Basic Models of Accident Causation

What people think about accidents

Accidents theories and models have been developed by considering the following views from different groups about the accident causations.

One group of professional proposes the theory of multiple causation and include the following reasons:

  • Inadequate maintenance
  • Poorly designed equipment
  • Untrained employees
  • Lack of policy enforcement or standard procedures (management control).

According to other group of professionals the following causes of accidents are advocated:

  • Mechanical failure due to improper tool or equipment design, size or application.
  • Health factors, physical limitations or physical incompatibility with the job.
  • Mental inability to perform the task, which includes attention deficit caused by the tedium of mundane jobs that is aggravated by a higher intelligence or inquisitiveness.
  • Lack or misuse of safety equipments or incorrect specifications for devices such as fire extinguishers, mechanical safeguards, personal protective equipment, fall protection equipment, rollover protection cages, handrails, warning labels and barriers.
  • Inadequate ergonomic design.
  • Physical stress induced by working in high noise environments, in prolonged temperature extremes and under conditions of labour fatigue.
  • Inadequate operational controls.

Other professionals are of the view of the following different set of opinions:

  • Lack of management support.
  • Poorly orchestrated downsizing or expansion.
  • A management style that appoints a safety manager and committees to solve the accident problem. Such an arrangement is almost always indicative of weak management arising from a lack of accountability.
  • Gloominess in the workplace.
  • The use of incorrect management logic, as in the following examples:
  • Management commitment is the key to success; in fact, management action is the key to success. (2) Poor employee attitudes cause accidents; actually, poor management practices cause poor employee attitudes. (3) Accidents drive costs; in fact, claims drive costs.
  • Diminished employee confidence in management's ability to provide safety due to a lack of programmes, too many programmes or half-baked, half-hearted, ineffective programmes for regulatory compliance. Abandonment of major programmes or negligence regarding stated plans has a demoralizing effect.
  • Not implementing total quality management (TQM) or implementing it incorrectly.
  • Lack of personal job fulfillment, inadequate or ineffective training. Conversely, there is the myth that "trained people will work safely".
  • Lack of safe work procedure implementation.
  • Chemical impairment.
  • Risk-taking behaviour among personnel who are either inherently high-risk takers or have risk-taking personalities.
  • Lack of shared safety responsibility.
  • Inadequate hiring strategies.
  • Inadequate physical communication systems and personal communication skills.
  • Physical and mental illness of workers, including such ailments as heart disease, untreated diabetes, untreated epilepsy, depression, homicidal or suicidal
  • Tendencies or chemical dependency. Suicide, for example, performed at work in a way that appears to be an accident is better compensated than suicide away from work that is made to look accidental. Homicides at work are frequently more difficult to identify and prove than homicides outside of work.
  • Sleep deficit and shift reassignment affecting the normal life.
  • Fraud.
  • No incentive programme or an inadequate incentive programme.

Other group is of the following views:

  • "act of God"
  • Some would claim that accidents can be caused by a lack of spiritual fitness. People who do not maintain a degree of spiritual fitness will find it difficult, if not impossible, to incorporate safety as part of their personal regimen.
  • Luck.
  • Weather.

The above views from different groups can be concluded by saying that accidents occur due to wrong decisions by senior management, lack of management's foresight for right policies and programmes, weakness in monitoring the day to day safety issues, workers health, workers behaviour and working conditions, incentives, weak regulations and monitoring, missing communication in all tiers, lessons from past accidents, money savings, and so on, etc.
The Bhopal is probably the site of the greatest industrial disaster in history and was a result of a combination of failure of legal, technological, organisational, and human behaviour.

Development process

Accident causation models are originally developed in order to assist people who had to investigate accidents, so that such accidents could be investigated effectively. Knowing how accidents are caused is also useful in a proactive sense in order to identify what types of failures or errors generally cause accidents, and so action can be taken to address these failures before they have the chance to occur. The Incident Ratio Pyramid was developed by researchers, based on data from a wide range of industrial accidents. They suggested that for every serious major injury there were an increasing number of minor injuries, property damage events and incidents with no visible injury or damage. These incidents could be seen to display a fixed relationship. This relationship has been subsequently validated by other work, and although the ratios have varied to a small extent, this concept has formed the basis of safety management systems. However, more recent work by a number of groups indicates that there is a different ratio pyramid where process safety incidents are concerned.

Incident pyramid
Process safety incidents are typically less frequent, have greater potential for harm, and 'near misses' are not as obvious. The barriers that need to be defeated to result in a process safety incident are also different from those which are relevant for an occupational safety incident.

In terms of incident investigation this means that approaches to occupational incidents need to be adapted to be able also to address process safety incidents. This adaption is necessary to allow the consideration of the complex people, plant and management system barriers that prevent, detect, control and mitigate process hazards.

Accident models provide a concept of the characteristics of the accident, which typically show the relation between causes and effects. They explain why accidents occur, and are used as techniques for risk assessment during system development, and for post hoc accident analysis to study the causes of the occurrence of an accident and further measures to control the accidents. Most of the engineering models originated before the introduction of digital technology; these models have been updated but have not kept pace with the fast change in technological revolution. Modern technology is having a significant impact on the nature of accidents, and this requires new causal explanatory mechanisms to understand them and in the development of new risk assessment techniques to prevent their occurrence.


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