Accident Theories for Accident Prevention
Summary
TLDRIn this presentation, Azman Abdul Rahman explores theories and models developed by safety experts to understand and prevent accidents. Key topics include the classification of accidents and incidents, the accident triangle ratio, and the causes of accidents. The presentation delves into the domino theory of accident causation and the importance of root cause analysis in preventing recurrence. The speaker emphasizes the application of these theories to workplace safety programs, suggesting a combination of theories and models for effective problem-solving.
Takeaways
- š Accidents and incidents are two different concepts: Accidents result in injury or damage, while incidents have the potential but do not cause actual harm.
- š Unsafe acts and conditions are significant contributors to workplace accidents, with acts like horseplay and conditions like slippery floors posing risks.
- š The accident triangle, introduced by Heinrich, illustrates the relationship between minor injuries, serious injuries, and near misses, suggesting that reducing minor incidents can lead to fewer major accidents.
- š·āāļø Unsafe acts are often caused by human error, which can be influenced by factors like training, attitudes, and fatigue.
- šļø Unsafe conditions can result from inadequate housekeeping, improper storage, or defective equipment, and are often a consequence of human actions.
- š Root cause analysis is crucial for preventing accidents by identifying and addressing the underlying causes rather than just the immediate symptoms.
- š” Maslow's Hierarchy of Needs provides insight into human motivation and behavior, which is important for managing safety in the workplace.
- š The iceberg model demonstrates that direct costs of accidents are often just the tip, with indirect costs like legal fees and lost business potentially much higher.
- š ļø Equipment suitability, proper handling of substances, and safe operating procedures are key components of a safe workplace.
- š Theories of accident causation, such as the domino theory and multiple factors theory, offer different perspectives on why accidents occur and how they can be prevented.
Q & A
What is the main purpose of the presentation by Azman Abdul Rahman?
-The main purpose of the presentation is to provide an understanding of various theories and models developed by safety experts to prevent accidents by addressing unsafe acts and conditions.
How are accidents and incidents differentiated according to the presentation?
-Accidents are unplanned and unexpected events that result in loss, injury, or damage, while incidents are similar events that have the potential to cause harm but do not actually result in injury or damage.
What is the significance of the accident triangle ratio introduced by Heinrich?
-Heinrich's accident triangle ratio suggests that for every 300 near misses, there will be 29 minor injuries and one major injury, indicating the importance of addressing minor accidents to prevent major ones.
What is the role of unsafe acts and conditions in causing accidents as per the presentation?
-Unsafe acts are actions by people that are not safe, such as horseplay or not using PPE, while unsafe conditions are workplace conditions that could cause injury or damage, like missing machine guards or slippery floors.
How does the presentation describe the relationship between near-misses and accidents?
-The presentation describes near-misses as incidents that have the potential to cause injury or damage but do not, and that they are precursors to accidents, which do result in injury or damage.
What is the iceberg model mentioned in the presentation, and how does it relate to accident costs?
-The iceberg model represents the costs of accidents, with direct costs being the visible tip and indirect costs being the larger, hidden portion beneath the surface, which can be significantly higher.
According to the presentation, what are the four main factors that contribute to workplace injuries?
-The four main factors contributing to workplace injuries are environment, equipment and materials, system and procedure, and worker factors such as training, skills, and attitudes.
What is the domino theory of accident causation as presented by Heinrich?
-Heinrich's domino theory suggests that accidents result from a chain of sequential events, and by removing one of the dominoes, typically an unsafe act, the chain can be broken to prevent accidents.
How does Bird's update of the domino theory differ from Heinrich's original model?
-Bird's update introduces the concept of management failure as a leading cause of accidents, emphasizing the role of inadequate systems, standards, and compliance by management in the chain of events leading to accidents.
What is the difference between root cause and basic cause in the context of accident analysis?
-Root cause is the most fundamental cause that, if corrected, can prevent the recurrence of an error, such as poor safety management or lack of training. Basic cause refers to the underlying reasons for unsafe acts or conditions.
Why is root cause analysis important in accident prevention programs?
-Root cause analysis is important because it identifies the fundamental causes of accidents, allowing for corrective actions that can prevent recurrence, rather than just addressing symptoms.
Outlines
š Introduction to Accident Theories and Models
Azman Abdul Rahman introduces various theories and models developed by safety experts to understand how accidents occur. These theories form the basis for accident prevention programs aimed at preventing unsafe acts and conditions. The presentation will cover the classification of accidents and incidents, the accident triangle ratio, causes of accidents, accident causation theories, and root cause analysis. The importance of applying these theories in workplace accident prevention is emphasized, suggesting that a combination of theories and models may offer the best approach to problem-solving. The difference between accidents and incidents is clarified, with accidents resulting in injury or damage and incidents having the potential but not causing harm.
