Investigation of Accidents and Incidents


Investigation of Accidents and Incidents

An accident is an undesired event and is normally defined as an unplanned event which interrupts the completion of an activity, and which may or may not include injury to the person, damage to the property and environment, or loss to the process.

An incident is also an undesired event and it usually refers to an unexpected event that did not cause injury or damage this time but had the potential. Near miss or dangerous occurrence are also terms for an event that might have caused harm but had not. The term incident is used in some situations to cover both an accident as well as an incident.

There are two theories for accidents/incidents. These as briefly described below.

  • WH Heinrich’s Domino theory – As per this theory the occurrence of an injury invariably results from a completed sequence of factors, the last one of these being the accident itself. The accident in turn is invariably caused or permitted directly by the unsafe act of a person and/or a mechanical or physical hazard.
  • Multiple cause theory – This theory states that behind every accident/incident there are many contributing factors, causes, and sub causes. These factors combine in a random fashion causing accidents. Hence the fundamental root causes are to be found and removed to prevent a recurrence.

Majority of accident prevention efforts are based on knowledge gained from earlier accidents/incidents and,  hence it is important to learn as much as possible from each accident/incident. Learning from accidents/incidents can be achieved by investigating them in detail. However these investigations are to be based on fact-finding instead of fault-finding.

An accident/incident investigation is a well planned analysis of an event that identifies the root cause and recommends corrective action to prevent the event from happening again. Incidents that involve no injury or property damage are still to be investigated for the determination of  the hazards which need to be corrected.

Accident/incident investigation is an important part of the safety activities in the organization. It is a common tool to guide the loss reduction efforts of the organization.

Investigation of accident and incidents is both a reactive and proactive process in that it uncovers the root cause and other contributory factors as well as providing valuable information to prevent similar accidents/incidents from occurring in the future. An organization cannot afford, nor is it acceptable to wait for hazards to identify themselves through someone?s accident

Investigations of accidents/incidents must be constructive, credible and timely. The investigator must try to figure out what happened and how to prevent similar situations, and must not try to place blame on any individual or group. If the investigation is antagonistic, and takes an approach that the things have been done in a wrong way, then the process becomes much more difficult, as employees do not want to be blamed or cooperate in a blame giving situation. A more constructive approach is  to find out what happened, and what can be done to prevent this from happening again.

A workplace accident/incident is required to be investigated for the following reasons.

  • For finding out what really happened
  • For finding out the cause or causes of the accident and to prevent similar accidents in the future
  • For identifying any unsafe conditions, acts or procedures
  • For fulfilling statutory requirements if there are any
  • For the determination of the cost of the accident
  • For the determination of the compliance with applicable safety rules and standards
  • Help management in identifying corrective measures

There are two major components which contribute to the cause of an accident/incident. These are (i) the work element, and  (ii) the root cause. The work element is the condition or act that directly caused the incident. Many times it is easy to determine what the work element is that directly caused the accident/incident. However, discovering the system failure that allowed the deficient work element to occur is sometimes more difficult. This system failure is also known as the root cause.

An example of a work element might be a small spill of oil on the floor that someone slipped on. The root cause is the system failure that allowed the work element to become deficient or to occur. For example, a root cause may be a lack of preventive maintenance that resulted in the fork truck leaking oil on the floor.

A thorough investigation reveals the root cause. The purpose of an investigation is to determine both the work elements and the root causes so as to assist in providing the organization with a solution to prevent recurrence. A well conducted investigation identifies the work element(s) that caused the accident/incident and helps to eliminate the root cause(s).

Accident/incident investigations have the potential to be a valuable tool when they are effectively used in the organizational settings. When properly used, they serve as an efficient means to identify the root problem that resulted in the accident/incident as well as determine effective corrective action. The function of accident/incident investigations is to continuously improve operations to reduce human losses, financial losses, and material losses. Conversely, they also have the potential to be exercises in frustration if they are improperly implemented and used.

Accidents/incidents cannot be analyzed if they are not reported. A common reason that they go unreported is that the accident/incident analysis process is perceived to be a search for the guilty rather than a search for the facts. Normally majority of the accidents/incidents are ultimately caused by missing or inadequate system weaknesses. When the organization handles accident/incident analysis as a search for the facts, then all the employees are more likely to work together to report accidents/incidents to correct the  deficiencies, be they procedural, training, human error, managerial, or any other. Management must assume responsibility for improving these system weaknesses.

