Optimal scheduling of rehabilitation and inspection/condition assessment in large buried pipes

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Conference4th International Conference on Water Pipeline Systems - Managing Pipeline Assets in an Evolving Market: 28 March 2001, York, UK
Pages181197; # of pages: 17
SubjectWater mains
AbstractA decision framework is described to assist municipal engineers and planners in optimising the scheduling of rehabilitation as well as inspection and condition assessment of large buried pipes. These may include water transmission pipes, trunk sewers or other buried pipes with high costs of failure and high costs of inspection/condition assessment. A semi-Markov process is used to model the deterioration of a buried asset. The life of the asset is discretised into condition states, whereby the waiting times in each state are assumed to be random variables with known probability distributions. These probability distributions can bederived in two ways. Initially, when data are scarce the probability distributions can be based on expert opinion. Over time, as observed deterioration data are collected these probability distributions are continually updated to reflect the new observations. Age-dependent transition probability matrices are compiled, using conditional survival probabilities in the various states. The expected discounted total cost associated with an asset is computed as a function of time. The time to schedule the next inspection/condition assessment is when the total expected discounted cost is minimum, while immediate intervention should be planned if the time of minimum cost is less than a threshold period (2 to 3 years) away.The proposed framework was implemented for proof of concept in a demonstration computer application. Although usable in its current form, this paper identifies some issues that require as yet unavailable data as well as more research in order to develop the framework into a comprehensive application tool.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number44487
NPARC number20386517
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Record identifier19efbf1b-b19e-4b6a-a305-4c8371fa00c8
Record created2012-07-25
Record modified2016-05-09
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