Wooden Pad Size Selection

Soil Bearing Capacity Table

Type of SoilLoad Bearing (Pounds Per Square Foot)

Load Bearing (kPa)

Rock w/ Gravel 6,000 psf + 287.28Gravel 5000 psf 239.4Sandy Gravel 5000 psf 239.4Sand 3000 psf 143.64Silt Sand 3000 psf 143.64Silt Gravel 3000 psf 143.64Gravel w/ Clay 3000 psf 143.64Clay 2000 psf 95.76Sandy Clay 2000 psf 95.76Silt Clay 2000 psf 95.76

Rule of Thumb formula and calculations for Wooden Pad area:

Sample Calculation:

Soil Type : Sandy Gravel

1 kN = 1000 N = 100 kg Mass of Crane = 40000 kgs or 400 KNMass of Load = 9000 kgs or 90 KN

Area of Cribbage = 0.65 X (400+90) / 239.4

Area of Cribbage = 1.33 m² or (1.15 m by 1.15 m) or ( 3.8 ft by 3.8 ft )