Drivers are now using part of the under-construction roundabout at the intersection of Highways 154 and Highway 246 in the Santa Ynez Valley.
Earlier this week, motorists traveling in both directions began driving through the partially completed roundabout as construction on other parts of the project continue.
Work began in January on the project to change the intersection from a four-way stop to a roundabout Caltrans contends will improve safety.
Since the change earlier this week, the California Highway Patrol reports no incidents at the intersection, Officer John Ortega said.
A roundabout is an intersection where traffic travels in a counter-clockwise direction around an island.
Drivers are allowed to enter the roundabout when there is a gap in traffic. Vehicles entering or exiting the roundabout must yield to all traffic, including pedestrians, state officials said.
Drivers are required to use turn signals when changing lanes or exiting the roundabout, state officials added.
Some local leaders opposed the roundabout, lobbying instead for a traffic signal at the intersection.
As construction continues, daytime lane closures are expected but shouldn’t delay traffic beyond 10 minutes, according to Caltrans.
Eastbound motorists on Highway 154 to reach Highway 246 are encouraged to use the roundabout and not make an abrupt right turn onto Highway 246, Caltrans said.
Armour Ranch Road is now open during this phase of the project. Motorists and bicyclists are encouraged to share the road.
The contractor for this $3.3 million project is Granite Construction of Watsonville.
Construction on the controversial traffic circle should be completed this summer, earlier than initially expected.
This is the second roundabout involving Highway 246. Another one was completed in 2012 on Highway 246 at La Purisima Road, east of Lompoc.