Accident Investigation

Personal damage occurrence ( “Accident “) Investigation

George from shares his considerable experience on the subject


Personal damage occurrences (“Accidents”) may be a source of learning and improvement for the safety management system if they are well investigated and appropriate corrective action implemented. The term accident is an emotionally laden term that infers blame, the term should be avoided.

Why do we investigate?

  1. Statutory requirement-Various safety legislation requires specified events is to be investigated
  2. Corporate policy-Various company policy requires investigations
  3. Aid to common law actions-Common law determinations require detailed evidence
  4. Io maintain employee relations-The majority of employers will say our people are our greatest assets and investigation is part of caring for employees
  5. Most importantly-Change for the future, not BLAME for the past

Analysis Reference Tree-Trunk Method of Personal Damage Occurrence Investigation (Developed by Geoff McDonald)

I have used this technique for ages and believe it produces very high quality investigations. I have been trained in a few other investigation methods and have read widely on the topic, I still keep coming back to A.R.T.T. For a number of years I used to teach a 2 day course on this method and some excellent investigations resulted. The course also allowed people to challenge the more common beliefs about safety.

There are 2 mental shifts required to use A.R.T.T.

Mental shift 1

Look for essential factors not causes. An essential factor is one without which the final damage would not have occurred. Cause is an emotionally laded term that infers blame.

Mental shift 2

Essentially the personal damage occurrence is represented by a tree-trunk lying on the ground, at the end of the tree-trunk you have Person elements, Machine elements and Environment elements, along the length of the tree-trunk you have 6 time zones and the annular or growths rings of the tree represent a number of Ergonomic elements. Instead of looking for “causes” you look for “essential factors” ( an essential factor is one without which the final personal damage could not have occurred) The idea is to look for essential factors where the various categories of the model above intersect.

The model is very easy to use and usually at least 30 essential factors will be found in each personal damage occurrence. This widens your options for control over some other methods of personal damage occurrence investigation.

Brisbane-based OHS consultants, Intersafe conduct reportedly excellent courses on the essential factors methodology and A.R.T.T.

Team approach

The type of investigation conducted depends on the seriousness or complexity of the incident, but it is best done as a team so all parties can contribute their skills and expertise to achieve the best result.

Investigators are collectors of evidence and must base their conclusions on that evidence.

Take the time to choose the right people to conduct the investigation.

The following people should be considered for the team:

  • Safety representatives where they exist;
  • Line manager/supervisor;
  • Safety person from the worksite; and
  • People with the relevant knowledge.
  • One person who knows a little about the Person, Machine and Environment issues
  • Investigation procedures need to be systematic. For any investigation the team should:
  • Act as soon as possible after the incident;
  • Visit the scene before physical evidence is disturbed;
  • Not prejudge the situation;
  • Not remove anything from the scene;
  • Enquire if anyone else has moved anything; and
  • Take photographs and/or sketches to assist in reconstructing the incident.
  • After the initial investigation is complete the team should:
  • Identify, label and keep all evidence. For example, tools, defective equipment, fragments, chemical
  • samples etc;
  • Interview witnesses separately;
  • Check to see if there have been any “near misses” in similar circumstances;
  • Note down all sources of information;
  • Keep records to show that the investigation was conducted in a fair and impartial manner;
  • Review all potentially useful information, including design specifications, operating logs, purchasing records, previous reports, procedures, equipment manuals, job safety analysis reports, records of training and
  • Instruction of the people involved and experiences of people in similar workplaces/industries; and
  • reconstruct the incident (while ensuring that another incident doesn’t occur) to assist in verifying facts, (Worksafe W.A.)
  • The best investigation approach I saw was where about 10 people per shift were trained to be part of investigation teams, this ensured a reasonable number of people were available at any one time taking account for normal absences.

General investigation tips

  • Provide first-aid and medical care to injured persons and make the site safe
  • Ensure Emergency Response Plans are activated
  • Conduct an assessment to determine level of notification, investigation and reporting
  • Report the event as required by local regulations and site procedures. Many organisations have a matrix outlining what types of incidents are reported to various company officers. Workplace Health & Safety Qld and the Police may have to be notified
  • Secure the site until the organisations and D.W.H.S. investigation is complete.
  • Notify next of kin
  • Investigate and report essential factors.
  • Sources of information include original design, design specification, drawings, operating logs, purchasing records, previous reports, maintenance logs, procedures, verbal instructions, inspection and test records, alteration or change of design records, job safety analysis, records of previous training and job performance of the employees and supervisors involved. Never make assumptions, it is appropriate to develop a hypothesis and test it against available evidence.
  • Have relevant persons sign a written statement
  • Use open questions.
  • Take heaps of photos from many angles
  • It may be appropriate to develop a sketch or diagram
  • Take samples, tag & preserve them
  • Do not move evidence
  • Identify the people involved and isolate and separate them. Interviews at both the scene and a quiet place will probably be required. It is essential to put those being interviewed at ease
  • It may be necessary to recreate the incident with due regard to safety
  • Report the findings
  • Develop a plan for short- and long-term corrective action using Haddon’s 10 countermeasures
  • Disseminate key learnings to stakeholders
  • Implement the corrective action plan
  • Obtain sign-off by management
  • Evaluate the effectiveness of the corrective action
  • Make changes for continuous improvement
  • Notify other sections of the organisation and your industry about the circumstances of the incident.

