Teoria Del Domino

Abstract

The accident investigation is consistently identified as an important role for the safety professional. While it is a small part of safety program administration, it is an essential management tool that can save an organization lost time, money and lives. In any discussion about what many call industrial safety or industrial accident investigation the term accident must be addressed first. Each year, work-related accidents cost the United States almost $50 billion. Over the years, several theories of accident causation have evolved that attempt to explain why accidents occur. Models based on these theories are used to predict and prevent accidents. The most widely known theories of accident causation are the domino theory, the human factors theory, the accident/incident theory, the epidemiological theory, the systems theory, the combination theory, and the behavioral theory.

Heinrich’s Domino Theory

An early pioneer of accident prevention and industrial safety was Herbert W. Heinrich, developed the Domino Theory while working at Travelers Insurance Company in 1929, and expanded on it many times over many years. Heinrich spent quite a few pages elaborating on the Domino Theory in the beginning of his famous book, Industrial Accident Prevention, first published in 1931.

Heinrich identified five types of action that comprise an accident sequence: ancestry and social environment, fault or person, unsafe act, unsafe condition, and injury. “Heinrich showed that by removing one of the intervening dominos (a preventative action) the remaining ones would not fall, and there would be no injury” (Ferry 1981, 127). Heinrich’s domino theory not only defined how accidents occur, but it also helped investigators to develop interventions and preventative measures to prevent accidents. (Oakley, 2012, p. 20)

Fig 1. Domino Theory

The Dominoes

Heinrich posits five metaphorical dominoes labeled with accident causes. They are Social Environment and Ancestry, Fault of Person, Unsafe Act or Mechanical or Physical Hazard (unsafe condition), Accident, and Injury. Heinrich defines each of these “dominoes” explicitly, and gives advice on minimizing or eliminating their presence in the sequence.

1. Social Environment and Ancestry: This first domino in the sequence deals with worker personality. Heinrich explains that undesirable personality traits, such as stubbornness, greed, and recklessness can be “passed along through inheritance” (12) or develop from a person’s social environment, and that both inheritance and environment (what we usually refer to now as “nature” and “nurture”) contribute to Faults of Person.

2. Fault of Person: The second domino also deals with worker personality traits. Heinrich explains that inborn or obtained character flaws (from 1) such as bad temper, inconsiderateness, ignorance, and recklessness contribute at one remove to accident causation. According to Heinrich, natural or environmental flaws in the worker’s family or life cause these secondary personal defects, which are themselves contributors to Unsafe Acts, or the existence of Unsafe Conditions.

3. Unsafe Act and/or Unsafe Condition: The third domino deals with Heinrich’s direct cause of incidents. As mentioned above, Heinrich defines these factors as things like “starting machinery without warning ... and absence of rail guards.” (12) Heinrich felt that unsafe acts and unsafe conditions were the central factor in preventing incidents, and the easiest causation factor to remedy, a process which he likened to lifting one of the dominoes out of the line. These combining factors (1, 2, and 3) cause accidents.

4. Accident: Of accidents, Heinrich says, “The occurrence of a preventable injury is the natural culmination of a series of events or circumstances which invariably occur in a fixed and logical order.” He defines accidents as, “events such as falls of persons, striking of persons by flying objects are typical accidents that cause injury.”

5. Injury: Injury results from accidents, and some types of injuries Heinrich specifies in his “Explanation of Factors”

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