Workplace Accident Investigation Guide

Workplace Incident and Accident Investigation Guide | 4-Stage Blueprint

Welcome to our Workplace Accident Investigation Guide

There are a few things that we want to achieve by the time you finish working through this Accident Investigation Guide, including:

  • Understand the obligations of employers when it comes to incident and accident investigation
  • Give you the confidence to get involved in workplace incident or accident investigation 
  • Provide you with a repeatable framework to carry out your first workplace accident investigation
Accident Investigation Ambulance

By the end of the guide, you’ll be better equipped to learn from adverse events.

Once you master it, you will be making a significant contribution to creating a safer workplace into the future. If you think you may need help from a H&S professional, check out our Accident Investigation Service.

Incident or Accident in the Workplace: Introduction

Why complete an Accident Investigation?

There are hazards in all workplaces; risk control measures are put in place to reduce the risk of accidents and cases of ill health to an acceptable level.

If an adverse event occurs, it may indicate that existing risk control measures are inadequate. At the very least, it’s an ideal time to re-assess the current state of controls.

Learning lessons from near misses can be a great way to make your business more robust. As an employer, there are a myriad of reasons why you should investigate incidents and accidents in the workplace. Let’s look at some of them…

Incident and Accident Investigation | Legal Reasons
  • Simply, to ensure you are operating your organisation within the law.
  • The Management of Health and Safety at Work Regulations 1999, regulation 5,
    requires employers to plan, organise, control, monitor and review their health
    and safety arrangements. Health and safety investigations form an essential
    part of this process.
  • Following the Woolf Report on civil action, you are expected to make
    full disclosure of the circumstances of an accident to the injured parties
    considering legal action.

The fear of litigation may make you think it is better not to investigate.

But, you can’t reduce the chance of future accidents if you don’t know what went wrong!

health and safety at work act

The fact that you thoroughly investigated an accident and took remedial action to prevent further accidents would demonstrate to a court that your company has a positive attitude to health and safety.

Your accident investigation findings will also provide essential information for your insurers in the event of a claim.

Download our free Accident Report templates pack to get off to a good start with recording and investigating accidents, incidents and near misses in your workplace environment.


Incident and Accident Investigation | Information and Insights 

The information gleaned from investigating an accident in the workplace will provide:

Workplace Incident and Accident Investigation Guide | 4-Stage Blueprint 1
  • an understanding of how and why things went wrong.
  • clarity on the ways people can be exposed to substances or
    conditions that may affect their health.
  • a true snapshot of what really happens and how work is actually done. (Workers
    almost invariably find short-cuts to make their work easier or quicker. Naturally, this can be at the expense of important risk controls.
  • insight into deficiencies in your risk control management, enabling you to reduce future risk across your organisation.
Incident and Accident Investigation: Other Benefits
accident investigation gathering evidence
  • The prevention of further similar adverse events. If there is a serious accident,
    the regulatory authorities will take a firm line if you have ignored previous
  • The prevention of business losses due to disruption, stoppage, lost orders and
    the costs of criminal and civil legal actions.
  • An improvement in employee morale and attitude towards health and safety.
  • Employees will be more cooperative in implementing new safety improvements if they were involved in an investigation and proactive response
  • The development of investigative leadership & managerial skills are transferable to other areas.

Should you investigate Near Misses?

While the argument for investigating accidents is fairly clear, the need to investigate near misses and unsafe conditions may not be so obvious.

However, both are very useful and normally easier than investigating accidents.

Adverse events where no one has been harmed can be scrutinised without having to deal with injured people, their families and a demoralised workforce.

Moreover, at this stage, there is no threat of criminal or civil legal action hanging over the company. Witnesses will be more likely to be helpful.

Consider the following responses:

‘I mistakenly turned the wrong valve which released the boiling water because the
valves all look the same’


‘I don’t know how John was scalded.’

Which is the likely response to a near miss and which to an accident?

More importantly, which is the most useful?

It is often pure luck that determines whether an undesired circumstance translates into a near miss or accident. The value of investigating each adverse event is the same.

An investigation is not an end in itself, but the first step in preventing future adverse events. A good incident or accident investigation will enable you to learn general lessons, which can be applied across your organisation.

