The crash was near the intersection with Kentucky Rd.
The road was closed for several hours and motorists were asked to take alternate routes through Karapiro Rd.
A reporter said traffic was backed up towards Tirau about 5.30pm, with both lanes of SH1 closed.
Waka Kotahi NZ Transport Agency earlier said the state highway was closed between SH29 and Karapiro Rd while police investigated the crash.
OKERE FALLS
No one was injured in a crash on State Highway 33 near Okere Falls tonight.
Police said it appeared two vehicles were involved in the collision around 7pm.
KAIMAI RANGE
Police said a vehicle hit a barrier about 50m southwest of the lookout about 8.50pm.
One of the passing lanes was blocked.
Visibility in the area was reported to be poor.