Transpower New Zealand has successfully completed an aerial laser survey (ALS) of 2000 km of transmission lines, with the help of PSC and Opten, the leading ALS service provider. This follows on from PSC’s ongoing 17 year involvement in aerial laser survey technology and data services delivered for a range of clients.

Aerial laser surveying of transmission lines is conducted by a helicopter fitted with a high accuracy laser scanning system. The laser scans a swath under the helicopter’s flight path, detecting conductors, towers, the ground plane, and other features such as roads, buildings and vegetation. Photo systems are used to supply imagery for object identification and as an accurate record at date of survey. GPS receivers are placed strategically along the route to provide differential GPS for accurate helicopter positioning. Weather recordings are also placed in the field to support accurate modeling through calculating the conductor temperature at time of survey. All this data enables the creation of accurate PLS-CADD models of the surveyed transmission lines to assist owners to manage their assets. ALS surveys using LiDAR are seen as an engineering best practice for management of lines assets.

Transpower New Zealand 2019 Survey.

2000 km of transmission line survey was completed, along with a variety of small area topographical surveys. A combined GPS and GLONASS positioning approach was used to provide maximum positioning accuracy and availability. Along with the LiDAR and positioning systems, two photo systems were onboard to supply high quality imagery, and ground weather stations placed by New Zealand’s National Institute of Water and Atmospheric Research (NIWA) provided the weather data input for the metrological modelling used for conductor temperature calculations. GCH Aviation was used to supply helicopter and aviation engineering services for the project. Now that the survey is completed, models of the Transmission line are being developed using industry leading processing and modelling tools. Transpower will receive final PLS-CADD models for engineering assessment and analysis, along with some specialist reporting around vegetation clearances and other aspects.