There could soon be more people working in the "new" South End.
The Boston Redevelopment Authority on Thursday approved construction of an 11-story office building at 321 Harrison Ave. overlooking the Massachusetts Turnpike. Developers say they would like to start work in the spring and open it by 2018.
The $80 million project, to be built by Burlington-based Nordblom Development Co. and New York-based investment firm Rubenstein Partners, would be the first new office building in a section of the South End that has seen a flood of housing development in recent years — more than 1,000 apartments and condos within a few blocks.
The mid-rise, with 230,000 square feet of office space on eight floors above a three-story garage, would stand alongside and share a lobby with an existing office building next door at 1000 Washington St. that houses state agencies.
It is across the street from the Ink Block complex and next door to a 585-unit apartment project that launched construction earlier this year. The formerly industrial neighborhood has bloomed after the city rezoned the area a few years ago to allow for taller buildings and more housing.
"We see it as a gateway to the South End, a headquarters location overlooking the intersection of the Massachusetts Turnpike and Interstate 93," said Todd Fremont-Smith, a senior vice president at Nordblom who's overseeing the project. "It's a rapidly evolving neighborhood."
Still, drawing office tenants to the area has proven tricky. The Druker Co., a developer, has waited to start construction on an 11-story office building nearby on East Berkeley Street until it can sign major tenants. The area remains farther from the T than many employers find ideal, brokers say — one-third of a mile from the nearest station — and doesn't yet have a critical mass of white-collar jobs.
Still, projects in the neighborhood could land big tenants if they can offer big blocks of space that is cheaper than in the Back Bay, Financial District, or Seaport, said Cathy Thompson, cofounder of real estate advisory firm Thompson Hennessey & Partners.
"There are few options out there right now for 100,000 square feet and above," she said. "If it's priced below rents in other markets it could be a good option."
The BRA on Thursday also approved a 171-unit apartment complex in Charlestown. Berkeley Investments is planning the project near Sullivan Square to reuse some older buildings and build new ones alongside them.
The BRA also approved two apartment developments in Brighton, one a 114-unit complex that Hamilton Company is proposing in Packard's Corner, the other an affordable housing development for veterans that Brighton Marine Health Center and WinnCompanies are planning on Commonwealth Avenue. Also in Brighton, the BRA OK'd new baseball and softball fields on 14 acres at Boston College.