The New Zealand Transport Agency (NZTA) has officially announced the completion of the $244m Newmarket Viaduct Replacement Project in Auckland.

The project included the replacement of the old viaduct, while keeping New Zealand’s busiest section of motorway open, the stretch from Harbour Bridge to the Greenlane interchange.

NZTA Auckland and Northland state highways manager Tommy Parker said that the innovation and engineering skill used on this project has attracted worldwide attention.

"Almost a quarter of a million vehicles use the viaduct and the streets under it every day, and to keep that traffic moving with a minimum of disruption is a remarkable and outstanding achievement," Parker added.

The scheme was completed in four stages, and involved more than 1.6 million man hours, with around a third of those spent on high risk works.

In the first phase, a new southbound viaduct was constructed, with the old southbound viaduct removed in the second stage.

"The innovation and engineering skill used on this project has attracted worldwide attention."

The new northbound lanes were constructed in the third phase, while the fourth stage included the removal of the old northbound viaduct.

One of the key innovations of the project was the use of the 860t launching gantry known as Big Blue, which lifted or lowered over 900 segments of concrete weighing on average 70t.

"New Zealand’s construction industry will benefit from the knowledge that has been gained and shared, and the standards that have been in safety management at Newmarket," Parker noted.

The Newmarket Viaduct Replacement Project was executed by the NGA Newmarket Alliance of NZTA with its partners, Leighton Contractors, Fulton Hogan, VSL, URS, Beca, Boffa Miskell and Tonkin & Taylor.

The scheme is one in a series of projects and investments that are part of the NZTA’s long-term goal to improve Auckland’s transport connections.