Site Preparation & Crane Setup
Ground conditions, outrigger deployment, cribbing, leveling procedures, ground bearing pressure, and tire requirements for on-rubber lifts.
- Evaluate ground conditions and calculate ground bearing pressure concerns
- Describe proper outrigger deployment, extension, and cribbing procedures
- Explain crane leveling requirements and verification methods
- Identify on-rubber lift setup requirements including tire inflation
Lección 1
Ground Conditions & Bearing Pressure
The Foundation of Every Lift
The ground beneath the crane is the foundation for the entire operation. If the ground cannot support the forces transmitted through the outriggers or tires, the crane can settle, tilt, or collapse into the ground - causing a catastrophic tip-over. Evaluating ground conditions is one of the first steps in any crane setup.
What Is Ground Bearing Pressure?
Ground bearing pressure is the force transmitted to the ground by the outrigger pads (or tires). It is measured in pounds per square foot (psf) and depends on:
- The total crane weight plus load weight
- The distribution of forces across the outriggers
- The size of the outrigger pads or mats
Reducing Ground Bearing Pressure
The most effective way to reduce ground bearing pressure is to use larger outrigger pads or mats to spread the load over a greater area. Doubling the pad area cuts the ground pressure in half.
Soil Bearing Capacities
| Soil Type | Approximate Bearing Capacity |
|---|---|
| Soft clay / wet soil | 500-1,000 psf |
| Medium clay | 1,500-2,500 psf |
| Compacted gravel | 3,000-4,000 psf |
| Compacted fill | 2,000-3,000 psf |
| Asphalt (over base) | 2,000-3,000 psf |
| Concrete (reinforced) | 5,000+ psf |
Underground Hazards
Always check for underground utilities, vaults, tanks, and excavations before placing outriggers. The ground surface may appear solid but collapse if a void exists below. Contact the site manager and call 811 before any crane setup.
Ground bearing pressure is the force transmitted to the ground by outrigger pads. It is reduced by using larger pads or mats to spread the load over a greater area. Always evaluate soil conditions and check for underground hazards before crane setup.