Accident Aetiology Health & Safety Management for Quarries Topic Three.

Accident Aetiology

Health & Safety Management for Quarries

Topic Three

Objectives of this Section

• To outline how accidents are caused.• To demonstrate the role of human error in

accident causation.• To outline strategies for reducing human

error.

The Domino Theory

• Accident sequence was likened to a row of dominoes knocking each other down.

• The accident is avoided by removing one of the dominoes, normally the middle one or unsafe act.

Updated Domino Theory

This update introduced two new concepts;• The influence of management and managerial error.• Loss, as the result of an accident could be production

losses, property damage as well as injuries.

Multi-Causation

Behind every accident there lies many contributing factors, causes and sub-causes.

ROOT CAUSE BASIC CAUSE IMMEDIATE INCIDENT/

(Lack of Control) CAUSE LOSS

cause a cause d cause f cause b cause e

cause c

Conclusion

• All accidents whether major or minor are caused, there is no such thing as an accidental accident!!

• Very few accidents, particularly in large organisations and complex technologies are associated with a single cause.

• The causes of accidents are usually complex and interactive.

The Role of Human Error in Accidents

“The actions of people account for 96% of all injuries” – (DuPont)

“80-90% of accidents are due to human error” (Heinrich et al, 1980)

“50-90% of accidents according to statistics are due to human failings” – Kletz (1990)

“We seem to have passed the era where the need was for further engineering safety guards….What we have

to do is to capture the Human Factor”

In recent years the UK has suffered a large number of tragic disasters. These include:

• Kings Cross Underground Fire (1987) 31 people killed

• Capsize of the Herald of Free Enterprise Ferry (1987)

189 people killed

• Clapham Junction rail crash (1988) 35 people killed and 500 injured

• Piper Alpha Oil Rig Explosion (1988) 167 people killed

Two common points arose from the Inquiries:

• The influence of human error in the chain of events leading to the accident.

• Failures in the management and organisation of safety.

The Traditional Concept of Human Error

• Look for the immediate cause – an unsafe act.

• Blame the individual concerned.

The Blame Approach - Options

• You accept that human error is inevitable, shrug your shoulders, tell him to be a bit more careful and carry on as before with your fingers crossed.

• Alternatively, you can say as he was responsible, you should discipline him, perhaps even sack him.

• Give him the benefit of the doubt and retrain the man (You will almost certainly therefore be reduced to repeating the training which you know has already failed!).

Organisational & Managerial Failures

Lessons from recent disasters

Inquiry into the King’s Cross Underground Station Fire

• Many of the shortcomings in the physical and human state of affairs at King’s Cross on 18 November 1987 had in fact been identified before by internal inquiries into escalator fires.....The many recommendations had not been adequately considered by senior managers...London Underground’s failure to carry through the proposals resulting from earlier fires......was a failure which I believe contributed to the disaster at King’s Cross.

• I have said unequivocally that we do not see what happened on the night of 18 November 1987 as being the fault of those in humble places.

Inquiry into the Kings Cross Underground Station Fire

• Although I accept that London Underground believed that safety was enshrined in the ethos of railway operation, it became clear that they had a blind spot....

Kings Cross Underground Station Fire

• I believe this arose because no one person was charged with overall responsibility for safety. Each director believed he was responsible for safety in his division, but that it covered principally the safety of staff. The operations director, who was responsible for the safe operation of the system, did not believe he was responsible for the safety of lifts and escalators which came within the engineering director’s department. Specialist safety staff were mainly in junior positions and concerned solely with safety of staff.

Inquiry into the capsize of the Herald of Free Enterprise

• Do they need an indicator light to tell them whether the deck storekeeper is awake and sober? My goodness!!

Inquiry into the Clapham Junction Rail Crash

• All concerned in management, from the members of the Board of Directors down to the junior superintendents, were guilty of fault in that all must be regarded as sharing responsibility for the failure of management. From the top to the bottom the body corporate was infected with the disease of sloppiness.

• The direct cause of the Clapham Junction accident was undoubtedly the wiring errors made by Mr. Hemmingway in his work in the Junction “A” relay room.

Later, the report goes on to state...

• The concept of absolute safety must be a gospel spread across the whole workforce and paramount in the minds of management. The vital importance of this concept .. was acknowledged time and again in the evidence which the Court heard ...

But, subsequently it also states..

• The concern for safety was permitted to co-exist with working practices which ... were positively dangerous ... The best of intentions regarding safe working practices was permitted to go hand in hand with the worst of inaction in ensuring that such practices were put into effect.

Inquiry into the Piper Alpha Oil Rig Fire

• I am convinced from the evidence ... that the quality of safety management .... is fundamental to off-shore safety. No amount of detailed regulations for safety improvements could make up for deficiencies in the way that safety is managed.

General conclusions which can be drawn from the above disasters:

• Not one of these organisations had, before the accidents, any serious reservations about their safety procedures, organisation or management, yet there were clearly many problems of which they were not aware.

• Errors made “at the sharp-end” must be seen in the wider context of the organisation and management climate in which they were committed.

• Actions speak louder than words. The best of written safety policies, the most detailed set of safety rules and procedures etc. are totally meaningless unless they are fully resourced, rigorously implemented and kept under regular review.

