Bowtie and Barrier Analysis makes those pathways visible and shows where protection is expected to come from.
Make the risk visible.
A risk register can tell you that a risk exists.
A bowtie helps explain how it can happen.
It connects:
THREATS
What can initiate the pathway?
PREVENTION
What stops the critical event occurring?
CRITICAL EVENT
Where is control of the hazard lost?
MITIGATION
What limits escalation or reduces the consequence?
CONSEQUENCES
How could people be harmed?
That creates a much stronger foundation for deciding what really matters.
A bowtie is a model of the risk.
It isn't the risk itself.
Every bowtie simplifies reality.
Its value comes from whether that simplification helps people understand:
What can happen.
How it can happen.
Where intervention is possible.
What controls are relied upon.
What those controls depend on.
Where protection could fail.
The goal isn't to create the most detailed diagram.
It's to create a useful model of the pathway to harm.
Start with a well-defined critical event.
The centre of the bowtie matters.
Too broad and the analysis becomes difficult to use.
Too narrow and important pathways may disappear.
A useful critical event describes the point at which control of the hazard or energy is lost and the potential for serious harm becomes materially greater.
For example:
Not:
Vehicles
But:
Unplanned interaction between operating mobile equipment and a pedestrian.
Not:
Working at height
But:
Person exposed to an uncontrolled fall from height.
Not:
Electricity
But:
Person exposed to hazardous electrical energy.
Clear events create clearer pathways.
Understand the energy.
Serious harm requires something capable of causing it.
Understanding the energy involved helps keep the analysis grounded in the mechanism of harm.
That may include:
GRAVITY
Falls, falling objects, collapse.
MOTION
Vehicles, mobile equipment, moving loads.
MECHANICAL
Machinery, stored mechanical energy, crushing and entanglement.
ELECTRICAL
Electrical contact, arc energy and energised systems.
PRESSURE
Hydraulic, pneumatic, compressed gas and stored pressure.
CHEMICAL
Toxic, corrosive, reactive or flammable substances.
THERMAL
Heat, cold, fire and hot materials.
RADIATION
Ionising and non-ionising radiation.
SOUND
Hazardous acoustic energy.
BIOLOGICAL
Biological agents and exposure pathways.
Energy gives the pathway something concrete to follow.
Understand the threats.
Threats are the conditions or events that can lead to the critical event.
They shouldn't simply become a list of generic hazards.
Ask:
What could actually initiate this pathway?
For mobile equipment interaction, that might include:
Restricted visibility.
Unplanned pedestrian access.
Vehicle deviation.
Changes to traffic flow.
Loss of communication.
Congested work areas.
Temporary work.
Each threat should create a meaningful pathway to analyse.
Then identify what stands in the way.
Controls should interrupt the pathway.
Not simply appear somewhere on the bowtie because they are part of the safety system.
NewEra groups barrier functions around three broad purposes:
PREVENT
Stop the critical event from occurring.
SEPARATION
Keep people and hazardous energy apart.
CONTAINMENT
Keep hazardous material or energy within defined boundaries.