State Highway One in the Brynderwyns, north of Auckland, has been closed due to a crash.
The road is closed between the SH1, Waipu, and Shoemaker Rd intersection and SH1 and SH12.
A police spokesman said a truck had rolled near the Brynderwyn Hills, blocking traffic in both directions.
Northbound and Southbound detours are in place and NZTA has advised motorists to delay their journey or use an alternative route.
The truck driver had not been seriously injured, the police spokesman said.
"Due to the nature of the incident, it will take some time for the road to be cleared.
"Police appreciate motorists' co-operation this evening while the scene is cleared."
The incident was reported to police just after 3pm.
Meanwhile, a serious crash near the Highbrook Drive off-ramp in Auckland has caused long delays.
The crash initially blocked three lanes, of which two have reopened but delays remain, NZTA said.