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Theory Of What Causes Accidents: Heinrich's Domino Theory

The Domino Theory

The Domino Theory was developed by G. W. Heinrich in 1931. There are five labeled dominoes in this theory of the cause of an accident. The dominoes are identified as follows,

  • Ancestry/Social Environment,

  • Fault/Person,

  • Unsafe act,

  • Unsafe condition, and

  • Injury.

The ancestry/social environment could be items that are inherited, for instance, bad character traits that influence individuals to act in an unsafe manner or behavior that is tolerated or not addressed (Goetsch, 2010). A supervisor who does not discuss fall protection requirements or safe work practice are examples of this.

The fault of person refers to those character traits, either influenced or obtained by individuals making them behave in an unsafe manner and the question of why the hazardous condition is present. An example would be a person’s tendency to be reckless and lack of care when it comes to safety. An employee is not utilizing proper personal protective equipment, having outbursts when instructed to comply with safety requirements can be viewed as an example of the fault of the person.

Unsafe acts are those actions taken by individuals that lead to an accident. For instance, failing to secure a load. As a result, items fall from a location causing injury to another worker. Another example of unsafe acts could be a failure to barricade an elevator shaft, causing an employee to fall and sustains an injury. Failure to utilize proper lifting techniques while moving a load; failing to follow posted safety signs are other examples.

Unsafe conditions are also another contributor to accidents. Unsafe conditions such as not correctly shoring the area around an excavation, an employee working in an area with hazardous vapors, and a worker working around energized equipment without employing lock-out-tag-out procedures. These can be viewed as unsafe conditions that could potentially cause accidents.

The final domino in Heinrich’s theory is the actual injury to an individual. An accident could be minor such a laceration to the finger; accident could be significant such as a broken bone or concussion.

Goetsch, D. L. (2010). Construction safety and the OSHA standards. Upper Saddle River, NJ: Prentice Hall.


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