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Project: T173700 #3272

The management of electric transmission line and rights-of-way clearances is a critical component of the safe and reliable operation of the North American power grid. It is also in the interest of national security in both the United States and Canada. Both ratepayers and stockholders are concerned with cost effective management and regulators are interested in maintaining one hundred percent system reliability 24/7. The utilization of industry best management practices is crucial for meeting these challenging objectives.

CEATI International Inc.’s (CEATI) Transmission Line Asset Management (TLAM) utilities selected Environmental Consultants (ECI) to investigate approaches for managing transmission line clearances in providing reliable results to operators and owners. The investigation provides a review of methods, frequencies, and technologies and a best practice guide for modern transmission managers. The investigation attempts to identify practical solutions for maintaining transmission line clearances, which best ensures compliance, but also has the potential to improve safety and reliability while reducing total cost of transmission operations. Building on the 2015 NERC issued a good practices document titled “Maintaining Transmission Line Ratings Consistent with As-Built Conditions”, the study places particular focus on the uses and benefits of remote sensing as it applies to achieving these objectives.

The study reviews current techniques and practices related to the identification and maintenance of hard clearances (e.g., structures, roads, bridges, rail lines, underbuilds, and encroachments into the right-of-way), as well as vegetative clearances on transmission lines for both routine maintenance, scheduled inspections, and regulatory compliance. Central to the study is an analysis of patrol frequencies, survey data recapture intervals, and clearance thresholds pertaining to keeping transmission lines within regulatory requirements. ECI obtained the foundational information via a combination of literature reviews, internal expertise, and interviews with remote sensing service providers, supplemented with a limited number of interviews with key transmission operators and innovators in the electric utility industry.

The final project include a written report describing the findings of the research, which will serve as a guide for maintaining practical transmission line clearances, along with methods used and their respective associated risks. The report includes tables, charts, interpretive narratives and qualitative explanations of best management practices, an evaluation matrix, a workbook and scenario analysis to test the tools developed. We anticipate that this study will help transmission operators and owners enhance their investments while providing a framework for optimizing transmission line-clearance maintenance practices.


Remote sensing, Light detection and ranging (LiDAR), Photographic detection and ranging (PhoDAR), Unmanned aerial system (UAS), Transmission line clearance, Ground patrols, Asset inspection, Vegetation management, Rights-of-way, Transmission line operations and maintenance, NERC compliance, FAC-008, FAC-003, Virtual reality, Artificial intelligence