The Transport Agency has announced the Manawatu Gorge road, the main link between Manawatu and Hawke's Bay, could be reopened to one lane of traffic by the end of the month.
The section of State Highway 3 was cut off by a massive slip in August.
The agency's state highways manager David McGonigal says two of the route's bridges are badly damaged.
"Unfortunately the bridges are damaged beyond repair, so we need to build new bridges. The good news is whilst we're building those bridges, we'll be opening the gorge up to traffic again."
Mr McGonigal says clearing the slip and reinstating the bridges is now expected to cost up to $20 million which is substantially up from the previous estimate of $11.5 million.
Mayor of Palmerston North has welcomed the news of a partial reopening.
Jono Naylor says it is pleasing the region now has some certainty.
The gorge was closed in October 2011 after a large slip caused severe damage.