Two-Way Radio and the Wrong Load
A self-erecting tower crane is lifting bundles of timber from a delivery truck to a third-floor loading bay. The operator is in the cab and cannot see the truck. A signaler on the ground uses a two-way radio. The site uses channel 4, but a neighbouring site also uses channel 4 and there is intermittent cross-talk. The signaler calls 'up slow' and the operator begins hoisting. The load is a bundle of 4.8 m timber, and the signaler has not checked that the bundle is slung at two points with the slings at a safe angle. The bundle is also longer than the loading bay opening, so it will need to be slewed and fed in at an angle. The signaler is standing near the truck, and a worker walks behind the load as it rises. The operator hears 'stop' but cannot tell whether it came from the signaler or the other site.
1. Analyse the communication failures and the risk they create.
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The radio channel is shared with another site, so commands may be heard from someone who is not controlling this lift. That makes every command ambiguous, including 'stop'. The operator cannot see the load, so the radio is the only link, and an ambiguous stop is a serious hazard. The signaler has not confirmed the slinging arrangement, so the load may be unstable or the slings may be overloaded. The bundle is longer than the bay opening, which requires a controlled slew and feed-in, and that needs clear, continuous communication. A worker walking behind the rising load is in the drop zone and may be struck if the load shifts. The signaler's position near the truck may not give a clear view of the landing point. The combination of cross-talk, a blind lift, unverified rigging and a person under the load means the lift should be stopped until communication and rigging are controlled.
2. State the controls you would put in place before the lift continues.
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Use a dedicated radio channel that is not shared, or a different communication method such as hand signals with a clear line of sight, or a combination. Confirm at the start of the lift that the operator and signaler can hear each other and agree on a test call. Only one nominated signaler should give commands, and the operator should stop if a command is unclear or comes from an unknown source. The slinging must be checked by a competent rigger: two points, slings at a safe angle, and the load balanced. The bundle should be rigged so it can be fed into the bay at an angle without fouling the opening. The exclusion zone under the load must be cleared, and the worker behind the load removed. The signaler should be positioned where they can see both the load and the landing point. The lift should not resume until these controls are in place and understood by everyone involved.