Accident Ratio

In regard to accident ratios, property damage accidents occur more often than any other type of accident. Property damage accidents are therefore opportunities to identify the basic causes and take steps to eliminate similar accidents. It will be appreciated that should a similar accident occur, because of hazards that have not been rectified, the outcome may be different. The next time the accident may result in injury, damage, business interruption, or a combination of these. 

Research has shown that every serious injury experienced as a result of an accident has been preceded by some minor injuries, many more property damage accidents, and there had been plenty of warnings in the form of near-miss incidents (close calls). 

FIGURE 4.2 The updated accident ratio. (From McKinnon, Ron C. 2012. Safety Management, Near Miss Identification, Recognition and Investigation. Boca Raton Taylor Francis. With permission.) 

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Property damage accidents are the most important in the accident ratio (Figure 4.2). They are also warnings that a failure exists in the management system. This creates... 

FIGURE 10.1 The accident ratio showing the luck factors. 

Disabling injury incidence rate Disabling injury severity rate Accident ratio Property damages... 

Metrics on accident ratios, hours-of-service violations, and out-of-service violations are used as key indicators of the effectiveness of our safety program. Metrics are used by all levels of our organization from driver to CEO to measure performance. ... 

A statistical ratio of incidents, which highlights the frequency and severity. The relationship is depicted in a graphical form of a triangle (see Figure A.l). Sometimes depicted as a loss pyramid, with frequencies on one side and severities on the adjacent side. See also Accident Ratios. 

FIGURE A.1 Various accident ratio/triangle studies. 

To test the validity of published accident ratios and triangles, I did the research resulting in the publication of a paper titled Injury Ratios. The most important conclusion drawn from that research is that variations on the inherent risk levels in industries and businesses—as indicated by the substantial differences in OSHA incidence recordable rates and the percent of incidents that result in lost workday cases—are so great that it is impossible to develop meaningful injury ratios which are universally applicable. 

The collection of accident data on a much broader base to facilitate the planning of control action has been undertaken by a number of researchers and one of the most widely applied accident ratios is that propounded by Bird in 1969. 

Bird went on further to look at a wide range of accident reports across a large number of companies in America. In 1969 he analysed the information and generated the Bird Accident Ratio Triangle . See Fig. 1.4 and Further Reading at the end of this chapter. 

In 1969, a study of industrial accidents was undertaken by Frank E. Bird, Jr., who was then the Director of Engineering Services for the Insurance Company of North America. He was interested in the accident ratio of 1 major injury to 29 minor injuries to 300 no-injury accidents first discussed in the 1931 book Industrial Accident Prevention by H. W. Heinrich. Since Mr. Heinrich estimated this relationship and stated further that the ratio related to the occurrence of a unit group of 330 accidents of the same kind and involving the same person, Mr. Bird wanted to determine what the actual reporting relationship of accidents was by the entire average population of workers [6]. 

Incidents and accidents rarely result from a single cause and many turn out to be complex. Most incidents involve multiple, interrelated causal factors. They can occur whenever significant deficiencies, oversights, errors, omissions or unexpected changes occur. Anyone of these can be the precursor for an accident or incident. There is a value on collecting data on all incidents and potential losses as it helps to prevent more serious events. (See Chapter 5 for accident ratios and definitions.)... 

Most people involved with workplace safety are aware of the iceberg theory, the safety triangle, or its correct terminology, the accident ratio. For every recorded injury or loss sitting above the surface, there are many unrecorded near miss incidents submerged below the surface. This was first proposed by H. W. Heinrich in 1931 when he published his 1 29 300 ratios. 

The accident ratio depicted in Model 1.1 shows that for every serious injury as a result of an accident there are some minor injuries, more property damage events, and plenty of near miss incidents. The only way to reduce the injuries that make up the peak of the triangle is to identify, investigate, and rectify the near miss events before they result in injuries or other losses. 

While the near miss incidents that form the base of the accident ratio are truly the foundation of a major injury, numerous high risk acts and conditions lie below on the next level (Model 1.2). Research has indicated that this lower level of unsafe situations could equate to as many as a thousand high risk situations for every serious injury experienced. While the actual numbers are debatable, the fact remains that there must be numerous high risk acts and conditions for the plenty of near miss incidents experienced. 

Over the years, researchers around the world have investigated the near miss theory and have compiled numerous accident ratios. They have researched the ratio between the near miss incidents, accidents causing damage, minor injuries, and serious injuries. Most of the research has indicated that there are more near miss incidents that have no visible sign of loss than injury- or damage-producing accidents. 

One of the first researchers was H. W. Heinrich (1931) whose accident ratio showed that for every 330 accidents (undesired events) there were 300 accidents that caused no injury, 29 that caused minor injury, and only 1 that caused a serious or major injury. The conclusion was that for every injury-causing accident there were numerous other undesired events (near miss incidents) that had the potential to cause injury (Model 2.1). 

MODEL 2.2 The Pearson accident ratio. (From the British Safety Council. 1974/1975 Tye-Pearson theory. With permission.)... 

Frank E. Bird, Jr. and George Germain Accident Ratio... 

This accident ratio, which was derived from a study by the Health and Safety Executive of Great Britain in 1993 (Model 2.3), showed that for every serious or disabling injury, 11 minor injuries were experienced and 441 accidents occurred that damaged property. 

MODEL 2.3 The HSE accident ratio. (From Health and Safety Executive, U.K. 2006. Online at www.hse.gov.uk/statistics/causinj/index.htm... 

The accident ratio conclusion is a generalization based on the work of safety research and studies conducted in some seven different countries. No figures are used, but the ratio concludes that there are plenty of near miss incidents where nothing happens, but where something might have happened, if circumstances had been slightly different. 

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