A pair of office and hotel towers could break ground near the western end of Newbury Street early next year, flanking a new pedestrian plaza and terrace overlooking the Massachusetts Turnpike.

Approved Thursday by the Boston Planning and Development Agency, the Elkus Manfredi Architects designs call for a 16-story office tower and 13-story hotel-condo building near the entrance to the Prudential Tunnel.

For decades, the Massachusetts Department of Transportation has sought development proposals for air rights parcels above the Massachusetts Turnpike. Boston-based Samuels & Assoc., the designated developer for parcel 12 at Massachusetts Avenue and Newbury Street, hopes to break ground in early 2020 on the 657,000-square-foot mixed-use development, said Abe Menzin, executive vice president at Samuels & Assoc.

In March, Samuels scaled back the retail podium to create a larger public space on the west side of Massachusetts Avenue, and added an elevated park on the roof of the first-floor retail space overlooking the Mass Pike.

“That will be a gathering space for the whole city at this really important point along the Newbury and Boylston Street corridor,” Menzin said. “The community pointed out to us that the view corridor to the west is a really interesting one, and it became clear that it should remain.”

Both buildings will be partially located on terra firma, preserving some views from Newbury Street to the west while reducing the complexities of construction above active highway and rail lines.

And the turnpike on-ramp will be narrowed and relocated further north, which should improve pedestrian safety, Menzin said.

Final designs, which require coordination with the Massachusetts Department of Transportation, are two-thirds complete, Menzin said. Samuels hopes to break ground in the first quarter of 2020.

The last air rights project completed in Boston was Copley Place in the early 1980s, but developers have made recent progress on long-delayed sites.

Gerding Edlen and Meredith Management Co. broke ground in January 2018 on a 315-unit apartment tower including a 12,500-square-foot air rights segment above the MBTA’s Lansdowne station. The project is the first phase of the Fenway Center project, which would include more than 430,000 square feet of office and residential space above the Mass Pike.

Another developer, Boston-based Weiner Ventures, received approval last year for a 108-unit condo tower called 1000 Boylston St. on MassDOT air rights parcel 15. Menzin said the proximity of the two projects will require close coordination of construction schedules.