Condition assessments for power transmission line infrastructure and conductors are essential to maintain a reliable and efficient system. LineScout is a high-performance robot designed to undertake detailed, comprehensive inspections of transmission lines, which contributes to maintaining the integrity of equipment and the safety of inspection crews. This paper outlines Hydro-Québec's LineScout Technology, describing briefly the main systems and key design issues and discussing the technology's impact and benefits on power transmission line inspection and maintenance practices. The paper then focuses on field results gathered over the past 2 years with LineScout Technology. Very important lessons were learned from more than 20 field deployments of the robot on live transmission lines. An appreciable amount of significant feedback came from these field visits and was decisive in improving the technology. Specifically, transportation and installation methods and onboard energy management strategy are presented. Also discussed, for the first time, is a simplified wheel contact radius estimate, useful for improving the wheel odometer readings. Finally, one field deployment on a large water crossing transmission line is presented in detail. The paper discusses the importance of the work done and of newly implemented features in terms of the quality and efficiency of inspections, the reliability of systems, and the safe operation of the technology. © 2011 Wiley Periodicals, Inc.