Site preparation, rigging, and load handling planning
Site preparation, rigging, and load handling planning
This domain tests the planning done before the crane moves: ground conditions, access, clearances, and the rigging that connects the load to the hook.
Ground and site
- Estimate ground bearing pressure: crane weight + counterweight + load + dynamic allowance, divided over the track contact area; compare with soil capacity and add steel mats or cribbing where needed. Watch for backfilled trenches, vaults, basements and buried utilities.
- The crane must sit level within the manufacturer's tolerance (often 1% or 0.5°); level is a precondition of the load chart.
- Plan swing clearance for counterweight and boom, and keep the whole swing path clear of stock, excavations and people.
- Respect approach distances to energized lines; commonly cited ASME B30.5 minimums are 3.0 m up to 50 kV, 4.6 m for 50–200 kV and 6.1 m for 200–350 kV, plus a spotter or de-energization.
Rigging
Confirm load weight from documents or a scale, not guesswork. Identify the centre of gravity, select slings by working load limit at the actual sling angle, protect sharp edges, and plan tag lines. Multi-leg slings lose capacity as the legs flatten toward horizontal.
Worked example
A 4 t load on a two-leg sling with 60° between the legs: each leg tension = 4 / (2 × cos 30°) = 2.31 t. A 2 t vertical-rated sling per leg is therefore not acceptable, because 2.31 t exceeds its WLL at that angle.
Traps
Using the vertical WLL for angled legs; measuring the included angle instead of the angle from horizontal; accepting "it looks solid" ground; forgetting the weight of spreader beams, slings and shackles in the plan.