting to provide printed proof the bridge deck had the capacity,” he added. “Both Empire Crane and Demag worked with us to help prepare the plan.”
The next challenge for Steel Giraffe was to hoist the materials without blocking both traffic lanes. Justin Melvin, general manager for Empire Crane, said: “The Mt. Hope Bridge only carries two lanes of traffic, and each lane measures only 11ft wide, so this was a perfect test of the AC 45 City’s compact design.” From counterweight to boom to jib, everything rides on the crane’s trim 28.4ft-long by 8.3ft-wide carrier.
The plan called for the AC 45 City crane to be positioned in one lane, leaving the other open to traffic. Steel Giraffe devised a plan using a 26ft boom radius with small outrigger basis. The night lift also helped to minimise traffic disruptions.
Steel Giraffe drove the AC 45 City approximately six miles (9.7km) to the project site and arrived by 9 p.m. The crew had the crane rigged and hook-ready to by 10 p.m. Kelly appreciated the ability to drive and operate the crane from the same cab without needing to exit.
Steel Giraffe completed nearly 20 picks in less than five hours, where crew members lowered a variety of equipment from compressors and generators to paint and tools to the work platform. The heaviest lifts consisted of two, 10ft steel shipping containers loaded with equipment, weighing 6,000lb (2.7t) each.