Crane Setup, Outriggers & Mats

A crane is only as stable as the ground under it. Outrigger pads that punch through soft soil, sink into a buried void or sit on a pavement edge cause many crane tip-overs. Good setup happens before the first lift.

• Crane operators
• Controlling contractors
• Riggers

Ground conditions

• OSHA requires the ground to be firm, drained and graded enough that, with mats or blocking, it meets the crane maker’s requirements for support and level.
• The controlling contractor must make sure ground preparations are done and must tell the crane user about known hazards under the surface: voids, tanks, utilities, vaults and recent fill.
• Rain, thawing and nearby excavations can change the ground during the job. Re-check it.

Outriggers and mats

• Extend outriggers exactly as the load chart you’re using requires (fully, mid or retracted), with the crane’s position sensors set to match.
• Use mats or pads sized to spread the outrigger load so the ground bearing pressure stays below what the soil can take. A qualified person can calculate this.
• Center the outrigger float on the mat, and place mats on level, compacted ground.
• Lift the tires off the ground when the chart requires it.
• Level the crane within the maker’s limit, often about 1%. A small tilt can greatly reduce capacity.

Stay back from

• Excavations, trenches and retaining walls
• Underground utilities, vaults, manholes and septic tanks
• Basement walls and slab edges
• Recently backfilled or saturated areas
• Overhead power lines. See Overhead Power Lines

Control the work area

• Barricade the swing radius of the counterweight so no one can be crushed between it and another object.
• Keep people out from under the load and boom.
• Plan traffic so vehicles don’t drive near outriggers.

Setup checklist

• Ground information from the controlling contractor reviewed
• Mats sized and placed; outriggers set as the chart requires
• Crane level within the maker’s limit
• LMI set for the actual configuration
• Swing radius barricaded
• Power lines identified and clearance planned
• Shift inspection done. See Crane Inspections

Last updated: October 2, 2026