An Unmanned Aircraft System for Marking Live Power Lines to Prevent Bird Collisions

Collisions with overhead power lines represent a significant cause of mortality for a number of large bird species worldwide. Certain threatened species are severely impacted by power line collisions, particularly those for which there are no other known significant threats. In South Africa, bird collisions with overhead power line cables, including collisions with phase conductors and shield wires, contribute significantly to annual threatened bird species mortalities associated with Eskom power lines. The most practical mitigation measure is to attach bird anti-collision devices as markers on the cables. Current marking methods involve installations by hand, where linemen are hoisted up to the cables via a bucket truck or helicopter. In 2016, we initiated a project to develop an unmanned aircraft system (UAS) that is able to mark live power lines as a safe, cost-effective alternative to the above-mentioned methods. To achieve this, we first tested the performance of the UAS flying near strong electromagnetic fields generated by high-voltage power lines at the National Electrical Test Facility in Gauteng, South Africa. Then, in 2021, following some refinements to the design of the marking mechanism, the system was tested in the field at 2 sites in the North West Province. Based on the results of marking 22-kV distribution line conductors, a comparison was made to the efficiency and cost-effectiveness of the UAS compared to a bucket truck. The UAS proved more cost-effective and more efficient; we estimate that Eskom could save >$16,000 USD per annum on marking power lines if the UAS method were used instead of a bucket truck. Moreover, the biggest advantage of the UAS method is that human safety risks involved in power line marking field operations can be significantly reduced.