What needs to be finished first
A chronological timeline with energy or hazard source, target person or target object, and the intervening actions is available.
What needs to be ready before start
Whiteboard or diagramming tool with a source -> barriers -> target sketch; table with columns for barrier, existent, functional, effective, failure reason, measure; access to procedures, training logs, audit reports, logs.
One analyst with RCA experience (lead); one to three domain specialists (plant, process, protection systems); one owner of the controls under review; one sponsor with authority to approve measures.
Incident description with damage and people involved; list of existing protective mechanisms (technical, procedural, organizational); risk assessment of the system; predecessor incidents.
2-4 h
Sketch the source on the left, the target on the right, and barriers as vertical lines in between. Prepare the table. Keep procedures and reports close at hand.
The one question this method answers
Which barriers were supposed to prevent the damage, which existed, functioned, and were effective enough, and which are missing or failed?
Marker: Phase
| Step | Duration | Action | Hint |
|---|---|---|---|
1Phase 1: Sketch the line of effect | 20-30 min | Name the energy or hazard source concretely, for example 'hot hydraulic fluid at 80 C, 30 bar'. Name the target person or target object. Draw the line of effect on the whiteboard. | If the source stays abstract ('risk'), the barrier analysis cannot be carried out. A concrete physical, procedural, or organizational line of effect is mandatory. |
2Phase 2: Inventory the barriers | 30-45 min | List all existing barriers: technical (guards, sensors, emergency shutdown), procedural (approvals, checklists), organizational (training, supervision). Add a short description per barrier. | Frequently only technical barriers are seen. Procedural and organizational barriers are often the first to fail and belong in the list. |
3Phase 3: Check existence, function, and effectiveness per barrier | 45-90 min | Answer three questions separately for each barrier: Did it exist at the time of the event? Did it function technically? Was it effective enough? Add evidence to each answer. If it failed, document the failure reason. | Mixed judgments ('it was there but not good enough') are a common mistake. Three separate questions create clarity. Failure reason distinguishes technical defect, operating error, and design weakness. |
4Phase 4: Identify missing barriers | 20-30 min | Check each phase of the line of effect: which barrier is missing that could have prevented the event? Reference industry standards, best practices, and audits. Record missing barriers as separate findings. | Missing barriers are easily overlooked because they did not fail, they were simply absent. Search actively with the question 'what should have been there?'. |
5Phase 5: Derive measures | 30-45 min | For every failure finding, define a measure: repair, replace, strengthen, or add the barrier. Prioritize measures by impact and effort. Assign owner and deadline per measure. | A measure like 'repeat training' is often a weak answer. If the failure reason was a design weakness, training is symptom treatment. Prefer engineered solutions first. |
What comes out at the end
Line-of-effect sketch (PNG or PDF) plus barrier table with status per column and failure reasons, list of missing barriers, measures backlog with owner and deadline. Often attached to an MORT or causal factor report.
Date, incident ID, and investigator in the header. Add a new status column for each measure iteration (open, in progress, done). For follow-up incidents, reference the previous analysis.
Compact working template for Barrier Analysis with context, input, output artifacts, and next step.
Analyzes which barriers should have prevented an incident and why they failed.
When and for what do we use this method?
Which data, observations, decisions, or materials are available?
Short notes along the runsheet.
Owner, date, and success signal.
Concrete filled scenario, fictional example
Concrete filled scenario, fictional example
Source: Hot hydraulic fluid at 78 C, pressure line from pump 3. Target: Maintenance technician (@ben) during filter replacement.
Barrier table:
| Barrier | Existent | Functional | Effective | Failure reason |
|---|---|---|---|---|
| LOTO lockout (technical) | Yes | Yes | No | LOTO only on main pump, not on bypass line |
| Pressure relief routine (procedural) | Yes | No | No | Routine assumed 20 min cooling time, only 8 min waited here |
| Hot-work training (organizational) | Yes | Yes | Partly | Training does not cover the bypass scenario |
| Heat-protective PPE (technical) | No | — | — | Not provided for regular filter maintenance |
Missing barriers:
Measures:
Status check in 8 weeks: 17.07.2026.
Recognize symptoms and steer against them
A barrier is rated as 'it was there, but it was not enough', while the failure reason stays vague.
Answer the three questions strictly separately. Use one column per question in the table. If the answer cannot be separated cleanly, gather more evidence.
The table contains sensors and valves, but no training, procedures, or supervision.
Walk through technical, procedural, and organizational categories as mandatory. Aim for at least one barrier per category per line of effect.
Only failing barriers are listed, while absent protective layers stay invisible.
Explicitly ask 'what else should have been there?'. Use industry standards, comparable systems, and audit recommendations.
Three out of four findings lead to 'repeat training', with no engineered solution.
Apply the hierarchy of controls: Elimination > Substitution > Engineering > Administrative > PPE. Use training as an administrative control only when higher levels are impossible.
The source is described as 'risk' or 'danger', and the barriers would fit any line of effect.
Make the source concrete in physical or procedural terms. If that is not possible, Barrier Analysis is not the right tool; use a risk matrix or FMEA instead.
Done signals checkable in under a minute
Go to the profile for purpose, similar methods, and sources or continue to the next method in the catalog.