Site Preparation, Setup, and Ground Conditions
Site Preparation, Setup, and Ground Conditions
This domain tests setup decisions that keep the crane stable: ground bearing, outrigger blocking, slope, clearances, and assembly areas. The exam looks for the difference between a level-looking site and a verified load-bearing setup.
Core rules
- Ground must support the maximum outrigger or track load with a factor of safety; use mats or cribbing to spread load. Never block on a void, utility, or uncompacted fill.
- Outrigger pads must be fully deployed per manufacturer; floats or mats must be sized for the pressure, not just the footprint.
- Set up level within manufacturer tolerance; grade and slope affect capacity and swing.
- Maintain clearance from excavations, trenches, underground utilities, and overhead obstructions. Barricade the swing radius and tail swing.
- Assembly/disassembly areas need controlled access and a qualified person directing the process.
Worked example: 96,000 lb crane, 75% of weight on two outriggers on one side, pad 3 ft × 3 ft. Load per pad = (96,000×0.75)/2 = 36,000 lb. Pressure = 36,000/9 = 4,000 psf (2.0 tsf). If the soil's allowable bearing is 3,000 psf, add a larger mat or relocate.
Traps
- Using the crane's total weight divided by four as outrigger load.
- Assuming mats help if they bridge a void.
- Setting up near a trench edge without a competent person's evaluation.
- Ignoring slope because the bubble is close enough.