An overview of Utility Arboriculture: A Study Guide for the ISA Utility Specialist Exam

By Randall H. Miller, Director of Research and Development

In 2007 Sharon Lilly, then with the International Society of Arboriculture (ISA), approached Asplundh Manager of Technical Services, Geoff Kempter and me to revise the utility specialist study guide, which was five years old at the time. Now, nearly a decade and six project managers later, the book has finally been published. While our intent has been to provide a study aid for the ISA Certified Arborist Utility Specialist™ exam, we worked independently of the ISA Certification Test Committee, who has sole authority over certification exam content. While it is likely that future exams assessments will include material from the new book, reading Utility Arboriculture alone will probably not sufficiently prepare a candidate to pass the test. One reason for the independence is the fundamental conflict of interest for an organization like the ISA to be the sole source of information for their own credential. Readers should understand that while the book provides the type of information that is covered in the credentialing assessment, other material and personal experience will also be necessary for proper preparation.

The new guide is not only intended to be a study aid, but also a comprehensive textbook for students or others interested in the field and a desktop reference for practicing utility arborists. It has been thoroughly vetted through peer review. Utility Arboriculture is close to 300 pages, with seven chapters, an introduction, glossary and reference section and is liberally illustrated. The seven chapters include safety, program management, utility pruning, integrated vegetation management, electrical knowledge, communication and storm response. The authors hope this guide will not only help utility arborists, but also raise our profession’s standing among utility departments outside of vegetation management, regulators, the general public and the wider arboricultural community.


The introduction provides a brief overview of the history of vegetation management dating back to the first telegraph lines. An important part of that history is the work of G.D. Blair, who wrote the first utility forestry text Tree Clearance for Overhead Lines: A Textbook of Public Utility Forestry (1940). Blair observed that the essential challenge of vegetation management is balancing the need for flawlessly reliable, safe electricity against the value trees provide to society. That essential challenge and responsibility of utility arboriculture remains today. The introduction establishes that the volume provides an overview of what is necessary to succeed in the complex field of modern utility arboriculture.


Chapter 1: Safety

The first chapter focuses on safety. Rightly so, as safety is of paramount importance in our profession. The objectives of the “Safety” chapter are to enable readers to clarify employer and worker safety responsibility, utilize behavior-based safety principles to decrease the likelihood of safety incidents, describe the potential injuries electricity can cause, practice electric safety precautions to prevent direct and indirect contact, and identify the elements of a safety culture. The chapter establishes that no business is worth asking people to sacrifice their health, physical ability or lives for work.

The chapter recognizes the term accident is in disfavor out of deference to the idea that it implies fate or bad luck. Injuries, however, are preventable and require a culture of safety to avoid. Safety professionals now use the term incident to refer to unplanned, undesirable events that could result in unintentional injuries or property damage. The chapter emphasizes the provisions of ANSI Z133 and outlines employee and employer responsibilities along with worker safety tools including a job briefing, training in active listening, use and adherence to procedures and self-checking.

The “Safety” chapter covers electrical safety concepts including the distinction between electric shock (the physiological reaction to the passage of electrical current through the human body) and electrocution (death from electrical shock), direct vs. indirect contact, touch and step potential, backfeed, and what to do when confronted by a tree on the line or downed power lines.

The chapter also provides detail about behavior-based safety. Behavior-based safety dates to the 1930s with research by Herbert Heinrich, who observed that incidents were caused by unsafe acts and unsafe conditions. He illustrated his theory with an accident pyramid where every fatality or serious injury was preceded by scores of minor injuries, hundreds of close calls and thousands of unsafe acts and conditions. Heinrich concluded that the best way to prevent serious incidents was to minimize unsafe acts and conditions. The text explains how Heinrich’s theory has been refined and improved through the years, how high reliability organizations operate and how to create a safety culture.

Chapter 2: Program and Personnel Management

The objectives of the “Program and Personnel Management” chapter are that readers will be able to develop a strategic plan for vegetation management programs, design work schedule plans, utilize project management techniques to execute project plans, prepare a UVM budget, characterize vegetation management service contracts and implement a personnel management strategy that encourages high performing staff.

The chapter emphasizes both strategic long-term planning and tactical short-term planning. It discusses the benefits of SWOT (strengths, weaknesses, opportunities and threats) analysis as a planning tool and describes specifications and work planning. It goes in depth on the advantages and disadvantages of different types of scheduling; results-based, just-in-time, crisis management and circuit or grid work.

There is a detailed section on program management concepts, which are used tactically. Triple constraint triangles, work breakdown structures (stratification of the scope of work needed to complete a project) and dependencies (relationships that dictate when tasks in a work breakdown structure begin and end) are highlighted. The program and personnel management section also touches on geographic information system-based work management software and how they are benefiting vegetation management.

Vegetation management is often a utility’s largest operations expense and utility arborists frequently lack training in the accounting needed to properly manage such large sums of money. The text delves into budgeting, reviewing cost types, budget preparation and the distinction between capital and operations maintenance. It reviews different types of budgeting; line-item, performance, program, zero-based and entrepreneurial. It also covers the advantages and disadvantages of time and material, unit price, firm fixed and performance contracts.

The chapter concludes with a leadership discussion, including the growth and fixed mindset concept of Carol Dweck. Dr. Dweck encourages a growth mindset characterized by mentoring and positive accountability. It is consistent with emotional intelligence, performance monitoring and evaluation, and resonant leadership.

