woensdag 21 september 2011

Discussing Heinrich, Part 3: Manuele

In comparison to the other two books, this one is strikingly thin (87 pages including everything), only A5 sized with an enormous font and something like double line space. As you can imagine something for a good afternoon’s read and no more.

Manuele’s aim was to eliminate “from our practice any old but still used premises that, upon examination, would be judged invalid” (p.1). A very worthy cause in my opinion, because there’s little I hate more than (so-called) professionals selling bullshit.
Since a lot of questionable premises are found in Heinrich’s work, Manuele set out to “review the origin of those premises, how they have changed over time, and their validity” (p.1) the results of which ended up in this booklet.

Manuele discusses the four original versions of Heinrich’s book among which there are apparently significant changes, something I was unable to check since I only have one version, but it doesn’t surprise me - the four versions came out over a 30 year period with approximately 10 years in-between each update; it would have been strange if there had been no changes. Sciences and the world move on, after all. What baffles me, however, is that Manuele doesn’t make one single mention of the 1980 reworked edition, especially since several (maybe even all?) of his comments are addressed and corrected in that version. No doubt that Manuele must have been aware of this fifth edition; he even quotes other work by Petersen. So I wonder why Manuele does neglect the 1980 version. Maybe because it makes his own booklet rather obsolete? Anyway, let’s see what Manuele has to say (all of which is neatly summed up in Chapter 11 that can nearly in its full been read on Heinrich’s Wikipedia page).

The introduction tells us a bit about Heinrich’s life and work and then lists the outline for further discussion. What surprises a bit is that Manuele excuses Heinrich for his out-of-date and sometimes sexist style of writing ("consider the times in which he wrote” - p.5), but doesn’t use similar considerations with regard to the difference in safety science we have at our disposition these days and the little that Heinrich had way back then.

Chapter 2 reflects on transitions in the work world from the 1930s to 2000 and then poses the question if workplace studies made in the 1920s still be valid today. This question is left rather unanswered, expect for an “I don’t think so”. Manuele uses a bit of statistics first, but as far as I can judge he throws together stuff you can’t just compare without further work (after all, disabling injuries and lost time injuries are NOT the same thing). Further more I’d like to pose the hypothesis that while a lot has changed in the past 80 or 90 years, the basic principles can be very valid today. And probably are.

Chapter 3 discusses psychology and safety and what Heinrich meant about this. As I said in my discussion of the ’41 book this certainly wasn’t Heinrich’s finest moment and much of what Manuele says I just agree with, although Manuele just like Heinrich doesn’t define what he understands as ‘psychology’ thus weakening his own point.

Chapter 4 takes on Heinrich’s 88 : 10 : 2 ratio in (direct) causes. Manuele says that he believes “that those who proclaim that unsafe acts are the principle causes of accidents do the world a disservice” (p.19). Amen to that. Fully and unashamed. Manuele thinks that this ratio has done the greatest harm to the practice of safety “Because when basing safety efforts on the premise that man failure causes the most accidents, the preventive efforts are directed at the worker rather than on the operating system in which the work is done” (p.22). I would say that the ratio coupled with Heinrich’s focus on direct causes has done the greatest damage. The ratio in itself, dealing with direct causes after all, could very well be a right one depending on what and how you count and what your definitions are. The problem, however, is that this may (will) be utterly insignificant for real substantial safety work since that should concentrate on underlying and root causes instead. And that focus is something that Heinrich does address (and suggests) at times but at other moments totally neglects or even downplays.

Chapter 5 deals with the pyramid and the 300 : 29 : 1 ratio. I wonder why Manuele is so obsessed by the exact ratios? We are safety professionals and not accountants, aren’t we? But no, he finds it necessary to discuss the numbers (something that Heinrich himself was not so straight about, and something that gets a lot of nuance in the fifth edition). It’s almost as if Manuele doesn’t (want to) see the big picture, greater “opportunity” (see the discussion of the 1980 edition) and the beauty of the metaphor. Also he totally neglects the Common Cause Hypothesis as the central thing. Quite disappointing for someone with so many safety science merits as Manuele apparently has. The next chapter carries on with the theme and I think that had Manuele taken the CCH as the basis in mind, this entire chapter would have looked differently. He now only focuses on consequences and goes on arguing that the causal factors between serious accidents and minor incidents are totally different. Of course, since he leaves out one crucial thing: they have to be similar accidents. The CCH, remember?! Just looking at the frequency of consequence is bullshit of course. And here Manuele goes astray just as Petersen et.al. in their update.

The 4 : 1 ratio of hidden costs is the subject of Chapter 7. Yes, Manuele does like his numbers. And maybe this is because it’s such an easy area to prove Heinrich wrong (which has been done in 1980 already, by the way, but in a much more forgiving way). Wouldn’t it be wiser instead to conclude that, okay, the numbers are not applicable always, but the big picture (the actual loss is much greater than just the damage/injury) is right?

Chapters 8 and 9 take on Heinrich’s Principles of Accident Prevention and Axioms of Industrial Safety, but it escapes my understanding what point Manuele is trying to make here. I feel that he agrees with some, disagrees with others but he isn’t really clear why and how.

Chapter 10 discusses the accident sequence (dominos) and makes some of the observations I have done with regard to the left dominos. Regrettably without tying in the more recent updates from the likes of Bird. I really don’t think that anybody actually uses the original Heinrich dominos anymore and he is only credited for coming up with the original metaphor back in 1931 while actually everybody uses one of the revised versions.

Details about the book:
Heinrich Revisited: Truisms Or Myths, Fred A. Manuele, 2002, National Safety Council/NSC Press (ISBN 0-87912-245-5)

To the next part of this article.

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