Life cycle cost of support poles in distribution lines

Wood poles are the most common support structures for distribution lines in North America. Wood poles typically have a service life of 40-50 years but may be replaced prematurely when they fail or are damaged by climatic loads or when they have degraded prematurely. The distribution network of Hydro-Québec comprises more than 2 million wood poles and the selection of an optimal class of poles for new or refurbished lines can potentially represent significant savings. In this project, wood poles from class 1 to 5 and steel poles are considered for new or refurbished lines using life-cycle-cost analysis.;The results indicate that the Class 4 poles that are currently used for the distribution network are not optimal from an economic point of view. For distribution lines located in regions with moderate ice hazard expositions, a Class 2 pole has a 15% cost advantage over the Class 4 poles. For distribution lines located in regions with severe ice hazard expositions, a Class 2 pole has a 30% advantage over the Class 4 poles.;The evaluation of life-cycle-costs of a line for a service life of 50 years was performed in two steps. A reliability model was first developed to estimate the probability of failure of single poles with climatic loads. The results of the reliability analysis were then integrated in an economic model that computes the Net Present Value of construction costs and pole replacement costs associated with failure under climatic loads of the whole line. Maintenance costs were neglected in this study since they were determined to be approximately similar for the various classes of poles.