Answer
ALARP (As Low As Reasonably Practicable) is the core risk management principle establishing that a risk must be reduced until the sacrifice (in time, effort, cost, and operational complexity) needed to reduce it further becomes grossly disproportionate to the safety benefit gained.
The Three Risk Regions (Carrot Diagram Framework)In formal risk assessments (such as IMO Formal Safety Assessment - FSA), risks are categorized into three distinct regions:
| Risk Region | Criteria | Required Action |
| Intolerable / Unacceptable | Risk level is too high to be justified under any normal operating conditions. | Operation must not proceed. Risk must be reduced regardless of cost, or the activity must be eliminated/refused. |
| ALARP / Tolerable | Risk is acceptable only if further mitigation is proven to be impracticable or grossly disproportionate in cost. | Risk must be actively managed and monitored. Control measures must be applied until additional safety gains no longer justify the resources required. |
| Broadly Acceptable | Risk is negligible or comparable to everyday ambient risks. | No additional formal measures required. Standard operating procedures (SOPs) and routine safety maintenance are sufficient. |
To demonstrate that a risk has been mitigated to ALARP, the burden of proof rests on the operator to show that further risk reduction is impracticable.
Hierarchy of Risk Controls to Achieve ALARPWhen evaluating controls to bring a risk down to the ALARP region, measures must be prioritized according to effectiveness:
Elimination: Physically remove the hazard (e.g., removing flammable gases prior to hot work).
Substitution: Replace the hazard with a safer alternative (e.g., switching from toxic chemical cleaning agents to water-based degreasers).
Engineering Controls: Isolate personnel from the hazard via physical barriers or automated safeguards (e.g., high-pressure fuel pipe double-sheathing, auto-stop oil mist detectors, dead-man switches).
Administrative Controls: Change the way people work through procedures and oversight (e.g., Permit to Work (PTW), Toolborn Risk Assessments, Management of Change (MOC) protocols).
Personal Protective Equipment (PPE): Protect the worker with physical gear (e.g., SCBA, chemical suits, safety harnesses) — least effective as a primary defense.
ISM Code (Section 1.2.2): Mandates that the Safety Management System (SMS) must assess all identified risks to the ship, personnel, and the environment, establishing appropriate safeguards to achieve an ALARP state.
IMO Formal Safety Assessment (FSA): A structured, 5-step risk-based methodology used by the IMO when drafting or amending international conventions (SOLAS, MARPOL):
Identification of Hazards (HAZID)
Risk Analysis (QRA / Frequency & Consequence)
Risk Control Options (RCOs)
Cost-Benefit Assessment (Evaluating ALARP & Gross Disproportion)
Recommendations for Decision Making
Shipboard Operational Risk Assessments (JSA): Used during routine and non-routine shipboard activities (e.g., enclosed space entry, overside work, critical machinery overhauls) to move residual risk from the Intolerable zone into the ALARP zone before issuing a work permit.