Work on the intersection of State Street and Ellsworth Road will enter its final phase Friday with the opening of the roundabout and the removal of the traffic light at the intersection.

Ellsworth Road will remain closed east of the intersection and State Street will continue to be limited to one lane in each direction both north and south of roundabout. The detour for Ellsworth Road utilizing Research Park Drive will remain in effect and access to businesses in the area will remain available.

Washtenaw County roads project engineer Mark McCulloch said the fourth and final phase of the project should be completed within approximately 10 days, weather permitting.

“The plan is to do the paving of Ellsworth at the end of next week and opening the road back up to full use after that,” he said. “We’re doing this for the safety and overall quality of the road.”

The plan calls for the closure of Ellsworth both east and west of the intersection for paving to occur on Friday and Saturday September 27 and 28. Once paving is completed, McCulloch said he anticipates both lanes of the intersection and both lanes being entirely open sometime the week of September 30.

The $2.4 million project included a $470,000 water main replacement by the City of Ann Arbor. The majority of the project, overseen by the Washtenaw County Road Commission, was paid for through two federal grants.

The project was initiated by Pittsfield Township in anticipation of increased traffic due to the completion of a new Costco store and other retail openings in the are. Costco also put $500,000 towards the project.

Issues with the water main repair and utilities have kept the project from being completed precisely on time.

“The goal was originally to be done somewhere around September 22, so we’re not too far over,” McCulloch said.

“The contractor is working hard to make up time because he has other jobs to get to. They’re very motivated because they’re not making money if they’re at a job site for too long.”

Once the intersection is fully open, McCulloch said that traffic will still likely move slowly during the first few weeks, but will gradually improve as people become more comfortable with the new traffic pattern.

“Typically in the roundabouts we’ve opened additional police presence hasn’t been necessary,” McCulloch said.

“Generally people have driven in them before and they’re typically overly cautious at first which is a good thing. People will go slowly and stop for each other for the first few weeks as they get used to it.”

Click on the interactive map for information on planned road closures:

Ben Freed is a business and general assignments reporter for The Ann Arbor News. Email him at benfreed@mlive.com and follow him on twitter at @BFreedinA2