The Desert Road/State Highway 1 is blocked between Rangipo and Waiouru following a crash overnight.

Police expect the road to remain closed for several hours.

"A truck and trailer unit rolled shortly after 1.30am near Waihohonu Bridge and a crane will be required to move it from the crash site.

"No other vehicles were involved in the crash and nobody was injured."

The following diversions are in place: for those heading south, use State Highway 46 and State Highway 47 to National Park, turn left on to State Highway 4, then left on to State Highway 49 to Waiouru.

The reverse applies for northbound travel.