Lidar, drones and remote sensing in vegetation management: what the sources report

This page describes what the named sources report. It does not teach survey or flying methods. The rules for clearing trees from lines are on utility line clearance and utility vegetation management rules.

What lidar is, in a utility's words

Seattle City Light's vegetation management manager wrote a post on August 8, 2025 describing the tool. She calls lidar, short for light detection and ranging, a remote sensing technology that uses laser pulses to build a 3D model of the landscape. The utility says it flies airborne surveys, typically by helicopter or drone, over its whole transmission system. The laser bounces off trees, towers, lines and the ground, and the result is a 3D map called a point cloud. The post says that map shows where vegetation is growing too close to lines, to a precision the utility describes as down to the inch.

The same post says the utility has 600 miles of transmission lines and lists four uses: building digital twins of corridors to assess system-wide risk, finding clearance issues before they become hazards, prioritizing work by actual proximity and risk instead of by location or calendar, and documenting compliance with NERC. It says lidar is combined with on-the-ground inspection in remote terrain, and names satellite imagery, artificial intelligence analytics and environmental data as tools it plans to add.

Why transmission owners survey at all

The NERC reliability standard FAC-003-5, Transmission Vegetation Management, states its purpose as maintaining a reliable transmission system with a defense-in-depth strategy for vegetation on transmission rights of way and vegetation next to them, to prevent vegetation-related outages that could lead to cascading. Its applicability section covers overhead transmission lines operated at 200 kV or higher, and some lower-voltage lines, including ones a planning coordinator or transmission planner identifies as important to reliability. Seattle City Light's post cites NERC clearance rules as the reason it documents corridors. The purpose and applicability sections of the standard do not mention lidar.

Public lidar data

The U.S. Geological Survey runs the 3D Elevation Program, whose stated mission is to respond to needs for high-quality topographic data and 3D representations of the nation's natural and constructed features. The program page says all 3DEP products are available free of charge and without use restrictions. It links to pages on lidar quality levels and to a spatial metadata layer, which it calls a good source of information on lidar data availability and basic information about lidar projects. It also describes a data collaboration announcement through which partners can work with the USGS to acquire elevation data.

What the research papers report

Paper	What it reports	Limits the authors name
Walker and Dahle, Arboriculture and Urban Forestry, May 2023, review of drones and lidar for distribution utility vegetation management	Reviews studies on collecting and processing drone-mounted lidar data. The authors conclude it may offer a faster, more accurate and more cost-effective inspection method than foot patrol, and may help utility foresters manage trees off the right of way.	They say more research is needed on detecting and managing fall-in risk along distribution lines. They describe early forestry lidar work with poor detection rates, for example 72 percent of dominant trees detected. They note NERC FAC-003 does not apply at the distribution level.
Wedegedara and colleagues, ISPRS Archives, July 2022, roadside vegetation risk on Connecticut distribution lines	Combines lidar-derived tree height, proximity and canopy cover, terrain, soil, trimming method, wire type and outage records from 2005 to 2017 in a machine-learning risk model. The abstract says roadside trees cause almost 90 percent of outages in the forested Northeastern US.	The abstract describes the goal and inputs. It reports no model accuracy figure.

Reading these together

The utility post is a first-party account by the utility and carries no independent evaluation. The two papers are research, one a literature review and one a modeling study, and neither tests a specific vendor. This page names no vendors. The USGS page establishes only that public lidar exists and how it is catalogued, not that it is detailed enough for any one corridor.