š Accident Classification and Heinrich's Theory
The script discusses how accidents can be classified by the extent of injury or property damage. Unsafe acts and conditions are identified as common causes of accidents. A near-miss is defined as an incident with potential for harm but no actual injury or damage. The concept of property damage due to negligence or acts of nature is introduced. The accident triangle, introduced by Herbert William Heinrich in 1931, illustrates the relationship between serious injuries, minor injuries, and no injuries in accidents. Heinrich's study suggests that for every 300 near-misses, there will be 29 minor injuries and one major injury, implying that reducing minor accidents can lead to a decrease in major accidents. Frank E Bird later refined the theory, proposing a different ratio based on a larger dataset.
š§ Human Factors in Accident Causation
The script emphasizes that accidents are caused by a combination of factors, including unsafe acts and conditions. Heinrich's studies indicate that 88% of accidents are due to unsafe actions, 10% due to unsafe conditions, and only 2% by uncontrolled factors. The shift in safety management from engineering to managing human error is highlighted, with human behavior becoming a crucial aspect of workplace safety. Abraham Maslow's Hierarchy of Needs is introduced as a model to understand human motivation, which includes physiological, security, belonging, esteem, and self-actualization needs. Employers are advised to be aware of contributing factors in their workplace, such as equipment suitability, substance handling, safe operating procedures, and environmental conditions.
š„ The Domino Theory and Accident Prevention
Herbert W. Heinrich's domino theory is presented, which suggests that accidents result from a chain of sequential events. The theory identifies injury, accident, unsafe act/condition, and person's fault as the dominoes that lead to an accident. The theory emphasizes the importance of preventing unsafe acts and conditions to avoid accidents. Bird and Loftus later updated the domino theory, adding management failure as a leading cause of accidents and suggesting that effective safety programs can prevent them. The script provides an example of how the updated domino model can be applied to analyze an accident involving a stamping machine, highlighting the importance of management's role in accident prevention.
š¬ Root Cause Analysis in Accident Investigation
The final paragraph discusses root cause analysis as a systematic process for identifying the underlying causes of problems or events and developing action plans to address them. It differentiates between basic or root causes, contributing causes, and direct causes, explaining that focusing only on the latter two may not prevent recurrence. Root cause analysis aims to answer key questions about what happened, how, and why, and what needs correction. The tools necessary for conducting root cause analysis are mentioned, and the presentation concludes with a hope that the information will aid in developing effective workplace accident prevention programs.
Mindmap
Keywords
š”Accident
š”Incident
š”Unsafe Acts and Conditions
š”Accident Triangle
š”Root Cause Analysis
š”Human Error
š”Maslow's Hierarchy of Needs
š”Iceberg Model
š”Domino Theory
š”Prevention Program
Highlights
The presentation discusses theories and models developed by safety experts to understand how accidents happen and prevent them.
Accident prevention programs aim to prevent unsafe acts and conditions, which are foundational to safety.
Understanding the classification of accidents and incidents is crucial for effective prevention strategies.
The accident triangle ratio, introduced by Heinrich, suggests a relationship between near-misses, minor injuries, and major injuries.
Unsafe acts and conditions are identified as primary causes of workplace accidents.
The concept of near-misses, or incidents with potential for injury but no actual harm, is explored.
Property damage and lost time injury (LTI) are discussed as consequences of accidents in the workplace.
The domino theory by Heinrich explains accidents as a chain of sequential events, emphasizing the prevention of unsafe acts.
Frank E Bird's amended accident triangle shows a different ratio, focusing on property damage and incidents without injury.
Human error in accident causation has become a significant area of study, with human behavior models like Maslow's Hierarchy of Needs being applied.
The iceberg model illustrates the direct and indirect costs of workplace accidents, highlighting the financial impact.
Single factor theory and multiple factors theory are compared in terms of their effectiveness in accident prevention.
Root cause analysis is defined and its importance in preventing accident recurrence is emphasized.
The presentation concludes with a call to action for developing effective workplace accident prevention programs.
A combination of theories and models may provide a better approach to solving safety problems in the workplace.
The importance of understanding the difference between root cause and basic cause of an accident is discussed for effective investigation.
