State Highway 6 through the Haast Pass was re-opened yesterday.
The highway was closed on Wednesday after heavy rain brought down a new slip at the problematic Diana Falls site, where work is still being done to stabilise a major slip which came down in September.
New Zealand Transport Agency senior network manager Mark Pinner said about 150cu m of rock and other material was cleared off the road yesterday morning.
The time available for motorists to travel the route is to be reduced by two hours each day from next week.
Because of work on the slip, the highway between Haast and Makarora has been closed at night and open between 8am and 6pm.
But Mr Pinner said from Monday the highway would open at 9am and close at 5pm.
''The changes in opening hours are a direct result of the onset of winter and shorter daylight hours. This is making conditions at the site unsafe for both our contractors and road users.''
Mr Pinner said poor light made it difficult for contractors to see what was happening on the slip surface.
''The topography of the site is such that even in daylight, light levels are particularly gloomy at the site early morning and evening.
''This is also having an impact on the safety for our contractors climbing up and off the slip face each day.''
Mr Pinner said work was on schedule and installation of the first debris fence was expected to start next month.
The project should be completed by September, he said.
However, weather would be a significant factor in achieving this date, Mr Pinner said.