Timing of the investigation of accident/incident is crucial to the outcome. If an employee reports an accident/incident after a lapse of certain time that had happened earlier, then all the investigator has to depend on what is remembered by the persons involved. The memories of the people fade and evidence may get disturbed and this hampers the investigation process. With timely reporting, an investigation can take significantly less time to complete, and the outcome is also more reliable.

The organizational policy is to be to analyze accidents/incidents to primarily determine how the system deficiencies can be fixed. Accidents/incidents are not to be investigated to determine the liability. A no-fault accident/incident analysis policy helps in ensuring the improvement in all aspects of organizational manufacturing processes.

Accident/incident investigations strengthen the internal responsibility system and is essential for building a positive safety culture in the work place.

The accident/incident investigation process involves the following steps.

  • Report the occurrence of accident/incident without delay which has happened within the organization.
  • Investigate the accident/incident immediately or as soon as possible.
  • The scene of the accident/incident is to be immediately controlled, secured and preserved.
  • The site of the accident/incident is to be visited and the site is to be observed thoroughly and photographs are to be taken.
  • The worker/workers involved in accident/incident and the witnesses are to be interviewed promptly while the information is fresh in their mind. Interview is to be carried out at individual level and not in a group. Interview is to be carried out on the basis of open questions.
  • The back ground information is to be collected and compiled.
  • Develop the sequence of events which has happened.
  • Identify the causes.
  • Report the findings.
  • Suggest corrective action.
  • Write the accident/incident investigation report

An accident is the final event in an accident process. Normally the information gathered in investigation of accidents/incidents is to determine the events prior to, during, and after the accident. Once the events are clearly understood, then the investigator can continue to examine each event for hazardous conditions and/or unsafe behaviors. Accident/incident investigations to place blame may not place adequate emphasis on this. Development of the sequence of events is critical in the accident analysis process to fix the system.

Preservation of physical evidence at the scene of an accident/incident is very important. No one shall disturb the scene of the accident/incident until authorized except to conduct the rescue of injured persons or mitigate an imminent danger. The scene is to be documented completely prior to disturbance or removal of physical evidence.

A thorough search for the facts is an important step in incident/accident analysis. Various tools and techniques are used to collect pertinent facts about the accident/incident in order to determine the direct cause of injury, hazardous conditions and unsafe employee/management behaviors (surface causes) that caused the accident/incident, and system weaknesses (root causes) that produced the surface causes for the accident/incident.

Gaining as much information as possible about the accident/incident is extremely important. Interviewing of the witnesses is both a science as well as an art, and can make the difference between a failed or a successful investigation. During the interviewing a message of cooperation and not intimidation  is to be communicated. Awareness of the interviewing techniques helps in a proper investigation.

It is critical to establish the root cause(s) of the accident/incident so that effective recommendations are made to correct the hazardous conditions and unsafe work practices, and make system improvements to prevent the accident/incident from recurring. The investigator must use appropriate methods to sort out the assembled facts, inferences, and judgments. Even when the cause of the accident/incident appears obvious, the investigator must still conduct a formal analysis to make sure any oversight, or a premature/erroneous judgment is not made.

Usually, making recommendations for corrective actions and system improvements follow in a rather straightforward manner from the cause(s) that were determined. A recommendation for corrective action and system improvement normally contains three parts namely (i) the recommendation itself, which describes the actions and improvements to be taken to prevent a recurrence of the accident/incident, (ii) the name of the person(s) or position(s) responsible for accomplishing actions and improvements, and (ii) the correction date(s).

The documentation of accident/incident investigation is required to contain the following specific elements.

