Incident Investigation Procedure and Root Cause Analysis
Every workplace—whether in construction, manufacturing, or industrial operations—faces the risk of accidents, near misses, or unsafe events.
When an incident occurs, it is not enough to simply fix what went wrong. Organizations must understand why it happened and how it can be prevented in the future.
This is the purpose of an Incident Investigation Procedure and Root Cause Analysis (RCA)—to uncover causes, correct weaknesses, and build stronger safety systems.
This guide explains:
- What incident investigation means
- Why it is important
- The step-by-step investigation process
- Methods of root cause analysis
- Roles, responsibilities, and reporting
- Common mistakes and best practices
What is Incident Investigation?
An Incident Investigation is a systematic process used to collect facts, analyze causes, and identify corrective actions after an accident, injury, or near-miss occurs.
Definition:
Incident investigation is the process of determining the facts, causes, and preventive measures of an accident or near-miss to prevent recurrence.
It is not about placing blame—it is about identifying system failures and preventing future harm.
Objectives of Incident Investigation
The primary goals of incident investigation are:
- Determine the root cause of the incident.
- Identify unsafe acts, conditions, or system failures.
- Recommend corrective and preventive actions.
- Share lessons learned with all relevant teams.
- Ensure compliance with legal and reporting requirements.
- Improve the organization’s overall safety culture.
Every incident, even a near miss, provides valuable lessons for improvement.
Types of Incidents That Require Investigation
| Type of Event | Example | Required Action |
|---|---|---|
| Accident | Worker injured by falling material | Full investigation |
| Near Miss | Scaffold plank dislodged but no injury | Investigation and preventive action |
| Unsafe Condition | Exposed cable on walkway | Immediate correction and documentation |
| Property Damage | Vehicle hits warehouse door | Review procedures and supervision |
| Environmental Incident | Chemical spill on ground | Investigation and reporting |
Near misses should always be investigated—because they are warnings of potential future accidents.
Step-by-Step Incident Investigation Procedure
A thorough investigation typically involves six steps:
Step 1: Immediate Response and Scene Control
When an incident occurs, the first priority is to protect life, property, and the environment.
Actions to take:
- Stop the work immediately.
- Provide first aid or call emergency services.
- Inform supervisors and the safety department.
- Secure the area and prevent unauthorized entry.
- Preserve evidence for analysis.
The first few minutes after an incident are critical for accurate data collection.
Step 2: Notification and Formation of the Investigation Team
Notify relevant personnel based on company policy and the incident’s severity.
Typical notification chain:
Worker → Supervisor → Safety Officer → HSE Manager → Senior Management → Client or Authorities (if required).
Investigation Team Members:
- HSE Officer (Lead Investigator)
- Area Supervisor
- Line Manager
- Witnesses (if available)
- Technical Expert (for specific cases)
- Worker Representative (optional)
The investigation team should be multidisciplinary for balanced analysis.
Step 3: Data Collection and Evidence Gathering
Gather all information and evidence related to the incident. This includes both physical and documentary evidence.
Sources of Information:
- Witness statements
- Photographs and videos of the scene
- Equipment inspection reports
- Work permits, risk assessments, and job safety analyses
- Training and attendance records
- Weather or environmental data
Types of Evidence:
| Evidence Type | Example |
|---|---|
| Physical | Damaged PPE, broken parts |
| Documentary | Permit to Work, SOP, inspection log |
| Human | Witness testimony |
| Environmental | Weather conditions, lighting, noise level |
Photograph the scene before moving equipment or debris. Documentation accuracy is essential.
Step 4: Data Analysis and Root Cause Identification
Once all information is collected, the team analyzes it to understand the true causes of the incident.
There are three types of causes:
- Direct Cause: The immediate unsafe act or condition (e.g., missing guardrail).
- Indirect Cause: Factors contributing to the unsafe condition (e.g., poor supervision).
- Root Cause: The fundamental system failure (e.g., lack of inspection program).
Root Cause Analysis (RCA) Methods
Root Cause Analysis (RCA) helps determine why an incident occurred and how it can be prevented in the future.
1. The 5 Whys Technique
A simple yet effective method to identify the underlying cause by repeatedly asking “Why?”.
Example:
- Why did the worker fall? → The guardrail was missing.
- Why was it missing? → It was removed for access.
- Why was it not replaced? → No inspection was done.
- Why was inspection missed? → No procedure required it.
- Root Cause: Lack of safety inspection procedure.
Usually, five levels of questioning reveal the true root cause.
2. Fishbone Diagram (Ishikawa Analysis)
This diagram identifies potential causes under categories such as:
- Man (human error, training)
- Machine (equipment failure)
- Method (procedure or process gap)
- Material (quality of materials)
- Management (policy or supervision)
- Environment (lighting, weather, workspace)
Each branch explores contributing factors to the main problem.
