Two-Way Radio With a Blind Side
You are slewing a 1.5 t steel beam onto the third-floor steelwork of a building under construction. The dogman is on the floor below the landing point and cannot see the beam's far end; a second rigger is at the far end but has no radio and is using hand signals. There are two tower cranes working overhead, a concrete pump boom swinging nearby, and a crew of five on the floor you are landing onto. Your radio is on the same channel as the concrete pump. You hear 'up slow, up slow' and then a burst of static and a different voice saying 'hold it, hold it'. The beam is 4 m above the landing point and drifting toward a column.
1. What are the communication failures here, and what is the immediate action?
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Failures: (1) shared radio channel with the concrete pump, so instructions are ambiguous and may not be from your dogman; (2) a rigger using hand signals from a position you may not be able to see while you are watching the load; (3) a 'hold it' from an unidentified voice - you cannot tell whether it is your dogman, the pump operator, or someone else; (4) no single designated signaller for the blind side. Immediate action: stop the crane - hold the load, do not slew toward the column. A stop instruction from any source is honoured first and questioned later; that is the safe default. Then establish identity: 'Who said hold? Identify yourself.' Do not move until you have a clear, identified instruction from your designated dogman, and do not drift toward the column while you sort it out - if drift continues, lower the load away from the structure under control.
2. How should the lift be re-planned before it continues?
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Designate one signaller in charge, with a clear view of the load path and the landing point, and give that person the only radio on a dedicated channel. Move the concrete pump to another channel. Put a radio on the far-end rigger, or reposition so the designated signaller can see both ends - a relay of hand signals through a third person is a last resort and must be briefed. Agree and brief standard signals, including an all-stop that everyone on the crew knows and will use. Brief the five-person crew on the landing floor that only the designated signaller speaks to the crane, and that anyone may call stop but must identify themselves. Walk the load path and confirm the blind side is covered before the lift restarts.
3. The far-end rigger waves 'stop' with a hand signal you can see, but your radio dogman says 'continue, continue'. What do you do?
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Stop. A stop signal from any person is obeyed - the far-end rigger may be seeing a hazard you cannot, such as the beam approaching a live edge or a person under the load. The radio dogman's 'continue' does not override a stop from someone with eyes on the far end. Hold the load, then resolve the conflict: ask the radio dogman what the far-end rigger is seeing, and if the dogman cannot see it, treat the far-end rigger's information as authoritative for that end of the load. Once the hazard is cleared and the designated signaller confirms, the lift may resume. The principle is that the crane stops for a stop from anyone, and only the designated signaller restarts it - and only after the reason for the stop is understood.