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Mission Impossible: Autonomous LiDAR Drone Inspection of a Tunnel

Mission Impossible: Autonomous LiDAR Drone Inspection of a Tunnel

Rio Tinto Tailrace Tunnel Autonomous Drone Survey from The McElhanney Group Ltd. on Vimeo.

In a groundbreaking feat of technological innovation and willpower, the Candrone Service team contracted by McElhanney achieved what was once thought impossible: the detailed inspection of a remote underground power station in British Columbia using advanced LiDAR drone technology. Operational since the 1950s, this power station presented a unique set of challenges that had previously made it impossible to inspect its tailrace tunnel for preemptive maintenance.

The Challenge

The power station's tailrace tunnel, crucial for its operations, extends 500 meters into a mountain, with a significant portion filled with rapidly flowing water. This environment, combined with a bend in the tunnel that placed the final 350 meters beyond line of sight and radio range, made traditional inspection methods unfeasible. The only viewpoint to the tunnel entrance was obstructed by a 300KV transmission line and dense foliage, further complicating any inspection attempts.

Innovative Solutions

The primary inspection was conducted using a Matrice 350 drone equipped with Hovermap and AL2 technology, capable of autonomous navigation and obstacle avoidance in GPS-denied environments. This technology was pivotal in overcoming the electromagnetic interference from high voltage power lines and the GPS-denied environment of a tunnel.

The Outcome

The mission, taking approximately 20 minutes, resulted in a half-hour of data processing to generate a detailed point cloud of the tunnel. This data provided the hydro station stakeholders with their first glimpse inside the tunnel in over seven decades, enabling them to make informed decisions about future maintenance.

This project won the 2023 Challenging Non-Cadastral Survey Project at the David Thompson Awards, hosted by the Association of Canada Lands Surveyors (ACLS).


Our successful mission at the British Columbia power station stands as a testament to the power of innovation and the relentless pursuit of solutions in the face of seemingly insurmountable challenges. By harnessing the capabilities of advanced drone and LiDAR technology, our team not only accomplished the mission impossible but also paved the way for future inspections in similarly challenging environments.

We're ready for the next challenge, contact our service team for your next project!

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