The outcomes should identify why the existing risk control measures failed and what improvements or additional measures are needed. It’s also important to find out why the existing risk control measures were inadequate.

Who should carry out an Accident Investigation?

For an investigation to be worthwhile, it is essential that the management and the workforce are fully involved.

Depending on the level of the investigation (and the size of the business), supervisors, line managers, health and safety professionals, union & employee representatives and senior management/
directors may all be involved.

Dangerous Occurrence RIDDOR

As well as being a legal duty, it has been found that where there is full cooperation and consultation with union representatives and employees, the number of accidents is half that of workplaces where there is no such employee involvement.

This joint approach to accident investigation will ensure that a wide range of practical knowledge and experience will be brought to bear and employees. In addition, their representatives will feel empowered and supportive of any remedial measures that are necessary.

A joint approach also reinforces the message that the investigation is for the benefit of everyone.

In addition to detailed knowledge of the work activities involved, members of the team should be familiar with:

  • health and safety good practice, standards and legal requirements.
  • The investigation team must include people who have the necessary investigative skills (eg information gathering, interviewing, evaluating and analysing).
  • Provide the team with sufficient time and resources to enable them to carry out the
    investigation efficiently.
Accident Investigation team
  • Led by, or reports directly to someone with the authority to act on their recommendations.

Does your business require Health and Safety support?

Accidents and Incidents: What should you Investigate?

Having been notified of an adverse event and been given basic information on what happened, you must decide whether it should be investigated and if so, in what depth.

It is the potential consequences and the likelihood of the adverse event recurring that should determine the level of investigation, not simply the injury or ill health suffered on this occasion.

For example:

Is the harm likely to be serious?

Is this likely to happen often?

Similarly, the causes of a near miss can have great potential for causing injury and ill health. When making your decision, you must also consider the potential for learning lessons.

For example if you have had a number of similar adverse events, it may be worth investigating, even if each single event is not worth investigating in isolation. Also, it is best practice to investigate all adverse events which may affect the public.

Of course, not all adverse events need to investigated to the same level of detail. We will look at how you might decide what is appropriate, later in this guide. 

Is the Workplace Accident actually 'work-related'?

A workplace incident or accident can only be considered ‘work-related’ if it can be demonstrated that the work environment caused or contributed to it.

It is essential to have an understanding of the circumstances of an event before it is possible to decide it’s ‘work relatedness’.

To decide if an Accident or Incident is ‘work-related’, it must be determined if the event was due to:

  • The way the work was organised, carried out or supervised
  • Any machinery, vehicle, plant, substances or equipment used for work
  • The condition of the site or premises where the event occurred

Incident and Accident Reporting Protocols

Depending on the business you work in, there may or may not be accident reporting protocols already established. It’s important to to get to grips with any current process that exists, and look at the history of incident and accident response, before you try to make any improvements.

For clues on how you might want to approach your accident investigations, check with the applicable enforcing authority for your business. This will typically be the Local Authority (e.g. Council) or the regualator e.g. Health and Safety Executive, depending on your type of business.

It is likely that there will local laws which outline how you must report, such as the RIDDOR Regulations 2013 (Great Britain).

When to Report | RIDDOR Regulations (UK)

RIDDOR can be a confusing subject to tackle, but once you grasp the key requirements, it should be reasonably easy to keep your business compliant.

RIDDOR stands for the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013. These Regulations in United Kingdom (England, Scotland and Wales) require employers, the self-employed and those in control of premises to report specified workplace incidents.

For a comprehensive guide on RIDDOR, please visit our post here. Also, listen to our podcast below for a summary…

Incident and Accident Event Definitions

When it comes to incidents or accidents in the workplace, it’s important to get to grips with the terminology used. This may of course vary across different companies, sectors and countries. Certain key words and phrases will be used regularly throughout this guide.

Adverse Events

Accident: an event that results in injury or ill health;

Incident: an incident may be classed as either a

near miss: an event that, while not causing harm, has the potential to cause
injury or ill health. (In this guidance, the term near miss will be taken to
include dangerous occurrences);


unsafe condition: a set of conditions or circumstances that have the potential to cause injury or ill health, e.g. untrained nurses handling heavy patients.
Dangerous occurrence: one of a number of specific, reportable adverse events,
as defined in the Reporting of Injuries, Diseases and Dangerous Occurrences
Regulations 1995 (RIDDOR).