Transcripts
Hello and welcome, my name is Azman AbdulĀ Rahman. In this presentation we look at someĀ Ā
of the theories and models that were developedĀ by safety expert to help better understandingĀ Ā
on how accidents happen. This theories providedĀ the foundation for accident prevention programĀ Ā
aimed at preventing accident, by preventingĀ unsafe acts and unsafe conditions.Ā
By the end of this presentationĀ you should be able to understandĀ Ā
how accident and incident are classified;Ā what are the accident triangle ratio ofĀ Ā
different types of accident; whatĀ are the cause involved in accident;Ā Ā
the theory of accident causation a theory thatĀ explains how accident happens; and the last oneĀ Ā
is root cause analysis, it helps to understandĀ difference between root cause and basic causeĀ Ā
of an accident. All of these theories are veryĀ useful when conducting accident investigation.Ā Ā
You can also apply these theories to yourĀ workplace accident prevention program.Ā Ā
A combination of theories and model may beĀ the better approach towards problem solution.Ā
Accident and incident are the twoĀ words that are easy to confuseĀ Ā
but they are not exactly the same. Let's begin byĀ defining exactly what accident and incident is.Ā Ā
Accident can be defined as an unplanned andĀ unexpected event that cause loss of lifeĀ Ā
injury property damage interruption ofĀ normal activities or damage to environment.Ā Ā
Incident is unplanned and unexpectedĀ event that has potential to cause injury,Ā Ā
illness or property damage, sometimes they areĀ called near-miss. So both events are unplanned,Ā Ā
both can present injury or damage, the differenceĀ is in accident the event results in injury,Ā Ā
however in incident the event does not but it hasĀ potential to cause injury. Basically by definitionĀ Ā
all accidents begin with an incident butĀ not all incidents result in an accident.
In this example you will see the relationshipĀ between incident and accident. BricksĀ Ā
and a hole in a walkway are hazard. Riding aĀ bicycle just beside the brick is an incident.Ā Ā
Riding a bicycle in theĀ hole will cause an accident.Ā Ā
Both are events, already happen. One hasĀ no result and the other caused an accident.
There are several ways to classify an accident,Ā this includes classification by the extentĀ Ā
of injury cause or by the level orĀ cause of the damage to property.
Unsafe acts are things that peopleĀ do that are obviously just not safe.Ā Ā
Some examples are horseplay not using PPE,Ā using damage tools, violating safety rules.
Unsafe conditions are a condition in the workplaceĀ that is likely to cause injury or property damage,Ā Ā
such as missing machine guards, damage equipment,Ā slippery floor and improper storage of material.
A near-miss is any form of incidentĀ that has the potential to causeĀ Ā
but does not actually result in injury or propertyĀ damage or any interruption to normal operation.Ā Ā
Near misses also may be referredĀ to as close call or near accident.
Property damage is damage or destruction ofĀ real or personal property caused by negligence,Ā Ā
willful destruction or act of nature.
Accident is any unplanned or unexpectedĀ event which causes injury or property damage.Ā Ā
Accident may involve lost time injury orĀ Ā
LTI, simply means that number of days the workersĀ cannot work due to the injury. LTI also includesĀ Ā
number of days the workers unable to performĀ his or her normal duties after returned to work.
Accident triangle shows a relationship between theĀ number of accidents resulting in serious injury,Ā Ā
minor injuries or no injuries. The relationshipĀ was first introduced in 1931 by Herbert WilliamĀ Ā
Heinrich. Heinrich was a pioneer in theĀ field of workplace safety and health.Ā Ā
From the study of 75 000 accident reports dataĀ he suggested for every 300 near misses thereĀ Ā
will be 29 minor injuries and one major injury.Ā He concluded that by reducing the number ofĀ Ā
minor accidents companies will see aĀ fall in the number of major accidents.Ā Ā
The triangle was widely used in theĀ industrial safety and health programĀ Ā
and was described as a foundationĀ of safety and health philosophy.
The theory was developed further by Frank E BirdĀ in 1966 based on the analysis of 1.7 millionĀ Ā
accident reports. He produced an amendedĀ triangle that showed a relationship ofĀ Ā
one serious injury accident to 10 minorĀ injury accidents to 30 property damageĀ Ā
caused by accidents to 600 incident orĀ near-misses without injury. Bird shows aĀ Ā
relationship between the number of reportedĀ incident and the number of major accidents,Ā Ā
and claimed that the majority of accidentĀ could be prevented by taking proper control.
Whenever an accident occurs someone always asksĀ how did it happen ? Accident do not just happen,Ā Ā
they are caused. Causes of accident can be unsafeĀ act, unsafe condition or a combination of both.Ā Ā
If you are going to prevent accident we must knowĀ what causes the unsafe act and unsafe condition.