3. Fault Tree Analysis (FTA)
FTA uses logic-based diagrams to analyze how multiple system failures can combine to cause an incident.
Example:
“Fire in storage room” caused by ignition source + flammable material + inadequate housekeeping.
4. Change Analysis
This method identifies changes that occurred before the incident:
- Was new equipment or process introduced?
- Were procedures or materials changed?
- Were new employees assigned to the task?
Most incidents are linked to uncontrolled changes in the workplace.
Step 5: Identify Corrective and Preventive Actions
After identifying root causes, develop corrective and preventive actions (CAPA) that are specific, measurable, and time-bound.
| Action Type | Example | Responsible Person | Target Date |
|---|---|---|---|
| Corrective | Replace damaged electrical tool | Maintenance Engineer | 5 Days |
| Preventive | Implement electrical inspection checklist | Safety Manager | 10 Days |
Corrective Actions: Eliminate the existing problem.
Preventive Actions: Ensure it does not happen again.
Step 6: Report Preparation and Communication
Once analysis and actions are completed, prepare a formal investigation report.
Report Format:
- Executive Summary
- Description of the Incident
- Sequence of Events
- Evidence and Findings
- Root Cause Analysis
- Corrective and Preventive Actions
- Attachments (photos, sketches, witness statements)
The report should be factual, concise, and free from personal blame.
Distribution:
- Line and project managers
- Safety committee
- Client representatives
- Workers (for awareness)
Sharing lessons learned prevents similar incidents elsewhere.
Roles and Responsibilities
| Role | Responsibilities |
|---|---|
| Supervisor | Report incidents, secure area, assist investigation |
| Safety Officer | Lead investigation, gather evidence, prepare report |
| Line Manager | Review findings, implement corrective actions |
| HSE Manager | Approve report and ensure CAPA completion |
| Top Management | Review performance and allocate resources |
| Workers | Cooperate and provide accurate information |
Accountability ensures consistent follow-up and compliance.
Example Incident Case
Incident:
Worker received an electric shock while using a grinder.
Findings:
- Cable insulation damaged.
- No pre-use inspection conducted.
- Worker not trained on electrical tool safety.
- Supervisor unaware of inspection requirements.
Root Cause:
No preventive maintenance or training procedure for portable tools.
Corrective Action:
Replace damaged grinder and inspect all tools.
Preventive Action:
Implement inspection checklist and safety training.
Result:
No similar incidents in the next six months.
Follow-Up and Effectiveness Review
Incident investigation must be followed by a review to confirm that actions were effective.
Follow-up checklist:
- Were corrective actions implemented on time?
- Have preventive measures reduced the risk?
- Were lessons shared across departments?
- Was the incident record closed properly?
Conduct a post-incident audit after 30–60 days to verify effectiveness.
Common Mistakes in Incident Investigations
- Closing cases too quickly without deep analysis.
- Assigning blame instead of identifying system weaknesses.
- Ignoring near-miss reporting.
- Poor or missing documentation.
- Not following up on corrective actions.
- Failure to communicate lessons learned.
Investigations must always focus on understanding the system, not punishing people.
Best Practices for Effective Investigations
- Create a standard investigation and RCA form.
- Train supervisors and HSE staff in investigation techniques.
- Encourage near-miss and unsafe act reporting.
- Promote a no-blame safety culture.
- Review incident trends during safety meetings.
- Integrate findings into risk assessments and training.
- Use digital tools for tracking and analysis.
Incident Classification and Reporting Timeline
| Severity | Type | Reporting Timeline | Investigation Lead |
|---|---|---|---|
| High | Fatality, Major Injury, Fire | Immediate | HSE Manager or Senior Management |
| Medium | Minor Injury, Property Damage | Within 24 hours | Safety Officer |
| Low | Near Miss, Unsafe Act | Within 48 hours | Supervisor |
Severity determines the level of reporting and investigation depth.
Conclusion
A well-structured Incident Investigation Procedure is essential for preventing recurrence and improving workplace safety performance.
By identifying root causes and implementing corrective actions, organizations can eliminate systemic failures, enhance training, and build a stronger safety culture.
The objective is not to find fault but to find solutions—because every incident teaches a lesson about prevention.
“Behind every incident lies a system failure waiting to be fixed.”
Toolbox Talk Procedure and Best Practices
Contractor Safety Management System (CSMS)
5 Levels of Risk Control (Hierarchy of Controls) Explained
Safety Walkthrough vs Safety Audit
Common Mistakes in HIRA and How to Avoid Them
For checklist and templates visit The HSE Tools.
