In-Depth Notes on Accident Causations

What is an Accident?

  • Definition: Any unwanted event that causes harm to people, property, or processes.

  • Incident: An observable human activity that is an unwanted event that might have had a negative impact on the people, property or process involved.

Nature of Accidents

  • The Event: The event itself must be prevented to avoid consequences.

  • Consequences: Resulting outcomes include injuries, illness, and material damage.

  • Consideration of "near misses"—events with no actual damage but potential for harm.

Accident Causation Theories

  • Significance: Theories aid in identifying problems and directing prevention efforts.

  • Approach: Accidents should be regarded as caused by specific factors rather than occurring by chance.

  • Goal: Provide a logical framework for accident investigation and prevention.

Common Accident Causation Theories

  1. Heinrich's Domino Theory

  2. Human Error/Factors Theory

  3. Accident/Incident Theory

  4. Systems Theory

  5. Combination Theory

Heinrich’s Domino Theory

  • Developed by Herbert W. Heinrich in the 1920s.

  • Concept of one domino effecting the others, linking:

    • Social Environment

    • Undesirable Traits

    • Unsafe Acts or Conditions

    • Accidents

    • Injuries

  • Statistics:

    • 75,000 accidents: 88% unsafe acts, 10% unsafe conditions, 2% unpreventable.

    • For every 330 incidents, results are 300 no injuries, 29 minor injuries, 1 lost-time injury (LTI).

Causes of Unsafe Acts and Conditions

Unsafe Acts:

  • •By-passing safety devices •Failure to wear PPE •Wearing unsafe clothing •Failure to secure/to warn •Unauthorised deviation from SOP •Using defective or improper equipment •Entering confined spaces without clearance •Horseplay •Working on equipment in operation •Throwing materials/tools instead of carrying or passing them

Unsafe Conditions:

  • •Defective tools and equipment •Defective/incomplete design •Ungrounded •Un-insulated •Improper or inadequate clothing •Improper stacking or piling •Inadequate space or clearance for moving objects •Excessive noise •Lack or poor of ventilation, lighting, illumination etc.

Human Factors Theory

  • Accidents attributed to human errors stemming from a series of events.

  • Focus on interaction among:

    • People

    • Tools/Technologies

    • Environment

    • Job

    • Organization

  • Error Types:

    • Errors of omission (failure to act)

    • Errors of commission (failure to act properly)

    • Sequence and timing errors

Accident/Incident Theory

  • Extends Human Factors Theory by adding ergonomic traps and management roles.

  • Identifies environmental and internal factors influencing human decisions, such as pressure and fatigue.

Systems Theory

  • Accidents arise from interactions between the person, machine, and workplace.

  • Changes in any of these factors can raise or decrease accident risks.

Combination Theory

  • Proposes that actual accident causes may integrate multiple models.

  • Caution against applying a single model to all scenarios.

Costs of Accidents

Iceberg Model

  • Direct Costs: Easy to quantify and visible (e.g. medical expenses, lost wages).

  • Indirect Costs: Hidden and often exceed direct costs (e.g. lost productivity, training for replacements).

  • Monetary Implications: Injuries can lead to damage claims, litigation, and loss of reputation.

Summary of Theories and Importance

  • Recognizing the different theories of accident causation helps understand the mechanisms behind accidents and informs prevention strategies.

  • It is crucial to grasp the variations and similarities across these theories for effective safety management.