A semi-Markov approach for modelling asset deterioration

Abstract

Considerable benefits have been gained from using Markov decision processes to select condition-based maintenance policies for the asset management of infrastructure systems. A key part of the method is using a Markov process to model the deterioration of condition. However, the Markov model assumes constant transition probabilities irrespective of how long an item has been in a state. The semi-Markov model relaxes this assumption. This paper describes how to fit a semi-Markov model to observed condition data and the results achieved on two data sets. Good results were obtained even where there was only 1 year of observation data.

Keywords:

• maintenance
• replacement
• infrastructure networks
• semi-Markov

Acknowledgements

This work was carried out in collaboration with the EA Technology Strategic Technology Programme (STP). We thank EA Technology and the companies participating in module 4 of the STP for permission to publish this work. Mary Black was supported by EPSRC Grant Number GR/N11575.