New study suggests that simultaneously burying broadband and electricity could be worth millions to people in MA towns
Modeling data shows that upfront investments in co-undergrounding wires, particularly in outage-prone areas, can pay off
April 8, 2025
AMHERST, Mass. — When it comes to upgrading electrical and broadband infrastructure, new research from the University of Massachusetts Amherst shows that a “dig once” approach is nearly 40% more cost effective than replacing them separately. The study also found that the greatest benefit comes from proactively undergrounding lines that are currently above ground, even if lines haven’t reached the end of their usefulness.
Co-undergrounding is the practice of burying both electric and broadband internet lines together. “One main benefit from undergrounding both electric and broadband together for us was cost saving that we can have from co-deployment of those utility lines,” says Mahsa Arabi, lead study author and an ELEVATE research fellow in the UMass Amherst Energy Transition Institute (ETI). This cost savings makes it feasible for even smaller towns in Massachusetts to make undergrounding upgrades. Using computational modeling across a variety of infrastructure upgrade scenarios, the researchers found that co-undergrounding is 39% more cost-effective than separately burying electrical and broadband wires.
One of the study authors, Erin Baker, faculty director of ETI and distinguished professor in the College of Engineering at UMass Amherst, explains that co-undergrounding wires is becoming more salient to decision makers who are focusing on the efficiency of infrastructure. “Instead of tearing up the road to do this and then a year later tear it up to do that, let’s think about doing it together,” she says.
The researchers also asked: how aggressively should towns pivot to putting lines underground? Should they wait until lines have reached the end of their lifespan and then replace as needed, or proactively move forward?
To answer this, the researchers defined three overarching considerations: the cost of converting lines from above ground to underground, the cost of outages and the hours of outages that can be avoided if lines are underground.
To quantify these factors, the researchers created a nuanced computational model. “A big driver of this whole thing is the cost,” adds Jimi Oke, director of NARS Lab, assistant professor of civil and environmental engineering and principal investigator of the study. “In previous studies, people just used estimates based on average values, but we essentially try to model the dependency of the cost on things like the soil composition, the network type or the other land use variables,” he says.
Using the town of Shrewsbury, Massachusetts as a case study, the team found that the most cost-effective solution is to be aggressively proactive in co-undergrounding and replacing existing infrastructure, as long as it can be confirmed that undergrounding wires reduces outages by at least 50%.
Over 40 years, the cost of an aggressive co-undergrounding strategy in Shrewsbury would be $45.4 million, but the benefit from avoiding outages is $55.1 million. This considers factors like spoiled food, damaged home appliances, missed remote work hours and increased use of backup power sources. For a power outage, the costs are estimated to be $10 per person per hour, $205 per business per hour and $15,000 per industrial customer per hour. In Massachusetts, the average outage duration per customer per year, for both broadband and electricity, is estimated to be 1.38 hours. The researchers also took into consideration an additional benefit of $1.5 million in increased property values from the aesthetic improvement of eliminating overhead lines.
Altogether, this created a net benefit of $11.3 million.
The strategy with the second-highest net benefit was to aggressively convert just the electrical wires from above ground to underground. While this is a less expensive strategy, the savings were notably diminished, for a net benefit that was five times lower than the co-undergrounding strategy. All other strategies, including moderately paced conversions, had a negative net benefit.
One of the biggest remaining question marks is determining exactly how many outages will be prevented by undergrounding. “There’s kind of an intuitive thing [that undergrounding will reduce outages], but there is kind of mixed information about exactly how much because there are outages for a lot of different reasons,” explains Baker. “It means for [undergrounding to be worthwhile] half the outages have to be caused by basically something weather induced. If more than half of your outages are caused by the plant breaking down, then you shouldn’t underground anything. But the moment it flips over and it becomes good enough to do something, it means you want to be fully aggressive.”
Storms aren’t the only causes of outages, says Oke, pointing to California wildfires. California utilities will institute planned outages in order to prevent additional fires, but putting wires underground could prevent the initial fire (and therefore the outage). Consider the 2018 Camp Fire in Northern California—the most destructive wildfire in the state's history. This fire was caused when a worn-out metal hook on a transmission tower failed, allowing a live line to fall and hit a transmission tower.
“We need to have a framework and a set of regulations that encourages utilities and towns to think strategically,” says Baker. She hopes that their findings can help decision makers do just this.
The team hopes that future research will quantify the impacts of co-undergrounding across a variety of geographic locations and scenarios. Other relevant future directions include investigating alternative underground routing options, and other potential outage mitigation strategies.
Journal
Cell Reports Sustainability
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Benefits of aggressively co-undergrounding electric and broadband lines outweigh costs
