Rain damaged State Highway 73 through Arthur's Pass could open as soon as 7am tomorrow morning.
Two bridges and one section of road were damaged when the area was inundated with rain and snow on Friday.
Parts of the highway between Jackson's Pass and Arthur's Pass were washed out, along with the approaches at Yorkey Creek Bridge and Goat Creek Bridge.
Transport Agency System Manager, Pete Connors, said teams have worked throughout the weekend to carry out urgent repair work and get the highway reopened as soon as safely possible.
He said drivers should expect delays when the three sites open, as they will be one lane for a "number of months" including Christmas and in the new year.
"We advise all drivers to build in extra time on both SH6 south of Hokitika and on the Otira Gorge SH73 routes until these sections of highway are fully reinstated and back to two lanes of traffic."