ACCIDENTS

Causation, Reporting & Investigation

Causation Theories

Single Cause Domino Theory

Multiple Causation

Single Cause Domino Theory

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

Single Cause Domino Theory

Ancestry & Social

Environment

Fault of Person Unsafe Act or

Condition

Accident Injury

Single Cause Domino Theory

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

Single Cause Domino Theory

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

Accident

Injury or

Damage

Cause d

Cause e

Unsafe

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 habits 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

Conditions

Acc

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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

Interviewing Witnesses

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

Interviewing Witnesses

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

Interviewing Witnesses

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?

Interviewing Witnesses

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

Interviewing Witnesses

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