Accident Investigation

AccidentsAccidents

Causation, Reporting & Investigation

Causation Theories

Single Cause Domino Theory

Multiple Causation


Heinrich’s theory Each factor is the fault of the factor

that immediately precedes it A preventable injury is the natural

culmination of a series of events or circumstances, which occur in a fixed logical order


Ancestry & Social Environment

Fault of Person Unsafe Act or Condition

Accident Injury


If one of the dominoes is removed then the chain of events will be halted, and the accident will not happen

Element 3 (unsafe act and/or mechanical or physical hazard) is probably the easiest factor to remove


Bird & Loftus extended Heinrich’s theory to encompass the influence of management in the cause & effect of accidents

They suggested a modified sequence as follows:• Lack of management control, permitting• Basic causes (personal & job factors), leading to• Immediate causes (substandard practices or conditions), which

are the direct cause of• The accident, which results in• Loss (negligible, minor, serious or catastrophic

This modified sequence can be applied to every accident and is of basic importance to loss control management

Multiple Causation

May be more than one cause, not only in sequence, but occurring at the same time

In accident investigation all causes must be identified

Usually simple accidents have a single cause

Major disasters normally have multiple causes

Multiple Causation

Cause a

Cause b Unsafe Act

Cause c

AccidentInjury orDamage

Cause d

Cause eUnsafe

Condition

Cause f

Unsafe Acts

Categories:• Operating without clearance• Operating at unsafe speed• Rendering safety devices inoperative• Using unsafe equipment, or using it unsafely• Unsafe methods e.g. loading, carrying, mixing• Adopting unsafe position or posture• Working on moving or dangerous equipment• Horseplay e.g. distracting, teasing, startling• Failure to wear PPE• Lack of concentration; fatigue or ill health• Human Factors

Unsafe Acts

Unsafe acts can be active or passive:• Active Unsafe Acts:

• Worker deliberately removes machine guard

• Passive Unsafe Acts:• More difficult to deal with• By pursuing an active safety policy, it is possible

to achieve a reduction in bad habit s and hence accidents

Unsafe Conditions

Categories:• Inadequate guarding• Unguarded machinery• Defective, rough, sharp, slippery, decayed, cracked surfaces• Unsafely designed equipment• Poor housekeeping, congestion• Inadequate lighting, glare, reflections• Inadequate ventilation, contaminated air• Unsafe clothing or PPE• Unsafe processes• Hot, humid or noisy environment

Unsafe Acts/Conditions

The picture shows how unsafe acts & conditions may interact to produce an accident. Accident potential is increased when unsafe acts & conditions occur simultaneously. Of course, this is not to say that an act or condition alone could not result in an accident.

Unsafe Acts Unsafe ConditionsA

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Accident Reporting

Information should be kept for all injuries, and preferably for near misses

The safety practitioner needs to design a suitable form to ensure that he gets the information that he needs for investigations

Accident Investigation Records

Format:• Name & personal details of victim• Date, day and time of accident• Location of accident• Occupation of victim• Job being done at time• Nature of injury or damage• What inflicted the injury or damage• Who had control of the cause of the injury or damage• What actually happened• Basic and immediate causes• Immediate remedial action taken• Recommendations to prevent recurrence

Use of Investigation Records

Accident records are useless if they are used only to count accidents. Detailed and thorough study of the records as part of the normal ongoing accident prevention programme should yield the following useful information:• Relative importance of the various injury & damage sources• Conditions, processes, machines and activities which cause the

injuries/damage• The extent of repetition of each type of injury or accident in

each operation• Accident repeaters, I.e. those workers who tend to be

repeatedly injured or are involved in more accidents• How to prevent similar accidents in future

Accident Investigation

Could be carried out by:• Safety Practitioner• Management or Supervisor• Safety Representative• Inspector

A joint investigation by company/safety rep is often a good idea

An investigation which does not discover what went wrong, and produce some useful information and recommendations for corrective action, is just a waste of time

Accident Investigation

Initial Actions• Questioning the victim

• Treatment of victim is first priority• Immediate questioning may not be possible - they should be

allowed to collect their thoughts and control their nerves

• Witnesses & Conditions• Investigator can usually go to accident scene and get a fairly

complete story from on-site conditions and witnesses• In all serious accidents and in all other cases where

practicable, conditions at accident scene should remain undisturbed until investigation is complete

Investigators

Immediate supervisor:• Likely to know most about the situation• Knows his own people better than anyone• Has personal interest in determining causes,

as accidents affect the efficiency and morale of his department

• Familiarity with staff could cause problems

Investigators

Recognising Hazards• Familiarity with plant, equipment and layout of operations

will assist in recognising hazards that have been overlooked for some time

• Unsafe acts, as well as conditions, contribute towards most accidents

• It is not sufficient merely to recommend fitting a guard while overlooking the unsafe act, such as rendering the guard ineffective or placing hands in the danger zone

