Safety Triangle of Heinrich

The Theory:

Herbert William Heinrich (1886 – June 22, 1962 ) was an American industrial safety pioneer from the 1930s. His findings were published his book Industrial Accident Prevention, A Scientific Approach in 1931.

He identified a common ration that for every accident that causes a major injury, there are 29 accidents that cause minor injuries and 300 accidents that cause no injuries. This was because many accidents share common root causes, addressing more commonplace accidents that cause no injuries can prevent accidents that cause injuries.

Heinrich’s work is claimed as the basis for the theory of behaviour-based safety by some experts of this field, which holds that as many as 95 percent of all workplace accidents are caused by unsafe acts.

Heinrich came to this conclusion after reviewing thousands of accident reports completed by supervisors, who generally blamed workers for causing accidents without conducting detailed investigations into the root causes.

Heinrich’s Triangle may also be known by the names Bird’s Triangle, The Safety Triangle or the Loss Control Triangle.

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How does it help En-Sync 8020 and our Clients?

It helps to understand if there is a standard reporting mechanism being employed and its current representation or indication of the safety controls. It also allows questions to be asked in trams of a close loops system, which are the controls for closing actions and feeding back to the employees and management.

It’s rarely machines, or environment that accounts for the majority of safety incidents but employee behaviour. Therefore a good safety system would encourage all employees to participate in creating a safe working environment and would remove the premise that it’s a task for Safety Managers to log hazards, record observations, maintain equipment and support safety officers in their inspections.

By focusing on reducing overall frequency of workplace injuries the number of severe or fatal injuries will consequently reduce. Therefore the involvements of the people closest to the execution of work are the most valuable when it come to a productive and proactive approach in safety management, safety culture improvement and risk reduction. Ultimately the more you focus on the numbers at the bottom level of the pyramid (see the diagram below) the more likely you are going to reduce the number of major safety incidents in the workplace.

  • The ratio must be as far away as possible i.e. a ratio of 1-50-500 is a lot better than 1-10-30
  • The higher the ratio is, the better your controls are
  • The more the company focuses on the numbers at the bottom of the pyramid the more likely it reduces the number of major safety incidents
  • Absence of management monitoring at the bottom of the pyramid prevents the company from avoiding accidents at the top
  • Absence of management monitoring at the bottom of the pyramid leads to lower ratio

The Heinrich’s Triangle is a great theory within the safety and risk management framework, whilst there are other KPIs which we often use, the Heinrich’s Triangle is a good starting point for an assessment.

Heinrich Safety Triangle Assessment

Please tick if you currently monitor any of these indicators
Major injuries (fatalities, disabilities, lost time, medical treatment)
Calculate your accident ratio (divide all measures by your number of major injuries)
Minor Injuries (first aid)
Calculate your accident ratio (divide all measures by your number of minor injuries)
Property Damages
Calculate your property damages ratio (divide all measures by your number of property damages)
Near Misses
Calculate your near misses ratio (divide all measures by your number of Near misses)
Non-compliance behaviours
Calculate your Non-compliance behaviours ratio (divide all measures by your number of reported Non-compliance behaviours)