PROJECT

Subtransmission Reconductoring

Our team provided design, permitting, construction and project management for the reconductoring and relocation of nearly 7 miles of 40-kV subtransmission lines with distribution underbuild.

The existing 40-kV subtransmission and 4.8/13.2-kV distribution underbuild infrastructure was degraded and had accessibility issues for maintenance. To increase reliability and support future maintenance, the line was reconductored on light-duty steel poles, and the alignment was moved out of a deep right-of-way position and into the road right-of-way. This strategic shift reduces long-term maintenance difficulties while enhancing service continuity for the local community. Additionally, the newly built subtransmission line is designed for uprating to a voltage of 69 kV to support future load growth in the region.

By dividing the project into multiple design releases, construction was able to proceed while portions of the project were still undergoing the resolution of vegetation agreements and private property easements. This proactive approach allowed for steady progress and reduced potential delays.

A portion of the work was performed while the circuit was shut down, requiring significant planning and coordination to minimize disruption. Our team implemented contingency and shutdown planning measures to enhance efficiency and ensure a safe working environment. The strategic engineering of the shutdown plan also reduced overall project cost by minimizing or eliminating the need for distributed generation resources or portable substations.

Client

DTE Energy

Location

Midwest

Region

Midwest

Services

Electrical Transmission & Distribution

Substations

Industry

Power

The infrastructure upgrade enhances grid reliability, improves accessibility for future maintenance, provides additional electric capacity for regional growth and extends the system’s service life. By leveraging progressive design methodologies and proactive construction strategies, the project successfully modernized a critical component of the electrical grid. The transition from wooden poles to steel structures further ensures long-term stability, reducing the quantity and duration of outages in the future.

The project included relocating and reconductoring 7 miles of subtransmission on 168 new steel poles with 636 AAC conductor. DTE 4.8/13.2-kV distribution was also rebuilt on the new steel poles with 636 AA conductor and two other local distribution providers were also rebuilt and co-located on the new steel poles which increased their reliability as well. Remoted operation and monitoring of the substations was enabled by installing single-mode fiber for improved communication. Additionally, 30 pole-mounted 4.8/13.2-kV transformers were installed to enhance distribution reliability.

This project demonstrates a commitment to providing sustainable, reliable, and efficient power delivery while prioritizing safety and operational efficiency for utility workers and the community.

Scope of Work

Install of 7 miles of new 40kV conductor and equipment

Install of 7 miles of new 4.8/13.2-kV conductor and equipment

Install 168 direct embed steel poles

Install of 7 miles of new single-mode fiber

30 pole-mounted 4.8/13.2-kV transformers

Removal of 7 miles of aged wood poles and wire