A Fulton Hogan worker was carrying out resurfacing works when he was fatally struck by a vehicle in Wellington's Ngauranga Gorge.
The 25-year-old man died at the scene around 9.30pm last night. A second person suffered moderate injuries.
The man was hit by a work vehicle during resurfacing work on State highway one.
WorkSafe NZ and police are investigating and work on the road has been suspended until further notice.
The NZTA will also conduct its own enquiries from a safety standpoint.
It is the fourth road worker death in a month and First Union is urging drivers to be careful.
The work was contracted by NZTA which said it was saddened by the tragic accident.
It will carry out its own review of the incident, separate to investigations being carried out by police and WorkSafe.
First Union transport, logistics and manufacturing secretary Jared Abbott said his heart went out to friends and family of the man.
"We do not know the full circumstances that have led to this fourth fatality inside a month, but it is a timely reminder to drive carefully around people working on our roads; they work hard to ensure our roads are safer for everyone. The speed signs aren't a target, drivers need to slow down around road workers."
It is the fourth road worker death in a month and First Union is urging drivers to be careful.
Last night the southbound lane was completely closed, however, it is now open.