VIACRAS is a process for determining the probability of failure of a sewer pipe and the life expectancy of a pipe. By knowing an approximation of the probability of failure, utilities will have guidance on prioritization of immediate repairs, an estimation of replacement costs in the future, and the ability to minimize risk of failure, disruption of service, and inconvenience to customers.
Not all sewer pipes deserve the same priority for replacement. Some pipes with more extensive damage and that are deteriorating faster should be repaired sooner, while others with less damage and fewer deterioration factors may not need repair for a very long time. Using the Viacras method utilities will have a process for structuring assessment and repair strategies now and for many years in the future.
The risk or failure, or life expectancy of a sewer pipe is primarily determined by the structural condition of the pipe. Once the structural condition of the pipe is known, the magnitude of specific deterioration factors affecting the pipe is quantified. Analysis of the existing defects and deterioration factors then provide a probability of failure and an estimate of remaining life.
The most essential information necessary for identifying the condition of the pipe is high quality internal CCTV inspection data.The CCTV data defines the defects within the pipe and identifies many deterioration factors that may affect the pipe. Other information including maintenance management records, repair history, GIS attribute data, etc help to categorize contributing factors that affect the performance of the pipe segment.
Knowing the life expectancy of a pipe not only provides guidance on what pipes should be repaired in the immediate future, but can be used to structure user fees and capital improvement program budgets several decades into the future