Operating a safe and reliable electric transmission system requires continuous monioring of transmission facilities and equipment.
This means that LCRA personnel are on the ground and in the right of way assessing portions of the transmission system owned by LCRA Transmission Service Corporation (LCRA TSC), investigating reported issues, completing detailed inspections and making spot repairs on an ongoing basis.
In addition, LCRA crews work at locations throughout the system every day to complete regularly scheduled maintenance such as replacing poles and insulators and clearing from the right of way vegetation that could interfere with the safe and reliable operation of the system.
Long-term vegetation control helps maintain safety and reliability. It also helps avoid increased transmission costs that result from frequent vegetation management activities. By managing transmission costs, LCRA TSC helps control the cost of electricity.
How does vegetation interfere with the safe operation of transmission lines?
Power lines can sag several feet during hot weather or when carrying heavy electric loads. Even before actual contact is made, electricity can arc or “flashover” from wires to nearby trees, causing electric current to flow through the tree to the ground.
If this happens, it could endanger the public’s safety, possibly causing injury or death to people near the affected trees. Flashover also can start fires, which can cause property damage.
Trees and branches near or touching power lines also can cause electric service interruptions. In fact, trees are a key contributor to major power outages in the United States. They not only disrupt service to homes and businesses, they also could disrupt power to hospitals, emergency response centers and life-support patients.
Additionally, LCRA must keep rights of way clear of vegetation that impedes access to its transmission facilities or interferes with the ability to set up equipment for line maintenance or emergency repairs.
Weather events such as ice storms or high winds can damage transmission structures and conductors and cause electrical outages. Without clear access up and down the right of way, it is difficult for work crews to identify problems. Furthermore, if large, woody vegetation is allowed to grow next to transmission structures, work crews cannot set up bucket trucks and other equipment necessary to complete repairs.
How much right of way will be cleared?
Like many utilities, LCRA TSC adopted the American National Standards Institute ANSI Z133.1-2001 that establishes minimum clearances to maintain between power lines and vegetation to ensure the line can be operated safely.
In addition to the institute’s standards, LCRA considers other factors when determining how much of the easement will be cleared. These factors include the line voltage and the type of transmission structures used, maximum wire sag and swing, physical attributes of the right of way, types of tree species growing in the right of way, the growing conditions, and distances between vegetation and the conductors and structures.
Based on those factors, most trees growing in the easement could interfere with the safe operation of the line over time and generally are removed. Under some circumstances, where line-to-ground clearances exceed 50 feet, trees might not be removed. Instead, they are trimmed sufficiently to remain a safe distance from LCRA TSC’s transmission lines for at least five years.
How does LCRA clear the rights of way?
LCRA typically uses large equipment like flail mowers to clear right of way. In some instances, clearing is done by hand.
Additionally, herbicides that have been approved by the U.S. Environmental Protection Agency are applied on tree stumps and around gates and transmission structures to help prevent regrowth.
In most cases, LCRA TSC’s easement agreements include the right to remove trees and other obstructions from the easement area, as well as the rights to access, inspect, repair and maintain its transmission lines.
How you can help ensure safety
Although LCRA inspects the right of way regularly, you can help avoid electrical accidents and outages while protecting yourself and your property by following these guidelines:
- Contact LCRA if you notice trees, limbs or tall, heavy brush growing in the rights of way.
- As a general rule, do not plant trees or shrubs in the rights of way.
- Talk with your local utility if you are considering planting near a transmission line right of way. Your utility can help you select plants that will not conflict with power lines.
- When thinking about what to plant, it is important to know how tall and wide the full-grown plant will be. Generally, trees and shrubs with a mature height of 10 feet or less will not cause problems within the utility rights of way unless they prevent access to lines, towers or poles.
- Select trees and shrubs that are adapted to the local climate and can withstand local storm conditions.
- Never place or construct any habitable structures in the easement area.
- Before you work in an easement area, contact LCRA to ensure your activities can be completed safely without interfering with the line.
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