Why does ATC have the right to remove trees near transmission lines?

As the owner of the electric transmission lines, ATC is responsible for ensuring that the facilities operate safely and reliably. Transmission lines are typically located on an easement. This easement provides a corridor of safety for protecting people and structures from the high voltage current, and to allow access for periodic maintenance. Within the easement, ATC will carry out its responsibility to clear the right-of-way, which may include cutting down trees and overhanging branches.  In some instances (with the property owner’s permission), herbicide is used to reduce re-growth.

What is a power line easement?

When a power line is constructed, utilities typically acquire easements rather than purchase the property outright.  An easement is a permanent, legal land right acquired by a utility to use the land or property of another for a special purpose.  In this case, the easement grants ATC the right to build, operate and maintain a power line. Landowners retain ownership of their property, but its use is restricted. The right-of-way, or the land area described in the easement, must generally be clear of trees and structures that could interfere with the safe and reliable operation of the power line.

Why is it important to keep trees away from transmission lines?

Trees and transmission lines are not compatible. When tall or fast-growing trees are planted under or near power lines, they present a risk to public safety and reliable electric service. Trees that grow too close to electric transmission lines can conduct electricity and provide a path for the electricity to reach the ground. If electricity flows through a tree, anyone touching, or in the area of, an energized tree could sustain serious injury or even electrocution.

High winds can also blow a tree or its limbs into an energized power line, pulling the wires down from supporting towers or poles, which creates a public safety hazard.  Trees don’t have to physically touch an energized power line to be dangerous. Electricity which arcs or jumps from a power line to nearby trees can cause a fire or energize a tree under the right conditions, such as a voltage surge on the line from a nearby lightning strike. This electric current can kill anyone caught near the tree. Keeping trees away from power lines is vital in preventing and controlling wildfires.

Why not trim tall trees to a height below the wires rather than remove them?

Continually trimming trees that are close to a high-voltage transmission line is not as safe as removing them. Several factors must be taken into account when clearing a right-of-way:

• Safety Zone – Maintaining a maximum vertical clearance between the conductors (wires) and the height of nearby trees and other structures is necessary to achieve a safe zone. The voltage, structure design and other operational conditions are factors in creating a safe vertical clearance.
• Growth rate and trimming cycle – We want to ensure the safety zone is maintained not only at the moment we trim, but after we trim, too, until we return for the next trimming cycle. This is typically five years.
• Transmission line sag – As power lines carry more electric load during periods of high usage, they heat up which causes the wire to sag.
• Transmission line sway - Wind conditions can cause power lines to swing between spans or "gallop" vertically up and down.

The combination of growth, the trimming cycle, maximum sag and sway, means that removal, rather than trimming, of tall trees is the prudent action for maintaining the adequate safety zone.  

What about planting low-growing vegetation in the right-of-way?

Many property owners plant gardens, flowers, grasses and low-growing vegetation within the border zone area of the easement. Near lower voltage transmission lines in urban areas, this vegetation may not pose problems for the property owner or our facilities. Under the terms of the easement however, any and all vegetation (as well as structures, sheds, etc.) located within the right-of-way is at risk of removal should circumstances warrant it. Keep in mind when planting that small, immature trees planted today can grow into problem trees in the future. Keeping tree plantings away from power lines can eliminate potential safety hazards and improve the reliability of your electric service.

While still subject to removal under the terms of the easement, the following species of grasses and flowers are less likely to interfere with access for emergency or maintenance crews than shrubs or tall-growing vegetation:

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Perennial Flowers

Asters, Aster species

Blazingstar, Liatris species

Bergamont, Monarda fistulosa

Black Eyed Susan, Rubeckia subtomentosa

Cardinal Flower, Lobelia cardinalis

Columbine, Aquilegia canadensis

Common Milkweed, Asciepias syriaca

Compassplant, Silphium laciniatum

Coneflower, Narrow-leaf Purple, Encinacea angustifolia

Coneflower, Purple, Encinacea purpurea

Coneflower, Yellow, Ratibida pinnata

Coreopsis, Stiff, Coreopsis palmata

Coreopsis, Tall, Coreopsis tripteris

Cupplant, Silphium perfoilatum

Goldenrods, Solidago species

Great Solomon’s Seal, Polygonatum canaliculatum

Lavender Hyssop, Agastacha foeniculum

Lupine, Lupinus perennis

New Jersey Tea, Ceanothus americanus

Purple Prairie clover, Petalostemon purpureum

Prairie Dock, Silphium terebinthinaceum

Sunflowers, Helianthus species

Grasses

Big Bluestem, Andropagon gerardi

Indiangrass, Sarghastrum nutans

Little Bluestem, Schizachyrium scoparium

Prairie Dropseed, Sporobolus heterolepis

Sideoats Grama, Bouteloua curtipendula

Switchgrass, Panicum virgatum

Wild Rye, Canada, Elymus canadensis

Wild Rye Virginia, Elymus virginicus

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