About 3500 vehicles have been using State Highway 1 north of Kaikōura each day since the quake damaged road re-opened last month.
The project to fix the stretch of road, which is part of the main route between Picton and Christchurch, took more than a year but it is still closed at night.
The Transport Agency's journey manager, Tresca Forrester, said the number of cars using the alternative inland route had dipped, but it was still well used over the holiday period, as it was the quickest way to get from Christchurch to Nelson.
"So it has dropped off a little by a 1000/1500, so obviously summer you're still going to get all that Nelson traffic, all that holiday traffic so I don't think we've got a true reflection of how it's going to impact longer term."
Tresca Forrester said about 700 of the vehicles using the highway each day were freight trucks.
She said many of the contractors fixing SH1 will return to work tomorrow, and motorists should expect delays.