Earlier this year someone wrote me with the question, “Where does the accident pyramid come from?” I thought that others might be interested so I am posting the answer here.
H.W. Heinrich was the source. In his book, Industrial Accident Prevention, 3rd edition, 1950, he published the following figure:
As I understand it, this came from his experience in the insurance industry in the 1920 and early 1930s. (Not exactly a recent source of research.)
Note that the original pyramid from the 30′s has changed to the one we see today with “unsafe acts” at its base.
Here is an article that takes issue with Heinrich’s the accident pyramid:
http://concreteproducts.com/mag/concrete_reevaluating_incident_pyramid/
One on-line source (now deactivated) actually had the following statement:
Heinrich reclassified 15% of the records originally classified as unsafe conditions to unsafe acts. By adding that 15% to the 73% that were initially recorded as unsafe acts, he concluded that 88% of all industrial accidents were caused primarily by unsafe acts of persons. During the same period of time the National Safety Council published a study that indicated that 87% of the industrial accidents were caused by unsafe acts and 78% by mechanical hazards. (The National Safety Council study allowed cases to be classified with multiple causes.) One can conclude from the National Safety Council that many industrial accidents of this era involved recognized mechanical hazards.
I like the concept that the pyramid represents – small problems can cause big accidents. I’m not sure that the concept should totally drive a safety program.
What do you think?
In our organization (an oil and natural gas drilling contractor), we use the Heinrich Pyramid strictly as a means of judging the level of unsafe acts or conditions reporting. In other words, we take a look at a division’s reported injuries and use the triangle to (very roughly) determine if the division is also reporting all of it’s unsafe acts and conditions as required by our HSE management system.
We attempt to prevent the major incidents by reviewing major incidents and high potential minor incidents and unsafe acts/conditions, requiring root cause investigations, and implementing resulting corrective actions.
Does the pyramid have a role? Most definitely. It provides us in the office a guide to ensuring we have the information we need to make sure those hard working employees who make our company money also get home safe to their families at the end of the day.
Where can this book by Mr.Heinrich be obtained ?
I am from India ,, Can I get it in India anywhere ?
Where can I get this book in India ?
Not sure where the book is available in India.
I looked on Amazon.com and they had one used one.
What book buying service is available in India?
Mark
Hi,
There is the Bird Pyramid’s.
Casaouis02
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check out the October 2011 issue of Professional Safety, the magazine of the ASSE which refutes the value of the Heinrich Pyramid.
I saw the October 2011 issue and read the article. He casts doubt on the validity of the exact statistics but I think is “proof” is far short of proving that there is something wrong with the theory that small problems can cause big accidents.
By the way, the theory is not that EVERY small problem can cause a big accident.
I think that the Heinrich pyramid model can be used for regular OSHA recordables and Lost-time cases, but, I am not sure it is a good model for catestrophic “normal accidents” or process safety related accidents. I think that organizations such as NASA and BP focused too much on reducing slips, trips, and falls……and not enough on a questioning attitude/culture.