Hazard: the potential to cause harm, including ill health and injury; damage to
property, plant, products or the environment, production losses or increased

Immediate cause: the most obvious reason why an adverse event happens, eg
the guard is missing; the employee slips etc. There may be several immediate
causes identified in any one adverse event.

  • fatal: work-related death;
  • major injury/ill health: (as defined in RIDDOR, Schedule 1), including fractures
    (other than fingers or toes), amputations, loss of sight, a burn or penetrating
    injury to the eye, any injury or acute illness resulting in unconsciousness, requiring
    resuscitation or requiring admittance to hospital for more than 24 hours;
  • serious injury/ill health: where the person affected is unfit to carry out his or her
    normal work for more than three consecutive days;
  • minor injury: all other injuries, where the injured person is unfit for his or her normal
    work for less than three days;
    damage only: damage to property, equipment, the environment or production
    losses. (This guidance only deals with events that have the potential to cause harm
    to people.)

When we talk about the ‘immediate cause‘, we are referring to the agent or direct source of the injury or ill health (e.g. tool, vehicle, substance). 

root cause analysis accident investigation

Beyond that, we can delve deeper into the reasons for an incident or accident occurring and aim to find:

Underlying cause: the less obvious ‘system’ or ’organisational’ reason for an
adverse event happening, eg pre-start-up machinery checks are not carried out
by supervisors; the hazard has not been adequately considered via a suitable risk assessment etc.

Root cause: an initiating event or failing from which all other causes or failings

Root causes are generally management, planning or organisational failings.

For either of the above, there may be more than one answer. That’s what our accident investigation aims to uncover!

How to Investigate an Accident in the Workplace

Near miss example

Now that we’ve built some context around investigating an incident or accident in the workplace, it’s time to look at the practical steps for accident investigation.

Our initial response would have included emergency response (first aid, medical treatment, making the area safe), followed by an initial high-level (not detailed) report. This would involve informing relevant stakeholders, including the regulator, if appropriate (RIDDOR).

After that, we need to determine the level of incident or accident investigation that would be appropriate for the specific adverse event.

Accident Investigation - what level is appropriate?

The table below will assist you in determining the level of investigation which is appropriate for the adverse event. Remember you must consider the worst potential consequences of the adverse event (eg a scaffold collapse may not have caused any injuries, but had the potential to cause major or fatal injuries).

Accident investigation tool
Accident investigation level
HSE Investigation Level Tool
  • In a minimal level investigation, the relevant supervisor will look into the circumstances of the event and try to learn any lessons which will prevent future occurrences.
  • A low level investigation will involve a short investigation by the relevant supervisor or line manager into the circumstances and immediate, underlying and root causes of the adverse event, to try to prevent a recurrence and to learn any general lessons.
  • A medium level investigation will involve a more detailed investigation by the relevant supervisor or line manager, the health and safety adviser and employee representatives and will look for the immediate, underlying and root causes.
  • A high level investigation will involve a team-based investigation, involving supervisors or line managers, health and safety advisers and employee representatives. It will be carried out under the supervision of senior management or directors and will look for the immediate, underlying, and root causes.

Gathering Evidence - Step 1

Gathering evidence is an essential first step when conducting an incident or accident investigation. Time is of the essence, and it’s important that someone is able to review the location/area of the event before any significant changes can be made to it. 

Taking photos &/or videos of the area and associated plant/equipment etc. that may have contributed to the incident is an important initial step in the process.

Once this is completed, the investigation team should start to gather related information to help build more context around the event. For example…

  • Collect and review the risk assessment/s for the work, were they being followed?
  • Look at the training records of those involved, are they current and would they be deemed competent?
  • Review the company standards, were they being followed?
  • Examine maintenance records, who carried out the maintenance and when was it done.
  • Look at recent audit reports, inspections and surveys for more clues.
  • Most importantly, interview those who have witnessed or been affected by the incident!
Interview Preparation & Guidance
Accident Investigation

Accident investigations should be seen as a golden opportunity to uncover the system in which the incident occurred. They should also be seen as problem solving exercises, not as an inquisition!

