Work to repair the State Highway 4 slip near Upokongaro will begin in March, Waka Kotahi/NZTA regional transport systems manager Ross l'Anson says.
A section of the state highway at Kukuta slipped into the Whanganui River after flooding in 2015, l'Anson said. That stretch of road became single lane and controlled by lights.
To enable repairs to be made the agency needed to purchase an adjoining property, and that was completed in January.
The news has thrilled Whanganui district councillor Helen Craig, who has been vocal about repairs to the highway.
"I'm thrilled they have finalised the purchase at long last. It did take far too long," she said.