Re, Up to now they do regular field inspections to ensure this
It's a bit more complicated ...
Here in Canberra....
ActewAGL helicopter patrols conclude
Friday 19 February 2016
ActewAGL would like to thank the community for its patience as the last of our helicopter inspections are now complete across parts of Canberra. The patrols commenced on 4 February and finished yesterday, 18 February. The patrols are an essential part of ActewAGL’s vegetation management and asset management program.
ActewAGL has the most reliable network in Australia. To help keep it that way we use helicopters to conduct inspections throughout the ACT and surrounding region. They allow us to cover vast areas to ensure trees and vegetation are kept clear of powerlines and to mitigate bushfires.
ActewAGL Manager Works Delivery Clinton McAlister said, “ActewAGL has been using helicopters since 1979 when we first borrowed a helicopter to inspect a large portion of our network. Since then we’ve been using helicopters in a few different ways.
“Helicopter patrols are the most accurate and effective way of detecting encroachments between the vegetation and our poles and wires. It allows us to look at the top of the infrastructure, the bits we can’t see from the ground to really understand if there are any problems with the top of the network.”
The helicopter uses Light Detection and Ranging (LiDAR) remote sensing technology to determine the distance between powerlines and vegetation. Vegetation deemed too close to powerlines are prioritised for cutting by ActewAGL’s authorised service providers in rural areas, or notifications are sent to customers or ACT Government depending on where trees are located in suburban areas.
https://www.actewagl.com.au/About-u...s/2016/02/19/helicopter-patrols-conclude.aspx
ActewAGL inspects ACT's power grid with helicopter patrols
View attachment 1217458
"We do a LIDAR scan of the network, which basically senses different types of vegetation and structure, and allows us to create a 3D model."
LIDAR — or light detection and ranging — is a sophisticated imaging technology that maps geography using laser pulses.
"We can then identify any vegetation that encroaches on the powerlines and we also take high-resolution images of the top."
https://www.canberratimes.com.au/na...-with-helicopter-patrols-20170209-gu8rpf.html
https://www.google.com.au/search?ei=3_hgW8X3N8eN8wX3-qXgCQ&q=ACTEW Helicopter 2018&oq=ACTEW Helicopter 2018&gs_l=psy-ab.12...7952.9469.0.11472.5.5.0.0.0.0.276.789.2-3.3.0....0...1.1.64.psy-ab..2.2.546...0i22i30k1j33i21k1j33i160k1.0.-sr8ZfLLKmk