Room for All: Trees in the Utility Corridor

The area near a utility is usually an easement corridor that must be left free from conflicting uses. Must this area be stark? In spaces where humans live closely, we often have several desires competing to use a space. Research has shown that humans gain a psychological lift when able to enjoy green space in ways not causing troubles among competing uses. When used thoughtfully, we can bring green landscape beauty to a space, even the public space where several uses need an exclusive share.

Utilities that bring goods and services legitimately must claim a share of these spaces for their user safety as well as the safety of persons or activities or nature nearby. Some utilities like roadways have areas that can be beautified, while others must remain clear of obstacles. Remember your mother's advice? High voltage electric power lines are similar to roads in having zones that must be accessible, zones that must be clear of any objects, and other areas where we can add compatible landscape plantings.

Maintaining rights-of-way

Utilities like roadways and electric power companies have federal and state-mandated priorities to provide safe reliable service to many stakeholders, some nearby, others farther away and unseen. Interstate highways and electric transmission lines do not directly serve homes or residences, but rather connect to interchanges and substations to distribution networks. Streets and electric distribution rights-of-way give access to a strip of land, or corridor, so that the utility may build, operate, and maintain local networks that serve homes and residences within a small area. Distribution rights of way vary depending on the agreement; they may be 50 feet wide for streets, or 30 feet wide for other utilities.

Utility service mandates require providers to keep their rights-of-way corridors clear of obstructions, impediments, and structures. Some properties are owned outright by purchase, and some property use easements are implied by their location in a municipality. Human safety is their highest concern. Further, rights-of-way obligations include other owned or environmental assets, like water supplies, neighboring utilities, lawns alongside, and wildlife. Regardless of the extent of the ownership or privilege of the utility, the success of everyone's functioning in a particular space lies in cooperating as stewards.

This tree was pruned extensively to maintain the clearance necessary to provide safety around the electric lines. Although this tree is about 100 years old and may have preceded the line, there is not the recommended space available for both tree and line without periodic pruning. Photo credit: Scott Sjolander, Penn State Extension

How can conflicts between trees and utilities be resolved?

Trees that can grow or fall into electric utility wires require special pruning practices. Electric utility pruning is designed to prevent interruption of electric service, improve public safety, and protect utility workers. Only specially trained line clearance tree trimmers are permitted to prune trees close to electrified lines that carry more than 750 volts, according to regulations of the U.S. Department of Labor Occupational Safety and Health Administration and the American National Standards Institute.

If you plan to prune or remove a tree requiring a person, tool, equipment, or any part of the tree to reach within 10 feet of an electrified line exceeding 750 watts, the work must be performed by a qualified line clearance tree trimmer, or the utility company must be notified several days in advance so that proper safety precautions can be arranged.

A best long-term solution is to replace incompatible trees (those that interfere with wires or other utilities) with new trees that will not grow into the conflict zone. Trees can be replaced all at once, or one at a time as trees become over-mature and unhealthy. The choice between sudden or gradual replacement depends on various considerations, including the type of landscape desired in a neighborhood. A formal design with uniformly spaced trees of the same kind and size requires planting all trees at the same time. An informal planting design can be implemented over several years, with less disruption of the neighborhood appearance.

The design concept of trees that are compatible with utilities has been called "the right tree in the right place."  The diagram below, prepared by Duquesne Light, shows where trees should be planted when being installed near energized electrical distribution equipment. When planning to plant in or near electric transmission line corridors, the distance between your tree and overhead power lines should significantly increase.

Space guidelines for planting trees near utility lines. Source: Duquesne Light

Please do not plant tall-growing trees under or near power lines. Inappropriately planted trees that interfere with overhead power lines or electrical equipment may be removed by qualified line clearance professionals or, at a minimum, will require future pruning and have the potential for disfigurement. Consult your local electric utility, Penn State Extension office, or accredited nursery grower for compatible low-growing trees that can safely be planted in the "red zone" nearest the conductors or structures because their mature height is less than 25 feet. Your electric utility may have a program to discuss your work plan.

Medium-size trees, up to 45 feet at maturity, can be planted near utility lines if they are offset at least 15 feet from the nearest wire. Adequate space for root growth also is an important consideration when deciding tree size and placement. Low-growing trees are most appropriate if the space for roots between the curb and the sidewalk is less than 4 feet wide. If pedestrians and vehicles pass by the planting site, the variety selected should have ascending branches and a single trunk that can be pruned as the planting grows to provide the needed clearance. This may mean clearing the roadway by about 17 feet and sidewalks by about 8 feet, depending on pertinent laws and usage.

Landscape Tree Factsheets is a useful resource for selecting appropriate trees for planting under or near utility lines. Another resource is the TreeVitalize Guide for Tree Selection, Planting, and Care, which has a list of recommended small stature trees appropriate for planting under utility lines.

Your utility corridor may have the space and conditions that allow you to add landscape beauty to the zone. You will benefit from the added value and the way it gives you the "green" lift that well-designed and maintained landscapes have been proven to do. Your landscape may not need to be starkly utilitarian at all!

Sources

Duke Energy. Right Tree Right Place

Duke Energy. What can you do in a Right of Way: Distribution Lines

Duquesne Light. Planting Trees

Elmendorf, William F. Pruning Landscape Trees. Penn State Extension. Article Updated: October 26, 2007.