IN FOCUS / BORGER CRANES
BORGER BARGES TRUSSES IN BRIDGE DISMANTLE
Borger Cranes recently completed a complex lift for NSW Roads and Maritime Services (RMS) involving the removal of timber truss spans from the Old Sportsman Bridge in Lawrence. THE PROCESS TO COMPLETE THE LIFT WAS not the most straightforward process. The complications included barging a 600t capacity crawler crane to site, the closure of the Pacific Highway, restrictions with tide times and daylight hours, and managing the barge’s ballast to ensure stability throughout the lift. The Borger Cranes team worked closely with New South Wales Roads and Maritime Services, as well as barge provider Ausbarge Marine Services, to ensure the safe removal of the timber trusses from the redundant bridge. Ausbarge Marine Services provided the tug and barge services to the project. Given the choice of crane that Borgers had recommended to NSW Roads
Total weight of the lift was 76t including the rigging equipment.
58 / CAL July 2019
and Maritime Services was a Demag CC2800, and the size of the bridge trusses themselves, the project required a barge with significant deadweight capacity, as well as being able to provide the stability to enable the CC2800 to slew with the bridge truss once lifted off the pile headstocks. Paul Muller has been with Borger Cranes since 2012 and looks after the Demag CC2800 600t crawler crane. He operated the CC2800 throughout the project. “We put the crane’s car body and tracks together on Harwood Marine Slipway and then walked the machine onto the barge. Grillage had been put down and welded on the barge and we walked the crane onto the grillage and finished building the crane,” he said. “A lot of logistics were involved and a lead time of around a week was required to build the crane before it arrived on site at Lawrence. “The barge and crane sailed under the Harwood Bridge on the Clarence River. The optimal time to open the bridge was discussed between Borger Cranes, the Barge Master and Roads and Maritime Services,” said Muller. The traffic on the Pacific Highway had to stop for ten minutes so the deck could be lifted and the bridge opened. The only time the highway could stop was before 8.00am and between 9.30am and 2.30 pm and after 5.00pm. The tide flow had to be slack to enable effective steering by the tugs through the narrow clearance between the bridge piers, and the barge could only move during daylight hours. “A number of elements were out of our control to enable us to travel to site we had to align these elements and meet the small windows of opportunity a number of times during the project. The barge was brought up to the side of the site and
anchored and we put our rigging gear on the hook the total weight we were pulling was 76t including the rigging equipment,” said Muller. “Two trusses were removed – one on each visit. We lifted the first truss and slowly brought it onto the barge and sailed it back to Harwood and unloaded it at the marine slipway and repeated the process for the second. The whole project took close to five days and it was a sensitive lift with a high degree of difficulty,” he said. The Demag CC 2800-1 is a crawler crane with a maximum lifting capacity of 600t. The maximum boom length is 138m with a maximum jib length of 96m. The tracks of the Demag CC 2800-1 are powered by two hydraulic motors, each through closed planetary gear reduction units running in oil baths. The gear units were designed to fit inside of the width of the crawler. The four hydraulic assembly-jacking cylinders are found on the car body for easy assembly of the crawlers and fold to a 3m width. Matt Steain is a supervisor at Borger Cranes responsible for planning the lift. “We engaged Ausbarge to provide the barge for the lift and we also engaged a naval architect who calculated the tides as well as calculating how much ballast was needed in the tanks for us to walk the crane on,” he said. “We ballast the back of the barge opposite to where we planned to walk the crane on which allows for the weight once the crane is walking on. It was a 30-minute process to get the crane completely on the barge. We put the toe of the tracks onto the barge, waited and transferred more ballast, moved the crane half on and transferred more ballast, then three quarters of the way on and
