The Transport Agency says the Manawatu Gorge road should reopen by early September.
The route was first closed in August last year after a massive slip dumped 370,000 cubic metres of debris on the highway.
A temporary road was opened in May, but closed again early in July when a section was washed out by after rising river levels.
Palmerston North state highways manager David McGonigal, says the repair has been a massive job, costing about $20 million dollars, but the end is now in sight.
Mr McGonigal says most of the work remaining is completing new bridges and retaining walls to replace ones destroyed by the slip.
He says work has also been done to stabilise the slope over the road.