We must look beyond the immediate cause and resist the temptation to allocate blame; but rather focus on preventing future accidents.

Of course, there may be circumstances when a person or person have acted inappropriately and contributed to an accident. But we can’t establish whether that is the case, until we complete an objective and unbiased investigation.

When carrying out an accident investigation, it is always necessary to interview the people involved in the accident, where possible.

The following points should be considered before completing interviews:

Prepare for the interview

  • Gather & review all supporting information
  • Visit the scene of the accident (as soon after the event as possible)
  • Allow adequate time (do not rush the interview process)
  • Plan against interruptions

Conducting the Interview – 7 tips to put into practice….

  1. Put the person at ease, one way is to ask questions which can be easily answered
  2. Ask what happened – try not to interrupt the interviewee – practice becoming a good listener!
  3. Avoiding asking leading questions i.e. where you suggest the answer in the question, or make assumptions.
  4. Don’t try to put words into the witness’s mouth. Some people will tell you what they think you want to know.
  5. Be considerate, not sarcastic – it may lead to distortions, so don’t appear in a bad light
  6. Ask questions to bring out the facts that you want to know
  7. Emphasise that the purpose of the investigation is primarily to prevent a recurrence

Analysing the Information - Step 2

Once you have completed the first step and gathered all of the available evidence, it’s time to analyse the information. One of the most common methods used to establish a root cause in an accident investigation, is 5-Why Analysis.

Investigation Techniques | 5 Why Analysis

One of the most simple and well known ways of investigating an incident or an accident to find the root cause is by using what’s known as the ‘5-Why’ method.

If you’re not familiar with the five whys method, don’t worry. We will look at what the methodology is and demonstrate a simple example of how it might be used.

Once you get comfortable with the theory, it will require you to use the method in real-life scenarios to truly get comfortable with the process.

5 why
What is the 5 Whys Method?

The 5 Whys method is really a simple but powerful tool that can be used for any problem-solving activity. And yes, we do use it in health and safety!

It’s a technique that will help you get past the immediate causes and symptoms of a problem down to the the underlying issues. This will allow you to come up with solutions that will hopefully help you avoid the same scenarios happening over and over again.

How come it’s named the 5 Whys?

Very simply, the method requires you to ask ‘why?’ five times. Generally, whenever you start with a problem statement and ask why over and over again by the fifth time that you do it, you are usually not far from the root cause of the issue. 

Sometimes it might only take you three or four whys, or indeed, it may take you more until you actually get to the root cause of the problem.

Additionally, there may be more than one root cause. It may be that multiple root causes need to be investigated or remedied.

Let’s take a look at a quick example of one. As with any health and safety accident or incident, we begin with a problem statement, which you always must agree on whether you’re working by yourself or in a group.

For 5 -Why, we start with the event. It is important to have a clear definition of the event under analysis

KEEP IT AS VISUAL AND SIMPLE AS POSSIBLE e.g. use post-it notes on a whiteboard

  • Focus on process not people
  • Do not include any possible causes

Remember: The initial statement should consist of a SUBJECT, a VERB & an OUTCOME

Accident Investigation Example

We’re going to use the case of someone (Subject) falling over (Verb) and breaking their wrist (Outcome) i.e. a slip or trip accident.

Something that often happens in workplaces. We start with our problem statement, which is that someone fell and broke their wrist.

Of course, the first thing we must do is ask ‘Why?’

Workplace Incident and Accident Investigation Guide | 4-Stage Blueprint 3

Typically, when we answer the first question within the 5 whys process we are usually looking at the more obvious aspects of a problem i.e. immediate causes. 

Read on and/or listen to our podcast to learn more…

The methodology encourages you to go deeper and deeper as you repeat that question to look into the underlying reasons as to why something happened.

In this case, if we asked ‘Why did someone fall and break their wrist?’ You may come up with an answer such as. ‘there was ice on the ground’. As well as that, it’s worth pointing out that there may be multiple reasons why something has happened.

