Detecting woodpecker damage on fibre-optic cables with drones – Connecto project
Hepta Airborne conducted a drone inspection project for Connecto to assess the extent of woodpecker damage on fibre-optic cables. During regular powerline inspections, the detection of woodpecker damage on poles is a regular task. But this was the first time Hepta Airborne conducted an inspection to find defects caused by woodpeckers in the fibre-optic grid.
Connecto specialises in the design, construction, and maintenance of electricity and telecommunications networks. Their main concern was of the frequent internet interruptions experienced by clients in the Mustla area. Mustla is a small village in Estonia, which was one of the first to use ELASA high speed internet. The cable is transmission cable – meaning it is used by all telecommunication companies in Estonia, such as Telia.
Upon observation, it was evident that woodpeckers were attracted to the hollow fibre-optic cable shell and were pecking eager holes into it, in search of food. This problem has been recorded globally in woodpecker habitats.
In 2020, the goal for Connecto was to find all of the damage and fix the defects causing connectivity issues. In this case, the cable is installed on the same towers as low voltage and other communication cables. Performing the assessment on foot would have required hiring an aerial work platform with a truck and two operators. It would also have been time-consuming, requiring lifting the team up and down, then moving forward and repeating the process multiple times at every single line section between the posts, all the while marking down the defects.
As Hepta Airborne is already conducting a powerline inspection project for Elektrilevi and has a team all over Estonia, Connecto was curious if a similar technique could be applied to an inspection of fibre-optic cables.
The Hepta Airborne team was up for the challenge, the first job was to inspect a one kilometre test section of line and display the results in uBird. After that, the Connecto team joined in to discuss the exact defects to search for, as well as which are the most cost-efficient and speedy options to gather data. It was important to agree on the defects and angles to capture. This kind of inspection takes a skilled drone pilot as most of the flying was done at a low altitude of four to five metres, under the lines, and very near vegetation.
The decision was to mark defects when at least one hole was present in the cable section between two posts, annotate it in uBird and allow the Connecto maintenance team to view it in uBird to plan the following actions. This means the inspection was conducted by a similar principle as storm inspection – Hepta Airborne only took photos of faulty parts of the cable and none of undamaged cables. Meaning that this project did not aim to create a fully digitized version of the grid, but rather the only goal was to document the defects.
Storm inspections can be done when the weather is still bad, but inspecting fibre-optic cable is weather sensitive and needs special conditions. The weather needs to be dry for a few days to avoid water droplets on the cable posing as false-positive defects. There also needs to be no wind, due to tight manoeuvring spaces. By the second day of the project, the drone pilot was already experienced enough to tell water droplets apart from real defects on the cable.
The inspection of the first kilometre took one day, while the rest of the Mustla grid was inspected in just two days. In total, it took 19 hours to inspect 6.9 km of the fibre-optic grid. A total of 220 photos were taken of 166 defects. All of the defects were recorded by photo with the exact coordinates for the maintenance team, and all with just one lineman-drone specialist’s effort!
Future plans involve taking part in projects with Connecto to conduct UAV based inspection for fibre-optic cable damage in the rest of Estonia.
In conclusion detecting defects on the fibre-optic cable with drones was not done this way before and Hepta Airborne found the damages quickly. Doing something better in an innovative way meant that the early adoption of a new approach paid off