A Spatial probabilistic model of pipeline failures

Abstract

A spatial probabilistic model is developed and applied to predict failure patterns over a water supply pipe network. The Zalaegerszeg waterworks is used to illustrate the methodology. The ageing of water supply pipes is a worldwide concern; therefore it is of high interest to identify the best interventions in time and space. Two-part models can be used; one is an economic by formulating time horizon total costs. The other part forecasts the break patterns in time and space. Spatial modeling is necessary since elements of the cost function depend on the location of failures. A network based model is developed for the internal part of the Zalaegerszeg waterworks since the system is homogeneous in a sense that the environmental and network features do not exhibit significant correlation with the occurrence of failures. Network based failure probabilities are described by a space-time Poisson process where non-homogeneous Poisson process (NHPP) refers to time and a stochastic point process refers to space. To es timate the intensity the whole area is covered by a grid system of 250 × 250 meters with an average pipe length of 703 meter in a cell. Both the number of and the distance between failures prove the applicability of the Poisson process. It is shown how a simulation procedure can be applied to generate possible pipe failure patterns which - by combining with the spatial cost functions - leads to estimate total costs per selected time periods.