Accident Causations Safety Theories

TOPIC 3 ACCIDENT CAUSATION THEORIES

OBJECTIVES: THEORY OF ACCIDENT CAUSATION CAUSATION LEARNING OUTCOMES By the end of this topic, you should be able to: 1. Revie eview w the the 7 theor theorie iess of acci accide dent nt causa causati tion on;; 2. Evalua valuate te the acciden accidentt causa causatio tion n fact factor orss of each each of the the 7 accident causation theories; and .

3. Justify the best accident causation theory to predict and prevent prevent accidents at workplace.


THEORY OF ACCIDENT CAUSATION

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3.1 Domino Theory 3.1.1 Heinrich’ Heinrich ’s Industrial Industria l Safety Principles Principl es 3.1.2 Heinrich’s Heinrich’s Domino Theory 3.2 Human Factors Factors Theory 3.2.1 Overload 3.2.2 Inappropriate Response/Unsuitable Response 3.2.3 Inappropriate Activities 3.3 Accident/Incident Theory 3.4 Epidemiological Theory 3.5 Systems Theory 3.6 Behavioral Theory 3.7 Bird’s Triangle Summary


INTRODUCTION When an accident occurs at the workplace, employers tend to claim that it is due to the negligence of workers. workers. - Is the negligence negligence of workers workers the cause cause of workplace accidents? - What are the effects effects of workplace accidents? - Have you ever wondered how accidents occur and what are their main causes?

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Years ago, several theories of accident causation had been established establishe d to explain why accidents accident s occur. occur. Models based on these theories were used to predict and prevent accidents from occurring.


3.1 DOMINO THEORY The Domino Theory was introduced by Herbert W. Heinrich (Figure Below) after studying the reports of 75,000 industrial accidents.

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From the study, he concluded that: 88% of industrial accidents were caused by unsafe acts committed by fellow workers 10% of industrial accidents were caused by unsafe conditions; and 2% were unavoidable.


3.1 DOMINO THEORY Examples of unsafe acts committed by fellow fellow workers included being negligent and not observing safety procedures. procedures. Examples of unsafe working conditions are: - working in high-rise buildings without proper safety gears and equipment, - the use of faulty or improperly insulated electrical appliances.

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On the other hand, unavoidable accidents include: - Floods - storms and - accidents caused by other individuals.


3.1.1 Heinrich’ Heinri ch’ss Industrial Industri al Safety Principles Princ iples Heinrich outlined 10 axioms known as the Axioms of Industrial Safety which must be adhered to by managers when managing occupational safety safety and health aspects at the t he workplace. No. Axioms 1. The occurrence of an injury invariably results results from a completed sequence of factors, factors, the last la st one of these being the accident itself. itself. 2. The accident in turn is invariably caused or permitted directly by the unsafe act of a person and/or and/or a mechanical or physical physical hazard. hazard. 3. Most industrial accidents are caused by unsafe acts committed committed by humans. .

4. An unsafe unsafe act or condition will not necessarily necessarily cause an accident accident or injury. injury. 5. The excuse given given for committing an unsafe act can be an indicator or lesson to do the right act.


3.1.1 Heinrich’ Heinri ch’ss Industrial Industri al Safety Principles Princ iples Heinrich outlined 10 axioms known as the Axioms of Industrial Safety which must be adhered to by managers when managing occupational safety safety and health aspects at the t he workplace. No.

Axioms

6. The seriousness of an accident cannot be planned or anticipated but what is for sure is that the th e accident can be avoided. 7. The best accident prevention techniques are analogous with the best quality and productivity techniques.

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8. Management should assume responsibility for safety due to its high position in the organiz o rganizational ational hierarchy hierarchy and because it is in the best position to get results. 9. The supervisor supervisor is the key key person in the prevention prevention of industrial industrial accidents. accidents. 10.

In addition to the direct costs of an accident (e.g. compensation, liability claims, medical costs and hospital expenses), there are also hidden and indirect costs.


3.1.2 Heinrich’s Heinrich’s Domino Theory According to Heinrich, there are five factors in the sequence of events leading up to an accident.

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Heinrich proposed a ‘5-factor accident sequence’ in his theory.


3.1.2 Heinrich’s Heinrich’s Domino Theory The sequence of accident factors are summarized in Table Table below: No.

Factor

1. Ancestry and Social Environment

2. Fault of Person .

Explanation The negative character traits that may lead people to behave in an unsafe manner may be inherited (ancestral) or acquired as a result of the social environment. Negative character traits whether inherited or acquired are the reasons behind why people behave in an unsafe manner and why hazardous conditions exist (e.g. smoking in an area which contains flammable materials).


Heinrich’s Domino Theory 3.1.2 Heinrich’s The sequence of accident factors are summarized in Table Table below: No. 3.

