13.1 Introduction

Recent years have seen the derivation and population of health indices to rank assets on the basis of condition (in relation to proximity to end of life) as a means of assisting asset managers in formulating and justifying replacement or refurbishment plans. This chapter looks at the concept of health indices, which are based on utilising existing information, and summarises the experience gained over the past few years with developing and implementing health indices. This enables initial health indices to be derived and populated quickly, without the need for large-scale information collection. This gives a knowledge of present asset condition that can be immediately used to provide a very structured, well defined assessment of future condition assessment activities that can be used to focus and direct future asset management activities.

Overall, the continuing experience with health indices is very positive. Recent experience has demonstrated that they are of great value for distribution and transmission assets. As utilities attempt to develop a more integrated, risk-based approach to asset management there is a growing awareness of asset condition and how this relates to future performance. This will become an increasingly important component of replacement policies and plans in the future.

13.2 Health indices in context

Throughout the UK, and indeed many other parts of the western world, there was large-scale expansion in distribution networks and investment in electricity systems in the 1950s, 1960s and early 1970s. Since this time, the rate of asset replacement due to non-condition factors has been...