Twelve 54-tonne concrete beams were installed over the weekend at the Bayfair flyover for the Bay Link project.

New Zealand Transport Agency Waka Kotahi infrastructure delivery regional manager Jo Wilton says the 28m long beams - which were the "main structural element" of the State Highway Two flyover - were lifted into place by a 300-tonne crane.

Wilton said the flyover would take SH2 traffic over the Bayfair roundabout, separating the state highway from local traffic and create a safer environment.

The work was carried out on Friday and Saturday with overnight lane closures and detours in place from 7pm until 7am both days.

Wilton said construction would now continue on the flyover's remaining pier and the northern ramp of the flyover would "emerge out of the ground".

Beams for the third span of the flyover were scheduled to be installed later this year.

She said the overall project - which has a total cost of $262 million - was on schedule and was set to be complete in late 2023.

Wilton said once complete the Bayfair flyover would "improve safety and accessibility and transform how people move through the area".

"Similar to the Hewletts Rd flyover, there will be a lane in each direction, separating heavy vehicles heading to the port from local traffic.

"In addition to the flyover lanes, there will be two ground level, grade-separated lanes [on] either side of the flyover for local traffic."

Credit: NZHerlad.co.nz