Factor

Unsafe Act / Mechanical & Physical Hazards 4. Accident

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5. Injury

Explanation Unsafe acts committed by a person and mechanical or physical hazards are the direct causes of accidents (e.g. negligence). Typically, Typically, accidents accident s lead to injuries injuri es and will have a negative effect on the performance and image of organisations. Accident injuries may range from minor cuts and scratches to serious ones such as loss of a limb or other disability. disability. Injuries such as lacerations and fractures have a negative effect on workers’ performance.


Heinrich’s Domino Theory 3.1.2 Heinrich’s Heinrich’s theory has 2 central points:

(a) Injuries Injuries are caused caused by by the actions actions of prece preceding ding factor factors; s; and (b) Removal Removal of the central central factor factor negate negatess the actions of preceding preceding factors factors and in doing so, prevents accidents and injuries.

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- However, However, the weakness of this theory theor y is that not no t all accident factors factors are inherited. - Accidents may occur due to negligence and mechanical failure.


3.2 HUMAN FACTORS THEORY

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3.2.1 Overload These factors are explained in detail in the following following sub-topics.

Overload is amounts to an imbalance between a person's capacity at any given time and the load being carried by a person in a given state. . Refer Refer to Figure below to see how work stress can be a human factor in workplace accidents.

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The figure illustrates illustrates how a worker worker who is experiencing chronic work stress has a greater chance to suffer from illnesses such as mental stress which, in turn, may cause an undesirable incident to occur


3.2.1 Overload A person's capacity is the combination combination of qualities such as his: -natural ability - training - state of mind - stress and; - physical condition. .

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The load that a person is carrying consists of tasks for which he is responsible, and other added burdens resulting from factors such as: (a) Environmental factors (noise, distractions, and so on); (b) Internal factors (personal problems, emotional stress, and worry); and; (c) Situatio Situational nal facto factors rs (level (level of risk, risk, uncle unclear ar instruct instructions ions,, and so on). on). The state in which a person is acting is the product of his motivational and arousal levels.


3.2.1 Overload A person's capacity is the combination of qualities such as his: -natural ability - training - state of mind - stress and; - physical condition. .

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The load that a person is carrying consists of tasks for which he is responsible, and other added burdens resulting from factors such as: (a) Environmental factors factors (noise, distractions, and so on); (b) Internal factors (personal problems, emotional stress, and worry); and; (c) Situatio Situational nal facto factors rs (level (level of risk, risk, uncle unclear ar instruct instructions ions,, and so on). The state in which a person is acting is the product of his motivational and arousal levels.


3.2.2 Inappropriate Response/Unsuitable Response How a person responds in a given situation can cause or prevent prevent an accident. If a person detects a hazardous condition but does nothing to rectify it, he has responded inappropriately. inappropriately. For example, workers at a construction construct ion site must wear hard hats and observe all other safety measures laid down by the management. .


3.2.2 Inappropriate Response/Unsuitable Response If a person removes a safeguard from a machine in an effort to increase output, he has responded inappropriately inappropriately.. Again, if a person disregards an established safety procedure, he has responded inappropriately. Such responses can lead to accidents.

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In addition to inappropriate responses, an unsuitable workplace or work environment can also contribute to accidents.


3.2.2 Inappropriate Response/Unsuitable Response The unsuitability of a person's workplace with regard to; - Physical size of the facilities available - Force - Reach - Feel & - Similar factors can lead to accidents and injuries.

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3.2.3 Inappropriate Activities Human error can be the result of inappropriate activities. An example is the undertaking of a task that a person does not know or not familiar with. Another example is misjudging the degree of risk involved involved in a given task. Such inappropriate activities can lead to accidents and injuries. .


3.2.3 Inappropriate Activities To help you understand this theory, please refer to Figure below

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3.3 ACCIDENT/INCIDEN ACCIDENT/INCIDENT T THEORY The accident/incident accident/incident theory is an extension of the human factors factors theory. It was developed by Dan Petersen and is sometimes sometime s referred to as the Petersen accident/incident theory. Petersen introduced such new elements as ergonomic traps, the decision to err, and systems failures. .


3.3 ACCIDENT/INCIDEN ACCIDENT/INCIDENT T THEORY

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3.3 ACCIDENT/INCIDEN ACCIDENT/INCIDENT T THEORY In this model, overload, ergonomic traps, or a decision to err may lead to human error. The decision to err may be conscious and based on logic, or it may be unconscious. A variety of pressures such as tight deadlines, peer pressure, and budget factors can lead to unsafe behaviors'. .

Another factor that can influence such a decision is the "It won't happen to me" syndrome.


