Were Herbert William Heinrich’s theories valid? Do they still matter?

Examining the foundation

Were Heinrich’s theories valid, and do they still matter?

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‘No longer applies’

Taubitz began questioning Heinrich’s model when he worked as global safety director for General Motors in the late 1980s. He and his colleagues noticed that the exposures causing fatalities had nothing to do with sprains, strains or other reportable injuries, “and we intuitively understood that the Heinrich model didn’t fit,” he said.

But when they took their case to senior management, Heinrich’s triangle “was a huge barrier to try to open eyes that something different is happening,” Taubitz continued. “The belief that if we drove minor injury rates almost to zero that somehow magically we would eliminate fatalities was a pervasive thought in the industry.”

That belief is “just wrong” and hinders efforts to advance safety and risk reduction, according to Bruce Main, president of Design Safety Engineering Inc. in Ann Arbor, MI. 

He said Heinrich’s work encourages people to look strictly at procedures and training instead of rethinking system design. He pointed out that the design may encourage unsafe acts, such as if a worker has to defeat an interlock system to go in and clear a machine.

“I think, fundamentally, Heinrich’s ideas were useful at the time, but I think it’s time for us to completely debunk Heinrich’s theories and ideas and start fresh,” Main said. “I’ve seen Heinrich’s ideas abused many times, and I’d like this whole idea to be given its fair due and then dismissed because it no longer applies.”

As an example of abuse, he recalled an insurance broker telling management, as part of a sales pitch, that 85 to 95 percent of accidents are caused by unsafe acts of persons. Main’s concern is that such claims let upper management off the hook – they can attribute accidents to unsafe acts and only buy insurance coverage. 

Likewise, Canada-based quality management consultant Wayne Pardy said some consultants practice what he termed “parrot-based safety” – they repeat unproven numbers based on Heinrich’s work to promote their solutions.

“When an idea has come to the point where nobody questions it, you lose that balance. I think we’ve lost a little bit of that balance,” Pardy said.

Redeeming qualities

A common charge against Heinrich is that he blamed the worker for workplace accidents. But LoMastro said critics are interpreting Heinrich’s theory the wrong way.

“The fact that most accidents result in unsafe behavior doesn’t mean the worker did it on purpose,” he said, adding that a worker may have been given poor training or improper tools.

Indeed, while Heinrich said unsafe acts of persons caused most accidents, his eighth axiom states: “Management has the best opportunity and ability to prevent accident occurrence, and therefore should assume the responsibility.” 

LoMastro also dismissed criticisms about the specific numbers in Heinrich’s book. “Heinrich’s theory was only a theory. It was never meant to be statistical data, so to speak,” he said.

Erickson noted that Heinrich’s work reflects the prevailing attitude of his times. Before him, Frederick Taylor had developed the concept of scientific management to increase industrial efficiency and productivity, and Henry Ford had started using the assembly line to manufacture cars. As Erickson put it, workers were viewed as a cog in the wheel.

Although not a fan of Heinrich’s beliefs, Pardy gives him credit for focusing on the human side of safety. Nevertheless, he said that the workplace has changed dramatically since 1930. Employers face an aging workforce and young workers with different values and expectations, making Heinrich’s work a starting point rather than the end.

“I think what Heinrich’s book did in the ’30s, it gave us the foundation,” Pardy said.

Value of research

If Heinrich was wrong, then what is the correct model for incident prevention?

Taubitz said the profession does not have a perfect model to help forecast severe accidents and fatalities, but he recommended a task-based approach. Main, also a proponent of task-based risk assessments, suggested replacing Heinrich with “prevention through design.”

Beyond Heinrich, Erickson called research “pivotal” in ensuring that employers do not waste time, money and effort on unproven interventions.

Pardy agreed. “I think what we need is more objective evaluation, more independent research into workplace safety and health management,” he said.

While not downplaying the importance of research, Main cautioned against arguing about the probability of a hazardous event occurring. “When you do risk assessments quite a bit, you figure out that there is often much less controversy over how we’re going to reduce the risk than there is over the ratings,” he said. “If you can get over that hump and focus on risk reduction, you can avoid the discussions and all the hand-wringing.”

In Howe’s opinion, time-crunched safety professionals often fail to take full advantage of available research. “Safety research can be very critical, and it’s undervalued in our profession,” he said. “There are a lot of important questions that have not been researched. There’s a huge opportunity in safety research. We should all be paying more attention to it.”

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