Studies by Heinrich shows that 88% ofĀ all accidents are caused by unsafe actionĀ Ā
or unsafe practices, such as reaching into aĀ running machine, operating a machine withoutĀ Ā
guards, using defective tools or equipment,Ā or horseplay during work. 10% are causedĀ Ā
by unsafe condition such as poor housekeeping,Ā improper storage, defective or broken equipment,Ā Ā
machine with no guards and so on. HoweverĀ unsafe condition exists as a result of personalĀ Ā
action of a person. And only two percent areĀ caused by uncontrolled factors or act of nature.
Over the period of time safetyĀ management approach has shifted fromĀ Ā
engineering to managing human to preventĀ human error. Recently a lot of study hasĀ Ā
been conducted about the role ofĀ human error in accident causation.Ā
Study of human behavior has become importantĀ aspect in managing safety at workplace. One ofĀ Ā
the good model for understanding what motivatesĀ human is Abraham Maslow's Hierarchy of Needs.Ā Ā
Maslow first introduced this concept in 1943. ThisĀ theory explained that people are motivated by fiveĀ Ā
basic categories of needs; they are physiologicalĀ security belonging esteem and self-actualization.Ā Ā
Needs lower down in the hierarchyĀ must be satisfied beforeĀ Ā
individuals can attend to the higher needs.
Accidents do not just happen, they are caused.Ā Ā
Accidents do not have single cause. The accidentsĀ are usually the result of a combination of factorsĀ Ā
which may vary from situation to situation.Ā There is a lot of possibilities for whatĀ Ā
can contribute or cause a workplaceĀ injury. They can be grouped into four,Ā Ā
that is environment, equipment and materials,Ā system and procedure or error of worker.
Employers should aware of these contributingĀ factors that may exist in their workplace.Ā Ā
Equipment, are equipment andĀ tools suitable for the task,Ā Ā
are substances used in the workplace beingĀ handled stored and disposed of properly.Ā Ā
System and procedure, areĀ their safe operating procedure,Ā Ā
are there any rules and force, are instructionĀ and training provided for each workers.Ā Ā
Environment, does the work environmentĀ such as facility layout, walking surfaces,Ā Ā
ventilation, lighting create any hazard, areĀ they comply with local environmental law.Ā Ā
Worker, are they trained and skilled inĀ performing the work, what are the workersĀ Ā
attitudes towards their work, are they focusedĀ when doing their work, are they overtired.
Any accident at work result in both direct andĀ Ā
indirect costs which are represented byĀ the iceberg model. Direct caused tendĀ Ā
to be the one that we think off first, theyĀ include medical costs and wage replacement.Ā Ā
Indirect costs are hidden costs, they account forĀ more of the overall cost of an accident. They canĀ Ā
be 8 to 36 times higher than direct cost dependingĀ on various factors following the accident.Ā Ā
Indirect injury costs include but are not limitedĀ to legal cost, repair or replacement of damagedĀ Ā
materials or equipment, product delay, loss ofĀ future business and so on. All this causes canĀ Ā
have an impact on company business. By avoidingĀ accident, company can save money and time.Ā Ā
You can estimate the magnitude of the accidentĀ by comparing the number of accidents with theĀ Ā
lost work days. You should also include in yourĀ report any course incurred during the accident
For decades people been asking this question :Ā why do accidents happen ? Over the years severalĀ Ā
theories of accident causation were introducedĀ that tried to explain why accidents occur.Ā Ā
Single factor theory assumed that an accidentĀ is the result of single course. Further, if thatĀ Ā
single course can be identified and eliminated theĀ incident will not be repeated. The reality is thatĀ Ā
accidents always have more than one contributingĀ factors. The multiple factors theory says thatĀ Ā
an accident occurs when a number of factors actĀ together cause an accident. Determining the causeĀ Ā
leading to an accident can be quite difficult asĀ there are so many factors to consider. An accidentĀ Ā
causation model is a systematic method of findingĀ what type of failure or area cause accidentĀ Ā
and so action can be taken to address thisĀ failure, before they have the chance to occur.
This example shows a comparison between singleĀ and multiple model of accident causation.Ā Ā
In this scenario a forklift accidentallyĀ hit a worker while walking at a warehouse.Ā Ā
According to the single model the only cause isĀ forklift operator fault for not being careful,Ā Ā
the solution is to take a disciplinary action.Ā Ā
When using the multiple model several causesĀ of accident can be identified, among them areĀ Ā
does the forklift operator properly trainedĀ on operating the forklift, does the operatorĀ Ā
authorize to operate the forklift, is there anyĀ safe operating procedure for operating a forklift,Ā Ā
thus the forklift is in good condition andĀ safe to drive, does the environmental conditionĀ Ā
such as lighting or ventilation at theĀ warehouse create hazard, and so on.
