American Transmission Co. projects

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News release: ATC’s year-long analysis near complete on undergrounding along Madison’s Beltline

ATC near completion of year-long analysis of underground construction alternatives
for proposed Rockdale – West Middleton power line
Overhead power lines remain the most affordable, practical industry standard

Madison, Wis. – The findings of American Transmission Company’s year-long analysis of burying portions of its proposed Rockdale – West Middleton transmission line will be made available to the Public Service Commission of Wisconsin. However, the company won’t be proposing underground lines or asking the PSC to approve them when its application is submitted for regulatory review next June. “Our analysis shows that overhead facilities are the better option,” said Mark Williamson, vice president of Major Projects.

Although ATC has not yet finalized its proposed route options for the proposed Rockdale – West Middleton line, there are concerns among local elected officials about placing overhead facilities along the Beltline. City of Madison officials have asked the PSC to give “serious consideration to undergrounding the line.”

“As a matter of practice, our project proposals for electric transmission lines always include an analysis of alternatives,” explains Williamson. “During the past year, we’ve been studying the costs and feasibility of placing portions of the Rockdale – West Middleton line underground. Our analysis overwhelmingly shows there’s no adequate justification for undergrounding the line within a mature commercial, controlled access highway corridor like the Beltline.”

Williamson acknowledged that advances are being made in the technology for burying transmission lines, but argued it’s still too costly and environmentally invasive. “The Beltline is not a justifiable candidate for undergrounding due to higher costs, increased environmental intrusion, and heightened electric system operational risks,” he said. “Underground construction adds between $9 million and $15 million per mile to the cost of these facilities compared to overhead lines. To bury the 15-mile portion between Stoughton Road and Middleton translates to between $135 million and $225 million in additional costs—more than doubling the total cost of the 35-mile project compared to building it entirely on overhead structures.”

Because the costs associated with major utility projects are spread among all electricity customers in ATC’s service area, Williamson said ATC is concerned about the precedent that would be created if lines were buried along the Beltline. “We have hundreds of communities throughout our service area that could make the same argument for burying lines,” he said. “Burying transmission lines in all the communities in which we are working would result in huge cost increases for industrial, commercial and residential customers.”

According to a 2006 report published by the Edison Electric Institute, studies of statewide undergrounding initiatives in Florida and North Carolina suggest undergrounding would require rate increases ranging from 80 percent to 125 percent from current rates. A Virginia study calculates the annual cost of a statewide undergrounding initiative at approximately $3,500 per customer.

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ATC is a Wisconsin-based company that moves energy along the regional electric grid in parts of Wisconsin, Michigan, Minnesota and Illinois, serving more than 5 million electric consumers. We are experts at what we do: planning, maintaining, operating and protecting the grid. As the electric industry moves toward renewable generation sources, we are transforming our system to continue delivering energy reliably and safely. We proudly support STEM education programs that empower youth with the skills needed to succeed in tomorrow’s energy workforce. For more information, visit and follow us on LinkedIn and X (Twitter).