Tilt Alarm, Concentrated Load and a Snagged Platform
At 10:30, two operators are cleaning the facade of a 20-storey hotel from a dual-point platform rated at 500 kg including persons and equipment. Each operator weighs about 75 kg; tools and water containers add 90 kg; eight bags of tile adhesive, each 25 kg, have been placed at the right-hand end for a later repair. The platform’s tilt alarm begins to chirp when both operators move right. Wind has risen from 18 km/h to 32 km/h with gusts of 45 km/h; the forecast mentions squally thunderstorms. The left suspension rope is touching a temporary pipe scaffold, and the platform has snagged on a scaffold coupler. The supervisor radios: “Free it by jogging the hoist; we only need ten more minutes.” The platform is at 8/F, about 24 m above a covered walkway. The load chart is inside the tool box on the roof.
1. Assess the load and its distribution. Is the platform within its rated load, and why is the tilt alarm significant?
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The total is 440 kg: two operators at 150 kg, tools and water at 90 kg, and eight adhesive bags at 200 kg. That is 60 kg below the 500 kg rated load, but the calculation is not the end of the assessment. The rated load is a maximum for the platform as a whole and normally assumes a reasonably distributed load. The adhesive is concentrated at the right-hand end, which can overload the platform floor locally, shift the centre of gravity and increase the load on one suspension point. The tilt alarm is therefore significant: it is warning that the platform is not level or that the suspension loads are uneven, not merely that the total is close to the limit. The operator should stop, remove or redistribute the adhesive, and check the load chart and manufacturer’s instructions before any further movement. The 60 kg margin does not justify continuing with a badly distributed load, and persons should not be used as counterweights.
2. How should the operator respond to the snag, the wind and the supervisor’s instruction?
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The operator should stop the platform and not “jog” the hoist to free it. Jogging a snagged platform can shock-load the suspension ropes, damage the hoist or brake, deform the platform and cause the rope to jump or the platform to swing. The operator should isolate the controls, keep everyone clear of the snag, and report the situation. The wind at 32 km/h gusting 45 km/h, with squally thunderstorms forecast, is likely to exceed the manufacturer’s permissible operating wind speed and the site’s risk-assessment limit; work should be stopped and the platform brought to a safe condition if this can be done without forcing it. The supervisor’s instruction is unsafe and should be refused. If the platform is jammed, a trained person should release it from a safe access point using the approved procedure, with the area below excluded. The platform should not be lowered while the rope is still caught on the scaffold. Communication should be maintained with the roof and ground, and the incident should be recorded.
3. What controls should be in place before facade work resumes?
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Before resuming, the snag should be cleared by a competent person, the suspension ropes and platform should be inspected for damage, and the hoist, brake and limiters should be function-tested. The load plan should be revised so that materials are distributed and secured, with the adhesive moved in smaller batches or by an alternative method. The tilt alarm should be tested, and the cause of the uneven loading should be corrected rather than ignored. Wind monitoring should be established at roof level, with a defined stop-work limit based on the manufacturer’s instructions and the site risk assessment. The exclusion zone below should be maintained, and the covered walkway should be protected. The supervisor and operators should receive a briefing on load control, snag response and the authority to stop work. The incident should be entered in the logbook, and any defect found should be reported and repaired before the platform is returned to service.