Work to raise the road by 1.25m began in January to reduce the risk of flooding. It was originally scheduled for completion in mid-June.
The works reduced SH1 to one lane most days with long delays between traffic flows.
NZ Transport Agency Waka Kotahi senior project manager Jason Forbes said the majority of the work was completed and expected to finish "well ahead of schedule".
All that remained was laying topsoil, grassing roadside slopes, installing signs, replacing fencing and the final shaping, as well as site clean-up.
Later this year another layer of chip seal would be added and lines would be marked.
"These works will require traffic management, and slower speeds for a short period, but the impact to road users will be minor."
The project, run by Whitestone Contracting, had progressed "very quickly", and the road was only reduced to a single lane when necessary, he said.
The Otago Daily Times recorded a wait of about six minutes heading north yesterday.
Travel delays are not the only reason the works are controversial.
When it was announced Waitaki mayor Gary Kircher criticised the work for potentially lacking foresight in how changing the water flow would affect other areas. Maheno residents supported his message.
NZTA responded to the criticism by saying the adverse effects of the roadworks were considered minor, while the resilience of the highway would be improved and communities could stay better connected during flooding events.