In 1931 Herbert W Heinrich presented a modelĀ known as the domino theory. This theoryĀ Ā
stated that the accident results from a chain ofĀ sequential events, just like a line of dominoesĀ Ā
falling over. When one of the dominoes falls itĀ triggers the next one and the next one and so on.Ā Ā
The sequence is, injury such asĀ cut, fracture. Injury is caused byĀ Ā
accident, the event that results in injuryĀ due to the unsafe act or unsafe condition,Ā Ā
due to the fault of the person that isĀ negative traits that lead to unsafe acts,Ā Ā
caused by their negative traits that inheritedĀ from social environment. According to HeinrichĀ Ā
the accident is avoided by removing one of theĀ dominoes normally the middle one or unsafe acts.Ā Ā
This theory provided foundationĀ for accident preventionĀ Ā
measure aim at preventingĀ unsafe act and unsafe condition.
The first update of the domino theoryĀ was presented by Bird and Loftus in 1976.Ā Ā
Using the same number of domino the elementsĀ are lack of control, refers to inadequate systemĀ Ā
standard and compliance by the management,Ā this lead to the basic courses that includesĀ Ā
human factors such as incompetent, and alsoĀ job factor such as inadequate work standard.Ā Ā
Immediate causes are unsafe act and unsafeĀ condition, they are symptoms of incident.
Accident is undesired events such as contact withĀ hazardous substances, contact with hot object. AndĀ Ā
loss is the result of accident, it can beĀ loss to human, property and environment.
Bird stated that managementĀ failure is another leading causeĀ Ā
of accident at work. Management should implementĀ Ā
an effective safety and health program thatĀ able to prevent accidents and avoid injury.
This example applied the bird domino model.Ā In this scenario a worker had an accidentĀ Ā
while operating a stamping machine.Ā Let's analyze each sequence of events.Ā Ā
Worker hand caught between moving object whileĀ trying to reach something in the machine,Ā Ā
as the result the worker's hand crushed andĀ suffers from major injury. Why the worker'sĀ Ā
hand crashed? because the workers put his handĀ inside the machine while it is in motion. HowĀ Ā
can the workers can enter dangerous partĀ of the machine? because the safety sensorsĀ Ā
that supposed to protect the workers is notĀ functioning. Why the sensor is not functioning?Ā Ā
because there is no one assignedĀ to repair the machine safety sensorĀ Ā
and the management did not performĀ routine check of the machine safety.
For the control measures, the managementĀ can control at the immediate courses thatĀ Ā
is remind the worker not to put his hand into theĀ machine, and at the same time put a warning sign.Ā Ā
However this is not an effective control as theĀ worker may forget and repeating to the unsafe act.Ā Ā
The best way is at the first dominoĀ that is repair or replace the sensorĀ Ā
and make sure it is functioning and tested dailyĀ before letting the worker operate the machine.Ā Ā
From here we can concluded that if theĀ safety sensor is repaired at the early stageĀ Ā
that is controlled from the management, accidentĀ will not happen and injury can be avoided.
Causes of accident can be classified intoĀ three. The basic or root cause is the mostĀ Ā
fundamental cause that can be corrected toĀ prevent recurrence of the error, such asĀ Ā
poor safety management rules not enforce lack ofĀ training and so on, they are underlying causes.
Contributing causes are even or conditions thatĀ increase probability or severity of the accident,Ā Ā
such as equipment failure missing guard andĀ so on. Direct causes is an immediate eventĀ Ā
usually the result of one or more unsafe act orĀ unsafe condition such as ignoring safety rules,Ā Ā
horseplay, and so on. They are the symptomsĀ showing signs of poor safety management system.
Corrective action that focusing only onĀ contributing and direct causes of an accidentĀ Ā
may eliminate the symptom of a problem, butĀ not the actual underlying problem itself.
This may lead to recurrence of similarĀ issue or problem in the future.
Root cause analysis is definedĀ as a systematic process forĀ Ā
identifying the root causes of problem or eventĀ and an action plan for responding to them.Ā Ā
A root cause analysis answered theseĀ questions : what happened? how did it happen?Ā Ā
why it happened? and what need to beĀ corrected. By conducting a root causeĀ Ā
analysis employer may be able to completelyĀ prevent the same incident from recurring.
Following are the tools necessary toĀ conduct root cause analysis. EmployersĀ Ā
should use a combination of theĀ tools to get an optimum result.
This concludes my today's presentation.Ā I hope this will be useful in developingĀ Ā
your workplace accident preventionĀ program. Thank you and see you again.
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