Friday, November 1, 2013

Heinrich's Law of Safety

A generalized statement of Heinrich's law is that industrial accidents follow a pyramid structure similar to the energy flow in a biological food chain.  Many minor incidents on the bottom.  Fewer, more severe accidents on top.

A fatality is a severe accident where the victim was unlucky and factors aligned such that the severity was sufficient to cause death.  There were many severe accidents (perhaps 10) which were not fatal for every fatality.

The important part of this concept is NOT the ratio.  It is not possible to define a fixed ratio since we are talking about luck and semi-random chance.  The two important things to grasp are that the ratio is small-but-significant and that fatalities are larger specimens of the same species as severe accidents.

A severe accident is no different than a minor accident except the victim was unlucky and factors aligned such that the severity was amplified.  There are many minor accidents (perhaps 100) for every ten severe accidents.  Example:  A pedestrian reacts more slowly to on-coming mobile equipment and is struck squarely rather than a glancing strike.

A minor accident is no different than a no-injury accident except the victim was unlucky and factors aligned such that the severity was amplified.  There are many no-injury accidents (perhaps 1,000) for every hundred minor accidents.  An example of a no-injury accident would be where the pedestrian is brushed by the mobile equipment but skin is not broken.

A no-injury accident is no different than a near-miss except the victim was unlucky and factors aligned such that the severity was amplified.  There are many near-misses (perhaps 10,000) for every thousand no-injury accidents.  An example of a near-miss would be where no contact is made...perhaps the mobile equipment swerved and some property damage (paint scarring) occurred or the pedestrian looked up in time to adjust his path.

A near-miss is no different than a hazard except the victim was unlucky and factors aligned such that the severity was amplified.  There are many hazards (perhaps 100,000) for every ten thousand near-misses.  An example of a hazard might occur each time mobile equipment operates in a footprint that is smaller than optimal.  Example, a fork truck moving material and contacting a guard rail when backing up.

Corollaries


It is not possible to prevent a fatality.  It is rarely possible to recognize a fatal incident before the fact. A fatality is often a matter of inches and fractions of seconds (pedestrian-mobile equipment accidents), or millimeters (electrical equipment), or grams (reloading ammunition), or milligrams or a letter in a name (pharmaceutical).


A fatality occurs when somebody encounters a hazard and is exceptionally unlucky.

Fatalities are so rare that it is impossible to validate the effectiveness of countermeasures.

The only effective way to eliminate accidents, including the ones that result in fatalities, is to eliminate exposure to hazard.

Things like:

---better pictures will be uploaded when #$%^&*@ Blogger cooperates---


 Obstructed view, driveway



Trip hazards and Exposed "sharps"

Entanglement hazards


Potential energy hazards (Called widow-makers in the wood lot).

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