In which case, you would branch off the answer and provide two or three reasons underneath the first why. For each of those subsequent answers then you actually ask another set of questions or ‘whys?’ underneath each one. In this this example, we’re just going to use one. The agreed answer was that ‘There was ice on the ground‘.

Again, you would ask why was that the case? Maybe that there was no salt or grit applied to the ground to remove the risk of someone slipping on the ice.

OK, let’s assume there was no salt or grit applied to the ground. You then ask why again and you’ll start to see that we’re getting deeper toward the root of the problem.

5 Whys
Digging deeper by asking Why?

Why was there no salt or grit applied to the ground? The answer may be something like ‘No one was given responsibility to apply salt or grit to the ground‘. You would then ask why again, and you may come up with an answer such as ‘It was not identified in the risk assessment for the site‘.

Okay, as you can see we’re getting towards the more systems and processes oriented aspects of this accident. Once you identify that the issue or the risk wasn’t included in a risk assessment for site, you would then ask then ask why again.

A typical answer for this might be – ‘the person who completed the risk assessment wasn’t trained or competent regarding health and safety‘.

In other words, they had no real understanding of this risk and the potential magnitude of it. If the need was not recognised, it may be easily missed.

As you can see by fifth time that you’ve asked that question ‘why?’, you’ve got to the point where you’re able to identify that there’s been a management failing. This would possibly relate to the training that’s been provided to the workforce and the people carrying out the work.

You may want to dig deeper into that if you like, but that’s for you to decide.

This example is only for illustrative purposes and demonstrates how asking ‘Why?’ five times can help you work towards the root cause of an incident or accident.

It’s something that’s helpful for team to use in the problem-solving process. The great thing about the 5 whys method is that it is fairly simple. It’s can be used by anyone provided they are shown correctly how to do it.

Identifying Risk Control Measures - Hierarchy etc. - Step 3

Once you have determined the main causes of an incident or accident, the next step is to determine improvement actions.

The Hierarchy of Controls (see our post here) or risk hierarchy is a system used in workplace environments to minimize or eliminate exposure to hazards. It can help guide you thought process as you consider your options.

The risk control concept is taught to managers in industry, to be promoted as standard practice in the workplace. Various illustrations are used to depict this system, most commonly a triangle. Let’s take look at what it looks like…

hierarchy of control

The levels in the risk hierarchy of control measures are, in order of decreasing effectiveness:

  • Elimination
  • Substitution
  • Engineering controls
  • Administrative controls
  • Personal protective equipment

These are typically the most effective control options – the main reason is that they do not usually depend on a repeated human interaction or behaviour to reduce risk. Let’s elaborate on those different levels of control, starting from the most effective.

1. Elimination:

Physical removal of the hazard — this is the most effective hazard control.

For example, if employees must work high above the ground, the hazard can be eliminated by moving the piece they are working on to ground level to eliminate the need to work at heights.

2. Substitution:

Substitution, the second most effective hazard control, involves replacing something that produces a hazard (similar to elimination) with something that does not produce a hazard—for example, replacing lead-based paint with titanium white.

To be an effective control, the new product must not produce another hazard. As airborne dust can be hazardous, if a product can be purchased with a larger particle size, the smaller product may effectively be substituted with the larger product.

3. Engineering Controls:

The third most effective means of risk control is engineered controls. These do not eliminate hazards, but rather isolate people from hazards.

Capital costs of engineered controls tend to be higher than less effective controls in the hierarchy, however they may reduce future costs.

LEV System Workplace Incident
Local Exhaust Ventilation (LEV)

For example, a crew might build a work platform rather than purchase, replace, and maintain fall arrest equipment.

“Enclosure and isolation” creates a physical barrier between personnel and hazards, such as using remotely controlled equipment. Fume hoods can remove airborne contaminants as a means of engineered control i.e. Local exhaust ventilation (LEV).

4. Administrative controls:

Administrative controls are changes to the way people work. Examples of administrative controls include procedure changes, employee training, and installation of signs and warning labels (such as those in the Workplace Hazardous Materials Information System).