Chapter 3: Pruning

The “Pruning” chapter is written on the premise that readers will be familiar with basic concepts of tree biology and natural target pruning. The chapter objectives are to enable readers to describe the purpose of utility pruning to both internal and external stakeholders, discuss how trees affect the intended use of rights-of-way and easements, describe how different pruning systems can be used to achieve pruning objectives, decide appropriate pruning cuts and styles to achieve different management objectives, identify the main objectives of utility pruning, explain the importance of determining appropriate pruning intervals and determine appropriate utility pruning methods for remote forested environments.

The chapter emphasizes that the purposes of pruning are safety, reliability, risk reduction and compliance. It covers pertinent standards and best practices, pruning systems, pruning cuts and tree response to utility pruning along with structural and directional pruning. It emphasizes that, in the 2017 version of ANSI A300 Part 1 Pruning, utility pruning is covered under pruning for clearance because the techniques used to clear power lines are the same as those that would be used to clear trees from buildings, billboards, street signs, blocking solar access or obstructing views. The point is, pruning for utility line clearance Is accomplished using mainstream pruning systems – usually natural, but occasionally with pollarding and topiary – to accomplish utility pruning objectives.

Pruning intervals should be determined by those who are qualified, and can depend on conditions, available resources and whether or not growth regulators (retardants) have been used. The chapter also reviews a discussion of when it is most appropriate to remove or prune a tree or palms and when to use mechanical tree cutters.

Chapter 4: Integrated Vegetation Management (IVM)

After completing the “IVM” chapter, the reader will be able to set site objectives based on the intended purpose of the site and available resources, evaluate the site to assess field conditions, compile and select from a broad array of treatment methods identify engineering alternatives in vegetation management, implement and monitor a vegetation management plan and efficacy of treatments, and describe key chemical properties of herbicides used in vegetation management.

The chapter reviews the various types of site evaluations using LiDAR, Level 1 and Level 2 tree risk evaluations, partial surveys using techniques from ecology and wildlife biology and complete inventories. It distinguishes between tolerance levels and action thresholds. Tolerance levels are the maximum incompatible plant pressures (species, density, height, location or condition) allowable before unacceptable consequences develop. Action thresholds are vegetation pressures where vegetation management treatments should occur to prevent conditions from reaching tolerance levels. Action thresholds need to be designed to trigger a response to prevent tolerance levels from ever being reached.

The chapter covers treatment methods including manual, mechanical, cultural, biological and chemical. It emphasizes the biological control of cover type conversion, removing plants that at any time in their lives will interfere with utility infrastructure (for example, power lines or pipelines) in favor of plants that will not do so. In many cases, meadow, prairie or other early successional plant communities can be established that provide habitat for pollinators and other environmentally sensitive species. The result has multiple benefits insofar as it protects the electrical grid and honors environmental stewardship in a cost-effective manner.

The “IVM” chapter goes into detail about chemicals and chemical treatment methods – not to emphasize chemical treatment methods above others, but because it is a critical step in cover type conversion. Chemicals need to be used appropriately and utility arborists must understand how to do so. The chapter also covers the wire-border zone concept, its developmental history with Bramble and Byrnes and how it is applied to pipelines.


Chapter 5: Electrical Knowledge

Electrical knowledge is perhaps the area that most separates utility arborists from our non-utility colleagues. The objectives of the “Electrical Knowledge” chapter are for readers to be able to communicate using appropriate electrical terminology, explain the electrical system from powerhouse to customer, describe basic functions of common electrical system hardware, identify vegetation conditions that could cause service interruptions and perform work around electrical hazards according to applicable standards.

The chapter describes how electricity is generated and contrasts fossil fuel and nuclear steam turbine generation with renewables including hydroelectric, wind, solar geothermal and ocean current. It goes in depth about various electrical facilities and hardware on both distribution and transmission systems including switches, protective devices, transformers, voltage regulators, capacitors and other equipment. There is also a discussion on how trees cause outages, which has applications to strategic planning for vegetation management programs.

Chapter 6: Storm Preparation and Response

The objectives of the “Storm Preparation and Response” chapter are to permit readers to assess the failure risk of vegetation given the type and intensity of typical storms in the region, develop an integrated, detailed storm response plan, mobilize a storm response appropriate for the extent of the storm damage, coordinate logistics so that crews can safely and efficiently respond to the storm, ensure that the needs of responding employees are met and recognize special safety concerns during a storm response.

The chapter investigates regional types of storms and their effects on trees. It goes in depth on pre-coordination and preparation for storms, including establishing a chain of command and the incident command system, emergency response centers, pre-storm communications check, practice drills, identifying suppliers, pre-negotiating terms and monitoring conditions, and pre-mobilizing. It covers the importance of storm tracking, staging crews and accommodations, what to bring to a storm and incorporating lessons learned and recognizing employees.

Chapter 7: Communications

“Communications” is the final chapter of Utility Arboriculture. Its objectives are that readers will be able to explain how vegetation management activities can influence customer perception of the utility brand, how to recognize different stakeholder interests in utility vegetation management, how to differentiate the roles of public relations, customer relations and customer service, how to describe various communication methods for interacting with the public and gives effective communication techniques when talking with customers to ease their concerns.

The text emphasizes the importance of customer communications in monitoring performance, influencing customer perception and addressing their potential dissatisfaction. It identifies various internal and external stakeholders from utility employees to federal, state or municipal employees, to individual landowners and others. It outlines various outreach methods including printed materials, emails, social media, press releases and community meetings.

Finally, the “Communications” chapter provides advice on how to speak to customers. It highlights how important first impressions are, the need for a positive attitude, operating with integrity, active listening, phone etiquette, dealing with angry customers and using customer-friendly language.


Utility Arboriculture will help prepare readers for the utility specialist certification exam, provide valuable information to work in the complex field of UVM, and inform non-utility arborists, regulators and the general public about what is involved in UVM and why it is necessary. The authors trust it will be a useful addition to any arborist’s library.