Both lanes of the Manawatu Gorge have reopened to all traffic for the first time this year.
The stretch of State Highway 3 which connects the Manawatu to the Wairarapa was closed after a large slip on August 6 last year.
The slip was cleared and the road reopened for three days, before another slip in October closed the road again.
One lane of the road has been open since August.
NZTA Palmerston North state highways manager David McGonigal said there are two small sections which are still down to one lane - at the Woodville end of the slip where crews are still at work, and also about 500m further towards Woodville, following damage caused by an isolated rock spill.
"Courtesy of Murphy's Law, we've had an isolated rock spill a few hundred metres down the road, just as we were getting ready to open the gorge to two lanes.
We've ensured that the hillside is secure, but we'll need to fix the damage which may mean briefly shutting the highway at a later date," Mr McGonigal said.
"This is the first time since the gorge closed last year that we've been able to get two lanes of traffic through the slip site. While it's not two lanes the whole way through, it's a huge leap forward and a sign that the end is near. It's been achieved ahead of schedule by a very dedicated crew, and they've earned a long holiday when all this is over."
Motorists have been forced to use the Saddle Road and Pahiatua Track routes for the past year, diverting traffic away from the town of Woodville, resulting in a drop in customers for local businesses.
"Having two lanes up and running means that everyone who has been patiently winding their way through the alternative routes can now return to the Manawatu Gorge, and save themselves time, petrol and peace of mind while they're at it," Mr McGonigal said.
Rockfall netting is being erected alongside the new section of the highway and 30km/h speed restrictions remain in these areas.