The road through the Manawatu Gorge is fully operational more than 15 months after being closed by a massive slip.
The stretch of State Highway 3 connecting Manawatu with Wairarapa was closed after a large slip on August 6 last year.
The slip was cleared and the road reopened for three days, before being closed after another slip in October.
In August one lane reopened, and in September both lanes were reopened, apart from two one-way sections controlled by lights.
Today all work on the road was completed, after road surfacing was laid and road markings were painted fresh.
Work would now begin on the Saddle Road to form a "solid alternative route'', New Zealand Transport Agency spokesman David McGonigal said.
"The Manawatu Gorge is, and always will be, a vital lifeline.
"While the last closure was an anomaly in terms of its scale and duration, the reality is that closures will happen from time to time, and we need to be ready.''