BOLD Transmission Line Project, Indiana
Marion, Ind.
Best Project

Owner: American Electric Power
Lead Design Firm: American Electric Power
General Contractor: Cianbro
 

The 35-mile project marks the debut of BOLD (Breakthrough Overhead Line Design), an innovative low-profile double-circuit transmission line system designed to maximize power delivery capacity while also minimizing visual impacts. The project replaced a vintage 138-kV, double-circuit line with a double-circuit, 345-kV/138-kV hybrid line without the need for additional right-of-way.

As the BOLD structure design required a different approach from conventional tower construction processes, the project team collaborated with the owner and material manufacturers to review component specifications and develop work packages. To ensure adherence to the owner’s exacting installation standards, the team also spent many hours reviewing, developing and refining quality plans.

This extensive review turned challenges arising from the new tower structures’ curved arm design and compact conductor spacing into opportunities to complete the two-year project below budget and ahead of schedule.

Transporting BOLD tower components using a combination of 48-ft and 25-ft flat-deck trailers substantially reduced the number of staging trips to each location. Tapping expert rigging assistance, the team assembled the unique curved arms using custom-length slings and designated pick points. This process minimized the number of new crane setups, allowing new structures to be set concurrent with removal of existing lattice towers. Changing the sequence of assembling conductor hardware and insulators provided a safer environment for helicopter crews to assist with installing conductor pulling ropes.

Other costs- and labor-saving innovations further expedited the installation process, including establishing a new structure arm tie-down and a method that allowed two conductors to be pulled simultaneously.

Originally published in ENR Midwest, November 10, 2020

NOTE: DDIN Stringing Blocks were used for this project which is why we re-published this article.