You've completed the initial of the accident analysis by gathering information and using it to break the accident down into an accurate sequence of events. You have a good mental picture of what happened. Now it's time to continue the analysis process by completing each of the following three phases of analysis to determine what caused those events. This module will introduce us to the three phases of analysis below:
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Injury Analysis: At this level of analysis, we do not attempt to determine what caused the accident, but rather we focus on trying to determine how harmful energy transfer caused the injury. Remember, the outcome of the accident process is an injury.
Surface Cause Analysis: Here you determine the hazardous conditions and unsafe behaviors described in the sequence of events that dynamically interact to produce the accident. The unique hazardous conditions and unsafe behaviors uncovered are the surface causes for the accident and give clues that point to possible system weaknesses.
Root cause Analysis: At this level, you're analyzing the weaknesses in the safety management system that contributed to the accident. You can usually uncover weaknesses related to inadequate safety policies, programs, plans, processes, or procedures. Root causes always pre-exist surface causes and may function through poor component design to allow, promote, encourage, or even require systems that result in hazardous conditions and unsafe behaviors. This level of investigation is also called "common cause" analysis (in quality terms) because you're identifying a system component that may contribute to common conditions and behaviors that exist or occur throughout the company.
One last important point to make is that most accident processes are far more complex than you might originally think. Some experts believe at least 10 or more factors come together to cause a serious injury accident. Other experts state that an average of 27 factors directly and indirectly contribute to a serious accident.
Only by thoroughly conducting all three levels of analysis can you design system improvements that effectively eliminate hazardous conditions and unsafe behaviors at all levels of the organization. The accident investigation can't serve as a proactive safety process unless system improvements effectively prevent future accidents.
In a comprehensive accident report, you'll be asked to determine the direct cause of the worker's injury. It's important to understand the nature of cause that resulted in the injury so that you can write a clearly describe what directly caused the injury in terms of a "cause and effect" relationship. Here's the cause-effect relationship: the harmful transfer of energy is always the cause of an injury which is the effect. Let's take a look at some examples that illustrate this important principle.
As you can see, in each example above, we identify some form of harmful energy transfer that results in an injury. And, simply put, that's how you describe the direct cause of an injury. If you don't describe the type of energy transfer involved and resulting injury, you're not writing an adequate statement.
As mentioned in the previous section, injuries are always caused by the harmful transfer of energy to the employee's body. The severity of the injury depends on the magnitude of the harmful energy. Below are the various forms of energy that can be harmful.
The surface causes of accidents are those unique hazardous conditions and unsafe or inappropriate behaviors that occur during the sequence of events that have caused or contributed in some way to the accident.
Let's look at some characteristics and examples of hazardous conditions:
Hazardous conditions may exist in any of the categories below.
It's important to know that most hazardous conditions in the workplace are the result of the unsafe or inappropriate behaviors that produced them. Let's look at some characteristics of unsafe or inappropriate behaviors:
Below are some examples of unsafe or inappropriate employee/manager behaviors.
We recommend using both the "5-Why Analysis" and "Fishbone Diagram" to help you conduct an event analysis to uncover surface causes. Follow the steps below to conduct a Fishbone Diagram:
The diagram you'll produce using this procedure should look something like the diagram to the right. In fact, it will probably look more complex. Each level of questioning will get you closer to the root cause(s) that contributed to the hazardous conditions or unsafe behaviors. Ultimately, you'll start identifying inadequate policies, programs, plans, processes, procedures and practices (the 6Ps): you're getting to the real root causes!
After we have identified the unique conditions and behaviors during event analysis, we need to analyze them to determine their related root causes.
The root causes for accidents are the underlying safety management system (SMS) weaknesses that somehow contribute to the conditions and behaviors we have identified. SMS weaknesses may take two forms:
Safety managers should work with safety engineers to eliminate or reduce exposure to hazards through effectively improving safety system components. Because systems design work common throughout the workplace, eliminating any single root cause may simultaneously eliminate many hazardous conditions and unsafe behaviors.
Since root causes reside within safety management systems, upper management -- those who formulate systems, are most likely going to be involved in making the necessary improvements. When analyzing for system weaknesses, it may be beneficial to coordinate closely with those who will be responsible for implementing system improvements.
Take a look at the Accident Weed, an excellent analogy that helps us understand the relationship between surface and root causes for accidents.
Most accidents in the workplace result from a hierarchy of causes:
This hierarchy implies that, ultimately, management system weaknesses contribute in some way to the vast majority of all workplace accidents. When you conduct accident investigations, assume contributing system weaknesses exist because it's true for most accidents. This fact also implies that it is usually inappropriate to discipline employees when they have accidents.
To effectively fulfill your responsibilities as an accident investigator, you must not close the investigation until you identify the root causes or prove they don't exist.
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