Duxbury may become a two-traffic signal town as part of a proposed expansion of the development at Island Creek. But will the signals be built in time to satisfy the traffic concerns of the Zoning Board of Appeals?

After months of public hearings between the board and the developers, a decision is looming over the proposed 238-unit expansion of an existing 40B project off Tremont Street. A 180-day deadline expires on June 11, however, at the most recent ZBA meeting Thursday the developer agreed to an extension until July 9.

The developer agreed to many of the changes suggested by the town’s review engineer, Robert Houston.

“We’ve been aggressively working on the site plan,” said the developer’s engineer Paul Brogna. “We’ve gone back to the drawing board.

Among the major changes to the Island Creek plan include the elimination of one of the three buildings planned for retail/commercial space, effectively cutting the original planned square footage in half, from 28,000 to 14,000.

The main street of the development that runs from the street to a proposed assisted living facility in the rear of the property will be widened, Brogna said. A “tot lot” playground was also created in a central location, and a second emergency entrance to the assisted living facility was added at the suggestion of the fire department.

Brogna also said the developer was willing to add up to 150 additional parking spaces, mostly on the west side of the property, that could be shared by the adjacent First Baptist Church.

Houston said that “many of the changes are positive” and commended the Island Creek team for their willingness to alter plans. He said there are a few sticking points, such as what material to use for the sidewalks along the main boulevard.

Jeffrey Dirk of Vanasse & Associates, Inc., traffic engineer for Island Creek, presented an updated traffic study to the Zoning Board of Appeals on Thursday. He said that new numbers from MassHighway and local police show that crash rates at the Route 53 intersection have gone down, although the developer is still willing to make improvements there. However, the ramps to Route 3, both north and south, are still traffic nightmares.

“The interchange area, in terms of safety, remains a focus,” said Dirk.

He presented several options for placing traffic signals, including a signal at the current entrance, a light directly across from the highway ramp in front of the First Baptist Church, and an “offset” intersection. However, a representative from the church present at Thursday’s meeting said they weren’t interested in selling a parcel of land that would be necessary for the second option.

Ed Marchant, a 40B consultant working with Island Creek, said the developer would like to proceed with the project as is.

“The traffic signals are warranted, but I’m not sure it’s absolutely necessary for those to be in place for this project to proceed,” he said.

When pressed by ZBA members, Dirk said that the intersection was a problem but met the engineering criteria for an efficient intersection. Houston was reluctant to call the interchange unsafe, but did say “it’s not optimal.”

Dirk also said that the project would help push Duxbury up the state’s list new traffic signals. He said the developer has already helped the town file some paperwork. Island Creek will be providing some financial assistance as well, said Marchant.

Marchant also asked if his team could meet with a non-quorum of the Zoning Board before the July public hearing to iron out some of the details on the site plan drawings.