Mobile Scaffold on a Sloping Ramp
You are asked to provide a mobile scaffold for ceiling work in a warehouse loading area. The floor is a concrete ramp sloping at 1:12 for 8 m, then level. The work is at 4.5 m height along the ramp section. The available mobile scaffold is a 2.5 m by 1.5 m frame unit with 1.8 m bays, castors with 125 mm wheels, and no outriggers on site. The duty required is light duty with one worker and tools. A colleague proposes chocking the castors with timber offcuts and using the scaffold on the slope because 'the wheels have brakes'. The ramp has a drainage channel 150 mm wide across it at the mid-point, and the ceiling has services running at 4.2 m.
1. Assess the suitability of using the mobile scaffold on the ramp and explain the stability issues.
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A mobile scaffold on a 1:12 slope is a stability problem, not a braking problem. Castor brakes lock rotation, not the tendency to roll or tip on a slope; timber chocks are not a designed restraint and can work loose. The scaffold's design assumes a level base unless the manufacturer permits sloping use with a specified maximum gradient and restraint. At 4.5 m working height on a 2.5 m by 1.5 m base, the height-to-base ratio is already high, and the slope shifts the centre of gravity toward the downslope edge, reducing the tipping margin. The 150 mm drainage channel is a further hazard: a castor can drop into it, shock-loading the frame and potentially tipping the unit. Before use, check the manufacturer's instructions for slope limits and outrigger requirements; if outriggers are required and none are available, the scaffold is not suitable. The correct answer is to reject the sloping placement and find a level base, or use a designed level platform or a different access method.
2. Propose a compliant alternative and list the controls you would apply.
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The compliant alternative is to work from a level base. Options: erect a static scaffold on base plates on the level floor beyond the ramp and use a designed platform to reach the ramp section, or use a mobile elevating work platform rated for the slope if one is available, or provide a designed level working platform spanning the ramp with edge protection. If a mobile scaffold must be used, place it only on the level section, with the work repositioned so the operative does not overreach. Controls for any mobile scaffold: check the manufacturer's height-to-base ratio and fit outriggers if required; use castors with brakes and lock them before climbing; provide a safe means of access, not climbing the frame; fit guardrails and toe boards on all open sides; keep the platform clear of the 4.2 m services; and secure the unit against movement. Brief the crew that chocking with timber is not permitted as a substitute for a designed restraint.