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Taking-off with BowTie

Posted on August 21, 2013 in Articles

Risk is termed as the effect of uncertainty on an organization's objectives.  Since all activities of an organization involve risk, to a certain degree, an organization needs to ensure that risk is managed effectively, efficiently and coherently across an organization.  

Risk assessment is that part of risk management which provides a structured process that identifies how objectives may be affected, and analyses the risk in term of consequences and their probabilities before deciding on whether further treatment is required.

There are many different ways to do risk assessment. BS EN 31010:2010 provides numerous risk assessment techniques. The popular question will be “Which risk assessment technique is best suited for an organization?”.   Instead of immersing with all the techniques, perhaps it will be best to recognize that the purpose of risk assessment is to provide evidence-based information and capturing the essence of the risk and manage it.  The easy way to do risk management is through visual.

What is a BowTie?
BowTie is a barrier based risk management methodology that visualizes the risk you are dealing with in just one, easy to understand picture.  The output is shaped like a bow-tie, creating a clear differentiation between proactive (left of BowTie Diagram) and reactive (right of BowTie Diagram) risk management (Figure 1).

Figure 1. BowTie Diagram

The results of a risk assessment with the help of BowTie, give a good understanding of major hazard risks and how they are controlled. The BowTie method is adapted by many of the global 500 companies especially in the high risk industries such as oil and gas, mining, aviation, refining and public services including health.  It is particularly useful for major incident prevention; nevertheless it is applicable to all levels of risk associated with Safety & Health, Environment, Quality and Business. 

Understanding the BowTie

1.    Identify
It is not feasible to take all hazards* and map it out into BowTie.  Prior to BowTie risk assessment, a preliminary hazard analysis is required to determine which hazards with potentials to major incidents, which requires clear communication, close monitoring and visual control as means of prevention.

Once certain hazards are chosen based on its’ criticality, with a dedicated team, BowTie risk assessment starts.

*Note: Hazard: Anything which is a source of potential loss or damage.  E.g. driving on road.

Starting with one of the significant Hazard, the team defines the Top Event.  Top Event is a point in time which describes the release or loss of control over a Hazard.  E.g. Loss of control over vehicle. 

The next step is to identify the threats which are the possible direct causes that will potentially release a Hazard by producing a Top Event (Figure 2).  E.g. Slippery road.

Figure 2. BowTie Structure

2.    Assess
Next, is to determine the consequences, potential events resulting from the release of a Hazard, which directly results in loss or damage.  Consequences are events.  E.g. Vehicle crashes into tree.  They are the actual risks.

3.    Control
Barriers or controls are then placed in between the Threat and Top Event (Figure 2).  They are the measures within the organization’s control.  The objective is to prevent the release of a Hazard by acting against a Threat or Top Event.  E.g. If the Threat is brake failure, the Barrier can be Scheduled Maintenance.

The barrier is proactive as it eliminates (e.g. removing or avoiding something) or prevents (obstructing of stopping something) the Threat from occurrence.

4.    Recover
Recovery measure (Figure 2) is also named as Barrier.  It acts on the likelihood or severity of a potential consequence. The barrier is reactive measure.  It either reduces (decreasing, lessening or limiting something) or mitigates (abating, excusing or diminution of something) the Top Event.  E.g. If the Consequence is Crash into Tree, the Barrier can be Guard Rail.

Visual Risk Management
One of the key advantages of using BowTie is managing the risk through visual or visual risk management.  Just imagine with lots of data and pages after pages of risk assessment done, it is often difficult to view who is controlling what, when, where, and how.  BowTie eliminates this complexity by giving one complete picture (Figure 3 and 4).

Using the colours in the BowTie diagram enables one to distinguish current state of control in the risk management.  E.g. If a barrier is Dark Green in colour, it means that the control is Very Good. Else, if it is Orange in colour, it is Poor (Figure 4). 

Assessed risk in visual form

Figure 3. Assessed risk in visual form


Visual Risk Management – Coloured Barriers

Figure 4. Visual Risk Management – Coloured Barriers


BowTie shows that risk management can be virtually seen.  It helps understanding by providing clear pictorial representation of the risk.  Through visual, Risk Manager or management can focus attention on barriers or controls which are supposed to be in place for both prevention and mitigation and their effectiveness.  There is no rocket science.  One does not need to be an expert to know which control is good or poor, who is responsible to execute the control or whether controls are missing.

There are more other good features that cannot be explicitly explained here.  Nevertheless, with this basic understanding, it is sufficient to acknowledge that the BowTie barrier based risk management is one effective way of managing risks that are significant.

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