The Operational Determinants of Utility Pole Decay and Optimal Replacement in the Pacific Northwest

Wood utility poles are central to many electrical distribution networks, yet there have been no published studies to determine what operational characteristics of utility poles are indicative of decay in the field. We apply survival analysis to a database of more than 17 000 utility poles in the Pacific Northwest, and find that larger circumference poles decay sooner, that Douglas fir poles do not last as long as western red cedar poles, that a split top has a large negative impact, and that the presence of a transformer makes decay more likely. We use our estimates for the size of these effects to calculate a pole-specific optimal replacement time that minimizes the cost of the pole. Our results are regional, and may not apply generally, but we document how our approach can be adapted to any electrical distribution network.