Administrative controls do not remove hazards, but limit or prevent people’s exposure to the hazards, such as completing road construction at night when fewer people are driving.

ppe Haswa
PPE: Hard Hats
5. Personal Protective Equipment:

Personal protective equipment (PPE) includes gloves, Nomex/Uniform, respiratorshard hatssafety glasseshigh-visibility clothing, and safety footwear.

PPE is the least effective means of controlling hazards because of the high potential for damage to render PPE ineffective.

Additionally, some PPE, such as respirators, increase physiological effort to complete a task and, therefore, may require medical examinations to ensure workers can use the PPE without risking their health.

Driving Improvement across your Business

When you are considering the corrective & preventative actions from your investigations, it’s important to consider them from (at least) these two perspectives, to ensure maximum impact.

  1. Learn the direct lessons of the accident analysis and seek to avoid the same event happening again.
  2. Using the analysis of the specific situation that caused the accident to identify and resolve safety problems in other work situations.

Look at the causes identified and decide which ones require action. Actions should be targeted at UNDERLYING or ROOT CAUSES.

ROOT causes are causes that, if corrected, would make a reoccurrence highly unlikely.

You may also want to consider sharing your learning with other sections of your organisation, fellow professionals in your network, industry standards groups etc. It is only by sharing experiences that we can collectively raise health and safety standards across different industries.

Issue Action Plan & Implement - Step 4

Work as a group to agree a set of actions that address the identified causes. Try to ensure that the actions address the problem and not the symptoms of the problem.

Share responsibilities for actions as much as possible to involve other people and spread ownership.

Keep the everyone that was involved in the event and others who were affected (e.g. people working in the area or on the same job) up to date with the investigation, its conclusions and the status of proposed actions.

Use the event and the findings from the investigation in the site communications/toolbox talk schedule. Also, consider sharing the learning’s with other locations/sites know about the learning i.e. via a safety alert/moment.

Incident Investigation | Common Mistakes

There is a great deal to learn when you are conducting your first incident investigation or completing your first accident investigation report. 

Depending on your experience-level, recognising certain critical elements may be much more obvious than others – we’ve made a short podcast to discuss some of the most common mistakes.

Avoid you’re own Bias

Be careful not to be inadvertently biased towards or against a certain outcome/s. This is something that health and safety representatives and incident investigators can get easily caught out by.

Make sure the incident investigation team is made of people with different perspectives and expertise, this will help you ensure that there is a balanced outcome to your investigation. 

organisational hazards

Remember, stick to the facts and making assumptions that are not supported by hard evidence.

Time is of the Essence

When an accident or incident occurs, it pays to collect the information and evidence as soon as possible. There are various reasons for this, not least that it’s critical to preserve the scene of an incident before conditions change or can be altered.

It’s also crucial to speak to/interview those involved in a timely manner to ensure that recollection of events is as accurately as possible. The longer time goes on, the more likely it will be that the quality of information deteriorates.

Don’t play the Blame Game

Blaming a person, persons or even a business, is not the objective of an incident investigation. 

There may be inclination for some of the people involved to deflect responsibility from themselves, self-preservation.

In reality, the goal of an investigation is about preventing future recurrences and this aim should be made clear to everyone involved. 

Don’t go it Alone

Going back to our first point on avoiding bias, a critical element of a thorough incident investigation is to pull on all of the expertise within your organisation.

covid 19 risk assessment

As an individual incident investigator, our role is to bring the evidence and expertise together.

This helps us create a picture of what happened, and produce recommendations on how to avoid similar incidents or accidents in the future.

Take the time to find the most suitable people in your business to help with your specific investigation.

Good Work Takes Time

We said at the beginning that time was of the essence.

This is true.

However, it is equally important not rush our investigation. Despite the internal and external pressures that may be facing you, it’s important to ensure that you gather all of the relevant information before drawing any conclusions.

That includes any important details regarding plant, equipment etc. that you need to review against the operating standards in the workplace you are investigating.

What to report RIDDOR - Incident Investigation

Workplace Accident Investigation Guide | Conclusion

Thanks for joining us for this guide on Accident Investigation – if your business requires any further help check out our Accident Investigation Service, or get in touch via Live Chat or the contact form below.


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