A method for generating condition histories for infrastructure items

When comparing different approaches for choosing an Asset Management policy, it is helpful to know what would have happened to an item if it had not been refurbished as knowing this allows the cost of different policies to be accurately determined. However, this requires the condition of each item to be known for each year, i.e. each item has to have a complete condition history – something that is not currently available for many infrastructure assets such as distribution transformers, switchgear and overhead line towers. Hence, this paper proposes a method for generating realistic condition histories. These condition histories can then be used to assess different Asset Management approaches. The method is based on specifying an average condition against time curve along with the expected standard deviation of condition about this curve at particular time points. Results show that sets of condition plotted against time curves that have similar average curves and spreads around this average curve can lead to significantly different predicted costs when analysing Asset Management policies.