Heinrich triangle

This method has generated a greater quantity of relevant and useful information than any other monitoring technique It identifies more seemingly minor errors or deficiencies and near misses. This is to be expected as the familiar Heinrich Triangle shows there are numerous near misses for every accident. 

Unreported problems can result in major accidents and serious injuries. Explains the Heinrich Triangle relating number of expected injuries from 330 incidents and percent of accidents resuiting from unsafe acts and conditions. 

To this day, safety practitioners use Heinrich s 300 29 1 ratios, known as the Heinrich triangle, as soundly based premises. But, a review of the Heinrich texts and the lack of documentation require that serious questions be asked as to their validity. In each of the editions following the first edition, the premise to which the ratios apply changed, with no explanation. 

The basis of the Heimich triangle or the Bird-Heinrich triangle as it is known in modified form (see Chapter 1), is the careful collection of data over a range of indnstries on different types of accidents. The accidents can be classified as ... 

Organization leaders must accept that the Heinrich triangle is not accurate predictively. The causal factors for serious injuries and fatalities are different in kind than those that underlie non-SIPs. It is implausible that a serious injury event is a fluke. Or a one-time employee mistake. (Heinrich claimed 88 percent of all workplace accidents and injuries/ illnesses are caused by man failures. ) It is erroneous to assume the conditions leading to a SIP have never previously occurred. SIFs have identifiable precursors. Identifying them on an ongoing systematic basis is fundamental to effective intervention strategy. 

The Heinrich Triangle. Most safety professionals are familiar with "Heinrich s Law." As illustrated in Figure 18.4, Heinrich proposed over 60 years ago a 300 29 1 ratio between "near-miss" incidents, minor injuries, and major injuries (Heinrich, 1931 Heinrich et al., 1980). Ever since, safety professionals have been encouraged to investigate near hits in order to reduce minor and major injuries. Heinrich also estimated that 88 percent of all near hits and workplace injuries resulted from imsafe acts. As a result, some presentations of "Heinrich s Law" add a wider base to the triangle with the label "unsafe acts."... 

W. H. Heinrich from America had attempted amore in-depth study on near miss. He investigated more than 5,000 injuries and found that in 330 similar accidents 300 accidents caused no injuries, 29 cases caused minor injuries along with 1 caused serious injury. That is to say, serious injury, minor injury and no injury accident number ratio is 1 29 300, which is the famous Heinrich law, called the accident triangle, as shown in Figure 3. 

A common strategy for evaluating incidents and for identifying root causes is to use the incident pyramid or triangle shown in Figure 1.10, a concept introduced in the year 1931 by H.W. Heinrich. The basic idea behind the triangle is that serious events such as fatalities, large environmental spills, and serious financial losses occur only rarely. By contrast, near-misses and low-consequence... 

The Foundation of a Major Injury, the 300 29 1 ratios (Heinrich s triangle), is the least tenable of his premises. 

Heinrich was the originator of the type of pyramid, or triangle, that depicted his 300-29-1 ratios. Other triangles with different ratios have appeared. None will withstand statistical analysis. Heinrich s wording in support of the 300-29-1 ratios has changed from edition to edition of his book. Here is the version that appears in the fourth edition ... 

The following discussion and statistics establish that the ratios upon which the foregoing citation is based are questionable and that reducing incident frequency does not necessarily achieve an equivalent reduction in injury severity. Heinrich s 300-29-1 ratios have been depicted as a triangle or a pyramid (Figure 10.1). 

The statistical pattern seen in the BUS data and in many individual companies calls into question one of the core assumptions of modern safety science. For the past 80 years the safety community has assumed that the Heinrich Safety Triangle (HST), first introduced in 1931, is an accurate depiction of the relationship among types of injuries, and how to prevent SIFs. 

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. 

Heinrich, Petersen, and Rods (1980) also developed a triangle that demonstrates the relationship between near misses and fatal accidents in industrial settings. They estimated that, for every fatal accident, there are 10,000 associated near accidents or near-miss scenarios. The triangle proposed by Heinrich et al. is presented in Figure 15.8. 

Heinrich introduced the accident pyramid in his hook Industrial Accident Prevention A Scientific Approach. This pyramid showed his accident-causation theory. Heinrich believed that unsafe acts led first to minor injuries, and then, over a period of time, to a major injury event. The accident pyramid proposed that 300 unsafe acts produced 29 minor injuries and one major injury. The concept of the accident pyramid remained unchallenged many years. However, some recent studies challenge the assumed shape of the equilateral triangle used by Heinrich. Some professionals now believe the actual shape of the model would depend on organizational structure and culture. 

California s experience with I2P2 shows little impact on business Challenging Heinrich s famous triangle... 

Various studies have identified that a tiered relationship exists between the severity of an incident and its frequency of occurrence (Heinrich 1931, Bird 1966, British Safety Council 1975, UK HSE 1993, lET 2009). These studies have concluded that for major injuries (i.e., fatal or serious), a large number of minor injuries and numerous non-injury events typically occur. A definitive numerical relationship has not be established (e.g., 1 to 30 to 300 or 1 to 10 to 600), but the principle and general magnitudes have been accepted by the industry and safety professionals (See Figure 2.6). One of the more important points this drives home is that there are more oppor-tnnities to identify incident canses by increasing the focus on incidents at the lower end of the triangle where there are statistically more opportunities to learn and apply corrective actions. 

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