The probabilistic approach to the design of overhead transmission lines (OHTL) has been considered best practice within the power industry for a number of decades after superseding the deterministic approach. This allowed asset owners to benefit from a risk based approach to system design that more closely aligned with the asset’s criticality to the network and/ or the environment in which it was operating. This shift had the effect of reducing the upfront capital investment required for lower risk assets which could then be deployed on assets of greater strategic importance or those exposed to harsher operating conditions.

While an OHTL's life is initiated using a risk based approach, from that point on lifecycle management is dominated by deterministic methods, such as routine inspections, scheduled component replacement and asset retirement, which are generally applied equally across the network with no consideration given to operational history, criticality or environment. This approach is in stark contrast to other major power system assets where a risk based approach has been successfully applied for more than 20 years using off and online monitoring techniques and collection of data sets to aid in the efficient planning of maintenance operations and strategies. A risk based approach also provides quantifiable justification in support of regulatory submissions for asset retirement and replacement programs. 

This presentation introduces the risk based approach to the management of overhead transmission line assets along with the systems, tools and techniques as applied to lattice steel towers, foundations and conductor systems.