Drivers on the new main route between Picton and Christchurch following the earthquakes faced long delays today.
The New Zealand Transport Agency (NZTA) said contractors were doing necessary maintenance on State Highway 63 south of Blenheim, near St Arnaud, due to heavy traffic.
There has been a noticeable increase in vehicles on the highway since the 7.8 magnitude earthquake on 14 November brought down landslips near Kaikōura, closing SH1.
NZTA highway manager Neil Walker said engineers were deciding what improvements would be needed for the road to cope with the extra traffic until SH1 was re-opened.
Stop-go signs were temporarily used today while one section was resealed, he said in a statement.
"The increase in traffic volumes on this route since the quake are very significant. Contractors are monitoring conditions closely, and have been repairing potholes and other damage daily."
Other upgrading and repair work, including widening the road in some places and adding extra signs, was expected.
It has been estimated it could take months to clear slips and fix the coastal highway.