Risk Management & Critical Controls

Modern mines manage fatal risks with structured risk assessment. Learn risk matrices, bowtie analysis (threats, top event, consequences, preventive and mitigating controls), critical control management (CCM), barrier effectiveness and residual risk, fatigue management and collision avoidance systems.

After analysing fatalities, industry bodies (ICMM) found that most were caused by a few recurring 'material unwanted events' with failed or missing controls. Critical Control Management focuses verification effort on the handful of controls that truly prevent fatalities.

An analogy

A bowtie is a map of an accident: on the left, the roads that lead to it (threats) and the roadblocks (preventive controls); on the right, the damage it could cause and the airbags (mitigating controls).

Risk assessment

Identify hazards (workplace inspections, JHA/JSA, HAZID), assess likelihood and consequence with a risk matrix, apply controls, and re-assess residual risk. Baseline, issue-based and task-based risk assessments operate at different levels.

Bowtie analysis

Centre: top event (e.g. loss of control of haul truck). Left: threats (brake failure, fatigue, poor road) with preventive controls. Right: consequences (collision, rollover) with mitigating controls (berms, ROPS cabins, emergency response).

Critical controls

A control is critical if its failure would significantly increase the risk of a fatality. Each has performance requirements, an owner and routine field verification. Examples: ground support standards, isolation (lock-out), proximity detection, gas monitoring.

Collision avoidance and fatigue

Vehicle interaction systems (Level 7–9 per EMESRT: warn, slow, stop) automatically intervene. Fatigue monitoring cameras detect microsleeps. Both are now expected controls for haulage fatal risks.

Formulas

• Residual frequency: f_res = f₀ × Π P_f,i (independent controls)
• Risk: Risk = likelihood × consequence
• Control effectiveness: Effectiveness = 1 − P_f

Worked example: Residual frequency

Given: Light vehicle enters haul road unseen: 0.5/yr; Traffic rules fail 0.3, proximity detection fails 0.1, auto-braking CAS fails 0.05

Find: Residual collision frequency.

• f = 0.5 × 0.3 × 0.1 × 0.05 = 7.5 × 10⁻⁴ /yr

Answer: ≈ 1 in 1300 years

Worked example: Without CAS

Given: Same case without automatic braking

Find: Frequency.

• f = 0.5 × 0.3 × 0.1 = 0.015/yr

Answer: 20× higher — CAS is a critical control

Common mistakes

• Wrong: Listing dozens of 'critical' controls. — Right: Focus on the few that truly prevent fatalities.
• Wrong: Assuming controls work without checking. — Right: Verify in the field against performance requirements.

Applications

• Fatal risk protocols: Company-wide standards for top risks.
• Field verification: Supervisors check critical controls each shift.
• Technology adoption: CAS, fatigue systems, remote operation.

Key takeaways

• Risk = likelihood × consequence.
• Bowtie: threats, top event, consequences, controls.
• Verify critical controls in the field.
• Residual = f₀ × Π P_fail.

Going further

• ICMM CCM guide: Industry framework for critical controls.
• EMESRT levels: Vehicle interaction control maturity.
• Human reliability: Error probabilities for operator controls.