As new developments and infrastructure improvements continue in Starkville and Columbus, residents are seeing more utility lines moved underground – a change that can offer several practical advantages. But how do they compare to traditional overhead systems, and what factors determine which option is used?
Underground versus overhead: what’s the difference?
The most obvious difference between underground and overhead utilities is where the infrastructure is located. Overhead lines are carried on poles above ground, while underground systems are buried in trenches beneath the surface.
Each approach comes with its own advantages and drawbacks, according to Jeff Atwell, co-owner of Starkville-based engineering consultant firm Atwell and Gent.
One of the biggest advantages of underground utilities is their resilience to storm-related damage, which is among the leading causes for outages for overhead systems, Atwell said. Because underground lines are shielded from those hazards, they experience fewer outages and generally require less maintenance over time.
However, that reliability comes at a cost. Underground utilities can cost six to seven times more than comparable overhead circuits, and when outages do occur, repairs are often more time consuming.
Overhead systems, meanwhile, are significantly less expensive to install and generally easier to repair.
“On overhead, the cause of the problem is usually obvious – a tree limb (or) a broken pole – something you can just drive up on,” Atwell said. “With underground, if a cable falls below-grade, you can’t see it. We have a number of ways of narrowing it down, but it just takes longer to find a below-grade failure because … you can’t visually see it.”
What determines whether utilities are installed above or below ground?
In most cases, cost is the primary factor, Atwell said.
Installing overhead utilities for main feeder circuits, which carry electricity throughout larger parts of town, typically cost about $350,000 per mile. Installing underground utilities for the same purpose can cost $1.75 million per mile or more.
Those estimates apply to new developments. Converting overhead systems to underground is often far more expensive because crews must work around existing roads, sidewalks and buildings.
“The takeaway is, it’s much easier to do it on the front end initially than to come back after the fact and try to convert it from overhead to underground,” Atwell said.
For smaller residential subdivisions, the cost gap is narrower, with underground utilities coming in at about three times the cost of overhead installations, he said.
Available space is another key consideration, according to Starkville Utilities General Manager Edward Kemp.
“You still have to have area on the ground for equipment,” Kemp said. “That’s transformers, switches (and) other telecommunication equipment that has to go underground as well. So if you’re in areas with very limited right of way or … very limited green space area to put equipment, it makes it very very difficult, if not impossible to go underground.”
Atwell, whose company is converting an overhead circuit to an underground system along Highway 182 in Starkville as part of the city’s revitalization project, said right-of-way limitations are especially challenging in Starkville, where many developments sit close to the street.
Are new developments choosing underground systems?
Many newer developments are moving in that direction.
Saunders Ramsey, of Live Adelaide LLC and Friendly City Development leader, is incorporating underground utilities into the new Parkview development in Columbus, where more than 70 lots between Third and Fourth Street and Second and Seventh Avenue North are being developed into a mixed-use area.
Ramsey said underground utilities align with modern development trends that emphasize walkability, shared green spaces and houses built closer together.
“You really have a hard time providing that product when you’ve got an overhead power line, either in the alleyway or along the street,” Ramsey told The Dispatch on Sunday. “… Your rural areas … maybe it makes more sense to be overhead, … but when you get into these more urban environments where beautification and access and shade canopy trees are of value, then you start to lean into the underground option.
“… It really just depends,” he added. “I do think (underground utilities) will be a continued trend for new developments. … I think it’s just a cost benefit of … aesthetics and reliability.”
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