Overhead Transmission Line Structure Selection

The transmission industry is evolving continuously as customer expectations, reliability, and resiliency play an ever-important role in the engineer’s selection of a transmission line structure. Transmission Engineers have an array of tools available to satisfy overhead transmission line project requirements. Most importantly, the engineer must select the most appropriate and economic supporting structure and foundation type. Factors to evaluate include project-specific electrical performance, weather-related loads, land use, terrain, geotechnical conditions, and constructability. When these are considered in combination, it is a challenging decision for the engineer to select the best structure for the project. This paper describes the advantages, disadvantages, and economy for various configurations of common overhead transmission line structure types. The engineer may consider latticed steel towers and tubular steel poles when selecting the most effective site-specific structure or structures for an entire project. This paper presents analytical procedures for comparing structure weights of common transmission structures, and their relationship to applied load versus weight. In addition, this paper includes project-specific parameters and their effects on structure selection: voltage class, structure type, terrain, cable size and tension, and structure loading.