Safety Theories

1. Heinrich Theory  
    Heinrich concluded that 98% of the accidents were caused either due to unsafe acts or unsafe conditions (mechanical or physical conditions) or both and can be prevented. Heinrich Theory of Chain of Injury Occurrence which may be summarized as under:

        ·       An injury occurs only as a result of an accident.

        ·       Accident occurs only due to unsafe act and unsafe condition.

        ·      Unsafe act and unsafe condition (i.e., horseplay) exist because of human faults.

        ·       Human faults are inherited or acquired from the environment.

        ·       Environment factors that causes human faults comprises of:

– Improper mechanical or physical or social environmental condition.

– Lack of knowledge and skill.

2. Bird’s Theory

    Bird’s study is an improvement over Heinrich accident ratio study in his 641 cases of accidents.

3. Domino’s 

     According to Domino’s theory accident are the result of many causes and sub causes and random combination of such factors result into accidents.

(i) Domino’s Multiple Causation Theory

(ii) Domino’s Causation Theory

Farrrel Theory

     University of Arizona’s theory of causation of accidents. According to Dr. Russell Ferrell:

• Accidents are the result of human errors.
• Human errors result because of casual chain of overload – situational incompatibility – incorrect response – accidents.

• Heinrich – social environment and unsafe act & conditions. Heinrich also not reported about property damage.
• Birds – lack of controls and unsafe acts & conditions.

Cost of an Accident

        ·       Cost of the Industry or Management

        ·       Cost to the Injured person

        ·       Cost to the Society