Electric utility asset managers and operators are increasingly relying on quantitative risk metrics when prioritizing asset repairs/replacements, and determining conditions under which a line should be deenergized. Working closely with California utilities, Exponent has developed an innovative, rigorous tool to assist in risk-informed capital project prioritization, maintenance and operational programs for overhead lines. This Operability Assessment (OA) tool employs elements of reliability theory and decision analysis originally developed for nuclear power plant design and recent state-of-the-art advancements in seismic risk assessment to inform business decisions.

Recent work by Exponent on behalf of its utility clients involves assessing the risk of power lines not just in their current condition, but in their likely condition at some future date. This extension of the OA tool incorporates degradation mechanisms, such as wood decay and steel corrosion, allowing asset managers to plan repairs/replacements in advance of significant strength loss. This presentation will focus on a wood decay model that predicts when wood poles will have experienced strength loss in excess of regulatory thresholds, and when their annual failure rates will exceed a risk tolerance set by the utility.