3.3 ACCIDENT/INCIDEN ACCIDENT/INCIDENT T THEORY The systems failure component is an important contribution of Petersen's theory. 1st, it shows the potential for a causal relationship between management managem ent decisions decisio ns or o r management managem ent behavior b ehavior,, and a nd safety. safety. 2nd, it establishes management's role in accident prevention prevention as well as the broader concepts of safety and health in the workplace. .


3.3 ACCIDENT/INCIDEN ACCIDENT/INCIDENT T THEORY Systems failure is normally caused by several acts or approaches which do not fulfils the requirements of occupational safety and health such as the following: following: (a) Management Management does does not establi establish sh a comprehe comprehensiv nsive e safety safety policy; policy; (b) Responsib Responsibili ility ty and authority with with regard regard to safety safety are not clearly clearly defined;

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(c) Safety Safety procedur procedures es such as measuremen measurement, t, inspection inspection,, correction, and investigation investigation are ignored or given insufficient attention; (d) Employees Employees do not receiv receive e proper proper orientati orientation; on; and (e) Employees are not given sufficient sufficient safety training. training.


3.4 EPIDEMIOLOGICAL THEORY Traditionally, safety theories and programs have focused on accidents and the resulting injuries. However, the current trend is towards a broader perspective that also encompasses the issue of industrial hygiene. Industrial hygiene concerns environmental environmental factors factors that, if not addressed properly, properly, can lead to sickness, disease, or other forms of health impairment. .

This trend has, in turn, t urn, led to the development of an epidemiological theory of accident causation


3.4 EPIDEMIOLOGICAL THEORY

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3.4 EPIDEMIOLOGICAL THEORY

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The epidemiology theory model Source: Geotsh. D. L. (2005)


3.4 EPIDEMIOLOGICAL THEORY Figure above illustrates the epidemiological theory of accident causation. The key components are predisposition characteristics and situational characteristics. characteristics. These characteristics, character istics, taken taken together, together, can either result in or prevent conditions that may result in an accident.

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3.4 EPIDEMIOLOGICAL THEORY For example,: If an employee who is particularly susceptible to peer pressure (predisposition characteristic) is pressured by his co-workers (situational characteristic) characteristic) to speed up his operation, a decision that might lead to carelessness and the result will be an increased probability of a workplace accident. .


3.5 SYSTEMS THEORY Are systems components interrelated? Can these elements, combined as a unified whole, cause accidents?

The systems model is a model developed by R.J. Firenzie. A system is a group of regularly interacting and interrelated interrelated components that together form a unified whole. .

This definition is the basis for the systems systems theory of accident causation.


3.5 SYSTEMS THEORY

The likelihood of an accident occurring is determined by how these components interact in performing performing a task.

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For example, example, a numerically controlled controlled five-axis machining centre in a shop is usually operated by an experienced employee. When she goes on a two-week vacation, vacation, her temporary replacement may be someone less experienced. This situation may lead to accidents.


3.5 SYSTEMS THEORY This change in one component of the system (person/host) increases the probability probability of an accident. Such a simple example is easily understood. However, not all changes in patterns of interaction are this simple.

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Some are so subtle that their analysis may require a team of people, each with a different type of expertise, to scrutinize the situation and learn where the problems lie.


3.5 SYSTEMS THEORY The primary components of the systems systems model are are the person person / machine/environment, machine/environment, information, decisions, risks, and the task to be performed. Each of the components has a bearing on the probability that an accident will occur. occur. This model is shown in Figure below:

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3.5 SYSTEMS THEORY As this model shows, even as a person interacts with a machine within an environment, environment, 3 activities take place between the system system and the task to be performed. Every Every time a task is performed, there is the risk that t hat an accident may occur. Sometimes the risks are great; at other times, they are small. This is where information collection collection and decision making come in. .


3.5 SYSTEMS THEORY Based on the information that has been collected by observing and mentally noting the current circumstances, circumstances, the person weighs the risks and decides whether to perform the task under existing circumstances. For example, say a machine operator is trying to fulfill a rush order that is behind schedule.

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An important safety device has malfunctioned on his machine, hampering normal operation. o peration. Simply taking taking it it off will interrupt interrupt work for only five five minutes, but doing so will also increase the probability of an accident, as there is now less safeguarding. safeguarding.


3.5 SYSTEMS THEORY However, replacing the faulty safety device could take up to an hour. Should the operator remove the safety guard and proceed with the task or take take the time to replace it? The operator and his supervisor may assess the situation (collect information), information), weigh the risks, risks, and make make a decision to proceed. .

If their information was right and their assessment of the risks accurate, the task will probably be accomplished without an accident.


3.5 SYSTEMS THEORY However, the environment in which the machine operator is working is unusually hectic, and the the pressure to complete complete an order order that is already behind schedule is intense. These factors factors are stressors stressors that can cloud the judgment of those collecting information, information, weighing risks, and making the decision. When stressors stressors are introduced between points 1 and 3 in Figure Feedback Loop, the likelihood likelihood of an a n accident increases. .


