Question 7 of 7: Case Study — Die-Rigging Crane Accident Resulting in Fatal-Risk Head Injury

Question 7: Case Study — Die-Rigging Crane Accident Resulting in Fatal-Risk Head Injury (20 marks: 7/7/6)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Determining the Causes of the Accident

Applying the unsafe-act/unsafe-condition framework and root-cause analysis used for accident investigation in this subject, the accident has one immediate cause and several contributing (root) causes:

• Immediate/direct cause: the die setter rigged his chain against the keeper pin instead of the intended die notch, and did not verify (double-check) the rigging before signalling readiness — an unsafe act, but one enabled by the conditions below.
• Contributing unsafe condition — no independent rigging verification step: the lifting procedure did not require a second person, or the co-worker, to independently inspect both rigging points before the crane took up slack; each worker rigged their own end with no cross-check, so a single rigging error on one side went undetected by the other.
• Contributing unsafe condition — ambiguous or insufficiently distinct attachment points: the keeper pin was rigging-accessible enough to be mistaken for the die notch under the chain, indicating the die/fixture design did not make the correct rigging point unambiguous (e.g. by shielding the keeper pin, colour-coding the notch, or making the pin physically incapable of accepting a chain).
• Contributing unsafe condition — premature signal to take up slack: the co-worker signalled the crane operator to take up slack without confirming the die setter had visually verified his own rigging and moved to a safe position first — the sequencing of the lift did not build in a positive "all clear/rigging verified" step before load was applied.
• Contributing unsafe condition — inadequate training/procedure on lift verification: the workers were apparently not trained on, or were not following, a formal pre-lift rigging-inspection procedure (a form of task-specific job safety analysis for die-handling lifts).
• Contributing physical-condition factor: the keeper pin sheared under sudden chain pressure — while this is a direct consequence of the rigging error rather than an independent design defect, it confirms the pin was never intended to bear a lifting load, reinforcing that the rigging point itself was fundamentally wrong, not merely imprecise.

The determined cause is therefore not simply "the die setter rigged it wrong": it is an unsafe act (an unverified, incorrect rigging point) made possible by the absence of an independent verification step, an attachment point that was not unambiguously distinguishable, and a lift sequence that applied load before confirming the rigging and the die setter's position were both safe.

(ii) Corrective Actions Required

1. Engineering control — make the correct rigging point unambiguous: modify the die/fixture so the keeper pin cannot physically accept a lifting chain (shield it, recess it, or use a distinct, differently shaped fitting for the die notch), removing the possibility of confusing the two.
2. Administrative control — require independent rigging verification: implement a mandatory two-person check (each rigger verifies the other's attachment point, not just their own) before any signal to take up slack is given, formalized in a written pre-lift procedure.
3. Administrative control — sequence the lift with a positive "all clear" step: require both riggers to visually confirm correct rigging AND move to a safe position clear of the load path before any signal to take up slack, rather than signalling as soon as rigging is believed complete.
4. Formalize a job safety analysis (JSA) for die-handling lifts specifically, covering rigging point identification, verification sequence, and safe positioning during slack take-up and travel, incorporated into a standard operating procedure for this recurring task.
5. Training — retrain all die setters and crane signal personnel on the revised procedure, the specific failure mode that occurred, and why the extra verification step is required even under production time pressure, reinforced with hands-on demonstration and competency verification.
6. Load-rated rigging point identification — ensure every fixture handled by crane has its designated lifting points clearly marked (permanently, not just by shape) and that any non-lifting hardware near the lifting points (such as a keeper pin) is visually and physically distinguishable from the rated lifting point.

(iii) Follow-Up Action Required

• Regulatory incident reporting — report the skull fracture/loss of consciousness to the applicable provincial OHS regulator within the mandated timeframe (a critical injury of this severity is reportable), and to the Workers' Compensation Board.
• Formal incident investigation and documentation — complete and retain a documented investigation using the root-cause analysis from part (i), forming the basis for the corrective actions in part (ii).
• Extend the corrective actions to every similar die/fixture and lift across the plant, not just the specific die involved, since the underlying unsafe condition (an ambiguous rigging point, no independent verification) is a design/procedure gap that could exist on other fixtures too.
• Verify and audit implementation — confirm the fixture modification, revised rigging-verification procedure, and training have actually been completed and are being followed in practice, with a scheduled follow-up audit (e.g. at 30/90 days) to confirm the change has not lapsed once production resumes.
• Review through the joint health and safety committee — present findings and corrective actions to the workplace committee, both to close the loop with worker representatives and to capture additional insight from crane/rigging crews doing the work daily.
• Manage the injured worker's medical follow-up and return-to-work plan, coordinated with the compensation board, reflecting the severity of a skull fracture and period of unconsciousness.
• Feed the incident into training program content as a case example for future rigging and crane-signal training, closing the loop from a real event back into prevention.