Slope stabilisation works on the Kings Highway near Clyde Mountain will begin on May 28.
NSW Roads and Maritime Services said on Wednesday the works would go on for a maximum of five weeks depending on weather. The Kings Highway will be closed from 8am each Tuesday until 5pm Thursday.
The last planned closure will be on Thursday, June 27, with detour routes posted online. Light vehicles will be diverted at Braidwood and Batemans Bay to detour via Nowra, adding about 2 hours to the journey.
Heavy vehicles will be required to use either Picton Road or the Snowy Mountains Highway.