In 2009, Companhia Energética de Minas Gerais (Cemig), the largest distribution utility and the third-largest transmission utility in Brazil, created a special program for the integrated management of the impact of trees on existing low-voltage overhead line networks.

The main goal of the program — Programa Especial de Manejo Integrado de Árvores e Redes (PREMIAR), which means Special Program of Integrated Management of Trees and Networks — was to reduce the number of network faults directly attributable to trees. On occasion, trees have caused total shutdowns of Cemig's central distribution network, which covers 805 cities and the state capital of Minas Gerais, Belo Horizonte. Another goal of the program was to assist municipalities in managing trees in urban areas.

Cemig selected the county of Pampulha in Belo Horizonte for a pilot project of the PREMIAR program. It's a densely forested county with approximately 25,000 trees in direct contact with conductors on the utility's distribution network. In Belo Horizonte, there are approximately 180,000 trees with close proximity to conductors.

During storms, outages also can be caused by momentary contact with wind-borne material, but by the time field crews are dispatched to the reported location of the fault, the cause cannot be identified. In these situations, the fault cause is often recorded as an “emergency” or “other” cause, and is not attributed to trees.

Cultural Change

In Brazil, the management of trees in urban areas is the responsibility of municipalities, but the majority of municipalities lack the resources needed for planning and efficient management. Therefore, Cemig, in common with other distribution utilities in Brazil, has concentrated primarily on pruning or trimming those trees in direct contact with overhead line conductors to reduce power outages. This practice reveals the extensive problem of trees being planted that, after a short growing period, interfere with the utility's existing distribution network. This problem is particularly significant for Cemig because its overhead line network extends to some 19,598 km (12,178 miles).

Currently, PREMIAR recommends the planting of tree species in small and mid-size public roads that, when mature, do not exceed 10 m (33 ft) in height. This practice is intended to minimize the impact of falling trees on distribution networks and other urban facilities.


Within the PREMIAR program, Cemig included a project management component of the urban tree population whereby, in addition to pruning, the utility assists the municipality in removing or replacing trees at risk of falling. This is a major challenge for PREMIAR to demonstrate the efficiency of integrated management in relation to pruning. Moreover, when distribution utilities remove urban trees, they must be careful to limit work to only those trees in close proximity to the existing network and equipment.

It is noteworthy that Cemig management now considers all integrated management activities in Belo Horizonte. This includes support to municipalities through planning what to plant; the assessment, monitoring, pruning, removal and replacement of urban trees; and the replacement of distribution networks to allow coexistence with local forests.

To support this management strategy, Cemig, through PREMIAR, formed a team of arborists with experience in tree planting and electrical systems. The team's task was to assess the condition of those trees in contact with the overhead line distribution network and define the best procedure to improve network performance while minimizing the least impact on urban areas.

Cemig arborists have been in service since 2009 and, to date, have inspected 7,412 km (4,606 miles) of the distribution network, and identified and selected 159,375 trees for removal or replacement. The trees that have been replaced are in accordance with the technical standards established by Cemig and the city of Belo Horizonte.

To date, the cost of replacement on the distribution network and periodic maintenance is more than R$2 million (about US$3.5 million). To change the culture within Cemig, PREMIAR has adopted and sponsored initiatives to implement techniques and tools for improving processes and managing projects to highlight the results of the program and ensure the actions implemented are consistent.

Already, nearly 100 employees have been trained in the best practices adopted by this program. In addition, 25 Green Belts have been trained in the methodology of Six Sigma process improvement. An additional 19 employees were trained in a workshop on the PRINCE2 project management methodology, and this led to the formation of study groups on project management, programs and process improvement.

The PREMIAR team believes in the use of methodologies like PRINCE2, MSP, Six Sigma and management of trees for best performance. The program also has served as a partner in the development and training of professionals, both on the program team and the utility's internal stakeholders, to improve the knowledge of these procedures and facilitate the implementation of projects with the support of business areas.

PREMIAR also requires suppliers to use these techniques to increase efficiency in services provided to Cemig. The intent is to reduce the maintenance costs of urban trees and increase the efficiency of the distribution network with the support of all parties involved in the program.

To ensure adherence with the new techniques, Cemig hired a team of planners who specialize in project management to review the PREMIAR team's acquired knowledge, and exchange and develop best practices in managing projects, programs and process improvements. To achieve cultural change, communication processes and technical development are essential, as is the support of leadership. Importantly, the support of sponsors is extremely relevant to the consolidation of these actions by the implementation teams.

