The Matahiwi slip on State Highway 4 was stable enough for work to begin on a temporary road across it this week.
Work began on Monday, after karakia, a New Zealand Transport Agency spokeswoman said. The agency hoped to have the temporary road finished early next year.
Early work had mainly consisted of draining the area and "hydroseeding" the slip face, to revegetate it. Heavy machinery and rocks had been moved to the construction site.
The suggested detours are still SH1, SH3 and SH49. The other alternatives, Field's Track and the Whanganui River Rd, are not suitable for state highway traffic, the agency says.
Many of the workers are staying in Raetihi, and have commented on the warm welcome they received. NZTA thanked the community for that.
Updates on the state of the road will start on Newstalk ZB on November 26, broadcast between 8am and 8.30am. NZTA is also planning community events to keep people informed - probably tables set up at shopping centres where people can ask questions, and probably starting in January.
People can also ring 0800 444 449 to get updates on state highways.