A new 2.1-mile transmission line would bring more reliable power to a stretch of Dorchester and South Boston poised for a development surge in the coming years, Eversource officials said last week.

The company is planning to run a line between substations in Andrew Square and Dewar Street in Savin Hill that would support the increased load and act as a backup if either station were overwhelmed.

Project managers walked the few attendees at an open house in the Boston Teachers’ Union through the proposal. A 115-kilovolt line would wind its way out of Andrew Square, run down Old Colony Avenue to Morrissey Boulevard, continue past Patten’s Cove, turn into Savin Hill by way of Grampian Way, and scoot across Interstate 93 to the Dewar Street substation.

At this stage, there is a time line, but no definitive cost estimate, consultant and project manager Nathan Dennis said. The project would require a series of permits from state and city authorities, with construction expected to start in late spring 2020 and the new line operational in 2021.

Richard Zbikowski, a senior system planning engineer, said it’s a “very simple approach; it’s a very effective approach” to the expected surge of new electricity needs without installing a handful of new lines.

The substations already reach a decent distance and around 80,000 people are served by the infrastructure in place, Zbikowski said, with the Andrew Square station connecting to Northeastern University.

“We have two issues there, one of which is growth,” Zbikowski said. “Anyone can tell you Boston’s growing and if you don’t have growth, something must be wrong. So we have some major projects coming online.”

He noted the Bayside redevelopment at the top of Columbia Point, the mixed-use proposals planned between Broadway and Andrew stations, the Mary Ellen McCormack housing project near the base of Moakley Park, and the strip of new development that will slide along Morrissey Boulevard between the JFK/UMass station and Patten’s Cove. That row of projects includes the former Boston Globe site and possible 22- and 25-story towers next door.

“We’re looking at this development over the next five years, ten years or so, and saying, you know, we’ve got to really provide the capacity,” Zbikowski said.

The state Department of Public Utilities will host a public meeting, likely in spring 2019, after Eversource submits its siting petition.

Construction would take place in phases so the entirety of the route would not be impassable or reduced in lane size all at once. Workers would put in pipes, insert manholes, and repave the roadways so the lines could then be threaded through the connected route.

Dennis said there should be no interruption in existing service. Residents would get a two-week heads up before any work came into their vicinity.

When deciding on their preferred route, Eversource officials cited several possible ways to run the line between South Boston and Dorchester, including the type of buildings surrounding it, roadway widths, and environmental impacts. Two open houses and a project page on their website will collect neighborhood feedback before the firm submits its their petition to the state.

For those worried that Dorchester Avenue would become a possible alternative — a point of discussion at a Columbia-Savin Hill Civic meeting earlier in the week — the planners got the message.

“That was the first one, can we put it down Dot Ave,” Dennis said, “and people that know the area said, “You can‘t do that. We don’t even need to think about that.’”

Paul Nutting, a Savin Hill resident, reviewed the plan. To him, it looks as efficient as it can within reason.

“It seems they’ve done their due diligence and homework on the route that doesn’t involve easements across private property,” he told the Reporter this week. “There are more direct routes that would involve easements, but I understand why that isn’t something they want to do. Hopefully the people that live on Savin Hill Ave and and Grampian [Way] aren’t adversely affected.”

Nutting was also pleased by the paving plans after the pipes are installed. Workers will initially just pave the trenches and allow the asphalt to settle before coming back and paving curb-to curb.