Efforts are being made to speed up repairs to damage on SH4 between Whanganui and Raetihi, but the work may take two years.
Record-setting rainfall across the district last June caused about $20 million worth of damage along the length of the highway, and closed the route for about a month to all but essential traffic.
Neil Walker, NZ Transport Agency regional highways manager, said 40 separate sites along the highway needed repairs.
"We've repaired the majority of the sites but the scale and complexity of the remaining sites meant it has taken longer to investigate options for repairs and costs," Mr Walker said.
"The remaining sites have all been made stable to ensure the safety of road users while this investigative work has been undertaken."
After its initial assessments NZTA engineers said it would take up to two years to complete the repairs.
Mr Walker said that in a bid to speed up the repair process the agency was working on contracts and tender documents at the same time as it was looking at repair options and costs.
"This means once options have been finalised and funding has been allocated, we can commence physical works."
Of those 40 sites, 17 were fixed using local contractors along with Higgins, but another 14 sites required major repairs and some were expected to take up to two years.
"We finalised repair options and funding for two of the sites and expect to be in a similar position soon with the remaining sites," he said.
Mr Walker said NZTA was working to get all repairs completed as soon as possible depending on the weather conditions.
Five-hundred slips occurred as a result of the June storm, at times blocking the highway or reducing it to a single lane.
NZTA also installed three sets of temporary traffic lights to aid traffic flows.
Contractors moved 75,000 cubic metres of material that had fallen on to SH4, added another 6000 tonnes of rock to make good areas scoured by flooded rivers as well as dumping 5000cu m of fill material to rebuild road embankments.
The impact of SH4's closure was particularly felt by heavy-transport companies, especially when snow and ice closed The Desert Rd section of SH1. It meant the only northbound route from Whanganui was SH3 through Taranaki.
In February, Raetihi farmer Winston Oliver questioned why repair of the Parapara was taking so long.
He said residents relied on SH4 through the Parapara to get them to their nearest city - Whanganui - for urgent health services and other business that couldn't be done in a rural area.
"And the road still hasn't been repaired after months. What are we supposed to do?
"It doesn't say much about help for people in rural communities.
"I travel at least twice week through State Highway 4 and there are still 14 washouts temporarily fenced off," Mr Oliver said.
"That means the traffic is down to one lane with traffic lights that keep you waiting - yet there are no workmen. There have been no workmen for months and the weather has been dry."
Mr Oliver said it wasn't a fair go with so many people in the Waimarino relying on the road - not to mention the emergency services of fire, police and ambulance.