Implementation of recommendations

The investigation is not over until the recommendations have been implemented. Investigations often do not reach their potential because recommendations are not implemented.

Some of the factors to be considered when assessing the degree of controllability include-

  1. Technical feasibility
  2. Reliability
  3. Initial and ongoing cost
  4. Durability
  5. Extent of change required
  6. Impact on other activities

Hazard Control Model

When developing controls for hazards the common wisdom is to apply the hierarchy of controls. It is my experience that applying Haddon’s 10 countermeasures will yield improved results

Various hazard control strategies and models have been developed by safety professionals over the years. One of the most effective but still easiest to apply is that devised by American researcher Bill Haddon

Haddon’s model for hazard control is as follows:

Countermeasure 1

Prevent the marshalling of the form of energy in the first place.

eg. Ripping seams – instead of blasting, substitution of radiation bin level sources with ultra-sonic level detectors, using water based cleaners rather than flammable solvents.

Countermeasure 2

Reduce the amount of energy marshalled.

eg. Radiation – gauge source strength, explosive store licence requirements, control number of gas cylinders in an area

Countermeasure 3

Prevent the release of the energy.

eg. handrails on work stations, isolating procedures, most interlock systems

Countermeasure 4

Modifying the rate or distribution of energy when it is released.

eg. slope of ramps, frangible plugs in gas bottles, seat belts.

Countermeasure 5

Separate in space or time the energy being released from the susceptible person or structure.

eg. minimum heights for powerlines, divided roads, blasting fuse.

Countermeasure 6

Interpose a material barrier to stop energy or to attenuate to acceptable levels.

eg. electrical insulation, personal protective equipment, machinery guards, crash barriers

Countermeasure 7

Modify the contact surface by rounding or softening to minimise damage when energy contacts susceptible body.

eg. round edges on furniture, building bumper bars, padded dashboards in cars.

Countermeasure 8

Strengthen the structure living or non-living that would otherwise be damaged by the energy exchange.

eg. earthquake and fire resistant buildings, weightlifting.

Countermeasure 9

To move rapidly to detect and evaluate damage and to counter its continuation and extension.

eg. sprinkler systems, emergency medical care, alarm systems of many types.

Countermeasure 10

Stabilisation of damage – long term rehabilitative and repair measure.

eg. clean-up procedures, spill disposal, physiotherapy


Generally the larger the amounts of energy involved in relation to the resistance of the structures at risk, the earlier in the countermeasure sequence must the strategy be selected. In many situations where preventative measures are being considered the application of more than one countermeasure may be appropriate.

Countermeasures may be ‘passive’ in that they require no action on the part of persons, or ‘active in the sense that they require some action or co-operation on the part of the persons, perhaps in association with a design related countermeasure (eg. seatbelts).

Passive’ countermeasures tend to be more reliable in the long term. A short term solution to an immediate problem may require the adoption of an ‘active’ countermeasure eg. toolbox sessions on replacing guards over a mechanical hazard, the long term or ‘passive’ countermeasure might be the fitting of interlocks to the guard so that power is off when the guard is off.


Further reading

Haddon, W ‘On the escape of tigers an ecologic note – strategy options in reducing losses in energy damaged people and property’ Technology Review Massachusetts Institute of Technology, 72;7, 44-53, 1970.

Meetings with the stakeholders using the above model to develop controls can be beneficial.


Personal damage occurrences (“Accidents”) may be a source of learning and improvement for the safety management system if they are well investigated and appropriate corrective action implemented. Investigation is best done in teams and appropriate training in investigation techniques is necessary. The Analysis Reference Tree Trunk method of investigation is the best method I have experienced. Some of the material in this paper is adapted from 2 accident investigation texts by Ted Ferry.

George can be contacted on, he welcomes debate on the above (it would be indeed a boring world if everybody agreed with George)

George Robotham, Cert. IV T.A.E.,. Dip. Training & Assessment Systems, Diploma in Frontline Management, Bachelor of Education (Adult & Workplace Education), (Queensland University of Technology), Graduate Certificate in Management of Organisational Change, (Charles Sturt University), Graduate Diploma of Occupational Hazard Management), (Ballarat University), Accredited Workplace Health & Safety Officer (Queensland),Justice of the Peace (Queensland), Australian Defence Medal, Brisbane, Australia,,,07-38021516, 0421860574, My passion is the reduction of permanently life altering (Class 1 ) personal damage


Note -This is what I regard as the ultimate kit, it will need to be tailored to your situation

  1. Digital camera with spare batteries
  2. Micro cassette recorder with spare batteries & tapes
  3. Tape measure (up to 50 metres)
  4. Specimen containers
  5. Number of sealable plastic bags
  6. Clipboard & writing paper
  7. Copies of accident report forms
  8. Stat. Dec. Forms witnessed by a J.P. may be necessary
  9. Disposable gloves
  10. High visibility barrier tape
  11. 4 cans Florescent spray pack paint (various colours)
  12. Dolphin torch & spare battery
  13. Stanley knife
  14. Marking pens
  15. Biros
  16. 2x Portable flashing yellow lights
  17. 6x Witches hats
  18. P.P.E. and high visibility, reflective vest
  19. First-aid kit
  20. Water
  21. Identification tags
  22. Compass
  23. Lock-out padlock may be needed
  24. Magnifying glass
  25. Paper towelling
  26. Danger & Out of Service tags
  27. Workers compensation claim paperwork
  28. Bag to carry stuff in

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