  • When the incident happened. Date and time may be crucial because of work load or shift change.
  • Who or what was affected or hurt by the accident/incident. If an employee was involved, or a piece of equipment damaged, the document is to be specific about which piece of equipment and the extent of damage or injury.
  • Where it happened. Again, specific details may be critical to the investigation analysis or trends that may be present.
  • What object, if any, caused the accident/incident.
  • Which of the work element was deficient and most directly caused the accident/incident. If there was a specific condition (i.e. lifting, twisting, spills, poor maintenance, falling object, defective equipment, lack of procedure, poor lighting, etc.) the same is to be documented.
  • What system failure (or root cause), if any, was evident that needs to be corrected that will prevent a recurrence (i.e. lack of a maintenance schedule, lack of training, lack of procedures, etc.).

The corrective actions which can be suggested in the investigation report falls into the following three categories.

  • Engineering based – These include (i) automation of hazardous process or equipment, (ii) modification of the equipment, (iii) substitution of high hazard materials for ones with lower hazard, (iv) change in the specification of equipment for job tasks, (v) change of layout, location or position of the equipment, (vi) change of position of employee at the equipment for operation, (vii) provision of barriers, warning signs or guard rails, and (viii) increase visibility in workspace etc.
  • Administrative nature – These include (i) modification of the employee functions, (ii) clarity in the defining of the expectations, (iii) to designate employees authorized to operate equipment, (iv) enforcement of disciplinary policy for violation of safety rules, (v) providing of training for the employees, (vi) modification in the job procedures and/or reporting procedures, (vii) review hazards and controls, and (vii) change of frequency and depth of safety inspections etc.
  • Personal protective equipment (PPE) – This includes (i) review of the specified requirements of PPE, (ii) adequacy in the provision of PPE, (iii) training of employees on purpose and usage of PPE, (iv) ensuring that the employees are wearing adequate PPE.

Once the documentation phase is complete, the report is given to the management who has to consider the findings and develop an action plan for taking corrective action and making system improvements. These corrective actions are to be implemented. Employees in the work area are to be notified of any equipment, procedures or additional training that has resulted from the investigation process. These corrective actions are to be followed up to assure they are effective, and that the employees are following the new procedures.

Other factors in accident/incident investigation

In 1932 Heinrich had identified five factors in the accident sequence (Fig 1_. The first factor is the social environment and ancestry. Traits such as recklessness, stubbornness, avariciousness, and other undesirable character traits may be passed along through inheritance. The second factor is the fault of the person. This factor states that inherited or acquired traits of the person; such as violent temper, lack of consideration, ignorance of safe practice, etc., are responsible for the person committing unsafe acts or allowing the existence of mechanical or physical hazards. The third factor is the unsafe act and/or mechanical or physical hazard. Unsafe acts include standing under suspended loads, failure to adhere to lock-out/tag-out policy, horseplay, and removal of safeguards. Mechanical or physical hazards include such items as unguarded machinery, unguarded pinch points, and insufficient light. The fourth factor is the accident. The accident includes events such as slips and trips, being struck by flying objects, being caught in machinery, or coming into contact with high energy sources. Finally, the fifth and last factor is the injury. Injuries include fractures, lacerations, etc., that result directly from accidents.

Five factors of Heinrich accident sequence

Fig 1 Heinrich five factors in the accident sequence

Heinrich had also arranged these five factors in a domino fashion such that the fall of the first domino results in the fall of the entire row. The domino arrangement illustrates Heinrich?s notion that each factor leads to the next with the end result being the injury. It also illustrates that if one of the factors (dominos) is removed, the sequence is unable to progress and the injury will not occur. While it may be difficult or impossible to change a person?s attitude (the first and second domino), proper supervision can guide the person?s behavior so that they do not perform a substandard act or allow a substandard condition to exist (the third domino) which leads to an accident (the fourth domino) that leads to an injury (the fifth and final domino).

Benefits of an effective Accident/Incident Investigation

The following are the benefits of an effective accident/incident investigation.

  • Management demonstrates its commitment to the safety to the employees and the public
  • Employees on the investigation team get trained in investigation techniques
  • Employees start understanding the importance of reporting accidents/incidents
  • Accidents/incidents are promptly reported
  • Accidents/incidents are immediately investigated
  • Root causes are identified
  • Corrective actions are implemented, monitored and evaluated
  • Employees get trained in how to prevent similar accidents/incidents
  • Pain and sufferings are reduced
  • Findings can be used to identify accident/incident trends
  • Associated costs of accidents and property damage are reduced