A well-attended public hearing Thursday night about the proposed expansion of the Vineyard Haven Stop & Shop supermarket focused on plans and concerns about how the expansion would impact already difficult Tisbury traffic.

Most of the three-hour public hearing was spent reviewing the expansion plans, which would consolidate three buildings — the existing store, the former Midnight Farm store and the building that once housed the Golden Dragon Chinese restaurant — into one 23,800 square-foot supermarket. There would be a 43-spot parking garage on the first floor, with the supermarket itself on the second floor. The existing proposal would reconfigure the town-owned parking lot next to the Stop & Shop market, eliminating one parking space as well as a town comfort station that provides public restrooms.

Stop & Shop purchased a house at 15 Cromwell Lane last year, with expansion plans hinging on tearing down the house to make way for the supermarket. But the Massachusetts Historical Commission determined that the circa 1850 Greek Revival house, built for mariner Caleb Prouty, is eligible for listing on the National Register of Historic Places. Stop & Shop has said they now plan to move the house.

The project was referred to the Martha’s Vineyard Commission as a development of regional impact.

“No doubt about it, it’s bigger than what’s there right now,” attorney Geoghan Coogan, who is representing Stop & Shop, told the commission. He noted that the Edgartown store is 30,000 square feet, 6,000 feet bigger than the proposed Vineyard Haven store. Mr. Coogan said the proposal meets the Island Plan’s criterion of having lively and accessible town centers, and would provide needed improvements to what is now an eyesore.

“We do understand it’s a big building, but we also think there are many positive impacts . . . this is a store that Tisbury needs,” he said. “We’re not looking to take this store and push it out of town, which we think is inappropriate.”

The parking lot reconfiguration would have traffic entering from Norton Lane and instead of going straight through to Water street, exit on the other side of the parking lot. Mr. Coogan said the traffic flow would be more pedestrian-friendly, and that 24 trees, twice the existing number, would be planted.

While the parking garage beneath the supermarket would be for Stop & Shop customers only, Mr. Coogan said an adjacent parking lot would not be monitored, and the only limitation would be no overnight parking. He said one proposal is to have two-hour parking spots, with Tisbury police officers monitoring and money from tickets going to the town.

The store’s location across the street from the Vineyard Haven Steamship Authority terminal and down the street from the notorious Five Corners intersection was a key part of the questions raised Thursday night.

“We look at a lot of gateways, but this is unquestionably the main gateway to the Island,” commission DRI coordinator Paul Foley said during his project overview.

A traffic study commissioned by Stop & Shop showed the new structure will likely result in traffic increases at Five Corners of less than five percent, and traffic increases at the Beach road/State road/Main street intersection of less than four percent. But a traffic consultant hired by the commission said she felt that more information was needed to get a full picture of the traffic impact.

The commissioners had several pointed questions about how the project would impact surrounding traffic and how delivery trucks would access a delivery bay.

The explanation of the plans, and some questions from commissioners, left about 20 minutes for public comment; the public hearing was continued to August 1.

Tony Peak, a member of the Tisbury planning board, said the board has a number of questions, as well as “reservations and concerns” that the plan was “developed without sufficient consideration for the context of the surrounding area.”

Several members of the Tisbury Historic Commission voiced concerns as well. “I do not believe the intent of the Island Plan was ever meant to embrace a project of this scope and this magnitude,” Harold Chapdelaine said, adding that the expansion of the store could hurt Main street businesses.

But others said they supported the project, which would improve the area aesthetically and provide better shopping options. ”The proposal will serve the community well and I urge you to give careful consideration for this project,” Martha’s Vineyard Museum director David Nathans said in a letter read to the commission that urged speedy approval. “It is needed in Vineyard Haven and will help revitalize the area.”

Catherine Scott, a Main street resident, said a two-story supermarket seems to be rare and that she was concerned that the new building would impact her view.

She also sought answers to a different question: “Why a pound of Stop & Shop butter costs $2.49 in Falmouth and it costs $3.99 in Vineyard Haven.”