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AWWA ACE99336
- Modeling the Occurrence of Breaks in Cast Iron Water Mains Using Methods of Survival Analysis
- Conference Proceeding by American Water Works Association, 01/01/1999
- Publisher: AWWA
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The deterioration of cast iron water mains is modeled as a semi-Markov process, where the "state" of a water main is represented by its number of breaks, and the "holding time" between states is the failure time between successive breaks. Simple methods for analysis of survival data are presented to estimate the probability distributions of the failure times. The effect of the length of a water main on failure time is used as an example to illustrate the methodology for evaluating contributory variables. Finally, a calibration method is developed for validating the model based on recent system performance.