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Toolbox talk · 10 min · Forklifts & Mobile Equipment

Excavator Swing Radius

Hazards: Struck by the rotating counterweight or tail · Pinned between the machine and a wall, truck or tree · Struck by a swinging bucket or load · Machine rolling into the excavation

Why it matters

On October 14, 2020, a truck driver finished talking with an excavator operator and turned back toward his truck. The operator swung right. The counterweight caught him and pinned him against a tree; his arm was crushed and amputated (OSHA Accident Search, Summary Nr 130483.015). He had just spoken to the operator. That is the whole lesson: being seen a moment ago is not the same as being seen now.

Key points

  • The tail is the hazard. The counterweight sweeps a circle the operator mostly cannot see, and it pinches you against whatever is behind you. Walk the circle before work starts and know where it reaches.
  • Barricade the zone, and keep it up. For crane-type equipment 1926.1424(a)(2) requires control lines, warning lines, railings or similar barriers — signs and high-visibility markings only where barriers are not feasible. On a digging excavator it is the same practice under 1926.20(b)(2) and 1926.21(b)(2). Tape that is down by 10 a.m. protects nobody.
  • Tell the operator before you go blind side. 1926.1424(a)(3): the operator is informed before anyone enters a hazard area out of view, and does not rotate until a pre-arranged signal says the person is clear. Same rule of thumb on any machine — get a stopped bucket and a thumbs-up, not a wave.
  • Never under a bucket or a load. 1926.651(e): no employee underneath loads handled by lifting or digging equipment, and stand clear of any vehicle being loaded so spillage cannot reach you.
  • Backing and edges need a system. 1926.602(a)(9)(ii): no reversing with an obstructed rear view unless a reverse alarm is working or someone signals it is safe. Near an excavation, 1926.651(f) requires barricades, signals or stop logs when the operator cannot see the edge.
  • Machine down before anyone approaches. Bucket on the ground, house locked, controls neutral. If you have to service or unplug something, the machine is off — not idling.

Do / Don't

Do

  • Approach from the front, in the operator's line of sight.
  • Wait for the boom to stop and the operator to acknowledge you.
  • Re-hang the barricade the second a truck knocks it down.

Don't

  • Cut behind a running machine to save twenty feet.
  • Stand between the tail and a truck, wall, tree or spoil pile.
  • Guide a bucket with your hands or reach under a suspended load.

Quick site check

  • Stand at the machine and turn a full circle — what is inside the tail swing?
  • Is the swing zone marked today, and does the barricade still stand?
  • Reverse alarm audible over the site noise, or do we need a spotter?
Discussion — ask the crew
  1. On this job, where does the tail of the machine swing into a space people walk through?
  2. How do we barricade the swing zone here — cones, tape, water barrier — and does it stay up all day?
  3. What signal do we use to tell the operator we are stepping behind the machine, and who taught it to the new guys?
  4. Where do people cut behind the excavator because it is a shorter walk to the truck?
  5. Who is watching the edge when the machine backs up near the trench?
Refs: 29 CFR 1926.1424 — Work area control (swing radius hazards, barriers, pre-arranged signal before rotating) · 29 CFR 1926.1400(c)(2) — Excavators, backhoes and loaders are excluded from subpart CC · 29 CFR 1926.651 — Specific excavation requirements ((e) no employee under loads handled by lifting or digging equipment, (f) warning system for mobile equipment) · 29 CFR 1926.602(a)(9) — Audible alarms: horn, and reverse alarm or a signaling employee when the rear view is obstructed · OSHA Accident Search — Summary Nr 130483.015 (10/14/2020)Sign-in sheet included in the printed version

Frequently asked questions

For equipment covered by the cranes and derricks standard, yes: 29 CFR 1926.1424(a)(2) requires the employer to train authorized personnel on the struck-by and pinch/crush zones and to erect and maintain control lines, warning lines, railings or similar barriers marking the hazard area. Where the employer can demonstrate barriers are not feasible on the ground or on the machine, the area must be marked with warning signs such as "Danger — Swing/Crush Zone" plus high-visibility markings on the equipment, and workers trained on what those markings mean.

No — and that surprises people. 29 CFR 1926.1400(c)(2) excludes power shovels, excavators, wheel loaders, backhoes, loader backhoes and track loaders from subpart CC, including when they are used with chains or slings to lift a suspended load. The swing zone of a digging excavator is instead controlled through 1926.651(e) and (f), 1926.602(a)(9), the employer's duty to inspect and instruct under 1926.20(b)(2) and 1926.21(b)(2), and the manufacturer's manual. The hazard is identical; only the paragraph number changes.

The counterweight and the rear of the house, not the bucket. The tail swings faster than it looks, it swings on the side the operator cannot see, and it does not need the machine to move an inch. When it catches you against a truck, a wall or a tree, there is no space left.

When mobile equipment operates adjacent to an excavation or has to approach the edge and the operator does not have a clear and direct view of it, a warning system such as barricades, hand or mechanical signals, or stop logs must be used — and the grade should slope away from the excavation if possible.

Sources & references

Content checked against these sources — last reviewed August 28, 2026.

Results are estimates for planning purposes and do not replace a competent person's evaluation or an engineer's design. Follow the OSHA standards that apply to your work and your employer's written program.

By — Editorial team of SteelToeTools.com (published by LSEA SAS) Updated