Load Control When a Tag Line Fails Mid-Slew
A 2.5 t fabricated frame, 3 m tall and 1.5 m wide, is being slewed from the laydown area to a foundation. Two tag lines are attached at the base. During the slew, one tag line parts at its attachment and the frame begins to rotate about the hook. The frame is 4 m from the nearest structure and 6 m from a worker who is inside the exclusion zone retrieving a tool. The crane operator has not yet noticed the rotation and is continuing the slew at normal speed. Wind is 15 km/h, gusting.
1. Describe your immediate actions as the dogger, in order, and explain the reasoning for each.
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First, signal stop to the operator - the unconditional stop command, by radio or hand signal, before anything else. A rotating load on a moving slew can swing into the structure or the worker, and every second of continued slew adds energy. Second, sound the alarm or shout to clear the exclusion zone, directing the worker out and away from the swing path rather than toward the load. Third, once the slew is stopped, assess the frame: is the remaining tag line holding, is the load stable, is there a risk of the frame swinging back? Keep clear of the swing radius yourself. Fourth, do not attempt to grab or restrain the frame by hand; use the remaining tag line from a safe position, or lower the load to the ground if it can be done safely. Fifth, report the parted tag line and the incursion, and do not resume until the tag line is replaced, the attachment inspected, and the exclusion zone re-briefed.
2. Explain why the worker inside the exclusion zone changes the risk picture, and what control should have prevented it.
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A person inside the exclusion zone is inside the drop and swing zone, so any loss of load control becomes a potential fatality rather than a near miss. The frame rotating about the hook sweeps a radius set by its height and the hook height; at 3 m tall and slewing, the base can move faster than the operator expects, and a person 6 m away may still be within the swept path if the load swings out. The worker's presence also removes the option of lowering the load quickly, because the drop zone is occupied.
The control that should have prevented it is a properly enforced exclusion zone with a single entry point, a banksman controlling access, and a rule that no one enters while a load is in the air. The tool retrieval should have waited until the load was landed, or been done before the lift started. The tag line failure is the trigger, but the uncontrolled access is what turned it into a serious incident. Both need correcting: inspect and replace tag lines and their attachments, and re-brief access control before the next lift.