Police arrived at West Coast Rd (State Highway 73) in Castle Hill shortly after 5am on Wednesday to find the truck had run off the road and had come to a stop among trees on the embankment.
Waka Kotahi NZ Transport Agency said an attempt to recover the truck could not be completed in the timeframe.
They will attempt to recover it again this afternoon. The road will be fully closed and the work is expected to go through to about 4.30pm.
Electronic signs warn of the closure.
Drivers can take the Lewis Pass route (SH7) via Waipara as an alternative, slightly longer, but fully open route.
The road was initially closed for several hours on Wednesday.
"Fortunately, the driver appears to have been uninjured," a police spokesperson said.
No ambulances were called to the scene.
By 4.55pm yesterday, the road had partially reopened but Waka Kotahi said stop/go signals were in operation.
-By Eva Wilson
Public Interest Journalism funded through NZ On Air
