Transport Agency sticking to Wellington's Transmission Gully motorway deadline

The New Zealand Transport Agency (NZTA) is sticking to its new deadline for the Transmission Gully motorway near Wellington.

The project was due to be finished in April this year but has been pushed back to September 2021 due to a series of delays.

"Currently we're 85 percent of the way through the project and we're on track to finish in September 2021," NZTA senior manager project delivery Andy Thackwray said.

The four-lane expressway north of Wellington began its construction in 2014, and faced a series of delays with the Kaikoura earthquake and COVID-19 lockdowns.

The project has blown the cost from $850 million to $1.2 billion.

But NZTA hopes there won't be any more setbacks.

"If there was a seismic event or extension of time to the project for some reason that's obviously going to increase the cost of the project," Thackwray said.

"But at this stage there's no reason to believe that's likely to happen."

Transmission Gully will stretch 27 kilometres from MacKays Crossing Interchange near Paraparaumu to Kenepuru - bypassing Porirua and taking the pressure off State Highway 1 traffic.

But even the opening next September will be gradual.

"Cars driving over Transmission Gully without it being fully open, we may have that, while the chip seal settles," Wellington Gateway Partnership CEO Sergio Mejia said.

All going to plan, motorists should be settling into the new motorway by this time next year.