• It is also insufficient to limit attention to an unsafe act if fitting a better guard would reduce the likelihood of injury

Investigators

Safety Practitioner• Necessary in more serious cases• Supervisor may not have necessary

authority• Should seek assistance from local

supervisor• Investigator must have authority to go

as far as is necessary to get to the cause of the problem

The Investigation

Promptness• As soon as possible after the event• Facts will be easier to determine and more details

will be remembered by those involved Fire

• Helpful if investigator is present during the fire• Investigator may gain useful information by watching

the activities of firemen

The Investigation

Evidence• Depending on severity of any injuries or

damage, investigator should be present during clear-up and reinstatement as valuable clues may otherwise be missed

• Failing which, supervisor should take it upon himself to collect the necessary evidence

The Investigation

Equipment• Photographic equipment• Portable lights (electricity may be switched off or accident

scene may be poorly lit)• Sketchpad, pencils and measuring equipment• Record-keeping equipment e.g. notebook and cassette recorder• Sample collection equipment e.g. jars, paper bags, cartons etc.• Tools for cleaning debris or spillages should also be available• Portable gas/vapour detecting equipment

Accident Investigation Procedure

1. Inspection of the accident scene to collect any information relating to physical conditions of the plant, equipment and building

2. Interview witnesses and others likely to give information concerning any unsafe acts or conditions which may have contributed to the accident

3. Summarise all available evidence accurately in a written report to management, recommending future actions to prevent a recurrence

Inspection of the Scene

Careful, detailed look at accident scene, evaluating and noting the following:• Extent & severity of damage• Damage to surrounding property• Environmental conditions which may have had some

bearing on the accident, such as temperature, ventilation, humidity and illumination

Survey the accident scene to see if there are any obvious dangerous physical conditions which may have been responsible for the accident

Inspection of the Scene

In the case of spillages, splashes or other escapes of poisonous, explosive, flammable or other dangerous material, it may be necessary to take samples for subsequent investigation

Where machinery or other equipment has been involved, it may be necessary to issue instructions prohibiting the use or repair of it until the investigation has been completed

Talking with On-Site Personnel

Easy to upset people when asking questions about what has been done, or what has not been done

Casual remarks made during the site inspection may be quite revealing and the investigator should continue to talk to any personnel involved near the scene of the accident

This would also serve as an ideal opportunity to explain the object of the exercise is to discover and root out the causes so as to prevent a repetition. It is not to apportion blame or to criticise any individual

Interviewing Witnesses

Types of Witness• Primary witness

• The victim

• Secondary witness• Extremely rare, the eyewitness• How many people really see the instant of an accident?

• Tertiary witness• Can offer variety of corroborative statements regarding the

acts of people or environmental


Putting witnesses at ease• Explain fully purpose of investigation• Encourage participation and involvement• Show interest in any ideas they might have about

possible preventive measures• Witness must be assured that the purpose of the

investigation is not to blame anyone, but to attempt to find out the cause and thereby reduce possibility of a recurrence


Interview Location• Best to carry out interviews at scene of

accident, as it is easier for those involved to communicate effectively with “props” close to hand

• Easier to explain what happened if witnesses are able to point out specific things and recall their actions related to specific locations


Question Phrasing• Open ended question - what, where, when, how or who• Questions starting with why may put witness on the

defensive• Typical questions:

• What happened? What did you see?What time was it?• Where were you at the time? Where was the victim?• When did you realise something was wrong?• How did it happen? How were you involved?• How could it have been prevented?• Who else was involved? Who else saw it? Who reported it?


Attitude• “What happened” will often promote the fullest response and it

is vital the investigator listens, without interruption, to the witness’s account of the accident

• If something is not understood, investigator should wait until witness has completed his account before asking for clarification

• Do not disagree with any of witness’s statement or make any judgements on his evidence alone

• What a witness believes to have happened will depend to some extent on just how he perceived the situation, even though this might conflict with the actual facts


Conclusion• When witness’s account of accident has been heard,

investigator should repeat it to witness to ensure account is fully understood

• Interview should be concluded on a positive note, which is best achieved by discussing any ideas he may have regarding prevention of a similar occurrence - this will serve to reaffirm the purpose of the interview and ensure the witness’s further co-operation, should it be needed

Interviewing the Victim

Ideally first to be interviewed Injuries may be serious, or may be

suffering from shock Should be interviewed at the

earliest opportunity General principles for interviewing

witnesses apply

What Should be Investigated

ALL incidents/accidents should be investigated

Purpose is to find the cause, with the intention of preventing a recurrence, rather than apportioning blame

An injury usually involves some degree of blame falling on management, supervision, victim or workers

Documents

Accident Investigation