Reimagining Foundation Design in the Electric Power Transmission Industry

The electric power infrastructure is rapidly growing and changing, driven by the need for more energy and a broad-based conversion from traditional generation to more sustainable sources. Managing this change has resulted in the need to streamline and modernize transmission line foundation design practices. Current industry approaches are fragmented and inconsistent, causing an impediment toward change. Guide documents developed by various utilities and engineering societies describe general design methodologies for foundation types used in the electric power industry, but their application, relevance and approach vary significantly from utility to utility. Industry transmission line and foundation engineers have come together under the DFI’s Electric Power System Foundations (EPSF) Committee to document the state of the practice in overhead transmission line foundation design and construction, delineate the shortcomings in these practices, and provide recommendations for the future development of consistent guidelines. This paper presents the scope and findings of the committee’s 2024 state of the practice report that identifies foundation design and construction best practices, the type and scope of guidelines needed to streamline design methods, and research needed by the industry to advance the practice. The DFI EPSF Committee report is followed by the formation of an ASCE subcommittee whose goal is to develop overhead power line and substation foundation design guidance through a comprehensive manual of practice (MOP). This paper also presents high level insight from the current draft of the MOP, including a summary of the work specific to new guidance on assessing appropriate foundations for varying environmental settings and best practice design methodologies that update prior allowable strength approaches to more modern reliability-based approaches that are expected to aid in minimizing the impact of foundation work on sensitive environments. Guidance is also provided on the reuse of existing transmission line and substation foundations for system upgrade projects, where more power is to be transmitted within exiting corridors. The new MOP will offer the opportunity for other industry sectors to understand how the power industry applies classical geotechnical design approaches for the foundation design of power line structures.