| Product(s): | WaterSight |
| Version(s): | 10.00. |
| Area: | Documentation |
Overview
The first step when calculating likelihood of failure (LOF) or consequence of failure (COF) involves the user defining which are the key criteria or aspects that can drive both LOF and COF, taking into consideration both the data available as well the specific context of the utility and the region. Some common aspects amongst water utilities that can drive LOF can include for example pipes age, material, break history, etc. Some common aspects that can drive COF can include for example number of affected customers, proximity to main roads, repair costs, etc. However the user is able to create any aspect he finds relevant for the analysis.
There are two different methods available for creating aspects or consequences:
- Through a new Decision Tree (this page)
- Through a new Predefined Aspect or Consequence
The main goal of the decision tree is to give the user a very flexible and customizable way to create and score aspects, taking advantage of attribute and geospatial queries. The decision tree method allows to account for almost every user requirement, from the most simplest to the most complex, including the combination of different multiple aspects together (for example analyzing age and material together).
Creating a Decision Tree
To create a new decision tree, the user should click on the “New” button >> Decision Tree, located in the top of the Likelihood of Failure or Consequence of Failure page.
From there, a new window will open to create a new decision tree.
1. Name
In the top left of the page, the user can define a name for the aspect or consequence to be created. The name should be as much intuitive as possible, as it will be used in the rest of the application to identify the created aspects or consequences.
The decision tree is composed by the conditions and the results or scores for each condition or group of conditions.
2. Condition Dialog
Start
Click Start, located below the name, to begin the creation of a new decision tree.
It will open a pop up for the user to start populate with the properties of the first condition:
Query Type
There are three types of queries available:
- Attribute – it will directly query all the attributes that exist in the pipe shapefile (imported by the user through the Admin > GIS)
- Proximity – it will do a geospatial query between the pipes shapefile and any another shapefile imported by the user (for example proximity to main roads shapefile)
- Intersect – it will do a geospatial query between the pipes shapefile and any another shapefile imported by the user (for example intersect with main roads shapefile or soils shapefile)
From
The user selects here from which shapefile the query type will be applied. Please note that for attribute "Query Type" only the pipe shapefile is valid.
Condition
Condition dropdown will populate with all the labels of the columns presented in the shapefile.
Operator
In case the condition field has numerical values, the operator options will be: =, !=, >, >, >=, <=.
In case the condition field has string values (letters) the operator options will be: is, is not.
Value
It will display the values of the condition field defined (and that is defined in the shapefile).
(+) Adding a new condition
By clicking in the plus signal the user can add another and condition. For example in image below, we are querying all pipes which break rate is greater than 93 and diameter is more than 10.
Delete
Click in the () to delete the condition.
Save/Cancel
User can save the condition query or cancel.
3. Adding new conditions
When the conditions are created and saved (using the Condition Dialog), they get represented in the decision tree by rectangular boxes, as shown below:
After the first condition(s) gets created, the user can click on the right or below the condition box to add another condition or to score it (by clicking in the + button).
If clicking Condition, a new condition dialog pop-up will appear, in order to be completed by the user. Take a look at the information described above in the Condition Dialog topic for more information.
When saving, the new condition will be added to the right side of the previous condition or below.
- By adding a new condition to the right side of an existent one, it means that the first condition needs to be true. The first and second condition get connected with a green link.
Example above: In this case the user is querying all pipes which diameter is greater than 10 inches and the material is concrete.
By adding a new condition below of an existent one, it means that the first condition needs to be false. The first and second condition get connected with a red link.
Example above: In this case the user is querying all pipes which diameter is not greater than 10 inches (this means below or equal 10 inches) and the material is concrete.
The decision tree method is flexible enough that the user can continue to add more conditions based on their requirements and rules.
4. Adding Scores
After the condition or conditions are defined, the user needs to score them in terms of relevance or impact for the likelihood or consequence of failure analysis. Scores are from 0 (lowest relevance) to 100 (highest relevance).
To add a score for the condition(s) just click on the plus (+) button located on the right side or below the condition dialog boxes.
- By clicking on new result button located on the right side of a condition dialog, it means that the condition(s) needs to be truth. The condition(s) are linked to the score with a green link.
- By clicking on new result button located below of a condition dialog, it means that the condition(s) needs to be false. The condition(s) are linked to the score with a red link.
Example above: If pipe material is concrete, score is 80. If pipe material is not concrete, score is 60.
The user can define any score from 0 to 100, in multipliers of 10. When analyzing the likelihood of failure, lowest scores mean lower probability of failure while higher values mean higher probability of failure. When analyzing the consequence of failure, lowest scores mean lower consequences while higher values mean higher consequences or impacts.
When defining a quantitative score, automatically a qualitative score or grade will also be associated with each pipe. The default ones are: high grade (score between 68-100), medium grade (score between 35-67) and low grade (score between 0-34). The user can change grade scores and names on the main Likelihood of Failure or Consequence of Failure pages.
The decision tree method is flexible enough that the user can continue to add more conditions and score them based on their requirements and rules. In the end we can have more simple or more complex decision trees, that include only one or more aspects together. Below an example of a decision tree aspect, where material and age is assed together.
Example above: All pipes installed after 1981 and material is different than concrete, are scored with a lower likelihood of failure (score is 20). All pipes installed before 1950 (and after 1910) and which material is concrete have the highest likelihood of failure (score is 100).
Editing an Existent Decision Tree
The user can easily edit existent decision trees:
- Clicking twice over a condition box will open the condition dialog in order to edit or update the condition (see detailed description above)
- Clicking twice over the score allows the user to edit the score (see detailed description above)
- Deleting a condition box or score is possible by selecting them with one click, and then clicking on the delete button
located on the top right.
Right-side Panel Results
Once the conditions are defined and scored, automatically the right-side panel gets updated with the results for those conditions, namely the number of pipes and length that falls into each score and grade. As mentioned before when defining a score, automatically a qualitative grade will also be associated to each pipe. The default ones are
- high grade (score between 68-100),
- medium grade (score between 35-67)
- and low grade (score between 0-34)
The user can change grade scores and names on the main Likelihood of Failure or Consequence of Failure pages.
Preview Results
Before saving and while editing or creating a new decision tree, it is possible to have access to a preview of the results in a map view. With this option it is easy to understand not only the number of pipes and length that is affected for each condition and score (displayed on the right-side panel), but also their location.
Additional Note about Geospatial Queries
There are two different ways of creating a geospatial query:
- To query all the pipes that are near or intersect a specific shapefile, just select Proximity or Intersect and in the “From” field, select the shapefile for which all pipes will intersect or be located nearby. Example below
- It is possible to query only some specific pipes that are near or intersect a specific shapefile. On the first condition just select for “Query Type field” the pipes attributes, and in the second condition fil with the shapefile where pipes will intersect or be located nearby, see example below.