Risk Calculations

To help you understand the calculations for each of the risk scores, let's take a look at an example risk model setup.

Risk Analysis Overview

Example setup with example component scores

We'll use the following weightings and component scores to illustrate the risk calculations. Remember that component scores are determined by the scoring ranges you set up when adding components, and you can find the component scores and weighted component scores on the Asset Details page.

Risk Setup

LoF (80%) + CoF (20%)

Likelihood of Failure (80%)

Category and component weightings	Example Component Score
Asset Condition (70%) [Category (weight)]
Structural Peak Score (100%) [Component (weight)]	10
Pipe Material (10%)
Pipe Material (100%)	5
Pipe Age (10%)
Pipe Installation Year (100%)	9
Repair History (10%)
Count of Past Repairs (100%)	9

Total LoF Score is equal to:

Sum of all weighted LoF component scores

The weighted LoF component scores are calculated as:

Component Score * Component Weight * Category Weight * LoF Weight

In this example, the weighted component scores are:

• Structural Peak Score: 10 * 100% * 70% * 80% = 5.6
• Pipe material: 5 * 100% * 10% * 80% = 0.4
• Pipe age: 9 * 100% * 10% * 80% = 0.72
• Repair history: 9 * 100% * 10% * 80% = 0.72

So, the Total LoF Score is: 5.6 + 0.4 + 0.72 + 0.72 = 7.44

Consequence of Failure (20%)

Category and component weightings	Example Component Score
Impact on Critical Facilities (50%) [Category (weight)]
[Components] Component weight = 100% for whichever component is used Proximity to Police Stations Proximity to Hospitals Proximity to Fire Stations 'Use highest score from components as overall category score' option is marked, so the highest component score will be used as the category score.	8 (highest score from the three components)
Impact on Surface Waters (25%)
Proximity to Rivers and Streams (100%)	0
Impact on Transportation (25%)
Proximity to Major Roads (50%) Proximity to Railroads (50%)	9 8

Total CoF Score is equal to:

Sum of all weighted CoF component scores

The weighted CoF component scores are calculated as:

Component Score * Component Weight * Category Weight * CoF Weight

In this example, the weighted component scores are:

• Impact on critical facilities: 8 * 100% * 50% * 20% = 0.8
• Proximity to rivers and streams: 0 * 100% * 25% * 20% = 0
• Proximity to major roads: 9 * 50% * 25% * 20% = 0.225
• Proximity to railroads: 8 * 50% * 25% * 20% = 0.2

So, the Total CoF Score is: 0.8 + 0 + 0.225 + 0.2 = 1.225

Risk Score

This Risk Score is calculated by either adding or multiplying the LoF and CoF scores, depending on which method you have chosen in the Risk Setup.

In this example, we have selected 'Added' so Total Risk Score = Total LoF + Total CoF.

So, the Risk Score is 7.44 + 1.225 = 8.665

A Risk Grade is also given based on the configuration in the Risk Setup tab.