Formally State Highway 1, SH59 is the main road into the capital, which Transmission Gully will eventually replace.
It is the second crash on this highway in less than a day, after a man died when his car flipped north of Pukerua Bay yesterday morning.
Emergency services rushed to the crash on State Highway 59 at around 11am on Monday but police confirmed the man died at the scene.
The road was closed for several hours.
A police spokesperson told the Herald they received reports of the single-vehicle crash on State Highway 59 at 10.38am on Monday.
A witness to the crash told the Herald the accident looked "pretty bad".
"A car has hit the bank and is on its roof ... it looked like people were stuck inside and construction workers nearby were trying to break the windows to get them out."
A second witness said the car was on its side with a man trapped inside as first responders tried to get him out.