Markov Chain–Based Inspection and Maintenance Model for Stormwater Pipes

Inspection and maintenance (M&R) of a buried network of stormwater drainage pipes is a challenging task for asset engineers due to a large number of pipes and restricted access. A Markov-based inspection model with a computational procedure was developed to estimate the lowest-cost inspection interval for various pipe conditions and an average total of M&R cost. The computational procedure is based on the innovative application of Markov deterioration model, the cost rate function, and Monte Carlo simulation. The results from a real case study show that the lowest-cost inspection intervals for stormwater pipe assets with a starting good condition of 1 are obtained between 9 and 11 years. The average number of undetected failure condition due to longer inspection interval is also presented and can be important in selecting the inspection interval when failure risk is concerned. The effect of penalty cost is shown to affect both the average cost rate and lowest-cost inspection interval. The annual interest rate is found to have a significant effect on total cost but has no impact on inspection interval.