Portland will open the Deering’s Corner Roundabout, the first to be built in the city, to traffic on Friday.

The roundabout, at the intersections of Deering and Brighton avenues and Falmouth Street near the University of Maine School of Law and University of Southern Maine, marks a significant change in how the city will handle the heavy traffic that passes through the neighborhood.

Engineers said it is expected to improve traffic flow and safety by replacing the existing traffic signal at what had been a six-way intersection, which operated inefficiently, involved long waits at red lights and was confusing to drivers.

The intersection’s temporary traffic signals will be turned off Friday and traffic will move through the roundabout in a counterclockwise direction, according to a project update posted on the city’s website. Drivers are urged to pay close attention to signage when approaching and driving in the roundabout.

City officials are urging drivers to yield to pedestrians at crosswalks when entering or exiting the roundabout, and to keep their speeds to 20 mph or less. Crosswalks at the roundabout have been raised to encourage slower vehicle speeds.

It was unclear Thursday night at what time Friday the roundabout would fully open to traffic. Jessica Grondin, the city’s spokesperson, said that decision will be left up to the contractor. Grondin said the roundabout could open overnight or sometime during the day Friday.

Grondin reminded the public that the roundabout, though open as of Friday, is not completely finished. It still needs to be paved and striped, most likely sometime in August. Streets will be closed during the paving project.

City staff and members of the City Council began meeting with the public in 2012 on possible ways to make the intersection safer and more efficient for drivers and pedestrians. The city settled on a design and the project went out to bid in December 2019.

The city, the Maine Department of Transportation and USM began construction on the roundabout in April 2020. The roundabout project cost about $5 million to design and build, according to a fact sheet on the city’s website.

The project includes a public art installation. In 2019, the Public Art Committee commissioned artist Mark Pettegrow, and his artwork, titled “Passing the Torch,” includes three bronze flame sculptures mounted on granite boulders in the roundabout’s center.

While there are now more than 20 roundabouts in the state, none had previously been built in Portland. Roundabouts are circular, one-way streets that move traffic through intersections while eliminating the need for traffic lights. Traffic moves more slowly through a roundabout than through a rotary.

The Deering’s Corner Roundabout is named after the Deering family, which donated a portion of its farm to the city in 1879 in exchange for a tax abatement. The donated land later became Deering Oaks park.