Traffic was switched onto the new Paengaroa roundabout last week, as part of the Tauranga Eastern Link project.
The New Zealand Transport Agency said drivers travelling along State Highway 2 and State Highway 33 would have welcomed the improvement to their journey.
Although not completely finished, the agency said it was a huge milestone for the Tauranga Eastern Link project and delivered immediate safety benefits to the region.
The new roundabout replaces the old SH2/ SH33 T-intersection, which had been identified as a high-risk intersection.
NZ Transport Agency acting Bay of Plenty highway manager Andrew Scott said the agency was thrilled to be able to improve safety for drivers in the region by putting the new Paengaroa roundabout into use ahead of the TEL opening next year.
"Our contractors (Fulton Hogan HEB Construction Alliance) have done a great job getting the roundabout up and running. It has been a complex operation to get the traffic onto the roundabout and off the old piece of road, while still carrying out the works."
The roundabout will be used by motorists travelling to Whakatane and the Eastern Bay of Plenty, Rotorua and the Central Bay of Plenty, Te Puke and eventually Tauranga via the tolled section of the Tauranga Eastern Link when it opens in 2015.
Over the next month the final construction of the Te Puke, Whakatane and Rotorua legs will be carried out with daytime and night-time works. The Transport Agency has asked drivers to please be patient while the work is completed and the temporary traffic management is in place.