By a single vote, a sharply divided Martha’s Vineyard Commission voted on Thursday night to approve the long-planned roundabout for the blinker intersection in Oak Bluffs.

After a three-hour discussion that was often contentious, the vote was 7-6 in favor of the traffic improvement project.

The roundabout has been on the drawing board in Oak Bluffs for 10 years and has the backing of the town selectmen and police chief.

Commissioner Chris Murphy, who chaired the meeting, cast the deciding vote.

Opinions on both sides were passionate.

Commissioner Leonard Jason Jr. led the charge against the roundabout, calling it a travesty and noting that it contravenes the Island’s regional transportation plan.

“This thing is an abortion . . . we’re going to end up killing some bicylists, I think we should just kill it,” he said.

“It is not in character with the rest of the Island . . . I’m not the least bit convinced this is going to be safe regardless of what experts have said,” said Camille Rose.

Others took a different view.

“The reports that the state gave us have shown that a roundabout is safer than the four-way stop,” said Holly Stephenson.

“If we can minimize amount of hardscape while still maximizing the functionality with flow and safety of pedestrians, I think we can say we’ve achieved something by improving an intersection that has been failing for many years,” said John Breckenridge.

And in the end, with Mr. Murphy as the tie-breaker, the full commission weighed in favor of the $1.2 million project, which will be paid for with state transportation funds.

A lengthy list of conditions for the approval address bus stops and issues of lighting and landscaping, among other things.