Set-Up, Stability, Ground Conditions, and Traffic/Spotter Control
Stability and traffic control decide whether the lift stays upright and whether anyone walks into it.
Ground and set-up
- Outriggers and stabilizers fully extended, set on rated pads, machine level per the manufacturer (often 2–5° maximum).
- Calculate pad load: machine plus occupants plus attachments, divided across the outriggers, can exceed 10,000 lb on a single pad. Check for vaults, culverts, septic tanks, uncompacted fill, asphalt softened by heat, and slope crests.
- Wheel chocks, parking brake applied, pothole protection deployed on scissor lifts.
- Keep the machine out of the drop zone of anything overhead and clear of excavations.
- Wind: reduce sail area and stop at the placard limit or the employer limit, whichever is lower.
Traffic and the exclusion zone
Follow MUTCD Chapter 6 principles: advance warning signs, cones and tapers, arrow board at night, and a lane-closure plan. The exclusion zone must cover the machine's swing, boom travel, and any dropped-object path - not just the footprint. A dedicated spotter in Class 2/3 hi-vis with a radio watches the blind spot behind the counterweight; the spotter does not also tend the load.
Worked example
A rough-terrain boom is set on new asphalt beside a drainage culvert in July. The outrigger pads sink and the level alarm sounds. Correct response: lower the platform, retract, move off the culvert, and set on steel pads or mats.
Traps
- Pads too small, concentrating load into the subgrade.
- Setting up on a slope crest, which reduces bearing capacity and invites a slide.
- Using cones as the whole traffic plan with no taper and no spotter.
- Letting the spotter leave the post to fetch tools.