Drone survey of HV Feeders for Vegetation Defect Mapping

October 20, 2020

Vegetation defect mapping along 4km of HV Feeders within surburban rail corridoR using drone LiDAR and photogrammetry modelling.

PROJECT OVERVIEW

Vegetation management for high voltage feeders, and the rail corridor in general, is a major area of asset maintenance for railway operators. A section of rail corridor that contained several areas of protected Blue Gum forests. These were in close proximity to two high voltage feeders. The need to maintain safe vegetation clearances while maintaining environmental protection requirements had raised concerns about the location of a new feeder alignment. Sydney Trains approached Diospatial to develop a detailed vegetation defect mapping and clearance survey for HV feeders.

PROJECT SCOPE

Drone-LiDAR

Classified Point Cloud

Google Earth and GIS reporting

Diospatial SOLUTION

Diospatial developed a methodology involving drone LiDAR. Drone LiDAR would be used to capture a digital twin of the site. The data would then be processed to analyse the vegetation clearances to the high voltage feeders. Our specialist drone pilots carried out 6 drone flights which captured LiDAR and photogrammetry data for the 3.8km of rail corridor.

Initially, LiDAR data was classified into ground, HV feeders, overhead wiring structures, 1500V OHL and buildings. The classified data was then analysed for vegetation to conductor clearances along the length of the two feeders. The defects were then reported in GoogleEarth compatible file formats. This could then be used to support field crews while completing vegetation clearing.

Classified point cloud detailing various asset categories including powerlines, 1500V OHL, OHWS, terrain, ballast and buildings — *The classified point cloud, accurate to 50mm and detailing various asset categories including powerlines, 1500V OHL, OHWS, terrain, ballast and buildings.*

Additionally, the survey report identified several areas where the existing pole location data was incorrect.

Included with the survey data was a complete topographic survey. Also included was survey of all structures and signals and ballast profiles. This was completed for the entire 3.8km suburban rail corridor.

Vegetation defect mapping reported through GoogleEarth and GIS compatible formats — *Vegetation clearance defects are reported in GoogleEarth and GIS compatible formats, allowing for easy distribution to field crews for scoping and works execution.*

Imagery was captured and processed in photogrammetry software to generate a 3D model for visual inspection of the rail line and encroachment of vegetation.