State Highway Two is closed after a large slip occurred in the Karangahake Gorge between the Coromandel and Kaimai ranges.
Police say contractors are clearing the slip east of Karangahake between School and Waitawheta roads, which might take some time.
Detours have been put in place via SH26, SH25 and SH25A between Paeroa and Waihi.
NZTA says motorists should allow for an extra hour while the detours are in place.
The road would be closed until further notice.