The concrete beams, manufactured in Te Puke, are 28m long each and weigh up to 54 tonnes.
They will be lifted into place with the help of a 300-tonne crane positioned at the Bayfair roundabout.
Following the placement of the beams, construction will continue on the flyover's northern ramp which will emerge out of the ground.
Beams for the fourth and final span of the flyover are currently expected to be installed in winter.
Once the Bayfair flyover is complete, it will improve safety and accessibility and transform how people move through the area, Waka Kotahi NZTA said.
Similar to the Hewletts Rd flyover, there will be a lane in each direction, separating heavy vehicles heading to the Port of Tauranga from local traffic.
There will also be two ground level lanes on either side of the flyover for local traffic.
Separating the state highway from local traffic will be safer for drivers.
The new flyover, which will take State Highway 2 traffic over the Bayfair roundabout, is expected to open in autumn next year.
The agency has asked drivers to expect delays and follow the directions provided on temporary traffic management signage.
If the work is impacted by weather or other unforeseen issues, it will be carried out on the next available night.
Detours
People travelling on State Highway 2/Maunganui Rd from Mount Maunganui to Pāpāmoa will not be able to proceed straight through the Bayfair roundabout.
A detour will be available via Girven Rd, Maranui Rd and Sandhurst Dr.
People travelling on State Highway 2/Maunganui Rd from Mount Maunganui to Matapihi will not be able to turn right at the Bayfair roundabout.
A detour will be available via Girven Rd, Maranui Rd, Sandhurst Dr and State Highway 2 north.
People travelling on State Highway 2/Maunganui Rd to Girven Rd will not be able to turn right at the Bayfair roundabout.
A detour will be available via the Golf Rd roundabout and State Highway 2 south.
People travelling on Matapihi Rd to Girven Rd will not be able to proceed straight through the Bayfair roundabout.
A detour will be available via the Golf Rd roundabout and State Highway 2 south.
People travelling on Matapihi Rd to Pāpāmoa will not be able to turn right at the Bayfair roundabout.
A detour will be available via the Golf Rd roundabout, SH2 south, Girven Rd, Maranui Rd and Sandhurst Dr.