Calculating Criticality

Criticality is a risk-based process. The risk is determined by the probability of failure and the consequence of failure. The assets that have the greatest probability of failure and the greatest consequences associated with failure will be the assets that are the highest risk and therefore most critical. The assets that have low probability and low consequence will be the least critical assets. 

To calculate the criticality score for a given asset, multiply the probability of failure ranking by the consequence of failure ranking for that asset.  

Criticality = Probability of Failure x Consequence of Failure 

Special attention should be given to areas where multiple critical assets exist within the same location. The impacts of one critical asset failing will have heightened impact due to the proximity to other critical assets, including those of another asset type. GIS is a useful tool to spatially identify high-concentration locations of critical assets, and this can then be factored into the prioritization framework for each asset type.  

The condition of the assets will change over time affecting the probability of failure. Costs of repair may increase, the community may grow, new roads may be built, rehabilitation may be completed, or similar factors may occur that cause the consequence of failure to change. Therefore, it is necessary to periodically review the criticality analysis and make adjustments to account for changes in the probability of failure and the consequence of failure. 

The probability of failure for gray and green assets will likely take different paths over time. As equipment wears, gray assets will require increased operations and maintenance, but this is not the case for many green assets. Green assets often become more resilient and effective as vegetation matures and adapts to local resource cycles. The flexible and adaptable nature of green assets extends their life cycle and often their performance level over time. Performance may eventually diminish but if installed properly with routine maintenance, green assets generally strengthen and improve unlike gray assets.