Setting up near each utility pole in a position where the cables were about 18 meters directly overhead, they scanned the entire 450-meter- long section in two scans, one from the top of the slope and one from the bottom. Collecting 26,600 points per second, each scan took about 10 minutes to complete, acquiring a 3D scan of all four power lines and two towers in 20 minutes. “The scanner is surprisingly quick and is quite precise,” Sellevoll said. “It can produce a 360-degree scan directly overhead. And it automatically registers the data so you don’t have to georeference the point cloud during post-processing, which is a huge time savings.” Back in the office, the Geomatikk Survey team used Trimble Business Center software to integrate the point cloud data and survey data. They then produced a vector-based report, coupled with supporting point- cloud screenshots, to verify that the power lines were adjusted to BKK specifications. That documentation was prepared in one day and delivered to BKK the day after. “We were very pleased with how smoothly the measurement went and that we could do it in real-time,” said Jan Reime, a project manager with BKK. “An additional bonus for us and our client was the ability to deliver a written report with the actual measurements enclosed.” “We could not have completed the field work or the project report as well and as quickly as we did with traditional total station technology,” Sellevel said. “The ability to switch between total station surveying and scanning with one instrument allows us to be so much more efficient, both in time and costs. As the scanning gives us the data and detail of an entire project, we can revisit the site virtually as many times as we need without having to leave the office. And with the auto- lock feature of the SX10, we now have the ability to take on projects that require real-time surveying, opening up a whole range of business development opportunities.” Indeed, based on their debut success in Leikanger, BKK commissioned Geomatikk Survey to return to a different section of the same power line and perform the same sag-measuring work. Colleagues all across Norway have also gotten wind of that project, and they all seem to be curious about the real-time aspect of surveying. This rising interest could lead to more helicopter rides in Sellevoll’s future. He knows there may be more of the unexpected, but he’s confident he has the right tools to resolve them.
Collecting 26,600 points per second, surveyors acquired a 3D scan of all four power lines and two towers in 20 minutes.
MARY JO WAGNER is a freelance writer, editor, and media consultant based in Vancouver, B.C.
Measuring to an accuracy of plus/minus 3 cm, the Geomatikk Survey team determined that each of the four power lines was hanging too low — between 1.5 meters and 2 meters below the acceptable sag limit.
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csengineermag.com
august 2018
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