Technical Development

To focus on evaluation and monitoring studies for improving the management of urban trees, the PREMIAR team has trained and developed arborists to have expertise in distribution networks. These professionals, whose training includes agricultural engineering, the environment and forestry, have considerable knowledge on the physiology and behavior of trees. To receive this qualification, arborists must undergo specific training provided by the University's Corporate Cemig (Univer-Cemig) to understand the characteristics of the distribution network, management processes of urban forestry and safety standards. The utility has trained 32 professionals to manage urban trees near distribution networks, including 12 professionals who work in Belo Horizonte.

The arborists conduct the assessment of trees with support from the municipality's urban arborists to identify the positions for tree pruning, removal, replacement and planting. All services identified by Cemig arborists must be validated by the municipality before being executed. The use of these professionals is intended to reduce costs related to the management of trees and also improve reliability of the distribution network. The use of experts in the reconciliation of urban forestry with electrical networks should ensure that management services employ the best-available techniques.

Along with the team of arborists, PREMIAR invests in the training of planners who specialize in project management methodologies to ensure the dissemination of knowledge within Cemig and successful strategies. Records are kept of actions that were not successful to broaden the utility's knowledge regarding the management of projects and programs.

In its short duration, PREMIAR has helped to implement the use of project management professionals in other Cemig programs, as well, such as Light for All, Intelligent Energy and Program for Research & Development Distribution.

In partnership with the utility's office of information technology, PREMIAR is now developing a system with a geographic information system on urban forestry and electrical networks, with the aim of expanding the knowledge base. The investment in the first stage of this project, which includes modules for risk surveys of trees, pruning, planting, assessment of occurrences caused by trees and environmental suitability of distribution networks, is on the order of R$600,000 (about US$960,000).

The first stage of the project has been implemented with the assessment module of trees at risk and the adequacy of networks. The pruning module is under final review and should be implemented in Belo Horizonte in the second half of 2011. The pruning module aims to identify approximately 180,000 trees in contact with the network and evaluate the pruning types suited for each tree. This survey can be implemented with standard drivers for major pruning.

Corridor Winds

Another area of work that focuses on technical development is the Corridor Winds project. The objective of this project is to study the behavior and impact of wind in rainy periods in urban areas. Often causing trees and branches to fall, wind is a predominant factor in network outages. Preliminary analysis indicates that hilly towns favor the formation of wind corridors, increasing the speed of gusts.

Stakeholder Communication

Since its inception, the PREMIAR program has employed media specialists to ensure proper disclosure and monitor actions to keep stakeholder perceptions aligned with the goals. This stimulates discussion of new projects or those underway.

Through the program, six workshops and 11 meetings have been held with stakeholders involving about 500 people, including coaches, leaders, government agencies and organizations involved with the environment. This year, Cemig intends to conduct workshops for the academic communities of engineering, biology, communication and planning. The monitoring of community perceptions also is constant. So far, the population of Belo Horizonte has supported the actions of the program with an acceptance rate of 95%.

The monitoring of stakeholders is an action that must be put ahead of the program, as doing this ensures a balance among the three pillars of the program — Cemig, city hall and society sectors — that interact at all times and often with divergent interests. To align these interests with the goals of the program, the communications team constantly updates the various stakeholders to ensure the continuity of the program and its objectives. The PREMIAR program strives to build bridges and partnerships with a view toward identifying best practices and improving reliability and efficiency of the distribution network.

Carlos Alberto de Sousa ( is the PREMIAR program coordinator. He specializes in political marketing and has 10 years of experience in coordinating the utility's relationship with government agencies. Sousa has worked as a facilitator in the implementation of good project management on projects such as Reluz, Conviver and the adjustment of transmission lines, as well as programs like energy efficiency and Light for All. He is a member of the Utility Arborist Association, the Game Theory Society and the audit committee of the Project Management Institute - Chapter Minas Gerais.

Juliana de Oliveira Pena ( is an environmental engineer specializing in integrated quality management environment. She has been trained as a lead auditor based on ISO 14001:2004 and has done post-graduate work in the strategic management of projects. Pena is currently a planning engineer for Cemig's PREMIAR program and is responsible for managing projects. Previously, she worked on environment and business management at Cemig, facilitating the implementation of quality management systems.

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