3.5 SYSTEMS THEORY For this reason, Firenzie recommended that 5 factors factors be considered before beginning the process of collecting information, weighing risks, and making a decision. These 5 factors factors are: (a) (a) Job Job req requi uire reme ment nts; s; (b) The work workers' ers' abilities abilities and and limitat limitations; ions; (c) The gain gain if if the task is success successfully fully accomplis accomplished; hed; .

(c) The loss loss if the task task is is attemp attempted ted but but fails; fails; and (e) The loss loss if the the task task is not not attem attempt pted. ed.


3.5 SYSTEMS THEORY These 5 factors can help a person achieve the proper perspective; - before collecting information, - weighing risks, and - making a decision.

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It is particularly important to consider these factors factors when stressors such as’ - noise, - time constraints, or - pressure from a supervisor may tend to cloud one's judgment. judgment.


3.6 BEHAVIORAL BEHAVIORAL THEORY The behavioral theory of accident causation and prevention is often referred to as behavior-based behavior- based safety, safety, introduced by E. Scott Geller (2001) (Figure below). Behavior-based safety is the application of behavioral theories from the field of psychology to the field of occupational safety. safety.

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E. Scott Geller


3.6 BEHAVIORAL BEHAVIORAL THEORY The following is the definition of the behavioral theory. theory.

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3.6 BEHAVIORAL BEHAVIORAL THEORY According to Geller, there are 7 basic principles of behavioral theory. These theories are explained in Table below. No. 1.

Intervention Intervention that is focused on employee behavior;

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Identification of external factors that will help understand understand and improve improve employee behavior (from the perspective of safety in the workplace); Direct behavior with activators or events antecedent to the desired behavior, and motivation of the employee to behave as desired with incentives and rewards that will follow the desired behavior;

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7 Basic Principles of Behavioral Behavioral Theory

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Focus on the positive consequences that will result from the desired behavior as a way to motivate employees;

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Application of the scientific method to improve improve attempts at behavioral interventions;

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Use of theory theory to integrate integrate information information rather rather than to to limit limit possibilities; possibilities; and

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Planned interventions with the feelings and attitudes of the individual employee in mind.


3.6 BEHAVIORAL BEHAVIORAL THEORY For example, workers are shown a video on positive and negative attitudes towards wearing safety hard hats. If a worker worker does not wear wear the safety hat, he has made a mistake mistake and may get injured due to falling objects.

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The consequences of the behavior is C, while wearing the hat or failure to wear the hat is B, and the video show is A (i.e. the antecedents to the behavior).


3.6 BEHAVIORAL BEHAVIORAL THEORY There is often a degree of difference between any theory of accident causation and reality. The various models presented with their corresponding theories in this topic attempt to explain why accidents occur. For some accidents, a given model may be very accurate. For others, it may be less so.

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Often, the cause of an accident cannot be adequately explained by just one model or theory. theory.


3.6 BEHAVIORAL BEHAVIORAL THEORY Thus, according to combination theory, the actual cause may combine parts of several different different models. Safety personnel should use these theories as appropriate both for accident prevention and accident investigation. However, they should avoid the tendency to try to apply one model to all accidents.

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3.7 BIRD’S TRIANGLE Frank Bird, an expert on accident loss control, showed a relationship between major, major, minor and no-injury no-injury accidents. accidents. His study is shown in Figure below. He found that all near miss accidents investigated and analyzed immediately immedi ately..

must

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The necessary actions must be taken as near miss accidents which occurred yesterday could become a serious accident tomorrow (Stranks, 2003). .


3.7 BIRD’S TRIANGLE In fact, according to Bird, near miss accidents tend to lead employers to be careless and be overconfident overconfident because there are no injuries or damage to properties. As a result, employers employers will tend to ignore such near misses. Such attitude will lead to the next level,

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i.e. damage to properties, minor injuries, and if still unchecked, then to the next level which involves involves serious or permanent injuries as explained by the 600:30:10:1 formula in next figure.


3.7 BIRD’S TRIANGLE

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Bird’s triangle Source: Stranks (2003)


SUMMARY Based on the discussion above, there are several theories, which can be used to explain the cause of, or factors leading to accidents. Among these factors factors are: (a) (a) Huma Human n err error or fac facto tor; r; (b) (b) Unsa Unsaffe workpl workplac ace; e; (c) Ergonomic factor; and (d) Syst Systems ems fail failur ure e and others. others.

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In brief, workplace accidents can occur due to a combination of several factors factors that interact interact with one another and not merely due to a single factor. Managers must be able to identify factors leading to accidents in order to prevent or reduce them.


Thank You

Accident Causations Safety Theories

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