The Tākaka Hill road has been restored to two lanes, almost four years after it was extensively damaged by Cyclone Gita.
Part of the road has been down to one lane and controlled by traffic lights since the storm in February 2018 caused extensive damage to the road, cutting offGolden Bay from the rest of the South Island.
The traffic lights were switched off on December 17 and the final lane marking was completed so the road could be opened ahead of Christmas and the busy summer period.
The complex repair programme is estimated to have cost $28 million.
Waka Kotahi senior project manager Andrew Adams said in a statement people needed to take care as the winding road was narrow in parts and drivers needed to keep to their side of the centreline.
"There are no median barriers on this route to safely separate oncoming traffic so we ask all drivers to stay alert and keep left."
Slips on the Tākaka Hill Rd after Cyclone Gita in February 2018. Photo / Supplied
There will be a 30km/h speed limit on the stretch of road while the work sites are tidied up before Christmas. It will then be raised to 50km/h until the new year when all roadside work is completed.
In the past four years, motorists on State Highway 60 have faced short waits each time they cross the hill.
Road access to and from Golden Bay was cut off for several days following the February 2018 incident but was reopened to a single lane after almost $3m of emergency repairs.
About 30,000cu m of slip material was removed, and several areas were widened to allow safe truck and trailer access.
Road access to and from Golden Bay was cut off for several days following the February 2018. Photo / Supplied
Traffic was initially allowed through in convoys at set times and traffic signals were later installed to control access through some one-lane sections of the hill.
Adams said there were 15 work sites along the 2.6km stretch of damaged road near Riwaka.
Of those, 10 of the most straightforward sites were remediated in the first two years.
The remaining five were more complex, highly engineered work sites with deep retaining walls that have taken the past 18 months to complete.
Adams said the first Covid-19 lockdown last April delayed the start of this work and pushed it into the winter months.
"The harsh conditions and complexity of work required in these steep gullies have been extremely challenging for the crews. It is very cold in winter on the south side of the hill."