• Commitment, positive safety attitudes and motivation together with constant vigilance throughout the organisation (but led from the top), are essential to high safety standards.

• You cannot rely on external prescription to achieve safety.

Classification of Human ErrorActive/Latent Failures

Active Failures

• Have an immediate consequence.• Are usually made by front-line people such as

drivers, control room and machine operators. • Immediately precede, and are the direct cause, of the

accident.

Latent Failures

• Those aspects of the organisation which can immediately predispose active failures.

• Common examples of latent failures include:

   Poor design of plant and equipment;

   Ineffective training;

   Inadequate supervision;

   Ineffective communications; and

   Uncertainties in roles and responsibilities.

Latent failures are important to accident prevention because:

• If they are not resolved, the probability of repeat accidents remains high regardless of what other action is taken.

• As one latent failure often influences several potential errors, removing latent failures can be a very cost-effective route to accident prevention.

Classifying Active Failures (1)

Knowledge-based

Rule-based Slips of action

Lapses of memory

Violations Human Errors

Mistakes

Skill-based errors

Routine

Situational

Exceptional

Human Failures

Slips and Lapses

• Occur in routine tasks with operators who know the process well and are experienced in their work.

• Action errors which occur whilst the task is being carried out.

• Often involved missing a step out of a sequence or getting steps in the wrong order and frequently arise from a lapse of attention.

• Typical examples: Operating the wrong control through a lapse in attention or accidentally selecting the wrong gear.

Classifying Active Failures (2)

Knowledge-based

Rule-based Slips of action

Lapses of memory

Violations Human Errors

Mistakes

Skill-based errors

Routine

Situational

Exceptional

Human Failures

Mistakes

• Inadvertent errors that occur when the elements of a task are being considered by the operator.

• Decisions that are subsequently found to be wrong, although at the time the operator would have believed them to be correct.

Violations

• Deliberate deviations from the rules which are deemed necessary for the safe operation of equipment.

• Breaches in these rules could be accidental or deliberate.

• Violations are seldom wilful acts of sabotage or vandalism.

• The majority stem from a genuine desire to perform work

satisfactorily given the constraints and expectations that exist.

Latent Failures

King’s Cross Underground Station Fire

The latent failures here included:

• While several minor escalator fires had occurred previously and had been investigated, apparently no one in the organisation seriously considered the fact that a major escalator fire was a possibility - consequently, as the inquiry states, little effective action had been taken on the warnings provided by the minor fires.

King’s Cross Underground Station Fire

• Similarly the inquiry also reported that there were serious flaws in the managerial and organisational responsibilities and accountability for safety with virtually all aspects of the organisation thinking passenger safety was someone else’s responsibility.

The Capsize of the Herald of Free Enterprise

Among the latent failures involved here are the following:

1. It was impossible for anyone to on the bridge to see whether the bow doors had been closed prior to setting sail.

2. Although there were organisational procedures in place the Officer in charge was, effectively, working on the basis of “faith” rather than any more positive feedback of information.

3. This design latent failure was compounded by the attitude of the senior management in the memos in reply to a request for an on-bridge warning device.

4. For a formal request concerning a major safety issue, from a senior operational manager, to be treated in such a way clearly indicates that there was apparently very little credibility given to potential safety issues.

Latent Failures

Attitudes to Safety• A safety culture depends on the attitudes to safety

shown by management and supervisors.

Rules & Procedures• Studies have shown that safety rules and procedures

are often:Written negatively, concentrating on should not be done

rather than on what should be done. Impractical. In conflict with other rules.

Training

• Little consideration is given to evaluating the effectiveness of training.

• Hazard awareness is often assumed rather than trained.

• Training should concentrate on what is safe, rather than unsafe, what to do, rather than what not to do.

• Training is not always consistent with the rules and procedures.

Equipment design & Maintenance

• Limitations in the standard of ergonomics applied to the design of the equipment/plant increase the risk of human error.

Strategies for Reducing Human Error

Reducing human error involves far more than taking disciplinary action against an

individual.

Actions for overcoming Active Failures

Slips and Lapses

• Design improvement is the most effective route for eliminating the cause of this type of human error.

Slips and Lapses - Typical problems:

Switches which are too close and can be inadvertently switched on or off.

Displays which force the user to bend or stretch to read them properly.

Critical displays not in the operators field of view.Poorly designed gauges.Displays which are cluttered with non-essential

information and are difficult to read.

Mistakes

• Training is the most effective way for reducing mistake type human errors.

• Based on defined training needs and objectives.

• Evaluated to see if it has had the desired improvement in performance.

Violations

• There is no single best avenue for reducing the potential for deliberate deviations from procedures.

• Consider the factors that reduce an individuals motivation to violate which include:

Under-estimation of the risk.Real or perceived pressure from the boss to adopt poor

work practices.Pressure from work-mates to adopt their poor working

practices.Cutting corners to save time and effort.

Addressing Latent Failures

The organisation must create an environment which:

• reduces the benefit to an individual from violating rules.

• reduces the risk of an operator making slips/lapses and mistakes.

This can be done by identifying and addressing latent failures.