Accident causation factors

An important part of aity safety strategy is the provision of an effective accident investigation methodology. For accident investigation to be meaningful, selecting the appropriate accident causation model is essential. 

Ar r accident will be the result of a number of events which have occurred. These events can be divided into essential and contributoiy factors. These events can be identified as follows  

Once these events are clearly identified, appropriate intervention can be applied to prevent similar accidents occurring. In the USA a recent Liberty Mutual study gives the ten leading causes of workplace injury. In descending order they are overexertion, fall on same level, bodily reaction, fall to lower level, struck by object, repetitive motion, highway accident, struck against object, caught in or compressed by equipment, and contact with temperature extremes. 

There are mai models of accident causation by diEFerent authors from mai disciplines such as engineering, psychology and science. These models relate events to outcomes and explain complex relationships between the employee and his or her work dynamics. A comprehensive list is given in the Appendix to this chapter. 

This is a systematic approach to accident analysis and is particularly good for trying to determine where hazards exist in technologically complex operations. The space industry would be well suited to this type of analysis as there are maity millions of operations which must come together to produce a successful mission launch. 

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Heinrich, at the time, was an insurarKe investigator, who based his research on examining accident reports completed by company supervisors prior to 1931. He concluded from his research that approximate 90% of all accidents were caused by the unsafe acts of workers. It would be interesting to know if those compare supervisors had adequate skills and knowledge of the work system to identify the true accident causation factors, or if they simply adopted a blame mentahty when accidents occurred. 

To morritor the work envirorrment for the purpose of iderrtrfying accident causation factors and hazards. 

Experience has shown that there have been occasions when hazards and potential accident causation factors have gone undetected because the workplace was not inspected under normal working conditions. There should not be an underestimation of the possible benefits that can be realized from having workplace inspections conducted by people who do not regularly work in the area. People carrying out inspections who are unfamiliar with a particular workplace or work system are forced to ask questions of the locals. The resulting exchange of information can lead to the identification of opportunities to improve safety levels overlooked by the locals because of either familiarity or complacency with their own work environment. 

The documentation should be seen as an organizational asset. As there is alw s considerable effort and expense associated with workplace irrspections, not to fully utilize the information is wasteful. The reports generated through workplace inspections could identify opportunities beyond the iderrtification of hazards and accident causation factors. Inspectiorrs can also iderrtify production improvements, better maintenance techniqnes, means of reducing wastage, and increased efficiency, all of which can contribute to an improved, more productive and safer work environment. 

If we knew all of the causes of accidents, an assumption could be made that we would prevent accidents by ehminating the causes. This is unUkely to occur for two reasons. Firstly, accident causation is complex and accidents generalty are cansed by matty factors. Rarely could you expect a single causative factor to result in an accident. It is most unlikely that two accidents would have the same causes, although the events may appear similar. There are ciurcntly several accident causation factors which are well known. Incorrect workplace l out, fatigue and lack of proper training ate a few examples. The tendency is to control, rather than eliminate, most known accident causes. This is done for practical purposes. 

As a result of these and other limitations on om knowledge of accident causation, matty of the current beliefs are based on what appears logical rather than what we know to be correct. The real influence alcohol and drugs have as accident causation factors in the workplace is assumed rather than known. It could be argued that all alcohol and drug exposme in the work enviromnent should be eliminated. However, the present and the future provision of resources available to target accident causation factors will dictate that we prioritize om expenditure on accident prevention in such a way as to achieve the best overall reduction in accidents for the effort and resources provided. 

It is possible to take atty of the accident causation factors and break them down further in order to closer examine the influence that particular factor is having on the work system. This second tier analysis further increases knowledge about the work system through developing a better understanding of the individual processes that make up the system. It is in this area of investigation and analysis where we come closest to discovering tme accident causation. 

The previous two sections dealt with accident causation factors and accident investigation. Here you are presented with a new w of looking at these issues. 

Theoretical study leading causes of casualties have been one hundred years of history. With the development of productive forces, changes in production methods, production relations, as reflected in the existence of differences in security perceptions. More research scholars tend to study the accident causation studies, the occurrence of the accident was due to human factors and physical factors trajectory of the intersection of the accident is the intersection of time and space. Meanwhile, track crossover theory as accident causation theory, emphasizing the human factor and physical factors occupy the same important position. So, in order to effectively prevent accidents, people must also take measures to eliminate unsafe behaviors and material insecurity. 

At least three types of factors need to be considered in accident causation. The first is the proximate event chain, which for the Herald of Free Enterprise includes the assistant boatswain s not closing the doors and the return of the first officer to the wheelhouse prematurely. Note that there was a redundant design here, with the first officer checking the work of the assistant boatswain, but it did not prevent the accident, as is often the case with redundancy [115,155]. 

This book suggests a new approach to engineering for safety that changes the focus from prevent failures to enforce behavioral safety constraints, from reliability to control. The approach is constructed on an extended model of accident causation that includes more than the traditional models, adding those factors that are increasingly causing accidents today. It allows us to deal with much more complex systems. What is surprising is that the techniques and tools described in part 111 that are built on STAMP and have been applied in practice on extremely complex systems have been easier to use and much more effective than the old ones. 

Note that the first proximate and most easily prevented cause is to be selected. That concept permeates Heinrich s work. It does not encompass what has been learned subsequently about the complexity of accident causation or that other causal factors may be more significant than the first proximate cause. 

Heinrich recognized that other studies on accident causation identified both unsafe acts and unsafe conditions as causal factors with almost equal frequency. Those studies produced results different from his 88 10 2 ratios, and Heinrich commented on those differences. For example, he cited the National Safety Council as a resource on such studies (Citation 22). 

Use of Heinrich s ideas has led to oversimplification and has encouraged identifying a single causal factor for incidents focusing on employee error. Johnson makes these statements about accident causation in MORT Safety Assurance Systems ... 

David M. DeJoy alluded to the inadequacy of prevention efforts centered on predispositions, motivations, and attitudes of workers in Toward a Comprehensive Human Factors Model of Workplace Accident Causation ... 

Toward a Comprehensive Human Factors Model of Workplace Accident Causation by David M. DeJoy... 

Description Failure to adjust to adverse conditions is a major factor in accident causation. The adverse conditions most frequently encountered cause reduced traction and... 

Accident causation theories include the human factors theory, the domino theory, the systems theory, the combination theory, the epidemiological theory, and the accident/inddent theory [1,2]. The first two of these theories are described below. 

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