The key information in the CCTV data is that of the defects. A list of defects is stored, and a defect scoring approach can be used to judge pipe condition.
To automatically calculate condition grades (displayed on the Scores page of the CCTV Survey Property Sheet) for CCTV Surveys:
Note: The condition grade profile is an extension to the scoring for CCTV surveys. In addition to the normal scoring (peak scores, etc.) a survey can be broken down into grades. The percentage of grades present from 1 to 5 can be calculated for each pipe based on a given resolution (the profile window size). The condition grade profile is currently calculated only for structural scores, not for service scores.
Defect scoring will be carried out as follows:
If Select scoring method based on each CCTV Survey's standard has not been checked, the Default scoring method will be used.
If Select scoring method based on each CCTV Survey's standard has been checked:
Assumptions about defect lengths are applied as detailed below.
The MSCC standard makes the following assumptions about defect lengths:
InfoAsset Manager also applies these assumptions when the chosen CCTV Standard is PACP, EU, WSAA or Custom.
The CH2M HILL SCREAM™ standard makes the following assumption about defect lengths:
InfoAsset Manager also assumes that point defects are 1 ft long.
A Likelihood score is calculated, providing an assessment of the likelihood of failure of a pipe. The score is closely related to structural grade and is calculated as follows for the different scoring methods:
CH2M HILL SCREAM™ - not supported; likelihood is not calculated
The Likelihood score field for a pipe is updated with the value in the CCTV survey field when Updating Pipe Condition from CCTV Data.