Pilot Highlights LiDAR Effectiveness

June 1, 2012
BC Hydro uses a software application to capture accurate vegetation inventories, risk assessments and treatment plans.

BC Hydro manages more than 18,000 km (11,185 miles) of transmission lines, operating at voltages from 60 kV to 500 kV, across some of the most rugged and remote terrain in North America. This creates logistical difficulties in surveying, managing and treating rights-of-way (ROW) and assets. Crews inspect the lines using a combination of aerial and ground-based surveys, whereby they collect site-specific information for treatment areas, treatment methods and environmental considerations in the field.

Producing management plans from these surveys is a difficult process that occasionally results in areas being treated unnecessarily, and, much more rarely, missing areas that should have been treated. The cost of vegetation management on electric corridors is approximately US$2 billion annually; the cost of power outages due to mismanaged vegetation is many magnitudes higher, ranging from $104 billion to $164 billion annually in the United States.

In 2008, BC Hydro initiated a joint pilot project with Bluewater Business Solutions to develop a service and software application to inventory transmission corridors and generate vegetation management treatment units to aid in vegetation management and collect inventory data on a large area or ROW.

Single-Tree vs. Area-Based Work

The software application used in the pilot project was Bluewater, developed by Bluewater Business Solutions, and was originally developed for logging operations. It was customized and adapted for vegetation management, in part for this pilot project.

There were three major objectives of the project:

  • To develop an inventory-generating system through light detection and ranging (LiDAR)-based surveys

  • To automatically analyze the inventory to generate vegetation management activities based on management guidelines and objectives

  • To develop a field-based management application to support field crews in treatment planning.

BC Hydro wanted a LiDAR-based inventory system that could accurately measure terrain and vegetation characteristics, and summarize the data into meaningful management units using as-flown conductor positions and modeled sag and swing positions where available. The developed inventory system describes areas as well as single-tree locations for the entire project area.

The Bluewater software application defines two types of work: single-tree-based work and area-based work.

Single-tree-based work is identified by a tree's proximity to transmission lines (as-flown or sag and swing condition). This type of work is classified as critical (exists within the circuit clearance zone [CCZ] of a transmission line), a hazard (can fall and pass through the CCZ) or a problem (can fall and almost pass through the CCZ).

Area-based work also is identified for areas with vegetation within or in proximity to the CCZ. Specific management rules can be customized to define what tolerances to the CCZs are allowed as well as what type of work should be performed based on that area's inventory.

For example, if an area is identified as requiring treatment, the management rules determine what type of activity the system will prescribe. The entire LiDAR-based inventory is automatically analyzed and a management plan is developed according to the specific treatment parameters to meet the identified vegetation tolerances.

Multi-Year Planning

The inventory system also was configured to permit examination of vegetation growth based on the individual trees. The LiDAR survey was able to classify deciduous versus coniferous trees (with 85% accuracy). The Bluewater software system allows users to input growth rates for deciduous and coniferous trees (as well as species-specific growth rates) for modeling purposes.

For this project, growth rates were selected for the fastest growing tree species in the region (lodgepole pine growth rates were used for coniferous vegetation and trembling aspen growth rates were used for deciduous vegetation [“Site Index Curves and Tables for British Columbia — Interior Species,” by J.S. Thrower, A.F.Nussbaum and C.M. Di Lucca]). The growth rate data allows the software system to project future vegetative growth and model potential vegetative encroachment for any given year, permitting multi-year planning.

Multi-Capability GIS

The inventory and software system creates a base plan of required treatment units and single-tree removals. However, the base plan requires in-field verification, editing of treatment units and single-tree selection, so a field module was developed that could simultaneously process the inventoried LiDAR data and permit in-field editing.

The resulting system was designed to perform as a multi-capability geographic information system (GIS) designed for field staff with little or no training on GIS-based systems. The field module was installed on a Trimble Yuma and can operate on most current laptops or rugged handheld tablets. The field module allows for the following functions:

  • Adding features (treatment units, single trees, access roads, wetlands, streams, etc.)

  • Hiding or displaying various features of interest including a canopy view, a terrain view, an aerial imagery view and a slope view.

  • Removing features

  • Changing the shape, location and attributes of existing features, for example

  • Changing a treatment unit from Mow: Level 1 to Mow: Level 3 when drainage problems have been observed, for example

  • Changing a treatment unit's size to add adjacent vegetation

  • Examining an area's inventory and adjusting it if desired

  • Integrating GPS (on-screen display, following mode)

  • Providing a descriptive help system.

The software system also includes an estimation module to examine the cost of the current or alternative project plans. To support estimation, default equipment and employees to perform the work are set in the system. Results for estimations can be viewed in a variety of reports, including summary reports and schedule reports.

Strong Potential

The BC Hydro pilot project demonstrated a system that has the potential to improve the reliability of vegetation management activities for utilities. Field crews can more easily identify problem areas, focusing attention and resources both internally and externally on effectively and efficiently dealing with management.

Overall, this project has shown the potential for developing quality vegetation inventories, and systematic and long-term lineal management plans, thereby streamlining and forecasting planned vegetation management activities while reducing the risk of electrical disruptions because of vegetative encroachment.

Geoff Helfrich is the northern interior operations manager for BC Hydro.

Darren Janzen is a project manager for Bluewater Business Solutions. He has a master's degree in natural resources and environmental sciences. He specializes in LiDAR, spatial modeling and computer programming.

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